fix(search): Make adding events to index idempotent.

crates/matrix-sdk-search/src/index.rs

@@ -14,15 +14,15 @@
 
 use std::{fmt, fs, path::Path, sync::Arc};
 
-use ruma::{OwnedEventId, OwnedRoomId, RoomId, events::AnySyncMessageLikeEvent};
+use ruma::{EventId, OwnedEventId, OwnedRoomId, RoomId, events::AnySyncMessageLikeEvent};
 use tantivy::{
     Index, IndexReader, TantivyDocument,
     collector::TopDocs,
     directory::{MmapDirectory, error::OpenDirectoryError},
     query::QueryParser,
     schema::Value,
 };
-use tracing::error;
+use tracing::{error, warn};
 
 use crate::{
     OpStamp, TANTIVY_INDEX_MEMORY_BUDGET,
@@ -129,9 +129,15 @@ impl RoomIndex {
     /// This which will add/remove/edit an event in the index based on the
     /// event type.
     pub fn handle_event(&mut self, event: AnySyncMessageLikeEvent) -> Result<(), IndexError> {
+        let event_id = event.event_id().to_owned();
+
         match self.schema.handle_event(event)? {
-            RoomIndexOperation::Add(document) => self.writer.add_document(document)?,
-        };
+            RoomIndexOperation::Add(document) => {
+                if !self.contains(&event_id) {
+                    self.writer.add_document(document)?;
+                }
+            }
+        }
         Ok(())
     }
 
@@ -184,6 +190,17 @@ impl RoomIndex {
 
         Ok(ret)
     }
+
+    fn contains(&self, event_id: &EventId) -> bool {
+        let search_result = self.search(format!("event_id:\"{event_id}\"").as_str(), 1);
+        match search_result {
+            Ok(results) => !results.is_empty(),
+            Err(err) => {
+                warn!("Failed to check if event has been indexed, assuming it has: {err}");
+                true
+            }
+        }
+    }
 }
 
 #[cfg(test)]
@@ -283,4 +300,76 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn test_index_contains_false() -> Result<(), Box<dyn Error>> {
+        let room_id = room_id!("!room_id:localhost");
+        let mut index =
+            RoomIndex::new_in_memory(room_id).expect("failed to make index in ram: {index:?}");
+
+        let event_id = event_id!("$event_id:localhost");
+
+        index.commit_and_reload()?;
+
+        assert!(!index.contains(event_id), "Index should not contain event");
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_index_contains_true() -> Result<(), Box<dyn Error>> {
+        let room_id = room_id!("!room_id:localhost");
+        let mut index =
+            RoomIndex::new_in_memory(room_id).expect("failed to make index in ram: {index:?}");
+
+        let event_id = event_id!("$event_id:localhost");
+        let event = EventFactory::new()
+            .text_msg("This is a sentence")
+            .event_id(event_id)
+            .room(room_id)
+            .sender(user_id!("@user_id:localhost"))
+            .into_any_sync_message_like_event();
+
+        index.handle_event(event)?;
+
+        index.commit_and_reload()?;
+
+        assert!(index.contains(event_id), "Index should contain event");
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_indexing_idempotency() -> Result<(), Box<dyn Error>> {
+        let room_id = room_id!("!room_id:localhost");
+        let mut index =
+            RoomIndex::new_in_memory(room_id).expect("failed to make index in ram: {index:?}");
+
+        let event_id = event_id!("$event_id:localhost");
+        let event = EventFactory::new()
+            .text_msg("This is a sentence")
+            .event_id(event_id)
+            .room(room_id)
+            .sender(user_id!("@user_id:localhost"))
+            .into_any_sync_message_like_event();
+
+        index.handle_event(event.clone())?;
+
+        index.commit_and_reload()?;
+
+        assert!(index.contains(event_id), "Index should contain event");
+
+        // indexing again should do nothing
+        index.handle_event(event)?;
+
+        index.commit_and_reload()?;
+
+        assert!(index.contains(event_id), "Index should still contain event");
+
+        let result = index.search("sentence", 10).expect("search failed with: {result:?}");
+
+        assert_eq!(result.len(), 1, "Index should have ignored second indexing");
+
+        Ok(())
+    }
 }