IDBObserver: Lifetime Management: Adding Observer

content/child/indexed_db/indexed_db_dispatcher.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_CHILD_INDEXED_DB_INDEXED_DB_DISPATCHER_H_
 #define CONTENT_CHILD_INDEXED_DB_INDEXED_DB_DISPATCHER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 18 matching lines @@
 
 struct IndexedDBDatabaseMetadata;
 struct IndexedDBMsg_CallbacksSuccessCursorContinue_Params;
 struct IndexedDBMsg_CallbacksSuccessCursorPrefetch_Params;
 struct IndexedDBMsg_CallbacksSuccessIDBCursor_Params;
 struct IndexedDBMsg_CallbacksSuccessArray_Params;
 struct IndexedDBMsg_CallbacksSuccessValue_Params;
 struct IndexedDBMsg_CallbacksUpgradeNeeded_Params;
 
 namespace blink {
+class IDBObserver;
 class WebData;
 }
 
 namespace content {
 class IndexedDBKey;
 class IndexedDBKeyPath;
 class IndexedDBKeyRange;
 class WebIDBCursorImpl;
 class WebIDBDatabaseImpl;
 class ThreadSafeSender;
@@ skipping 17 matching lines @@
   // WorkerThread::Observer implementation.
   void WillStopCurrentWorkerThread() override;
 
   static blink::WebIDBMetadata ConvertMetadata(
       const IndexedDBDatabaseMetadata& idb_metadata);
 
   void OnMessageReceived(const IPC::Message& msg);
 
   // This method is virtual so it can be overridden in unit tests.
   virtual bool Send(IPC::Message* msg);
 

[dmurph, 2016/06/15 12:49:44]

Also add RemoveIDBObservers, which accepts a vector of IDs, and is called by
webidbdatabase_impl in close()

+  void AddIDBObserver(int32_t ipc_database_id,

[dmurph, 2016/06/15 12:49:43]

Have this return the observe ID so you can store it in the webdatabase_impl

[palakj1, 2016/06/16 07:05:41]

Done

+                      int64_t transaction_id,
+                      blink::IDBObserver* observer);
+
   void RequestIDBFactoryGetDatabaseNames(blink::WebIDBCallbacks* callbacks,
                                          const url::Origin& origin);
 
   void RequestIDBFactoryOpen(const base::string16& name,
                              int64_t version,
                              int64_t transaction_id,
                              blink::WebIDBCallbacks* callbacks,
                              blink::WebIDBDatabaseCallbacks* database_callbacks,
                              const url::Origin& origin);
 
@@ skipping 157 matching lines @@
   void OnForcedClose(int32_t ipc_thread_id, int32_t ipc_database_id);
   void OnVersionChange(int32_t ipc_thread_id,
                        int32_t ipc_database_id,
                        int64_t old_version,
                        int64_t new_version);
 
   // Reset cursor prefetch caches for all cursors except exception_cursor_id.
   void ResetCursorPrefetchCaches(int64_t transaction_id,
                                  int32_t ipc_exception_cursor_id);
 
+  // int64_t nextObserverId() {
+  //   // Only keep a 32-bit counter to allow ports to use the other 32
+  //   // bits of the id.
+  //   // overflow??
+  //   static int currentObserverId = 0;
+  //   return atomicIncrement(&currentObserverId);
+  // }
+
   scoped_refptr<ThreadSafeSender> thread_safe_sender_;
 
   // Maximum size (in bytes) of value/key pair allowed for put requests. Any
   // requests larger than this size will be rejected.
   // Used by unit tests to exercise behavior without allocating huge chunks
   // of memory.
   size_t max_put_value_size_ = kMaxIDBMessageSizeInBytes;
-
+  int maxObserverId = 0;

[dmurph, 2016/06/15 12:49:44]

remove this since IDMap will handle id allocation.

   // Careful! WebIDBCallbacks wraps non-threadsafe data types. It must be
   // destroyed and used on the same thread it was created on.
   IDMap<blink::WebIDBCallbacks, IDMapOwnPointer> pending_callbacks_;
   IDMap<blink::WebIDBDatabaseCallbacks, IDMapOwnPointer>
       pending_database_callbacks_;
 
   // Maps the ipc_callback_id from an open cursor request to the request's
   // transaction_id. Used to assign the transaction_id to the WebIDBCursorImpl
   // when it is created.
   std::map<int32_t, int64_t> cursor_transaction_ids_;
 
   // Map from cursor id to WebIDBCursorImpl.
   std::map<int32_t, WebIDBCursorImpl*> cursors_;
 
   std::map<int32_t, WebIDBDatabaseImpl*> databases_;
+  std::map<int64_t, blink::IDBObserver*> observers_;

[dmurph, 2016/06/15 12:49:44]

Use IDMap like above, but we need to make sure the lifetime story works. This
means we'll be using a RefPtr. So something like:
IDMap<RefPtr<blink::IDBObserver>, IDMapOwnPointer>>

The only quirk here is that we'll be allocating the RefPtr on the heap and not
the stack, as the map expects to be given a pointer.

[palakj1, 2016/06/16 07:05:40]

Do we use IDMap cause it provides some performance benefits (auto generating id)
over std::map? Or can we not use std::map in this context at all?
Also, I can't make IDMap work with IDBObserver, unable to include it in header
(relative path trouble) and IDMap has a concrete destructor, so forward
declaration doesn't work. 
Deferring it to another patch.

 
   DISALLOW_COPY_AND_ASSIGN(IndexedDBDispatcher);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_INDEXED_DB_INDEXED_DB_DISPATCHER_H_