Merge #4509

4509: Rest embedder r=ManyTheFish a=dureuill

Fixes #4531 

See [Usage page](https://meilisearch.notion.site/v1-8-AI-search-API-usage-135552d6e85a4a52bc7109be82aeca42?pvs=25#e6f58c3b742c4effb4ddc625ce12ee16)

### Implementation changes

- Remove tokio, futures, reqwests
- Add a new `milli::vector::rest::Embedder` embedder
- Update OpenAI and Ollama embedders to use the REST embedder internally
- Make Embedder::embed a sync method
- Add the new embedder source as described in the usage


Co-authored-by: Louis Dureuil <louis@meilisearch.com>

Cargo.lock

@@ -3338,7 +3338,6 @@ dependencies = [
  "filter-parser",
  "flatten-serde-json",
  "fst",
- "futures",
  "fxhash",
  "geoutils",
  "grenad",
@@ -3362,7 +3361,6 @@ dependencies = [
  "rand",
  "rand_pcg",
  "rayon",
- "reqwest",
  "roaring",
  "rstar",
  "serde",
@@ -3376,8 +3374,9 @@ dependencies = [
  "tiktoken-rs",
  "time",
  "tokenizers",
- "tokio",
  "tracing",
+ "ureq",
+ "url",
  "uuid",
 ]
 

meilisearch-types/src/error.rs

@@ -353,6 +353,7 @@ impl ErrorCode for milli::Error {
                     | UserError::InvalidOpenAiModelDimensions { .. }
                     | UserError::InvalidOpenAiModelDimensionsMax { .. }
                     | UserError::InvalidSettingsDimensions { .. }
+                    | UserError::InvalidUrl { .. }
                     | UserError::InvalidPrompt(_) => Code::InvalidSettingsEmbedders,
                     UserError::TooManyEmbedders(_) => Code::InvalidSettingsEmbedders,
                     UserError::InvalidPromptForEmbeddings(..) => Code::InvalidSettingsEmbedders,

meilisearch/src/routes/indexes/search.rs

@@ -202,7 +202,7 @@ pub async fn search_with_url_query(
     let index = index_scheduler.index(&index_uid)?;
     let features = index_scheduler.features();
 
-    let distribution = embed(&mut query, index_scheduler.get_ref(), &index).await?;
+    let distribution = embed(&mut query, index_scheduler.get_ref(), &index)?;
 
     let search_result =
         tokio::task::spawn_blocking(move || perform_search(&index, query, features, distribution))
@@ -241,7 +241,7 @@ pub async fn search_with_post(
 
     let features = index_scheduler.features();
 
-    let distribution = embed(&mut query, index_scheduler.get_ref(), &index).await?;
+    let distribution = embed(&mut query, index_scheduler.get_ref(), &index)?;
 
     let search_result =
         tokio::task::spawn_blocking(move || perform_search(&index, query, features, distribution))
@@ -260,7 +260,7 @@ pub async fn search_with_post(
     Ok(HttpResponse::Ok().json(search_result))
 }
 
-pub async fn embed(
+pub fn embed(
     query: &mut SearchQuery,
     index_scheduler: &IndexScheduler,
     index: &milli::Index,
@@ -287,7 +287,6 @@ pub async fn embed(
 
             let embeddings = embedder
                 .embed(vec![q.to_owned()])
-                .await
                 .map_err(milli::vector::Error::from)
                 .map_err(milli::Error::from)?
                 .pop()

meilisearch/src/routes/indexes/settings.rs

@@ -605,6 +605,7 @@ fn embedder_analytics(
                 EmbedderSource::HuggingFace => sources.insert("huggingFace"),
                 EmbedderSource::UserProvided => sources.insert("userProvided"),
                 EmbedderSource::Ollama => sources.insert("ollama"),
+                EmbedderSource::Rest => sources.insert("rest"),
             };
         }
     };

meilisearch/src/routes/multi_search.rs

@@ -75,9 +75,8 @@ pub async fn multi_search_with_post(
                 })
                 .with_index(query_index)?;
 
-            let distribution = embed(&mut query, index_scheduler.get_ref(), &index)
+            let distribution =
-                .await
+                embed(&mut query, index_scheduler.get_ref(), &index).with_index(query_index)?;
-                .with_index(query_index)?;
 
             let search_result = tokio::task::spawn_blocking(move || {
                 perform_search(&index, query, features, distribution)

milli/Cargo.toml

@@ -80,17 +80,13 @@ tokenizers = { git = "https://github.com/huggingface/tokenizers.git", tag = "v0.
 hf-hub = { git = "https://github.com/dureuill/hf-hub.git", branch = "rust_tls", default_features = false, features = [
     "online",
 ] }
-tokio = { version = "1.35.1", features = ["rt"] }
-futures = "0.3.30"
-reqwest = { version = "0.11.23", features = [
-    "rustls-tls",
-    "json",
-], default-features = false }
 tiktoken-rs = "0.5.8"
 liquid = "0.26.4"
 arroy = "0.2.0"
 rand = "0.8.5"
 tracing = "0.1.40"
+ureq = { version = "2.9.6", features = ["json"] }
+url = "2.5.0"
 
 [dev-dependencies]
 mimalloc = { version = "0.1.39", default-features = false }

milli/src/error.rs

@@ -243,6 +243,8 @@ only composed of alphanumeric characters (a-z A-Z 0-9), hyphens (-) and undersco
     },
     #[error("`.embedders.{embedder_name}.dimensions`: `dimensions` cannot be zero")]
     InvalidSettingsDimensions { embedder_name: String },
+    #[error("`.embedders.{embedder_name}.url`: could not parse `{url}`: {inner_error}")]
+    InvalidUrl { embedder_name: String, inner_error: url::ParseError, url: String },
 }
 
 impl From<crate::vector::Error> for Error {

milli/src/update/index_documents/extract/extract_vector_points.rs

@@ -339,6 +339,7 @@ pub fn extract_embeddings<R: io::Read + io::Seek>(
     prompt_reader: grenad::Reader<R>,
     indexer: GrenadParameters,
     embedder: Arc<Embedder>,
+    request_threads: &rayon::ThreadPool,
 ) -> Result<grenad::Reader<BufReader<File>>> {
     puffin::profile_function!();
     let n_chunks = embedder.chunk_count_hint(); // chunk level parallelism
@@ -376,7 +377,10 @@ pub fn extract_embeddings<R: io::Read + io::Seek>(
 
         if chunks.len() == chunks.capacity() {
             let chunked_embeds = embedder
-                .embed_chunks(std::mem::replace(&mut chunks, Vec::with_capacity(n_chunks)))
+                .embed_chunks(
+                    std::mem::replace(&mut chunks, Vec::with_capacity(n_chunks)),
+                    request_threads,
+                )
                 .map_err(crate::vector::Error::from)
                 .map_err(crate::Error::from)?;
 
@@ -394,7 +398,7 @@ pub fn extract_embeddings<R: io::Read + io::Seek>(
     // send last chunk
     if !chunks.is_empty() {
         let chunked_embeds = embedder
-            .embed_chunks(std::mem::take(&mut chunks))
+            .embed_chunks(std::mem::take(&mut chunks), request_threads)
             .map_err(crate::vector::Error::from)
             .map_err(crate::Error::from)?;
         for (docid, embeddings) in chunks_ids
@@ -408,7 +412,7 @@ pub fn extract_embeddings<R: io::Read + io::Seek>(
 
     if !current_chunk.is_empty() {
         let embeds = embedder
-            .embed_chunks(vec![std::mem::take(&mut current_chunk)])
+            .embed_chunks(vec![std::mem::take(&mut current_chunk)], request_threads)
             .map_err(crate::vector::Error::from)
             .map_err(crate::Error::from)?;
 

milli/src/update/index_documents/extract/mod.rs

@@ -238,6 +238,12 @@ fn send_original_documents_data(
 
     let documents_chunk_cloned = original_documents_chunk.clone();
     let lmdb_writer_sx_cloned = lmdb_writer_sx.clone();
+
+    let request_threads = rayon::ThreadPoolBuilder::new()
+        .num_threads(crate::vector::REQUEST_PARALLELISM)
+        .thread_name(|index| format!("embedding-request-{index}"))
+        .build()?;
+
     rayon::spawn(move || {
         for (name, (embedder, prompt)) in embedders {
             let result = extract_vector_points(
@@ -249,7 +255,12 @@ fn send_original_documents_data(
             );
             match result {
                 Ok(ExtractedVectorPoints { manual_vectors, remove_vectors, prompts }) => {
-                    let embeddings = match extract_embeddings(prompts, indexer, embedder.clone()) {
+                    let embeddings = match extract_embeddings(
+                        prompts,
+                        indexer,
+                        embedder.clone(),
+                        &request_threads,
+                    ) {
                         Ok(results) => Some(results),
                         Err(error) => {
                             let _ = lmdb_writer_sx_cloned.send(Err(error));

milli/src/update/index_documents/mod.rs

@@ -2646,6 +2646,12 @@ mod tests {
                         api_key: Setting::NotSet,
                         dimensions: Setting::Set(3),
                         document_template: Setting::NotSet,
+                        url: Setting::NotSet,
+                        query: Setting::NotSet,
+                        input_field: Setting::NotSet,
+                        path_to_embeddings: Setting::NotSet,
+                        embedding_object: Setting::NotSet,
+                        input_type: Setting::NotSet,
                     }),
                 );
                 settings.set_embedder_settings(embedders);

milli/src/update/settings.rs

@@ -1140,6 +1140,12 @@ fn validate_prompt(
             api_key,
             dimensions,
             document_template: Setting::Set(template),
+            url,
+            query,
+            input_field,
+            path_to_embeddings,
+            embedding_object,
+            input_type,
         }) => {
             // validate
             let template = crate::prompt::Prompt::new(template)
@@ -1153,6 +1159,12 @@ fn validate_prompt(
                 api_key,
                 dimensions,
                 document_template: Setting::Set(template),
+                url,
+                query,
+                input_field,
+                path_to_embeddings,
+                embedding_object,
+                input_type,
             }))
         }
         new => Ok(new),
@@ -1165,8 +1177,20 @@ pub fn validate_embedding_settings(
 ) -> Result<Setting<EmbeddingSettings>> {
     let settings = validate_prompt(name, settings)?;
     let Setting::Set(settings) = settings else { return Ok(settings) };
-    let EmbeddingSettings { source, model, revision, api_key, dimensions, document_template } =
+    let EmbeddingSettings {
-        settings;
+        source,
+        model,
+        revision,
+        api_key,
+        dimensions,
+        document_template,
+        url,
+        query,
+        input_field,
+        path_to_embeddings,
+        embedding_object,
+        input_type,
+    } = settings;
 
     if let Some(0) = dimensions.set() {
         return Err(crate::error::UserError::InvalidSettingsDimensions {
@@ -1175,6 +1199,14 @@ pub fn validate_embedding_settings(
         .into());
     }
 
+    if let Some(url) = url.as_ref().set() {
+        url::Url::parse(url).map_err(|error| crate::error::UserError::InvalidUrl {
+            embedder_name: name.to_owned(),
+            inner_error: error,
+            url: url.to_owned(),
+        })?;
+    }
+
     let Some(inferred_source) = source.set() else {
         return Ok(Setting::Set(EmbeddingSettings {
             source,
@@ -1183,11 +1215,25 @@ pub fn validate_embedding_settings(
             api_key,
             dimensions,
             document_template,
+            url,
+            query,
+            input_field,
+            path_to_embeddings,
+            embedding_object,
+            input_type,
         }));
     };
     match inferred_source {
         EmbedderSource::OpenAi => {
             check_unset(&revision, "revision", inferred_source, name)?;
+
+            check_unset(&url, "url", inferred_source, name)?;
+            check_unset(&query, "query", inferred_source, name)?;
+            check_unset(&input_field, "inputField", inferred_source, name)?;
+            check_unset(&path_to_embeddings, "pathToEmbeddings", inferred_source, name)?;
+            check_unset(&embedding_object, "embeddingObject", inferred_source, name)?;
+            check_unset(&input_type, "inputType", inferred_source, name)?;
+
             if let Setting::Set(model) = &model {
                 let model = crate::vector::openai::EmbeddingModel::from_name(model.as_str())
                     .ok_or(crate::error::UserError::InvalidOpenAiModel {
@@ -1224,10 +1270,24 @@ pub fn validate_embedding_settings(
             check_set(&model, "model", inferred_source, name)?;
             check_unset(&api_key, "apiKey", inferred_source, name)?;
             check_unset(&revision, "revision", inferred_source, name)?;
+
+            check_unset(&url, "url", inferred_source, name)?;
+            check_unset(&query, "query", inferred_source, name)?;
+            check_unset(&input_field, "inputField", inferred_source, name)?;
+            check_unset(&path_to_embeddings, "pathToEmbeddings", inferred_source, name)?;
+            check_unset(&embedding_object, "embeddingObject", inferred_source, name)?;
+            check_unset(&input_type, "inputType", inferred_source, name)?;
         }
         EmbedderSource::HuggingFace => {
             check_unset(&api_key, "apiKey", inferred_source, name)?;
             check_unset(&dimensions, "dimensions", inferred_source, name)?;
+
+            check_unset(&url, "url", inferred_source, name)?;
+            check_unset(&query, "query", inferred_source, name)?;
+            check_unset(&input_field, "inputField", inferred_source, name)?;
+            check_unset(&path_to_embeddings, "pathToEmbeddings", inferred_source, name)?;
+            check_unset(&embedding_object, "embeddingObject", inferred_source, name)?;
+            check_unset(&input_type, "inputType", inferred_source, name)?;
         }
         EmbedderSource::UserProvided => {
             check_unset(&model, "model", inferred_source, name)?;
@@ -1235,6 +1295,18 @@ pub fn validate_embedding_settings(
             check_unset(&api_key, "apiKey", inferred_source, name)?;
             check_unset(&document_template, "documentTemplate", inferred_source, name)?;
             check_set(&dimensions, "dimensions", inferred_source, name)?;
+
+            check_unset(&url, "url", inferred_source, name)?;
+            check_unset(&query, "query", inferred_source, name)?;
+            check_unset(&input_field, "inputField", inferred_source, name)?;
+            check_unset(&path_to_embeddings, "pathToEmbeddings", inferred_source, name)?;
+            check_unset(&embedding_object, "embeddingObject", inferred_source, name)?;
+            check_unset(&input_type, "inputType", inferred_source, name)?;
+        }
+        EmbedderSource::Rest => {
+            check_unset(&model, "model", inferred_source, name)?;
+            check_unset(&revision, "revision", inferred_source, name)?;
+            check_set(&url, "url", inferred_source, name)?;
         }
     }
     Ok(Setting::Set(EmbeddingSettings {
@@ -1244,6 +1316,12 @@ pub fn validate_embedding_settings(
         api_key,
         dimensions,
         document_template,
+        url,
+        query,
+        input_field,
+        path_to_embeddings,
+        embedding_object,
+        input_type,
     }))
 }
 

milli/src/vector/error.rs

@@ -2,9 +2,7 @@ use std::path::PathBuf;
 
 use hf_hub::api::sync::ApiError;
 
-use super::ollama::OllamaError;
 use crate::error::FaultSource;
-use crate::vector::openai::OpenAiError;
 
 #[derive(Debug, thiserror::Error)]
 #[error("Error while generating embeddings: {inner}")]
@@ -52,37 +50,34 @@ pub enum EmbedErrorKind {
     TensorValue(candle_core::Error),
     #[error("could not run model: {0}")]
     ModelForward(candle_core::Error),
-    #[error("could not reach OpenAI: {0}")]
-    OpenAiNetwork(reqwest::Error),
-    #[error("unexpected response from OpenAI: {0}")]
-    OpenAiUnexpected(reqwest::Error),
-    #[error("could not authenticate against OpenAI: {0}")]
-    OpenAiAuth(OpenAiError),
-    #[error("sent too many requests to OpenAI: {0}")]
-    OpenAiTooManyRequests(OpenAiError),
-    #[error("received internal error from OpenAI: {0:?}")]
-    OpenAiInternalServerError(Option<OpenAiError>),
-    #[error("sent too many tokens in a request to OpenAI: {0}")]
-    OpenAiTooManyTokens(OpenAiError),
-    #[error("received unhandled HTTP status code {0} from OpenAI")]
-    OpenAiUnhandledStatusCode(u16),
     #[error("attempt to embed the following text in a configuration where embeddings must be user provided: {0:?}")]
     ManualEmbed(String),
-    #[error("could not initialize asynchronous runtime: {0}")]
+    #[error("model not found. Meilisearch will not automatically download models from the Ollama library, please pull the model manually: {0:?}")]
-    OpenAiRuntimeInit(std::io::Error),
+    OllamaModelNotFoundError(Option<String>),
-    #[error("initializing web client for sending embedding requests failed: {0}")]
+    #[error("error deserialization the response body as JSON: {0}")]
-    InitWebClient(reqwest::Error),
+    RestResponseDeserialization(std::io::Error),
-    // Dedicated Ollama error kinds, might have to merge them into one cohesive error type for all backends.
+    #[error("component `{0}` not found in path `{1}` in response: `{2}`")]
-    #[error("unexpected response from Ollama: {0}")]
+    RestResponseMissingEmbeddings(String, String, String),
-    OllamaUnexpected(reqwest::Error),
+    #[error("expected a response parseable as a vector or an array of vectors: {0}")]
-    #[error("sent too many requests to Ollama: {0}")]
+    RestResponseFormat(serde_json::Error),
-    OllamaTooManyRequests(OllamaError),
+    #[error("expected a response containing {0} embeddings, got only {1}")]
-    #[error("received internal error from Ollama: {0}")]
+    RestResponseEmbeddingCount(usize, usize),
-    OllamaInternalServerError(OllamaError),
+    #[error("could not authenticate against embedding server: {0:?}")]
-    #[error("model not found. Meilisearch will not automatically download models from the Ollama library, please pull the model manually: {0}")]
+    RestUnauthorized(Option<String>),
-    OllamaModelNotFoundError(OllamaError),
+    #[error("sent too many requests to embedding server: {0:?}")]
-    #[error("received unhandled HTTP status code {0} from Ollama")]
+    RestTooManyRequests(Option<String>),
-    OllamaUnhandledStatusCode(u16),
+    #[error("sent a bad request to embedding server: {0:?}")]
+    RestBadRequest(Option<String>),
+    #[error("received internal error from embedding server: {0:?}")]
+    RestInternalServerError(u16, Option<String>),
+    #[error("received HTTP {0} from embedding server: {0:?}")]
+    RestOtherStatusCode(u16, Option<String>),
+    #[error("could not reach embedding server: {0}")]
+    RestNetwork(ureq::Transport),
+    #[error("was expected '{}' to be an object in query '{0}'", .1.join("."))]
+    RestNotAnObject(serde_json::Value, Vec<String>),
+    #[error("while embedding tokenized, was expecting embeddings of dimension `{0}`, got embeddings of dimensions `{1}`")]
+    OpenAiUnexpectedDimension(usize, usize),
 }
 
 impl EmbedError {
@@ -102,64 +97,98 @@ impl EmbedError {
         Self { kind: EmbedErrorKind::ModelForward(inner), fault: FaultSource::Runtime }
     }
 
-    pub fn openai_network(inner: reqwest::Error) -> Self {
-        Self { kind: EmbedErrorKind::OpenAiNetwork(inner), fault: FaultSource::Runtime }
-    }
-
-    pub fn openai_unexpected(inner: reqwest::Error) -> EmbedError {
-        Self { kind: EmbedErrorKind::OpenAiUnexpected(inner), fault: FaultSource::Bug }
-    }
-
-    pub(crate) fn openai_auth_error(inner: OpenAiError) -> EmbedError {
-        Self { kind: EmbedErrorKind::OpenAiAuth(inner), fault: FaultSource::User }
-    }
-
-    pub(crate) fn openai_too_many_requests(inner: OpenAiError) -> EmbedError {
-        Self { kind: EmbedErrorKind::OpenAiTooManyRequests(inner), fault: FaultSource::Runtime }
-    }
-
-    pub(crate) fn openai_internal_server_error(inner: Option<OpenAiError>) -> EmbedError {
-        Self { kind: EmbedErrorKind::OpenAiInternalServerError(inner), fault: FaultSource::Runtime }
-    }
-
-    pub(crate) fn openai_too_many_tokens(inner: OpenAiError) -> EmbedError {
-        Self { kind: EmbedErrorKind::OpenAiTooManyTokens(inner), fault: FaultSource::Bug }
-    }
-
-    pub(crate) fn openai_unhandled_status_code(code: u16) -> EmbedError {
-        Self { kind: EmbedErrorKind::OpenAiUnhandledStatusCode(code), fault: FaultSource::Bug }
-    }
-
     pub(crate) fn embed_on_manual_embedder(texts: String) -> EmbedError {
         Self { kind: EmbedErrorKind::ManualEmbed(texts), fault: FaultSource::User }
     }
 
-    pub(crate) fn openai_runtime_init(inner: std::io::Error) -> EmbedError {
+    pub(crate) fn ollama_model_not_found(inner: Option<String>) -> EmbedError {
-        Self { kind: EmbedErrorKind::OpenAiRuntimeInit(inner), fault: FaultSource::Runtime }
-    }
-
-    pub fn openai_initialize_web_client(inner: reqwest::Error) -> Self {
-        Self { kind: EmbedErrorKind::InitWebClient(inner), fault: FaultSource::Runtime }
-    }
-
-    pub(crate) fn ollama_unexpected(inner: reqwest::Error) -> EmbedError {
-        Self { kind: EmbedErrorKind::OllamaUnexpected(inner), fault: FaultSource::Bug }
-    }
-
-    pub(crate) fn ollama_model_not_found(inner: OllamaError) -> EmbedError {
         Self { kind: EmbedErrorKind::OllamaModelNotFoundError(inner), fault: FaultSource::User }
     }
 
-    pub(crate) fn ollama_too_many_requests(inner: OllamaError) -> EmbedError {
+    pub(crate) fn rest_response_deserialization(error: std::io::Error) -> EmbedError {
-        Self { kind: EmbedErrorKind::OllamaTooManyRequests(inner), fault: FaultSource::Runtime }
+        Self {
+            kind: EmbedErrorKind::RestResponseDeserialization(error),
+            fault: FaultSource::Runtime,
+        }
     }
 
-    pub(crate) fn ollama_internal_server_error(inner: OllamaError) -> EmbedError {
+    pub(crate) fn rest_response_missing_embeddings<S: AsRef<str>>(
-        Self { kind: EmbedErrorKind::OllamaInternalServerError(inner), fault: FaultSource::Runtime }
+        response: serde_json::Value,
+        component: &str,
+        response_field: &[S],
+    ) -> EmbedError {
+        let response_field: Vec<&str> = response_field.iter().map(AsRef::as_ref).collect();
+        let response_field = response_field.join(".");
+
+        Self {
+            kind: EmbedErrorKind::RestResponseMissingEmbeddings(
+                component.to_owned(),
+                response_field,
+                serde_json::to_string_pretty(&response).unwrap_or_default(),
+            ),
+            fault: FaultSource::Undecided,
+        }
     }
 
-    pub(crate) fn ollama_unhandled_status_code(code: u16) -> EmbedError {
+    pub(crate) fn rest_response_format(error: serde_json::Error) -> EmbedError {
-        Self { kind: EmbedErrorKind::OllamaUnhandledStatusCode(code), fault: FaultSource::Bug }
+        Self { kind: EmbedErrorKind::RestResponseFormat(error), fault: FaultSource::Undecided }
+    }
+
+    pub(crate) fn rest_response_embedding_count(expected: usize, got: usize) -> EmbedError {
+        Self {
+            kind: EmbedErrorKind::RestResponseEmbeddingCount(expected, got),
+            fault: FaultSource::Runtime,
+        }
+    }
+
+    pub(crate) fn rest_unauthorized(error_response: Option<String>) -> EmbedError {
+        Self { kind: EmbedErrorKind::RestUnauthorized(error_response), fault: FaultSource::User }
+    }
+
+    pub(crate) fn rest_too_many_requests(error_response: Option<String>) -> EmbedError {
+        Self {
+            kind: EmbedErrorKind::RestTooManyRequests(error_response),
+            fault: FaultSource::Runtime,
+        }
+    }
+
+    pub(crate) fn rest_bad_request(error_response: Option<String>) -> EmbedError {
+        Self { kind: EmbedErrorKind::RestBadRequest(error_response), fault: FaultSource::User }
+    }
+
+    pub(crate) fn rest_internal_server_error(
+        code: u16,
+        error_response: Option<String>,
+    ) -> EmbedError {
+        Self {
+            kind: EmbedErrorKind::RestInternalServerError(code, error_response),
+            fault: FaultSource::Runtime,
+        }
+    }
+
+    pub(crate) fn rest_other_status_code(code: u16, error_response: Option<String>) -> EmbedError {
+        Self {
+            kind: EmbedErrorKind::RestOtherStatusCode(code, error_response),
+            fault: FaultSource::Undecided,
+        }
+    }
+
+    pub(crate) fn rest_network(transport: ureq::Transport) -> EmbedError {
+        Self { kind: EmbedErrorKind::RestNetwork(transport), fault: FaultSource::Runtime }
+    }
+
+    pub(crate) fn rest_not_an_object(
+        query: serde_json::Value,
+        input_path: Vec<String>,
+    ) -> EmbedError {
+        Self { kind: EmbedErrorKind::RestNotAnObject(query, input_path), fault: FaultSource::User }
+    }
+
+    pub(crate) fn openai_unexpected_dimension(expected: usize, got: usize) -> EmbedError {
+        Self {
+            kind: EmbedErrorKind::OpenAiUnexpectedDimension(expected, got),
+            fault: FaultSource::Runtime,
+        }
     }
 }
 
@@ -220,23 +249,12 @@ impl NewEmbedderError {
         Self { kind: NewEmbedderErrorKind::LoadModel(inner), fault: FaultSource::Runtime }
     }
 
-    pub fn hf_could_not_determine_dimension(inner: EmbedError) -> NewEmbedderError {
+    pub fn could_not_determine_dimension(inner: EmbedError) -> NewEmbedderError {
         Self {
             kind: NewEmbedderErrorKind::CouldNotDetermineDimension(inner),
             fault: FaultSource::Runtime,
         }
     }
-
-    pub fn ollama_could_not_determine_dimension(inner: EmbedError) -> NewEmbedderError {
-        Self {
-            kind: NewEmbedderErrorKind::CouldNotDetermineDimension(inner),
-            fault: FaultSource::User,
-        }
-    }
-
-    pub fn openai_invalid_api_key_format(inner: reqwest::header::InvalidHeaderValue) -> Self {
-        Self { kind: NewEmbedderErrorKind::InvalidApiKeyFormat(inner), fault: FaultSource::User }
-    }
 }
 
 #[derive(Debug, thiserror::Error)]
@@ -283,7 +301,4 @@ pub enum NewEmbedderErrorKind {
     CouldNotDetermineDimension(EmbedError),
     #[error("loading model failed: {0}")]
     LoadModel(candle_core::Error),
-    // openai
-    #[error("The API key passed to Authorization error was in an invalid format: {0}")]
-    InvalidApiKeyFormat(reqwest::header::InvalidHeaderValue),
 }

milli/src/vector/hf.rs

@@ -131,7 +131,7 @@ impl Embedder {
 
         let embeddings = this
             .embed(vec!["test".into()])
-            .map_err(NewEmbedderError::hf_could_not_determine_dimension)?;
+            .map_err(NewEmbedderError::could_not_determine_dimension)?;
         this.dimensions = embeddings.first().unwrap().dimension();
 
         Ok(this)
@@ -194,7 +194,10 @@ impl Embedder {
 
     pub fn distribution(&self) -> Option<DistributionShift> {
         if self.options.model == "BAAI/bge-base-en-v1.5" {
-            Some(DistributionShift { current_mean: 0.85, current_sigma: 0.1 })
+            Some(DistributionShift {
+                current_mean: ordered_float::OrderedFloat(0.85),
+                current_sigma: ordered_float::OrderedFloat(0.1),
+            })
         } else {
             None
         }

milli/src/vector/mod.rs

@@ -1,6 +1,9 @@
 use std::collections::HashMap;
 use std::sync::Arc;
 
+use ordered_float::OrderedFloat;
+use serde::{Deserialize, Serialize};
+
 use self::error::{EmbedError, NewEmbedderError};
 use crate::prompt::{Prompt, PromptData};
 
@@ -11,51 +14,70 @@ pub mod openai;
 pub mod settings;
 
 pub mod ollama;
+pub mod rest;
 
 pub use self::error::Error;
 
 pub type Embedding = Vec<f32>;
 
+pub const REQUEST_PARALLELISM: usize = 40;
+
+/// One or multiple embeddings stored consecutively in a flat vector.
 pub struct Embeddings<F> {
     data: Vec<F>,
     dimension: usize,
 }
 
 impl<F> Embeddings<F> {
+    /// Declares an empty  vector of embeddings of the specified dimensions.
     pub fn new(dimension: usize) -> Self {
         Self { data: Default::default(), dimension }
     }
 
+    /// Declares a vector of embeddings containing a single element.
+    ///
+    /// The dimension is inferred from the length of the passed embedding.
     pub fn from_single_embedding(embedding: Vec<F>) -> Self {
         Self { dimension: embedding.len(), data: embedding }
     }
 
+    /// Declares a vector of embeddings from its components.
+    ///
+    /// `data.len()` must be a multiple of `dimension`, otherwise an error is returned.
     pub fn from_inner(data: Vec<F>, dimension: usize) -> Result<Self, Vec<F>> {
         let mut this = Self::new(dimension);
         this.append(data)?;
         Ok(this)
     }
 
+    /// Returns the number of embeddings in this vector of embeddings.
     pub fn embedding_count(&self) -> usize {
         self.data.len() / self.dimension
     }
 
+    /// Dimension of a single embedding.
     pub fn dimension(&self) -> usize {
         self.dimension
     }
 
+    /// Deconstructs self into the inner flat vector.
     pub fn into_inner(self) -> Vec<F> {
         self.data
     }
 
+    /// A reference to the inner flat vector.
     pub fn as_inner(&self) -> &[F] {
         &self.data
     }
 
+    /// Iterates over the embeddings contained in the flat vector.
     pub fn iter(&self) -> impl Iterator<Item = &'_ [F]> + '_ {
         self.data.as_slice().chunks_exact(self.dimension)
     }
 
+    /// Push an embedding at the end of the embeddings.
+    ///
+    /// If `embedding.len() != self.dimension`, then the push operation fails.
     pub fn push(&mut self, mut embedding: Vec<F>) -> Result<(), Vec<F>> {
         if embedding.len() != self.dimension {
             return Err(embedding);
@@ -64,6 +86,9 @@ impl<F> Embeddings<F> {
         Ok(())
     }
 
+    /// Append a flat vector of embeddings a the end of the embeddings.
+    ///
+    /// If `embeddings.len() % self.dimension != 0`, then the append operation fails.
     pub fn append(&mut self, mut embeddings: Vec<F>) -> Result<(), Vec<F>> {
         if embeddings.len() % self.dimension != 0 {
             return Err(embeddings);
@@ -73,37 +98,60 @@ impl<F> Embeddings<F> {
     }
 }
 
+/// An embedder can be used to transform text into embeddings.
 #[derive(Debug)]
 pub enum Embedder {
+    /// An embedder based on running local models, fetched from the Hugging Face Hub.
     HuggingFace(hf::Embedder),
+    /// An embedder based on making embedding queries against the OpenAI API.
     OpenAi(openai::Embedder),
+    /// An embedder based on the user providing the embeddings in the documents and queries.
     UserProvided(manual::Embedder),
+    /// An embedder based on making embedding queries against an <https://ollama.com> embedding server.
     Ollama(ollama::Embedder),
+    /// An embedder based on making embedding queries against a generic JSON/REST embedding server.
+    Rest(rest::Embedder),
 }
 
+/// Configuration for an embedder.
 #[derive(Debug, Clone, Default, serde::Deserialize, serde::Serialize)]
 pub struct EmbeddingConfig {
+    /// Options of the embedder, specific to each kind of embedder
     pub embedder_options: EmbedderOptions,
+    /// Document template
     pub prompt: PromptData,
     // TODO: add metrics and anything needed
 }
 
+/// Map of embedder configurations.
+///
+/// Each configuration is mapped to a name.
 #[derive(Clone, Default)]
 pub struct EmbeddingConfigs(HashMap<String, (Arc<Embedder>, Arc<Prompt>)>);
 
 impl EmbeddingConfigs {
+    /// Create the map from its internal component.s
     pub fn new(data: HashMap<String, (Arc<Embedder>, Arc<Prompt>)>) -> Self {
         Self(data)
     }
 
+    /// Get an embedder configuration and template from its name.
     pub fn get(&self, name: &str) -> Option<(Arc<Embedder>, Arc<Prompt>)> {
         self.0.get(name).cloned()
     }
 
+    /// Get the default embedder configuration, if any.
     pub fn get_default(&self) -> Option<(Arc<Embedder>, Arc<Prompt>)> {
         self.get_default_embedder_name().and_then(|default| self.get(&default))
     }
 
+    /// Get the name of the default embedder configuration.
+    ///
+    /// The default embedder is determined as follows:
+    ///
+    /// - If there is only one embedder, it is always the default.
+    /// - If there are multiple embedders and one of them is called `default`, then that one is the default embedder.
+    /// - In all other cases, there is no default embedder.
     pub fn get_default_embedder_name(&self) -> Option<String> {
         let mut it = self.0.keys();
         let first_name = it.next();
@@ -126,12 +174,14 @@ impl IntoIterator for EmbeddingConfigs {
     }
 }
 
+/// Options of an embedder, specific to each kind of embedder.
 #[derive(Debug, Clone, Hash, PartialEq, Eq, serde::Deserialize, serde::Serialize)]
 pub enum EmbedderOptions {
     HuggingFace(hf::EmbedderOptions),
     OpenAi(openai::EmbedderOptions),
     Ollama(ollama::EmbedderOptions),
     UserProvided(manual::EmbedderOptions),
+    Rest(rest::EmbedderOptions),
 }
 
 impl Default for EmbedderOptions {
@@ -141,10 +191,12 @@ impl Default for EmbedderOptions {
 }
 
 impl EmbedderOptions {
+    /// Default options for the Hugging Face embedder
     pub fn huggingface() -> Self {
         Self::HuggingFace(hf::EmbedderOptions::new())
     }
 
+    /// Default options for the OpenAI embedder
     pub fn openai(api_key: Option<String>) -> Self {
         Self::OpenAi(openai::EmbedderOptions::with_default_model(api_key))
     }
@@ -155,6 +207,7 @@ impl EmbedderOptions {
 }
 
 impl Embedder {
+    /// Spawns a new embedder built from its options.
     pub fn new(options: EmbedderOptions) -> std::result::Result<Self, NewEmbedderError> {
         Ok(match options {
             EmbedderOptions::HuggingFace(options) => Self::HuggingFace(hf::Embedder::new(options)?),
@@ -163,83 +216,133 @@ impl Embedder {
             EmbedderOptions::UserProvided(options) => {
                 Self::UserProvided(manual::Embedder::new(options))
             }
+            EmbedderOptions::Rest(options) => Self::Rest(rest::Embedder::new(options)?),
         })
     }
 
-    pub async fn embed(
+    /// Embed one or multiple texts.
+    ///
+    /// Each text can be embedded as one or multiple embeddings.
+    pub fn embed(
         &self,
         texts: Vec<String>,
     ) -> std::result::Result<Vec<Embeddings<f32>>, EmbedError> {
         match self {
             Embedder::HuggingFace(embedder) => embedder.embed(texts),
-            Embedder::OpenAi(embedder) => {
+            Embedder::OpenAi(embedder) => embedder.embed(texts),
-                let client = embedder.new_client()?;
+            Embedder::Ollama(embedder) => embedder.embed(texts),
-                embedder.embed(texts, &client).await
-            }
-            Embedder::Ollama(embedder) => {
-                let client = embedder.new_client()?;
-                embedder.embed(texts, &client).await
-            }
             Embedder::UserProvided(embedder) => embedder.embed(texts),
+            Embedder::Rest(embedder) => embedder.embed(texts),
         }
     }
 
-    /// # Panics
+    /// Embed multiple chunks of texts.
     ///
-    /// - if called from an asynchronous context
+    /// Each chunk is composed of one or multiple texts.
     pub fn embed_chunks(
         &self,
         text_chunks: Vec<Vec<String>>,
+        threads: &rayon::ThreadPool,
     ) -> std::result::Result<Vec<Vec<Embeddings<f32>>>, EmbedError> {
         match self {
             Embedder::HuggingFace(embedder) => embedder.embed_chunks(text_chunks),
-            Embedder::OpenAi(embedder) => embedder.embed_chunks(text_chunks),
+            Embedder::OpenAi(embedder) => embedder.embed_chunks(text_chunks, threads),
-            Embedder::Ollama(embedder) => embedder.embed_chunks(text_chunks),
+            Embedder::Ollama(embedder) => embedder.embed_chunks(text_chunks, threads),
             Embedder::UserProvided(embedder) => embedder.embed_chunks(text_chunks),
+            Embedder::Rest(embedder) => embedder.embed_chunks(text_chunks, threads),
         }
     }
 
+    /// Indicates the preferred number of chunks to pass to [`Self::embed_chunks`]
     pub fn chunk_count_hint(&self) -> usize {
         match self {
             Embedder::HuggingFace(embedder) => embedder.chunk_count_hint(),
             Embedder::OpenAi(embedder) => embedder.chunk_count_hint(),
             Embedder::Ollama(embedder) => embedder.chunk_count_hint(),
             Embedder::UserProvided(_) => 1,
+            Embedder::Rest(embedder) => embedder.chunk_count_hint(),
         }
     }
 
+    /// Indicates the preferred number of texts in a single chunk passed to [`Self::embed`]
     pub fn prompt_count_in_chunk_hint(&self) -> usize {
         match self {
             Embedder::HuggingFace(embedder) => embedder.prompt_count_in_chunk_hint(),
             Embedder::OpenAi(embedder) => embedder.prompt_count_in_chunk_hint(),
             Embedder::Ollama(embedder) => embedder.prompt_count_in_chunk_hint(),
             Embedder::UserProvided(_) => 1,
+            Embedder::Rest(embedder) => embedder.prompt_count_in_chunk_hint(),
         }
     }
 
+    /// Indicates the dimensions of a single embedding produced by the embedder.
     pub fn dimensions(&self) -> usize {
         match self {
             Embedder::HuggingFace(embedder) => embedder.dimensions(),
             Embedder::OpenAi(embedder) => embedder.dimensions(),
             Embedder::Ollama(embedder) => embedder.dimensions(),
             Embedder::UserProvided(embedder) => embedder.dimensions(),
+            Embedder::Rest(embedder) => embedder.dimensions(),
         }
     }
 
+    /// An optional distribution used to apply an affine transformation to the similarity score of a document.
     pub fn distribution(&self) -> Option<DistributionShift> {
         match self {
             Embedder::HuggingFace(embedder) => embedder.distribution(),
             Embedder::OpenAi(embedder) => embedder.distribution(),
             Embedder::Ollama(embedder) => embedder.distribution(),
             Embedder::UserProvided(_embedder) => None,
+            Embedder::Rest(embedder) => embedder.distribution(),
         }
     }
 }
 
-#[derive(Debug, Clone, Copy)]
+/// Describes the mean and sigma of distribution of embedding similarity in the embedding space.
+///
+/// The intended use is to make the similarity score more comparable to the regular ranking score.
+/// This allows to correct effects where results are too "packed" around a certain value.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Deserialize, Serialize)]
+#[serde(from = "DistributionShiftSerializable")]
+#[serde(into = "DistributionShiftSerializable")]
 pub struct DistributionShift {
-    pub current_mean: f32,
+    /// Value where the results are "packed".
-    pub current_sigma: f32,
+    ///
+    /// Similarity scores are translated so that they are packed around 0.5 instead
+    pub current_mean: OrderedFloat<f32>,
+
+    /// standard deviation of a similarity score.
+    ///
+    /// Set below 0.4 to make the results less packed around the mean, and above 0.4 to make them more packed.
+    pub current_sigma: OrderedFloat<f32>,
+}
+
+#[derive(Serialize, Deserialize)]
+struct DistributionShiftSerializable {
+    current_mean: f32,
+    current_sigma: f32,
+}
+
+impl From<DistributionShift> for DistributionShiftSerializable {
+    fn from(
+        DistributionShift {
+            current_mean: OrderedFloat(current_mean),
+            current_sigma: OrderedFloat(current_sigma),
+        }: DistributionShift,
+    ) -> Self {
+        Self { current_mean, current_sigma }
+    }
+}
+
+impl From<DistributionShiftSerializable> for DistributionShift {
+    fn from(
+        DistributionShiftSerializable { current_mean, current_sigma }: DistributionShiftSerializable,
+    ) -> Self {
+        Self {
+            current_mean: OrderedFloat(current_mean),
+            current_sigma: OrderedFloat(current_sigma),
+        }
+    }
 }
 
 impl DistributionShift {
@@ -248,11 +351,13 @@ impl DistributionShift {
         if sigma <= 0.0 {
             None
         } else {
-            Some(Self { current_mean: mean, current_sigma: sigma })
+            Some(Self { current_mean: OrderedFloat(mean), current_sigma: OrderedFloat(sigma) })
         }
     }
 
     pub fn shift(&self, score: f32) -> f32 {
+        let current_mean = self.current_mean.0;
+        let current_sigma = self.current_sigma.0;
         // <https://math.stackexchange.com/a/2894689>
         // We're somewhat abusively mapping the distribution of distances to a gaussian.
         // The parameters we're given is the mean and sigma of the native result distribution.
@@ -262,9 +367,9 @@ impl DistributionShift {
         let target_sigma = 0.4;
 
         // a^2 sig1^2 = sig2^2 => a^2 = sig2^2 / sig1^2 => a = sig2 / sig1, assuming a, sig1, and sig2 positive.
-        let factor = target_sigma / self.current_sigma;
+        let factor = target_sigma / current_sigma;
         // a*mu1 + b = mu2 => b = mu2 - a*mu1
-        let offset = target_mean - (factor * self.current_mean);
+        let offset = target_mean - (factor * current_mean);
 
         let mut score = factor * score + offset;
 
@@ -280,6 +385,7 @@ impl DistributionShift {
     }
 }
 
+/// Whether CUDA is supported in this version of Meilisearch.
 pub const fn is_cuda_enabled() -> bool {
     cfg!(feature = "cuda")
 }

milli/src/vector/ollama.rs

@@ -1,293 +1,94 @@
-// Copied from "openai.rs" with the sections I actually understand changed for Ollama.
+use rayon::iter::{IntoParallelIterator as _, ParallelIterator as _};
-// The common components of the Ollama and OpenAI interfaces might need to be extracted.
 
-use std::fmt::Display;
+use super::error::{EmbedError, EmbedErrorKind, NewEmbedderError, NewEmbedderErrorKind};
-
+use super::rest::{Embedder as RestEmbedder, EmbedderOptions as RestEmbedderOptions};
-use reqwest::StatusCode;
+use super::{DistributionShift, Embeddings};
-
-use super::error::{EmbedError, NewEmbedderError};
-use super::openai::Retry;
-use super::{DistributionShift, Embedding, Embeddings};
 
 #[derive(Debug)]
 pub struct Embedder {
-    headers: reqwest::header::HeaderMap,
+    rest_embedder: RestEmbedder,
-    options: EmbedderOptions,
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, serde::Deserialize, serde::Serialize)]
 pub struct EmbedderOptions {
-    pub embedding_model: EmbeddingModel,
+    pub embedding_model: String,
-}
-
-#[derive(
-    Debug, Clone, Hash, PartialEq, Eq, serde::Serialize, serde::Deserialize, deserr::Deserr,
-)]
-#[deserr(deny_unknown_fields)]
-pub struct EmbeddingModel {
-    name: String,
-    dimensions: usize,
-}
-
-#[derive(Debug, serde::Serialize)]
-struct OllamaRequest<'a> {
-    model: &'a str,
-    prompt: &'a str,
-}
-
-#[derive(Debug, serde::Deserialize)]
-struct OllamaResponse {
-    embedding: Embedding,
-}
-
-#[derive(Debug, serde::Deserialize)]
-pub struct OllamaError {
-    error: String,
-}
-
-impl EmbeddingModel {
-    pub fn max_token(&self) -> usize {
-        // this might not be the same for all models
-        8192
-    }
-
-    pub fn default_dimensions(&self) -> usize {
-        // Dimensions for nomic-embed-text
-        768
-    }
-
-    pub fn name(&self) -> String {
-        self.name.clone()
-    }
-
-    pub fn from_name(name: &str) -> Self {
-        Self { name: name.to_string(), dimensions: 0 }
-    }
-
-    pub fn supports_overriding_dimensions(&self) -> bool {
-        false
-    }
-}
-
-impl Default for EmbeddingModel {
-    fn default() -> Self {
-        Self { name: "nomic-embed-text".to_string(), dimensions: 0 }
-    }
 }
 
 impl EmbedderOptions {
     pub fn with_default_model() -> Self {
-        Self { embedding_model: Default::default() }
+        Self { embedding_model: "nomic-embed-text".into() }
     }
 
-    pub fn with_embedding_model(embedding_model: EmbeddingModel) -> Self {
+    pub fn with_embedding_model(embedding_model: String) -> Self {
         Self { embedding_model }
     }
 }
 
 impl Embedder {
-    pub fn new_client(&self) -> Result<reqwest::Client, EmbedError> {
-        reqwest::ClientBuilder::new()
-            .default_headers(self.headers.clone())
-            .build()
-            .map_err(EmbedError::openai_initialize_web_client)
-    }
-
     pub fn new(options: EmbedderOptions) -> Result<Self, NewEmbedderError> {
-        let mut headers = reqwest::header::HeaderMap::new();
+        let model = options.embedding_model.as_str();
-        headers.insert(
+        let rest_embedder = match RestEmbedder::new(RestEmbedderOptions {
-            reqwest::header::CONTENT_TYPE,
+            api_key: None,
-            reqwest::header::HeaderValue::from_static("application/json"),
+            distribution: None,
-        );
+            dimensions: None,
-
+            url: get_ollama_path(),
-        let mut embedder = Self { options, headers };
+            query: serde_json::json!({
-
+                "model": model,
-        let rt = tokio::runtime::Builder::new_current_thread()
+            }),
-            .enable_io()
+            input_field: vec!["prompt".to_owned()],
-            .enable_time()
+            path_to_embeddings: Default::default(),
-            .build()
+            embedding_object: vec!["embedding".to_owned()],
-            .map_err(EmbedError::openai_runtime_init)
+            input_type: super::rest::InputType::Text,
-            .map_err(NewEmbedderError::ollama_could_not_determine_dimension)?;
+        }) {
-
+            Ok(embedder) => embedder,
-        // Get dimensions from Ollama
+            Err(NewEmbedderError {
-        let request =
+                kind:
-            OllamaRequest { model: &embedder.options.embedding_model.name(), prompt: "test" };
+                    NewEmbedderErrorKind::CouldNotDetermineDimension(EmbedError {
-        // TODO: Refactor into shared error type
+                        kind: super::error::EmbedErrorKind::RestOtherStatusCode(404, error),
-        let client = embedder
+                        fault: _,
-            .new_client()
+                    }),
-            .map_err(NewEmbedderError::ollama_could_not_determine_dimension)?;
+                fault: _,
-
+            }) => {
-        rt.block_on(async move {
+                return Err(NewEmbedderError::could_not_determine_dimension(
-            let response = client
+                    EmbedError::ollama_model_not_found(error),
-                .post(get_ollama_path())
+                ))
-                .json(&request)
-                .send()
-                .await
-                .map_err(EmbedError::ollama_unexpected)
-                .map_err(NewEmbedderError::ollama_could_not_determine_dimension)?;
-
-            // Process error in case model not found
-            let response = Self::check_response(response).await.map_err(|_err| {
-                let e = EmbedError::ollama_model_not_found(OllamaError {
-                    error: format!("model: {}", embedder.options.embedding_model.name()),
-                });
-                NewEmbedderError::ollama_could_not_determine_dimension(e)
-            })?;
-
-            let response: OllamaResponse = response
-                .json()
-                .await
-                .map_err(EmbedError::ollama_unexpected)
-                .map_err(NewEmbedderError::ollama_could_not_determine_dimension)?;
-
-            let embedding = Embeddings::from_single_embedding(response.embedding);
-
-            embedder.options.embedding_model.dimensions = embedding.dimension();
-
-            tracing::info!(
-                "ollama model {} with dimensionality {} added",
-                embedder.options.embedding_model.name(),
-                embedding.dimension()
-            );
-
-            Ok(embedder)
-        })
-    }
-
-    async fn check_response(response: reqwest::Response) -> Result<reqwest::Response, Retry> {
-        if !response.status().is_success() {
-            // Not the same number of possible error cases covered as with OpenAI.
-            match response.status() {
-                StatusCode::TOO_MANY_REQUESTS => {
-                    let error_response: OllamaError = response
-                        .json()
-                        .await
-                        .map_err(EmbedError::ollama_unexpected)
-                        .map_err(Retry::retry_later)?;
-
-                    return Err(Retry::rate_limited(EmbedError::ollama_too_many_requests(
-                        OllamaError { error: error_response.error },
-                    )));
-                }
-                StatusCode::SERVICE_UNAVAILABLE => {
-                    let error_response: OllamaError = response
-                        .json()
-                        .await
-                        .map_err(EmbedError::ollama_unexpected)
-                        .map_err(Retry::retry_later)?;
-                    return Err(Retry::retry_later(EmbedError::ollama_internal_server_error(
-                        OllamaError { error: error_response.error },
-                    )));
-                }
-                StatusCode::NOT_FOUND => {
-                    let error_response: OllamaError = response
-                        .json()
-                        .await
-                        .map_err(EmbedError::ollama_unexpected)
-                        .map_err(Retry::give_up)?;
-
-                    return Err(Retry::give_up(EmbedError::ollama_model_not_found(OllamaError {
-                        error: error_response.error,
-                    })));
-                }
-                code => {
-                    return Err(Retry::give_up(EmbedError::ollama_unhandled_status_code(
-                        code.as_u16(),
-                    )));
-                }
             }
-        }
+            Err(error) => return Err(error),
-        Ok(response)
+        };
+
+        Ok(Self { rest_embedder })
     }
 
-    pub async fn embed(
+    pub fn embed(&self, texts: Vec<String>) -> Result<Vec<Embeddings<f32>>, EmbedError> {
-        &self,
+        match self.rest_embedder.embed(texts) {
-        texts: Vec<String>,
+            Ok(embeddings) => Ok(embeddings),
-        client: &reqwest::Client,
+            Err(EmbedError { kind: EmbedErrorKind::RestOtherStatusCode(404, error), fault: _ }) => {
-    ) -> Result<Vec<Embeddings<f32>>, EmbedError> {
+                Err(EmbedError::ollama_model_not_found(error))
-        // Ollama only embedds one document at a time.
-        let mut results = Vec::with_capacity(texts.len());
-
-        // The retry loop is inside the texts loop, might have to switch that around
-        for text in texts {
-            // Retries copied from openai.rs
-            for attempt in 0..7 {
-                let retry_duration = match self.try_embed(&text, client).await {
-                    Ok(result) => {
-                        results.push(result);
-                        break;
-                    }
-                    Err(retry) => {
-                        tracing::warn!("Failed: {}", retry.error);
-                        retry.into_duration(attempt)
-                    }
-                }?;
-                tracing::warn!(
-                    "Attempt #{}, retrying after {}ms.",
-                    attempt,
-                    retry_duration.as_millis()
-                );
-                tokio::time::sleep(retry_duration).await;
             }
+            Err(error) => Err(error),
         }
-
-        Ok(results)
-    }
-
-    async fn try_embed(
-        &self,
-        text: &str,
-        client: &reqwest::Client,
-    ) -> Result<Embeddings<f32>, Retry> {
-        let request = OllamaRequest { model: &self.options.embedding_model.name(), prompt: text };
-        let response = client
-            .post(get_ollama_path())
-            .json(&request)
-            .send()
-            .await
-            .map_err(EmbedError::openai_network)
-            .map_err(Retry::retry_later)?;
-
-        let response = Self::check_response(response).await?;
-
-        let response: OllamaResponse = response
-            .json()
-            .await
-            .map_err(EmbedError::openai_unexpected)
-            .map_err(Retry::retry_later)?;
-
-        tracing::trace!("response: {:?}", response.embedding);
-
-        let embedding = Embeddings::from_single_embedding(response.embedding);
-        Ok(embedding)
     }
 
     pub fn embed_chunks(
         &self,
         text_chunks: Vec<Vec<String>>,
+        threads: &rayon::ThreadPool,
     ) -> Result<Vec<Vec<Embeddings<f32>>>, EmbedError> {
-        let rt = tokio::runtime::Builder::new_current_thread()
+        threads.install(move || {
-            .enable_io()
+            text_chunks.into_par_iter().map(move |chunk| self.embed(chunk)).collect()
-            .enable_time()
+        })
-            .build()
-            .map_err(EmbedError::openai_runtime_init)?;
-        let client = self.new_client()?;
-        rt.block_on(futures::future::try_join_all(
-            text_chunks.into_iter().map(|prompts| self.embed(prompts, &client)),
-        ))
     }
 
-    // Defaults copied from openai.rs
     pub fn chunk_count_hint(&self) -> usize {
-        10
+        self.rest_embedder.chunk_count_hint()
     }
 
     pub fn prompt_count_in_chunk_hint(&self) -> usize {
-        10
+        self.rest_embedder.prompt_count_in_chunk_hint()
     }
 
     pub fn dimensions(&self) -> usize {
-        self.options.embedding_model.dimensions
+        self.rest_embedder.dimensions()
     }
 
     pub fn distribution(&self) -> Option<DistributionShift> {
@@ -295,12 +96,6 @@ impl Embedder {
     }
 }
 
-impl Display for OllamaError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", self.error)
-    }
-}
-
 fn get_ollama_path() -> String {
     // Important: Hostname not enough, has to be entire path to embeddings endpoint
     std::env::var("MEILI_OLLAMA_URL").unwrap_or("http://localhost:11434/api/embeddings".to_string())

milli/src/vector/openai.rs

@@ -1,17 +1,10 @@
-use std::fmt::Display;
+use ordered_float::OrderedFloat;
-
+use rayon::iter::{IntoParallelIterator, ParallelIterator as _};
-use reqwest::StatusCode;
-use serde::{Deserialize, Serialize};
 
 use super::error::{EmbedError, NewEmbedderError};
-use super::{DistributionShift, Embedding, Embeddings};
+use super::rest::{Embedder as RestEmbedder, EmbedderOptions as RestEmbedderOptions};
-
+use super::{DistributionShift, Embeddings};
-#[derive(Debug)]
+use crate::vector::error::EmbedErrorKind;
-pub struct Embedder {
-    headers: reqwest::header::HeaderMap,
-    tokenizer: tiktoken_rs::CoreBPE,
-    options: EmbedderOptions,
-}
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, serde::Deserialize, serde::Serialize)]
 pub struct EmbedderOptions {
@@ -20,6 +13,32 @@ pub struct EmbedderOptions {
     pub dimensions: Option<usize>,
 }
 
+impl EmbedderOptions {
+    pub fn dimensions(&self) -> usize {
+        if self.embedding_model.supports_overriding_dimensions() {
+            self.dimensions.unwrap_or(self.embedding_model.default_dimensions())
+        } else {
+            self.embedding_model.default_dimensions()
+        }
+    }
+
+    pub fn query(&self) -> serde_json::Value {
+        let model = self.embedding_model.name();
+
+        let mut query = serde_json::json!({
+            "model": model,
+        });
+
+        if self.embedding_model.supports_overriding_dimensions() {
+            if let Some(dimensions) = self.dimensions {
+                query["dimensions"] = dimensions.into();
+            }
+        }
+
+        query
+    }
+}
+
 #[derive(
     Debug,
     Clone,
@@ -92,15 +111,18 @@ impl EmbeddingModel {
 
     fn distribution(&self) -> Option<DistributionShift> {
         match self {
-            EmbeddingModel::TextEmbeddingAda002 => {
+            EmbeddingModel::TextEmbeddingAda002 => Some(DistributionShift {
-                Some(DistributionShift { current_mean: 0.90, current_sigma: 0.08 })
+                current_mean: OrderedFloat(0.90),
-            }
+                current_sigma: OrderedFloat(0.08),
-            EmbeddingModel::TextEmbedding3Large => {
+            }),
-                Some(DistributionShift { current_mean: 0.70, current_sigma: 0.1 })
+            EmbeddingModel::TextEmbedding3Large => Some(DistributionShift {
-            }
+                current_mean: OrderedFloat(0.70),
-            EmbeddingModel::TextEmbedding3Small => {
+                current_sigma: OrderedFloat(0.1),
-                Some(DistributionShift { current_mean: 0.75, current_sigma: 0.1 })
+            }),
-            }
+            EmbeddingModel::TextEmbedding3Small => Some(DistributionShift {
+                current_mean: OrderedFloat(0.75),
+                current_sigma: OrderedFloat(0.1),
+            }),
         }
     }
 
@@ -125,178 +147,57 @@ impl EmbedderOptions {
     }
 }
 
-impl Embedder {
+fn infer_api_key() -> String {
-    pub fn new_client(&self) -> Result<reqwest::Client, EmbedError> {
+    std::env::var("MEILI_OPENAI_API_KEY")
-        reqwest::ClientBuilder::new()
+        .or_else(|_| std::env::var("OPENAI_API_KEY"))
-            .default_headers(self.headers.clone())
+        .unwrap_or_default()
-            .build()
+}
-            .map_err(EmbedError::openai_initialize_web_client)
-    }
 
+#[derive(Debug)]
+pub struct Embedder {
+    tokenizer: tiktoken_rs::CoreBPE,
+    rest_embedder: RestEmbedder,
+    options: EmbedderOptions,
+}
+
+impl Embedder {
     pub fn new(options: EmbedderOptions) -> Result<Self, NewEmbedderError> {
-        let mut headers = reqwest::header::HeaderMap::new();
         let mut inferred_api_key = Default::default();
         let api_key = options.api_key.as_ref().unwrap_or_else(|| {
             inferred_api_key = infer_api_key();
             &inferred_api_key
         });
-        headers.insert(
+
-            reqwest::header::AUTHORIZATION,
+        let rest_embedder = RestEmbedder::new(RestEmbedderOptions {
-            reqwest::header::HeaderValue::from_str(&format!("Bearer {}", api_key))
+            api_key: Some(api_key.clone()),
-                .map_err(NewEmbedderError::openai_invalid_api_key_format)?,
+            distribution: options.embedding_model.distribution(),
-        );
+            dimensions: Some(options.dimensions()),
-        headers.insert(
+            url: OPENAI_EMBEDDINGS_URL.to_owned(),
-            reqwest::header::CONTENT_TYPE,
+            query: options.query(),
-            reqwest::header::HeaderValue::from_static("application/json"),
+            input_field: vec!["input".to_owned()],
-        );
+            input_type: crate::vector::rest::InputType::TextArray,
+            path_to_embeddings: vec!["data".to_owned()],
+            embedding_object: vec!["embedding".to_owned()],
+        })?;
 
         // looking at the code it is very unclear that this can actually fail.
         let tokenizer = tiktoken_rs::cl100k_base().unwrap();
 
-        Ok(Self { options, headers, tokenizer })
+        Ok(Self { options, rest_embedder, tokenizer })
     }
 
-    pub async fn embed(
+    pub fn embed(&self, texts: Vec<String>) -> Result<Vec<Embeddings<f32>>, EmbedError> {
-        &self,
+        match self.rest_embedder.embed_ref(&texts) {
-        texts: Vec<String>,
+            Ok(embeddings) => Ok(embeddings),
-        client: &reqwest::Client,
+            Err(EmbedError { kind: EmbedErrorKind::RestBadRequest(error), fault: _ }) => {
-    ) -> Result<Vec<Embeddings<f32>>, EmbedError> {
+                tracing::warn!(error=?error, "OpenAI: received `BAD_REQUEST`. Input was maybe too long, retrying on tokenized version. For best performance, limit the size of your document template.");
-        let mut tokenized = false;
+                self.try_embed_tokenized(&texts)
-
-        for attempt in 0..7 {
-            let result = if tokenized {
-                self.try_embed_tokenized(&texts, client).await
-            } else {
-                self.try_embed(&texts, client).await
-            };
-
-            let retry_duration = match result {
-                Ok(embeddings) => return Ok(embeddings),
-                Err(retry) => {
-                    tracing::warn!("Failed: {}", retry.error);
-                    tokenized |= retry.must_tokenize();
-                    retry.into_duration(attempt)
-                }
-            }?;
-
-            let retry_duration = retry_duration.min(std::time::Duration::from_secs(60)); // don't wait more than a minute
-            tracing::warn!(
-                "Attempt #{}, retrying after {}ms.",
-                attempt,
-                retry_duration.as_millis()
-            );
-            tokio::time::sleep(retry_duration).await;
-        }
-
-        let result = if tokenized {
-            self.try_embed_tokenized(&texts, client).await
-        } else {
-            self.try_embed(&texts, client).await
-        };
-
-        result.map_err(Retry::into_error)
-    }
-
-    async fn check_response(response: reqwest::Response) -> Result<reqwest::Response, Retry> {
-        if !response.status().is_success() {
-            match response.status() {
-                StatusCode::UNAUTHORIZED => {
-                    let error_response: OpenAiErrorResponse = response
-                        .json()
-                        .await
-                        .map_err(EmbedError::openai_unexpected)
-                        .map_err(Retry::retry_later)?;
-
-                    return Err(Retry::give_up(EmbedError::openai_auth_error(
-                        error_response.error,
-                    )));
-                }
-                StatusCode::TOO_MANY_REQUESTS => {
-                    let error_response: OpenAiErrorResponse = response
-                        .json()
-                        .await
-                        .map_err(EmbedError::openai_unexpected)
-                        .map_err(Retry::retry_later)?;
-
-                    return Err(Retry::rate_limited(EmbedError::openai_too_many_requests(
-                        error_response.error,
-                    )));
-                }
-                StatusCode::INTERNAL_SERVER_ERROR
-                | StatusCode::BAD_GATEWAY
-                | StatusCode::SERVICE_UNAVAILABLE => {
-                    let error_response: Result<OpenAiErrorResponse, _> = response.json().await;
-                    return Err(Retry::retry_later(EmbedError::openai_internal_server_error(
-                        error_response.ok().map(|error_response| error_response.error),
-                    )));
-                }
-                StatusCode::BAD_REQUEST => {
-                    // Most probably, one text contained too many tokens
-                    let error_response: OpenAiErrorResponse = response
-                        .json()
-                        .await
-                        .map_err(EmbedError::openai_unexpected)
-                        .map_err(Retry::retry_later)?;
-
-                    tracing::warn!("OpenAI: received `BAD_REQUEST`. Input was maybe too long, retrying on tokenized version. For best performance, limit the size of your prompt.");
-
-                    return Err(Retry::retry_tokenized(EmbedError::openai_too_many_tokens(
-                        error_response.error,
-                    )));
-                }
-                code => {
-                    return Err(Retry::retry_later(EmbedError::openai_unhandled_status_code(
-                        code.as_u16(),
-                    )));
-                }
             }
+            Err(error) => Err(error),
         }
-        Ok(response)
     }
 
-    async fn try_embed<S: AsRef<str> + serde::Serialize>(
+    fn try_embed_tokenized(&self, text: &[String]) -> Result<Vec<Embeddings<f32>>, EmbedError> {
-        &self,
-        texts: &[S],
-        client: &reqwest::Client,
-    ) -> Result<Vec<Embeddings<f32>>, Retry> {
-        for text in texts {
-            tracing::trace!("Received prompt: {}", text.as_ref())
-        }
-        let request = OpenAiRequest {
-            model: self.options.embedding_model.name(),
-            input: texts,
-            dimensions: self.overriden_dimensions(),
-        };
-        let response = client
-            .post(OPENAI_EMBEDDINGS_URL)
-            .json(&request)
-            .send()
-            .await
-            .map_err(EmbedError::openai_network)
-            .map_err(Retry::retry_later)?;
-
-        let response = Self::check_response(response).await?;
-
-        let response: OpenAiResponse = response
-            .json()
-            .await
-            .map_err(EmbedError::openai_unexpected)
-            .map_err(Retry::retry_later)?;
-
-        tracing::trace!("response: {:?}", response.data);
-
-        Ok(response
-            .data
-            .into_iter()
-            .map(|data| Embeddings::from_single_embedding(data.embedding))
-            .collect())
-    }
-
-    async fn try_embed_tokenized(
-        &self,
-        text: &[String],
-        client: &reqwest::Client,
-    ) -> Result<Vec<Embeddings<f32>>, Retry> {
         pub const OVERLAP_SIZE: usize = 200;
         let mut all_embeddings = Vec::with_capacity(text.len());
         for text in text {
@@ -304,7 +205,7 @@ impl Embedder {
             let encoded = self.tokenizer.encode_ordinary(text.as_str());
             let len = encoded.len();
             if len < max_token_count {
-                all_embeddings.append(&mut self.try_embed(&[text], client).await?);
+                all_embeddings.append(&mut self.rest_embedder.embed_ref(&[text])?);
                 continue;
             }
 
@@ -312,215 +213,49 @@ impl Embedder {
             let mut embeddings_for_prompt = Embeddings::new(self.dimensions());
             while tokens.len() > max_token_count {
                 let window = &tokens[..max_token_count];
-                embeddings_for_prompt.push(self.embed_tokens(window, client).await?).unwrap();
+                let embedding = self.rest_embedder.embed_tokens(window)?;
+                embeddings_for_prompt.append(embedding.into_inner()).map_err(|got| {
+                    EmbedError::openai_unexpected_dimension(self.dimensions(), got.len())
+                })?;
 
                 tokens = &tokens[max_token_count - OVERLAP_SIZE..];
             }
 
             // end of text
-            embeddings_for_prompt.push(self.embed_tokens(tokens, client).await?).unwrap();
+            let embedding = self.rest_embedder.embed_tokens(tokens)?;
+
+            embeddings_for_prompt.append(embedding.into_inner()).map_err(|got| {
+                EmbedError::openai_unexpected_dimension(self.dimensions(), got.len())
+            })?;
 
             all_embeddings.push(embeddings_for_prompt);
         }
         Ok(all_embeddings)
     }
 
-    async fn embed_tokens(
-        &self,
-        tokens: &[usize],
-        client: &reqwest::Client,
-    ) -> Result<Embedding, Retry> {
-        for attempt in 0..9 {
-            let duration = match self.try_embed_tokens(tokens, client).await {
-                Ok(embedding) => return Ok(embedding),
-                Err(retry) => retry.into_duration(attempt),
-            }
-            .map_err(Retry::retry_later)?;
-
-            tokio::time::sleep(duration).await;
-        }
-
-        self.try_embed_tokens(tokens, client)
-            .await
-            .map_err(|retry| Retry::give_up(retry.into_error()))
-    }
-
-    async fn try_embed_tokens(
-        &self,
-        tokens: &[usize],
-        client: &reqwest::Client,
-    ) -> Result<Embedding, Retry> {
-        let request = OpenAiTokensRequest {
-            model: self.options.embedding_model.name(),
-            input: tokens,
-            dimensions: self.overriden_dimensions(),
-        };
-        let response = client
-            .post(OPENAI_EMBEDDINGS_URL)
-            .json(&request)
-            .send()
-            .await
-            .map_err(EmbedError::openai_network)
-            .map_err(Retry::retry_later)?;
-
-        let response = Self::check_response(response).await?;
-
-        let mut response: OpenAiResponse = response
-            .json()
-            .await
-            .map_err(EmbedError::openai_unexpected)
-            .map_err(Retry::retry_later)?;
-        Ok(response.data.pop().map(|data| data.embedding).unwrap_or_default())
-    }
-
     pub fn embed_chunks(
         &self,
         text_chunks: Vec<Vec<String>>,
+        threads: &rayon::ThreadPool,
     ) -> Result<Vec<Vec<Embeddings<f32>>>, EmbedError> {
-        let rt = tokio::runtime::Builder::new_current_thread()
+        threads.install(move || {
-            .enable_io()
+            text_chunks.into_par_iter().map(move |chunk| self.embed(chunk)).collect()
-            .enable_time()
+        })
-            .build()
-            .map_err(EmbedError::openai_runtime_init)?;
-        let client = self.new_client()?;
-        rt.block_on(futures::future::try_join_all(
-            text_chunks.into_iter().map(|prompts| self.embed(prompts, &client)),
-        ))
     }
 
     pub fn chunk_count_hint(&self) -> usize {
-        10
+        self.rest_embedder.chunk_count_hint()
     }
 
     pub fn prompt_count_in_chunk_hint(&self) -> usize {
-        10
+        self.rest_embedder.prompt_count_in_chunk_hint()
     }
 
     pub fn dimensions(&self) -> usize {
-        if self.options.embedding_model.supports_overriding_dimensions() {
+        self.options.dimensions()
-            self.options.dimensions.unwrap_or(self.options.embedding_model.default_dimensions())
-        } else {
-            self.options.embedding_model.default_dimensions()
-        }
     }
 
     pub fn distribution(&self) -> Option<DistributionShift> {
         self.options.embedding_model.distribution()
     }
-
-    fn overriden_dimensions(&self) -> Option<usize> {
-        if self.options.embedding_model.supports_overriding_dimensions() {
-            self.options.dimensions
-        } else {
-            None
-        }
-    }
-}
-
-// retrying in case of failure
-
-pub struct Retry {
-    pub error: EmbedError,
-    strategy: RetryStrategy,
-}
-
-pub enum RetryStrategy {
-    GiveUp,
-    Retry,
-    RetryTokenized,
-    RetryAfterRateLimit,
-}
-
-impl Retry {
-    pub fn give_up(error: EmbedError) -> Self {
-        Self { error, strategy: RetryStrategy::GiveUp }
-    }
-
-    pub fn retry_later(error: EmbedError) -> Self {
-        Self { error, strategy: RetryStrategy::Retry }
-    }
-
-    pub fn retry_tokenized(error: EmbedError) -> Self {
-        Self { error, strategy: RetryStrategy::RetryTokenized }
-    }
-
-    pub fn rate_limited(error: EmbedError) -> Self {
-        Self { error, strategy: RetryStrategy::RetryAfterRateLimit }
-    }
-
-    pub fn into_duration(self, attempt: u32) -> Result<tokio::time::Duration, EmbedError> {
-        match self.strategy {
-            RetryStrategy::GiveUp => Err(self.error),
-            RetryStrategy::Retry => Ok(tokio::time::Duration::from_millis((10u64).pow(attempt))),
-            RetryStrategy::RetryTokenized => Ok(tokio::time::Duration::from_millis(1)),
-            RetryStrategy::RetryAfterRateLimit => {
-                Ok(tokio::time::Duration::from_millis(100 + 10u64.pow(attempt)))
-            }
-        }
-    }
-
-    pub fn must_tokenize(&self) -> bool {
-        matches!(self.strategy, RetryStrategy::RetryTokenized)
-    }
-
-    pub fn into_error(self) -> EmbedError {
-        self.error
-    }
-}
-
-// openai api structs
-
-#[derive(Debug, Serialize)]
-struct OpenAiRequest<'a, S: AsRef<str> + serde::Serialize> {
-    model: &'a str,
-    input: &'a [S],
-    #[serde(skip_serializing_if = "Option::is_none")]
-    dimensions: Option<usize>,
-}
-
-#[derive(Debug, Serialize)]
-struct OpenAiTokensRequest<'a> {
-    model: &'a str,
-    input: &'a [usize],
-    #[serde(skip_serializing_if = "Option::is_none")]
-    dimensions: Option<usize>,
-}
-
-#[derive(Debug, Deserialize)]
-struct OpenAiResponse {
-    data: Vec<OpenAiEmbedding>,
-}
-
-#[derive(Debug, Deserialize)]
-struct OpenAiErrorResponse {
-    error: OpenAiError,
-}
-
-#[derive(Debug, Deserialize)]
-pub struct OpenAiError {
-    message: String,
-    // type: String,
-    code: Option<String>,
-}
-
-impl Display for OpenAiError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match &self.code {
-            Some(code) => write!(f, "{} ({})", self.message, code),
-            None => write!(f, "{}", self.message),
-        }
-    }
-}
-
-#[derive(Debug, Deserialize)]
-struct OpenAiEmbedding {
-    embedding: Embedding,
-    // object: String,
-    // index: usize,
-}
-
-fn infer_api_key() -> String {
-    std::env::var("MEILI_OPENAI_API_KEY")
-        .or_else(|_| std::env::var("OPENAI_API_KEY"))
-        .unwrap_or_default()
 }

milli/src/vector/rest.rs

@@ -0,0 +1,373 @@
+use deserr::Deserr;
+use rayon::iter::{IntoParallelIterator as _, ParallelIterator as _};
+use serde::{Deserialize, Serialize};
+
+use super::{
+    DistributionShift, EmbedError, Embedding, Embeddings, NewEmbedderError, REQUEST_PARALLELISM,
+};
+
+// retrying in case of failure
+
+pub struct Retry {
+    pub error: EmbedError,
+    strategy: RetryStrategy,
+}
+
+pub enum RetryStrategy {
+    GiveUp,
+    Retry,
+    RetryTokenized,
+    RetryAfterRateLimit,
+}
+
+impl Retry {
+    pub fn give_up(error: EmbedError) -> Self {
+        Self { error, strategy: RetryStrategy::GiveUp }
+    }
+
+    pub fn retry_later(error: EmbedError) -> Self {
+        Self { error, strategy: RetryStrategy::Retry }
+    }
+
+    pub fn retry_tokenized(error: EmbedError) -> Self {
+        Self { error, strategy: RetryStrategy::RetryTokenized }
+    }
+
+    pub fn rate_limited(error: EmbedError) -> Self {
+        Self { error, strategy: RetryStrategy::RetryAfterRateLimit }
+    }
+
+    pub fn into_duration(self, attempt: u32) -> Result<std::time::Duration, EmbedError> {
+        match self.strategy {
+            RetryStrategy::GiveUp => Err(self.error),
+            RetryStrategy::Retry => Ok(std::time::Duration::from_millis((10u64).pow(attempt))),
+            RetryStrategy::RetryTokenized => Ok(std::time::Duration::from_millis(1)),
+            RetryStrategy::RetryAfterRateLimit => {
+                Ok(std::time::Duration::from_millis(100 + 10u64.pow(attempt)))
+            }
+        }
+    }
+
+    pub fn must_tokenize(&self) -> bool {
+        matches!(self.strategy, RetryStrategy::RetryTokenized)
+    }
+
+    pub fn into_error(self) -> EmbedError {
+        self.error
+    }
+}
+
+#[derive(Debug)]
+pub struct Embedder {
+    client: ureq::Agent,
+    options: EmbedderOptions,
+    bearer: Option<String>,
+    dimensions: usize,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize)]
+pub struct EmbedderOptions {
+    pub api_key: Option<String>,
+    pub distribution: Option<DistributionShift>,
+    pub dimensions: Option<usize>,
+    pub url: String,
+    pub query: serde_json::Value,
+    pub input_field: Vec<String>,
+    // path to the array of embeddings
+    pub path_to_embeddings: Vec<String>,
+    // shape of a single embedding
+    pub embedding_object: Vec<String>,
+    pub input_type: InputType,
+}
+
+impl Default for EmbedderOptions {
+    fn default() -> Self {
+        Self {
+            url: Default::default(),
+            query: Default::default(),
+            input_field: vec!["input".into()],
+            path_to_embeddings: vec!["data".into()],
+            embedding_object: vec!["embedding".into()],
+            input_type: InputType::Text,
+            api_key: None,
+            distribution: None,
+            dimensions: None,
+        }
+    }
+}
+
+impl std::hash::Hash for EmbedderOptions {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.api_key.hash(state);
+        self.distribution.hash(state);
+        self.dimensions.hash(state);
+        self.url.hash(state);
+        // skip hashing the query
+        // collisions in regular usage should be minimal,
+        // and the list is limited to 256 values anyway
+        self.input_field.hash(state);
+        self.path_to_embeddings.hash(state);
+        self.embedding_object.hash(state);
+        self.input_type.hash(state);
+    }
+}
+
+#[derive(Debug, Clone, Copy, Deserialize, Serialize, PartialEq, Eq, Hash, Deserr)]
+#[serde(rename_all = "camelCase")]
+#[deserr(rename_all = camelCase, deny_unknown_fields)]
+pub enum InputType {
+    Text,
+    TextArray,
+}
+
+impl Embedder {
+    pub fn new(options: EmbedderOptions) -> Result<Self, NewEmbedderError> {
+        let bearer = options.api_key.as_deref().map(|api_key| format!("Bearer {api_key}"));
+
+        let client = ureq::AgentBuilder::new()
+            .max_idle_connections(REQUEST_PARALLELISM * 2)
+            .max_idle_connections_per_host(REQUEST_PARALLELISM * 2)
+            .build();
+
+        let dimensions = if let Some(dimensions) = options.dimensions {
+            dimensions
+        } else {
+            infer_dimensions(&client, &options, bearer.as_deref())?
+        };
+
+        Ok(Self { client, dimensions, options, bearer })
+    }
+
+    pub fn embed(&self, texts: Vec<String>) -> Result<Vec<Embeddings<f32>>, EmbedError> {
+        embed(&self.client, &self.options, self.bearer.as_deref(), texts.as_slice(), texts.len())
+    }
+
+    pub fn embed_ref<S>(&self, texts: &[S]) -> Result<Vec<Embeddings<f32>>, EmbedError>
+    where
+        S: AsRef<str> + Serialize,
+    {
+        embed(&self.client, &self.options, self.bearer.as_deref(), texts, texts.len())
+    }
+
+    pub fn embed_tokens(&self, tokens: &[usize]) -> Result<Embeddings<f32>, EmbedError> {
+        let mut embeddings = embed(&self.client, &self.options, self.bearer.as_deref(), tokens, 1)?;
+        // unwrap: guaranteed that embeddings.len() == 1, otherwise the previous line terminated in error
+        Ok(embeddings.pop().unwrap())
+    }
+
+    pub fn embed_chunks(
+        &self,
+        text_chunks: Vec<Vec<String>>,
+        threads: &rayon::ThreadPool,
+    ) -> Result<Vec<Vec<Embeddings<f32>>>, EmbedError> {
+        threads.install(move || {
+            text_chunks.into_par_iter().map(move |chunk| self.embed(chunk)).collect()
+        })
+    }
+
+    pub fn chunk_count_hint(&self) -> usize {
+        super::REQUEST_PARALLELISM
+    }
+
+    pub fn prompt_count_in_chunk_hint(&self) -> usize {
+        match self.options.input_type {
+            InputType::Text => 1,
+            InputType::TextArray => 10,
+        }
+    }
+
+    pub fn dimensions(&self) -> usize {
+        self.dimensions
+    }
+
+    pub fn distribution(&self) -> Option<DistributionShift> {
+        self.options.distribution
+    }
+}
+
+fn infer_dimensions(
+    client: &ureq::Agent,
+    options: &EmbedderOptions,
+    bearer: Option<&str>,
+) -> Result<usize, NewEmbedderError> {
+    let v = embed(client, options, bearer, ["test"].as_slice(), 1)
+        .map_err(NewEmbedderError::could_not_determine_dimension)?;
+    // unwrap: guaranteed that v.len() == 1, otherwise the previous line terminated in error
+    Ok(v.first().unwrap().dimension())
+}
+
+fn embed<S>(
+    client: &ureq::Agent,
+    options: &EmbedderOptions,
+    bearer: Option<&str>,
+    inputs: &[S],
+    expected_count: usize,
+) -> Result<Vec<Embeddings<f32>>, EmbedError>
+where
+    S: Serialize,
+{
+    let request = client.post(&options.url);
+    let request =
+        if let Some(bearer) = bearer { request.set("Authorization", bearer) } else { request };
+    let request = request.set("Content-Type", "application/json");
+
+    let input_value = match options.input_type {
+        InputType::Text => serde_json::json!(inputs.first()),
+        InputType::TextArray => serde_json::json!(inputs),
+    };
+
+    let body = match options.input_field.as_slice() {
+        [] => {
+            // inject input in body
+            input_value
+        }
+        [input] => {
+            let mut body = options.query.clone();
+
+            body.as_object_mut()
+                .ok_or_else(|| {
+                    EmbedError::rest_not_an_object(
+                        options.query.clone(),
+                        options.input_field.clone(),
+                    )
+                })?
+                .insert(input.clone(), input_value);
+            body
+        }
+        [path @ .., input] => {
+            let mut body = options.query.clone();
+
+            let mut current_value = &mut body;
+            for component in path {
+                current_value = current_value
+                    .as_object_mut()
+                    .ok_or_else(|| {
+                        EmbedError::rest_not_an_object(
+                            options.query.clone(),
+                            options.input_field.clone(),
+                        )
+                    })?
+                    .entry(component.clone())
+                    .or_insert(serde_json::json!({}));
+            }
+
+            current_value.as_object_mut().unwrap().insert(input.clone(), input_value);
+            body
+        }
+    };
+
+    for attempt in 0..7 {
+        let response = request.clone().send_json(&body);
+        let result = check_response(response);
+
+        let retry_duration = match result {
+            Ok(response) => return response_to_embedding(response, options, expected_count),
+            Err(retry) => {
+                tracing::warn!("Failed: {}", retry.error);
+                retry.into_duration(attempt)
+            }
+        }?;
+
+        let retry_duration = retry_duration.min(std::time::Duration::from_secs(60)); // don't wait more than a minute
+        tracing::warn!("Attempt #{}, retrying after {}ms.", attempt, retry_duration.as_millis());
+        std::thread::sleep(retry_duration);
+    }
+
+    let response = request.send_json(&body);
+    let result = check_response(response);
+    result
+        .map_err(Retry::into_error)
+        .and_then(|response| response_to_embedding(response, options, expected_count))
+}
+
+fn check_response(response: Result<ureq::Response, ureq::Error>) -> Result<ureq::Response, Retry> {
+    match response {
+        Ok(response) => Ok(response),
+        Err(ureq::Error::Status(code, response)) => {
+            let error_response: Option<String> = response.into_string().ok();
+            Err(match code {
+                401 => Retry::give_up(EmbedError::rest_unauthorized(error_response)),
+                429 => Retry::rate_limited(EmbedError::rest_too_many_requests(error_response)),
+                400 => Retry::give_up(EmbedError::rest_bad_request(error_response)),
+                500..=599 => {
+                    Retry::retry_later(EmbedError::rest_internal_server_error(code, error_response))
+                }
+                402..=499 => {
+                    Retry::give_up(EmbedError::rest_other_status_code(code, error_response))
+                }
+                _ => Retry::retry_later(EmbedError::rest_other_status_code(code, error_response)),
+            })
+        }
+        Err(ureq::Error::Transport(transport)) => {
+            Err(Retry::retry_later(EmbedError::rest_network(transport)))
+        }
+    }
+}
+
+fn response_to_embedding(
+    response: ureq::Response,
+    options: &EmbedderOptions,
+    expected_count: usize,
+) -> Result<Vec<Embeddings<f32>>, EmbedError> {
+    let response: serde_json::Value =
+        response.into_json().map_err(EmbedError::rest_response_deserialization)?;
+
+    let mut current_value = &response;
+    for component in &options.path_to_embeddings {
+        let component = component.as_ref();
+        current_value = current_value.get(component).ok_or_else(|| {
+            EmbedError::rest_response_missing_embeddings(
+                response.clone(),
+                component,
+                &options.path_to_embeddings,
+            )
+        })?;
+    }
+
+    let embeddings = match options.input_type {
+        InputType::Text => {
+            for component in &options.embedding_object {
+                current_value = current_value.get(component).ok_or_else(|| {
+                    EmbedError::rest_response_missing_embeddings(
+                        response.clone(),
+                        component,
+                        &options.embedding_object,
+                    )
+                })?;
+            }
+            let embeddings = current_value.to_owned();
+            let embeddings: Embedding =
+                serde_json::from_value(embeddings).map_err(EmbedError::rest_response_format)?;
+
+            vec![Embeddings::from_single_embedding(embeddings)]
+        }
+        InputType::TextArray => {
+            let empty = vec![];
+            let values = current_value.as_array().unwrap_or(&empty);
+            let mut embeddings: Vec<Embeddings<f32>> = Vec::with_capacity(expected_count);
+            for value in values {
+                let mut current_value = value;
+                for component in &options.embedding_object {
+                    current_value = current_value.get(component).ok_or_else(|| {
+                        EmbedError::rest_response_missing_embeddings(
+                            response.clone(),
+                            component,
+                            &options.embedding_object,
+                        )
+                    })?;
+                }
+                let embedding = current_value.to_owned();
+                let embedding: Embedding =
+                    serde_json::from_value(embedding).map_err(EmbedError::rest_response_format)?;
+                embeddings.push(Embeddings::from_single_embedding(embedding));
+            }
+            embeddings
+        }
+    };
+
+    if embeddings.len() != expected_count {
+        return Err(EmbedError::rest_response_embedding_count(expected_count, embeddings.len()));
+    }
+
+    Ok(embeddings)
+}

milli/src/vector/settings.rs

@@ -1,6 +1,7 @@
 use deserr::Deserr;
 use serde::{Deserialize, Serialize};
 
+use super::rest::InputType;
 use super::{ollama, openai};
 use crate::prompt::PromptData;
 use crate::update::Setting;
@@ -29,6 +30,24 @@ pub struct EmbeddingSettings {
     #[serde(default, skip_serializing_if = "Setting::is_not_set")]
     #[deserr(default)]
     pub document_template: Setting<String>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub url: Setting<String>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub query: Setting<serde_json::Value>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub input_field: Setting<Vec<String>>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub path_to_embeddings: Setting<Vec<String>>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub embedding_object: Setting<Vec<String>>,
+    #[serde(default, skip_serializing_if = "Setting::is_not_set")]
+    #[deserr(default)]
+    pub input_type: Setting<InputType>,
 }
 
 pub fn check_unset<T>(
@@ -75,20 +94,42 @@ impl EmbeddingSettings {
     pub const DIMENSIONS: &'static str = "dimensions";
     pub const DOCUMENT_TEMPLATE: &'static str = "documentTemplate";
 
+    pub const URL: &'static str = "url";
+    pub const QUERY: &'static str = "query";
+    pub const INPUT_FIELD: &'static str = "inputField";
+    pub const PATH_TO_EMBEDDINGS: &'static str = "pathToEmbeddings";
+    pub const EMBEDDING_OBJECT: &'static str = "embeddingObject";
+    pub const INPUT_TYPE: &'static str = "inputType";
+
     pub fn allowed_sources_for_field(field: &'static str) -> &'static [EmbedderSource] {
         match field {
-            Self::SOURCE => {
+            Self::SOURCE => &[
-                &[EmbedderSource::HuggingFace, EmbedderSource::OpenAi, EmbedderSource::UserProvided]
+                EmbedderSource::HuggingFace,
-            }
+                EmbedderSource::OpenAi,
+                EmbedderSource::UserProvided,
+                EmbedderSource::Rest,
+                EmbedderSource::Ollama,
+            ],
             Self::MODEL => {
                 &[EmbedderSource::HuggingFace, EmbedderSource::OpenAi, EmbedderSource::Ollama]
             }
             Self::REVISION => &[EmbedderSource::HuggingFace],
-            Self::API_KEY => &[EmbedderSource::OpenAi],
+            Self::API_KEY => &[EmbedderSource::OpenAi, EmbedderSource::Rest],
-            Self::DIMENSIONS => &[EmbedderSource::OpenAi, EmbedderSource::UserProvided],
+            Self::DIMENSIONS => {
-            Self::DOCUMENT_TEMPLATE => {
+                &[EmbedderSource::OpenAi, EmbedderSource::UserProvided, EmbedderSource::Rest]
-                &[EmbedderSource::HuggingFace, EmbedderSource::OpenAi, EmbedderSource::Ollama]
             }
+            Self::DOCUMENT_TEMPLATE => &[
+                EmbedderSource::HuggingFace,
+                EmbedderSource::OpenAi,
+                EmbedderSource::Ollama,
+                EmbedderSource::Rest,
+            ],
+            Self::URL => &[EmbedderSource::Rest],
+            Self::QUERY => &[EmbedderSource::Rest],
+            Self::INPUT_FIELD => &[EmbedderSource::Rest],
+            Self::PATH_TO_EMBEDDINGS => &[EmbedderSource::Rest],
+            Self::EMBEDDING_OBJECT => &[EmbedderSource::Rest],
+            Self::INPUT_TYPE => &[EmbedderSource::Rest],
             _other => unreachable!("unknown field"),
         }
     }
@@ -107,6 +148,18 @@ impl EmbeddingSettings {
             }
             EmbedderSource::Ollama => &[Self::SOURCE, Self::MODEL, Self::DOCUMENT_TEMPLATE],
             EmbedderSource::UserProvided => &[Self::SOURCE, Self::DIMENSIONS],
+            EmbedderSource::Rest => &[
+                Self::SOURCE,
+                Self::API_KEY,
+                Self::DIMENSIONS,
+                Self::DOCUMENT_TEMPLATE,
+                Self::URL,
+                Self::QUERY,
+                Self::INPUT_FIELD,
+                Self::PATH_TO_EMBEDDINGS,
+                Self::EMBEDDING_OBJECT,
+                Self::INPUT_TYPE,
+            ],
         }
     }
 
@@ -141,6 +194,7 @@ pub enum EmbedderSource {
     HuggingFace,
     Ollama,
     UserProvided,
+    Rest,
 }
 
 impl std::fmt::Display for EmbedderSource {
@@ -150,6 +204,7 @@ impl std::fmt::Display for EmbedderSource {
             EmbedderSource::HuggingFace => "huggingFace",
             EmbedderSource::UserProvided => "userProvided",
             EmbedderSource::Ollama => "ollama",
+            EmbedderSource::Rest => "rest",
         };
         f.write_str(s)
     }
@@ -157,8 +212,20 @@ impl std::fmt::Display for EmbedderSource {
 
 impl EmbeddingSettings {
     pub fn apply(&mut self, new: Self) {
-        let EmbeddingSettings { source, model, revision, api_key, dimensions, document_template } =
+        let EmbeddingSettings {
-            new;
+            source,
+            model,
+            revision,
+            api_key,
+            dimensions,
+            document_template,
+            url,
+            query,
+            input_field,
+            path_to_embeddings,
+            embedding_object,
+            input_type,
+        } = new;
         let old_source = self.source;
         self.source.apply(source);
         // Reinitialize the whole setting object on a source change
@@ -170,6 +237,12 @@ impl EmbeddingSettings {
                 api_key,
                 dimensions,
                 document_template,
+                url,
+                query,
+                input_field,
+                path_to_embeddings,
+                embedding_object,
+                input_type,
             };
             return;
         }
@@ -179,6 +252,13 @@ impl EmbeddingSettings {
         self.api_key.apply(api_key);
         self.dimensions.apply(dimensions);
         self.document_template.apply(document_template);
+
+        self.url.apply(url);
+        self.query.apply(query);
+        self.input_field.apply(input_field);
+        self.path_to_embeddings.apply(path_to_embeddings);
+        self.embedding_object.apply(embedding_object);
+        self.input_type.apply(input_type);
     }
 }
 
@@ -193,6 +273,12 @@ impl From<EmbeddingConfig> for EmbeddingSettings {
                 api_key: Setting::NotSet,
                 dimensions: Setting::NotSet,
                 document_template: Setting::Set(prompt.template),
+                url: Setting::NotSet,
+                query: Setting::NotSet,
+                input_field: Setting::NotSet,
+                path_to_embeddings: Setting::NotSet,
+                embedding_object: Setting::NotSet,
+                input_type: Setting::NotSet,
             },
             super::EmbedderOptions::OpenAi(options) => Self {
                 source: Setting::Set(EmbedderSource::OpenAi),
@@ -201,14 +287,26 @@ impl From<EmbeddingConfig> for EmbeddingSettings {
                 api_key: options.api_key.map(Setting::Set).unwrap_or_default(),
                 dimensions: options.dimensions.map(Setting::Set).unwrap_or_default(),
                 document_template: Setting::Set(prompt.template),
+                url: Setting::NotSet,
+                query: Setting::NotSet,
+                input_field: Setting::NotSet,
+                path_to_embeddings: Setting::NotSet,
+                embedding_object: Setting::NotSet,
+                input_type: Setting::NotSet,
             },
             super::EmbedderOptions::Ollama(options) => Self {
                 source: Setting::Set(EmbedderSource::Ollama),
-                model: Setting::Set(options.embedding_model.name().to_owned()),
+                model: Setting::Set(options.embedding_model.to_owned()),
                 revision: Setting::NotSet,
                 api_key: Setting::NotSet,
                 dimensions: Setting::NotSet,
                 document_template: Setting::Set(prompt.template),
+                url: Setting::NotSet,
+                query: Setting::NotSet,
+                input_field: Setting::NotSet,
+                path_to_embeddings: Setting::NotSet,
+                embedding_object: Setting::NotSet,
+                input_type: Setting::NotSet,
             },
             super::EmbedderOptions::UserProvided(options) => Self {
                 source: Setting::Set(EmbedderSource::UserProvided),
@@ -217,6 +315,37 @@ impl From<EmbeddingConfig> for EmbeddingSettings {
                 api_key: Setting::NotSet,
                 dimensions: Setting::Set(options.dimensions),
                 document_template: Setting::NotSet,
+                url: Setting::NotSet,
+                query: Setting::NotSet,
+                input_field: Setting::NotSet,
+                path_to_embeddings: Setting::NotSet,
+                embedding_object: Setting::NotSet,
+                input_type: Setting::NotSet,
+            },
+            super::EmbedderOptions::Rest(super::rest::EmbedderOptions {
+                api_key,
+                // TODO: support distribution
+                distribution: _,
+                dimensions,
+                url,
+                query,
+                input_field,
+                path_to_embeddings,
+                embedding_object,
+                input_type,
+            }) => Self {
+                source: Setting::Set(EmbedderSource::Rest),
+                model: Setting::NotSet,
+                revision: Setting::NotSet,
+                api_key: api_key.map(Setting::Set).unwrap_or_default(),
+                dimensions: dimensions.map(Setting::Set).unwrap_or_default(),
+                document_template: Setting::Set(prompt.template),
+                url: Setting::Set(url),
+                query: Setting::Set(query),
+                input_field: Setting::Set(input_field),
+                path_to_embeddings: Setting::Set(path_to_embeddings),
+                embedding_object: Setting::Set(embedding_object),
+                input_type: Setting::Set(input_type),
             },
         }
     }
@@ -225,8 +354,20 @@ impl From<EmbeddingConfig> for EmbeddingSettings {
 impl From<EmbeddingSettings> for EmbeddingConfig {
     fn from(value: EmbeddingSettings) -> Self {
         let mut this = Self::default();
-        let EmbeddingSettings { source, model, revision, api_key, dimensions, document_template } =
+        let EmbeddingSettings {
-            value;
+            source,
+            model,
+            revision,
+            api_key,
+            dimensions,
+            document_template,
+            url,
+            query,
+            input_field,
+            path_to_embeddings,
+            embedding_object,
+            input_type,
+        } = value;
         if let Some(source) = source.set() {
             match source {
                 EmbedderSource::OpenAi => {
@@ -248,7 +389,7 @@ impl From<EmbeddingSettings> for EmbeddingConfig {
                     let mut options: ollama::EmbedderOptions =
                         super::ollama::EmbedderOptions::with_default_model();
                     if let Some(model) = model.set() {
-                        options.embedding_model = super::ollama::EmbeddingModel::from_name(&model);
+                        options.embedding_model = model;
                     }
                     this.embedder_options = super::EmbedderOptions::Ollama(options);
                 }
@@ -274,6 +415,26 @@ impl From<EmbeddingSettings> for EmbeddingConfig {
                             dimensions: dimensions.set().unwrap(),
                         });
                 }
+                EmbedderSource::Rest => {
+                    let embedder_options = super::rest::EmbedderOptions::default();
+
+                    this.embedder_options =
+                        super::EmbedderOptions::Rest(super::rest::EmbedderOptions {
+                            api_key: api_key.set(),
+                            distribution: None,
+                            dimensions: dimensions.set(),
+                            url: url.set().unwrap(),
+                            query: query.set().unwrap_or(embedder_options.query),
+                            input_field: input_field.set().unwrap_or(embedder_options.input_field),
+                            path_to_embeddings: path_to_embeddings
+                                .set()
+                                .unwrap_or(embedder_options.path_to_embeddings),
+                            embedding_object: embedding_object
+                                .set()
+                                .unwrap_or(embedder_options.embedding_object),
+                            input_type: input_type.set().unwrap_or(embedder_options.input_type),
+                        })
+                }
             }
         }