Dispatch IndexedDB IPC messages to worker threads

content/renderer/indexed_db_dispatcher.h

Index: content/renderer/indexed_db_dispatcher.h
diff --git a/content/renderer/indexed_db_dispatcher.h b/content/renderer/indexed_db_dispatcher.h
index 28071580c195e2ce2c271bc67bf566306b97c46a..870d4536c6a7de5bc7a4aa78de97b052725ea9d2 100644
--- a/content/renderer/indexed_db_dispatcher.h
+++ b/content/renderer/indexed_db_dispatcher.h
@@ -11,6 +11,8 @@
 
 #include "base/id_map.h"
 #include "base/nullable_string16.h"
+#include "content/common/child_thread.h"
+#include "content/renderer/indexed_db_message_filter.h"
 #include "ipc/ipc_channel.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebExceptionCode.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebIDBCallbacks.h"
@@ -32,13 +34,14 @@ class SerializedScriptValue;
 }
 
 // Handle the indexed db related communication for this entire renderer.
-class IndexedDBDispatcher : public IPC::Channel::Listener {
+class IndexedDBDispatcher :
+  public base::RefCountedThreadSafe<IndexedDBDispatcher> {
  public:
-  IndexedDBDispatcher();
+  IndexedDBDispatcher(IndexedDBMessageFilter*);
   virtual ~IndexedDBDispatcher();
 
-  // IPC::Channel::Listener implementation.
-  virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
+  void OnMessageReceived(const IPC::Message& msg);
+  void Send(IPC::Message* msg);
 
   void RequestIDBFactoryGetDatabaseNames(
       WebKit::WebIDBCallbacks* callbacks,
@@ -184,13 +187,47 @@ class IndexedDBDispatcher : public IPC::Channel::Listener {
   void OnComplete(int32 transaction_id);
   void OnVersionChange(int32 database_id, const string16& newVersion);
 
+  // This class facilitates mapping incoming ids to threads.  It:
+  // * Gets process-unique ids for each stored IDBCallbacks.
+  // * Registers incoming transaction and database ids that are created in
+  //   the browser process.  We'll need to revisit this scheme if the browser
+  //   stops generating unique ids.
+  // * Ensures, through IDMap, that it is only called on a single thread.

[hans, 2011/11/30 15:05:40]

mabye point out in the comments that this map is intended to map from ids to
callbacks? or maybe rename the T typename to CallbacksType or something?

I was just confused below because it looked like a generic map, but the
parameters were called "callbacks".
Or maybe just rename those parameters to "value" or something?

[dgrogan, 2011/11/30 21:34:35]

You're right.  Updated the comments and name to reflect that this is only
intended to be used with callbacks.

[michaeln, 2011/11/30 21:48:14]

"ThreadSafe" usually means safe to call from multiple threads, but that's not
your intent here.

[dgrogan, 2011/11/30 23:25:18]

You're right.  I renamed it CallbacksIDMap in a later patch.

+  template<class T>
+  class ThreadSafeIDMap

[hans, 2011/11/30 15:05:40]

ultra nit: curly brace on same line

[dgrogan, 2011/11/30 21:34:35]

Done.

+  {
+   public:
+    ThreadSafeIDMap(IndexedDBMessageFilter* filter) {
+      filter_ = filter;

[hans, 2011/11/30 15:05:40]

nit: maybe use constructor initializer list?

[dgrogan, 2011/11/30 21:34:35]

Done.

+    }
+    void AddWithID(T* callbacks, int32 id) {
+      filter_->NotifyAddWithIDForType(id, callbacks);
+      map_.AddWithID(callbacks, id);
+    }
+    int32 Add(T* callbacks) {
+      int id = filter_->GetUniqueID();
+      map_.AddWithID(callbacks, id);
+      return id;
+    }
+    void Remove(int32 id) {
+      filter_->RemoveForType(id, (T*)NULL);
+      map_.Remove(id);
+    }
+    T* Lookup(int32 id) {
+      return map_.Lookup(id);
+    }
+   private:
+    // The filter is alive for the life of the process, nothing deletes it.
+    IndexedDBMessageFilter* filter_;
+    IDMap<T, IDMapOwnPointer> map_;
+  };
+
   // Careful! WebIDBCallbacks wraps non-threadsafe data types. It must be
   // destroyed and used on the same thread it was created on.
-  IDMap<WebKit::WebIDBCallbacks, IDMapOwnPointer> pending_callbacks_;
-  IDMap<WebKit::WebIDBTransactionCallbacks, IDMapOwnPointer>
+  ThreadSafeIDMap<WebKit::WebIDBCallbacks> pending_callbacks_;
+  ThreadSafeIDMap<WebKit::WebIDBTransactionCallbacks>
       pending_transaction_callbacks_;
-  IDMap<WebKit::WebIDBDatabaseCallbacks, IDMapOwnPointer>
-      pending_database_callbacks_;
+  ThreadSafeIDMap<WebKit::WebIDBDatabaseCallbacks> pending_database_callbacks_;
 
   // Map from cursor id to RendererWebIDBCursorImpl.
   std::map<int32, RendererWebIDBCursorImpl*> cursors_;