meilisearch/src/store/updates.rs

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use std::convert::TryInto;
use rkv::Value;
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use crate::update::Update;
#[derive(Copy, Clone)]
pub struct Updates {
pub(crate) updates: rkv::SingleStore,
}
impl Updates {
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// TODO we should use the MDB_LAST op but
// it is not exposed by the rkv library
fn last_update_id<'a, T: rkv::Readable>(
&self,
reader: &'a T,
) -> Result<Option<(u64, Option<Value<'a>>)>, rkv::StoreError>
{
let mut last = None;
let iter = self.updates.iter_start(reader)?;
for result in iter {
let (key, data) = result?;
last = Some((key, data));
}
let (last_key, last_data) = match last {
Some(entry) => entry,
None => return Ok(None),
};
let array = last_key.try_into().unwrap();
let number = u64::from_be_bytes(array);
Ok(Some((number, last_data)))
}
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pub fn contains<T: rkv::Readable>(
&self,
reader: &T,
update_id: u64,
) -> Result<bool, rkv::StoreError>
{
let update_id_bytes = update_id.to_be_bytes();
self.updates.get(reader, update_id_bytes).map(|v| v.is_some())
}
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pub fn push_back(
&self,
writer: &mut rkv::Writer,
update: &Update,
) -> Result<u64, rkv::StoreError>
{
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let last_update_id = self.last_update_id(writer)?;
let last_update_id = last_update_id.map_or(0, |(n, _)| n + 1);
let last_update_id_bytes = last_update_id.to_be_bytes();
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let update = rmp_serde::to_vec_named(&update).unwrap();
let blob = Value::Blob(&update);
self.updates.put(writer, last_update_id_bytes, &blob)?;
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Ok(last_update_id)
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}
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pub fn pop_back(
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&self,
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writer: &mut rkv::Writer,
) -> Result<Option<(u64, Update)>, rkv::StoreError>
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{
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let (last_id, last_data) = match self.last_update_id(writer)? {
Some(entry) => entry,
None => return Ok(None),
};
match last_data {
Some(Value::Blob(bytes)) => {
let update = rmp_serde::from_read_ref(&bytes).unwrap();
Ok(Some((last_id, update)))
},
Some(value) => panic!("invalid type {:?}", value),
None => Ok(None),
}
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}
}