IndexedDB: Recycle cursor objects when calling continue().

content/renderer/indexed_db_dispatcher.cc

Index: content/renderer/indexed_db_dispatcher.cc
diff --git a/content/renderer/indexed_db_dispatcher.cc b/content/renderer/indexed_db_dispatcher.cc
index c3eea0e949e87aa64a1326f261f215cdc2ec8a60..e2b7d304719b16281dc93f83c1932568f4069433 100644
--- a/content/renderer/indexed_db_dispatcher.cc
+++ b/content/renderer/indexed_db_dispatcher.cc
@@ -42,6 +42,8 @@ bool IndexedDBDispatcher::OnMessageReceived(const IPC::Message& msg) {
   IPC_BEGIN_MESSAGE_MAP(IndexedDBDispatcher, msg)
     IPC_MESSAGE_HANDLER(IndexedDBMsg_CallbacksSuccessIDBCursor,
                         OnSuccessOpenCursor)
+    IPC_MESSAGE_HANDLER(IndexedDBMsg_CallbacksSuccessCursorContinue,
+                        OnSuccessCursorContinue)
     IPC_MESSAGE_HANDLER(IndexedDBMsg_CallbacksSuccessIDBDatabase,
                         OnSuccessIDBDatabase)
     IPC_MESSAGE_HANDLER(IndexedDBMsg_CallbacksSuccessIndexedDBKey,
@@ -85,10 +87,13 @@ void IndexedDBDispatcher::RequestIDBCursorContinue(
   scoped_ptr<WebIDBCallbacks> callbacks(callbacks_ptr);
 
   int32 response_id = pending_callbacks_.Add(callbacks.release());
+  pending_cursor_continues_[response_id] = idb_cursor_id;
   RenderThreadImpl::current()->Send(
       new IndexedDBHostMsg_CursorContinue(idb_cursor_id, response_id, key, ec));
-  if (*ec)
+  if (*ec) {
     pending_callbacks_.Remove(response_id);
+    pending_cursor_continues_.erase(idb_cursor_id);
+  }
 }
 
 void IndexedDBDispatcher::RequestIDBCursorDelete(
@@ -432,9 +437,32 @@ void IndexedDBDispatcher::OnSuccessOpenCursor(int32 repsonse_id,
       pending_callbacks_.Lookup(repsonse_id);
   callbacks->onSuccess(new RendererWebIDBCursorImpl(object_id, key,
                        primaryKey, value));

[dgrogan, 2011/10/29 00:54:28]

You can remove the non-object_id parameters.

[hans, 2011/10/31 16:11:52]

Done.

+
+  cursor_key_[object_id] = key;

[dgrogan, 2011/10/29 00:54:28]

If the onSuccess call is synchronous, shouldn't these be before it?  I don't
know if it is.

[hans, 2011/10/31 16:11:52]

It's not synchronous, but it certainly looks weird. Fixed.

+  cursor_primary_key_[object_id] = primaryKey;
+  cursor_value_[object_id] = value;
+
   pending_callbacks_.Remove(repsonse_id);
 }
 
+void IndexedDBDispatcher::OnSuccessCursorContinue(
+    int32 response_id,

[michaeln, 2011/10/30 21:54:06]

cursor_id could be a useful here, i think you wouldn't need the
pending_cursor_continues_ map

[hans, 2011/10/31 16:11:52]

Done.

+    const IndexedDBKey& key,
+    const IndexedDBKey& primary_key,
+    const content::SerializedScriptValue& value) {
+  int32 cursor_id = pending_cursor_continues_[response_id];
+

[michaeln, 2011/10/30 21:54:06]

Is there any chance the cursor was deleted prior to this completion callback?

[hans, 2011/10/31 16:11:52]

No, according to the comment in ~RendererWebIDBCursorImpl, the callback object
holds a reference to the cursor.

+  cursor_key_[cursor_id] = key;
+  cursor_primary_key_[cursor_id] = primary_key;
+  cursor_value_[cursor_id] = value;

[michaeln, 2011/10/30 21:54:06]

The RendererWebIDBCursorImpl has data members for each of these things. It might
be cleaner to keep these values in an instance of that object instead of in
these maps.

I think what's missing is a way to lookup a RendererWebIDBCursorImpl by id.

std::map<int32, RendererWebIDBCursorImpl*> cursors_; 

[hans, 2011/10/31 16:11:52]

Yes, doing that.
Doing that.

+
+  WebIDBCallbacks* callbacks = pending_callbacks_.Lookup(response_id);
+  callbacks->onSuccessCursorContinue();
+
+  pending_callbacks_.Remove(response_id);
+  pending_cursor_continues_.erase(response_id);
+}
+
 void IndexedDBDispatcher::OnBlocked(int32 response_id) {
   WebIDBCallbacks* callbacks = pending_callbacks_.Lookup(response_id);
   callbacks->onBlocked();
@@ -470,3 +498,22 @@ void IndexedDBDispatcher::OnVersionChange(int32 database_id,
   if (callbacks)
     callbacks->onVersionChange(newVersion);
 }
+
+IndexedDBKey IndexedDBDispatcher::getCursorKey(int32 cursor_id) {
+  return cursor_key_[cursor_id];
+}
+
+IndexedDBKey IndexedDBDispatcher::getCursorPrimaryKey(int32 cursor_id) {
+  return cursor_primary_key_[cursor_id];
+}
+
+content::SerializedScriptValue IndexedDBDispatcher::getCursorValue(
+    int32 cursor_id) {
+  return cursor_value_[cursor_id];
+}
+
+void IndexedDBDispatcher::CursorDestroyed(int32 cursor_id) {
+  cursor_key_.erase(cursor_id);
+  cursor_primary_key_.erase(cursor_id);
+  cursor_value_.erase(cursor_id);
+}