database: handle event deletions in DatabaseIndexes::index_event

Add `DatabaseIndexes::has_been_deleted`
Check if `EventId` was deleted in `NostrDatabase::has_event_already_been_saved`

crates/nostr-database/src/index.rs

@@ -123,6 +123,7 @@ pub struct EventIndexResult {
 #[derive(Debug, Clone, Default)]
 pub struct DatabaseIndexes {
     index: Arc<RwLock<BTreeSet<EventIndex>>>,
+    deleted: Arc<RwLock<HashSet<EventId>>>,
 }
 
 impl DatabaseIndexes {
@@ -148,6 +149,8 @@ impl DatabaseIndexes {
     }
 
     /// Index [`Event`]
+    ///
+    /// **This method assume that [`Event`] was already verified**
     #[tracing::instrument(skip_all, level = "trace")]
     pub async fn index_event(&self, event: &Event) -> EventIndexResult {
         // Check if it's expired or ephemeral
@@ -186,6 +189,18 @@ impl DatabaseIndexes {
                 }
                 None => should_insert = false,
             }
+        } else if event.kind == Kind::EventDeletion {
+            let mut deleted = self.deleted.write().await;
+            let ids = event.event_ids().copied();
+            let filter = Filter::new().ids(ids);
+            let pubkey_prefix: PublicKeyPrefix = PublicKeyPrefix::from(event.pubkey);
+            for ev in self.internal_query(&index, filter).await {
+                if ev.pubkey == pubkey_prefix {
+                    to_discard.insert(ev.event_id);
+                    deleted.insert(ev.event_id);
+                }
+            }
+            // TODO: support event deletion by coordinate (`a` tag)
         }
 
         // Remove events
@@ -253,6 +268,12 @@ impl DatabaseIndexes {
         matching_ids.into_iter().map(|e| e.event_id).collect()
     }
 
+    /// Check if an event was deleted
+    pub async fn has_been_deleted(&self, event_id: &EventId) -> bool {
+        let deleted = self.deleted.read().await;
+        deleted.contains(event_id)
+    }
+
     /// Clear indexes
     pub async fn clear(&self) {
         let mut index = self.index.write().await;

crates/nostr-database/src/memory.rs

@@ -112,7 +112,9 @@ impl NostrDatabase for MemoryDatabase {
     }
 
     async fn has_event_already_been_saved(&self, event_id: EventId) -> Result<bool, Self::Err> {
-        if self.opts.events {
+        if self.indexes.has_been_deleted(&event_id).await {
+            Ok(true)
+        } else if self.opts.events {
             let events = self.events.read().await;
             Ok(events.contains_key(&event_id))
         } else {

crates/nostr-indexeddb/src/lib.rs

@@ -301,12 +301,16 @@ impl_nostr_database!({
         &self,
         event_id: EventId,
     ) -> Result<bool, IndexedDBError> {
-        let tx = self
-            .db
-            .transaction_on_one_with_mode(EVENTS_CF, IdbTransactionMode::Readonly)?;
-        let store = tx.object_store(EVENTS_CF)?;
-        let key = JsValue::from(event_id.to_hex());
-        Ok(store.get(&key)?.await?.is_some())
+        if self.indexes.has_been_deleted(&event_id).await {
+            Ok(true)
+        } else {
+            let tx = self
+                .db
+                .transaction_on_one_with_mode(EVENTS_CF, IdbTransactionMode::Readonly)?;
+            let store = tx.object_store(EVENTS_CF)?;
+            let key = JsValue::from(event_id.to_hex());
+            Ok(store.get(&key)?.await?.is_some())
+        }
     }
 
     async fn has_event_already_been_seen(&self, event_id: EventId) -> Result<bool, IndexedDBError> {

crates/nostr-rocksdb/src/lib.rs

@@ -199,8 +199,12 @@ impl NostrDatabase for RocksDatabase {
     }
 
     async fn has_event_already_been_saved(&self, event_id: EventId) -> Result<bool, Self::Err> {
-        let cf = self.cf_handle(EVENTS_CF)?;
-        Ok(self.db.key_may_exist_cf(&cf, event_id.as_bytes()))
+        if self.indexes.has_been_deleted(&event_id).await {
+            Ok(true)
+        } else {
+            let cf = self.cf_handle(EVENTS_CF)?;
+            Ok(self.db.key_may_exist_cf(&cf, event_id.as_bytes()))
+        }
     }
 
     async fn has_event_already_been_seen(&self, event_id: EventId) -> Result<bool, Self::Err> {

crates/nostr-sqlite/src/lib.rs

@@ -175,19 +175,23 @@ impl NostrDatabase for SQLiteDatabase {
     }
 
     async fn has_event_already_been_saved(&self, event_id: EventId) -> Result<bool, Self::Err> {
-        let conn = self.acquire().await?;
-        conn.interact(move |conn| {
-            let mut stmt = conn.prepare_cached(
-                "SELECT EXISTS(SELECT 1 FROM events WHERE event_id = ? LIMIT 1);",
-            )?;
-            let mut rows = stmt.query([event_id.to_hex()])?;
-            let exists: u8 = match rows.next()? {
-                Some(row) => row.get(0)?,
-                None => 0,
-            };
-            Ok(exists == 1)
-        })
-        .await?
+        if self.indexes.has_been_deleted(&event_id).await {
+            Ok(true)
+        } else {
+            let conn = self.acquire().await?;
+            conn.interact(move |conn| {
+                let mut stmt = conn.prepare_cached(
+                    "SELECT EXISTS(SELECT 1 FROM events WHERE event_id = ? LIMIT 1);",
+                )?;
+                let mut rows = stmt.query([event_id.to_hex()])?;
+                let exists: u8 = match rows.next()? {
+                    Some(row) => row.get(0)?,
+                    None => 0,
+                };
+                Ok(exists == 1)
+            })
+            .await?
+        }
     }
 
     async fn has_event_already_been_seen(&self, event_id: EventId) -> Result<bool, Self::Err> {