From 48aae76b154d6e7014dc0f2fb3b689c28ae45990 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Lecrenier?= <loic.lecrenier@me.com>
Date: Tue, 21 Feb 2023 09:48:05 +0100
Subject: [PATCH] Introduce a function to find the docids of a set of paths in
 a graph

---
 .../new/ranking_rule_graph/resolve_paths.rs   | 81 +++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 milli/src/search/new/ranking_rule_graph/resolve_paths.rs

diff --git a/milli/src/search/new/ranking_rule_graph/resolve_paths.rs b/milli/src/search/new/ranking_rule_graph/resolve_paths.rs
new file mode 100644
index 000000000..76823a32a
--- /dev/null
+++ b/milli/src/search/new/ranking_rule_graph/resolve_paths.rs
@@ -0,0 +1,81 @@
+#![allow(clippy::too_many_arguments)]
+
+use heed::RoTxn;
+use roaring::{MultiOps, RoaringBitmap};
+
+use super::edge_docids_cache::EdgeDocidsCache;
+use super::empty_paths_cache::EmptyPathsCache;
+use super::paths_map::PathsMap;
+use super::{RankingRuleGraph, RankingRuleGraphTrait};
+use crate::new::db_cache::DatabaseCache;
+use crate::new::ranking_rule_graph::Edge;
+use crate::new::BitmapOrAllRef;
+use crate::{Index, Result};
+
+impl<G: RankingRuleGraphTrait> RankingRuleGraph<G> {
+    pub fn resolve_paths<'transaction>(
+        &mut self,
+        index: &Index,
+        txn: &'transaction RoTxn,
+        db_cache: &mut DatabaseCache<'transaction>,
+        edge_docids_cache: &mut EdgeDocidsCache<G>,
+        empty_paths_cache: &mut EmptyPathsCache,
+        universe: &RoaringBitmap,
+        mut paths: PathsMap<u64>,
+    ) -> Result<RoaringBitmap> {
+        let mut path_bitmaps = vec![];
+
+        paths.remove_edges(&empty_paths_cache.empty_edges);
+        paths.remove_prefixes(&empty_paths_cache.empty_prefixes);
+
+        'path_loop: while let Some((edge_indexes, _)) = paths.remove_first() {
+            // if path is excluded, continue...
+            let mut processed_edges = vec![];
+            let mut path_bitmap = universe.clone();
+            'edge_loop: for edge_index in edge_indexes {
+                processed_edges.push(edge_index);
+                let edge_docids =
+                    edge_docids_cache.get_edge_docids(index, txn, db_cache, &edge_index, self)?;
+                match edge_docids {
+                    BitmapOrAllRef::Bitmap(edge_docids) => {
+                        if edge_docids.is_disjoint(universe) {
+                            // 1. Store in the cache that this edge is empty for this universe
+                            empty_paths_cache.empty_edges.insert(edge_index);
+                            // 2. remove all the paths that contain this edge for this universe
+                            paths.remove_edge(&edge_index);
+                            // 3. remove this edge from the proximity graph
+
+                            self.remove_edge(edge_index);
+
+                            // 4. continue executing this function again on the remaining paths
+                            continue 'path_loop;
+                        } else {
+                            path_bitmap &= edge_docids;
+                            if path_bitmap.is_disjoint(universe) {
+                                // 1. Store in the cache that this prefix is empty for this universe
+                                empty_paths_cache
+                                    .empty_prefixes
+                                    .insert(processed_edges.iter().copied(), ());
+                                // 2. remove all the paths beginning with this prefix
+                                paths.remove_prefix(&processed_edges);
+                                // 3. continue executing this function again on the remaining paths?
+                                continue 'path_loop;
+                            }
+                        }
+                    }
+                    BitmapOrAllRef::All => continue 'edge_loop,
+                }
+            }
+            path_bitmaps.push(path_bitmap);
+        }
+        let docids = MultiOps::union(path_bitmaps);
+        Ok(docids)
+        // for each path, translate it to an intersection of cached roaring bitmaps
+        // then do a union for all paths
+
+        // get the docids of the given paths in the proximity graph
+        // in the fastest possible way
+        // 1. roaring MultiOps (before we can do the Frozen+AST thing)
+        // 2. minimize number of operations
+    }
+}