IDBObserver: Lifetime Management: Adding Observer

content/browser/indexed_db/indexed_db_transaction.h

 // Copyright (c) 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_BROWSER_INDEXED_DB_INDEXED_DB_TRANSACTION_H_
 #define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_TRANSACTION_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <queue>
 #include <set>
 #include <stack>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "content/browser/indexed_db/indexed_db_backing_store.h"
+#include "content/browser/indexed_db/indexed_db_connection.h"
 #include "content/browser/indexed_db/indexed_db_database.h"
 #include "content/browser/indexed_db/indexed_db_database_error.h"
 #include "third_party/WebKit/public/platform/modules/indexeddb/WebIDBTypes.h"
 
 namespace content {
 
 class BlobWriteCallbackImpl;
 class IndexedDBCursor;
 class IndexedDBDatabaseCallbacks;
+class IndexedDBObserver;
 
 class CONTENT_EXPORT IndexedDBTransaction
     : public NON_EXPORTED_BASE(base::RefCounted<IndexedDBTransaction>) {
  public:
   typedef base::Callback<void(IndexedDBTransaction*)> Operation;
 
   enum State {
     CREATED,     // Created, but not yet started by coordinator.
     STARTED,     // Started by the coordinator.
     COMMITTING,  // In the process of committing, possibly waiting for blobs
@@ skipping 16 matching lines @@
   }
   void ScheduleTask(blink::WebIDBTaskType, Operation task);
   void ScheduleAbortTask(Operation abort_task);
   void RegisterOpenCursor(IndexedDBCursor* cursor);
   void UnregisterOpenCursor(IndexedDBCursor* cursor);
   void AddPreemptiveEvent() { pending_preemptive_events_++; }
   void DidCompletePreemptiveEvent() {
     pending_preemptive_events_--;
     DCHECK_GE(pending_preemptive_events_, 0);
   }
+  void AddPendingObserver(int32_t observer_id);
+  // Removes |pending_observer_ids| from |pending_observers_| if it is present.

[cmumford, 2016/07/01 18:35:01]

Nit: I think the comment is a little odd because pending_observers_ isn't a
collection of the same type, and it really deletes the observer too. Maybe a
less specific comment like:

// Delete pending observers with ID's listed in |pending_observer_ids|.

[palakj1, 2016/07/02 00:48:14]

Done.

+  void RemovePendingObservers(const std::vector<int32_t>& pending_observer_ids);
+
   IndexedDBBackingStore::Transaction* BackingStoreTransaction() {
     return transaction_.get();
   }
   int64_t id() const { return id_; }
 
   IndexedDBDatabase* database() const { return database_.get(); }
-  IndexedDBDatabaseCallbacks* connection() const { return callbacks_.get(); }

[cmumford, 2016/07/01 18:35:01]

Thanks for fixing this incorrect name.

+  IndexedDBDatabaseCallbacks* callbacks() const { return callbacks_.get(); }
+  IndexedDBConnection* connection() const { return connection_.get(); }
 
   State state() const { return state_; }
   bool IsTimeoutTimerRunning() const { return timeout_timer_.IsRunning(); }
 
   struct Diagnostics {
     base::Time creation_time;
     base::Time start_time;
     int tasks_scheduled;
     int tasks_completed;
   };
 
   const Diagnostics& diagnostics() const { return diagnostics_; }
 
  protected:
   // Test classes may derive, but most creation should be done via
   // IndexedDBClassFactory.
   IndexedDBTransaction(
       int64_t id,
-      scoped_refptr<IndexedDBDatabaseCallbacks> callbacks,
+      base::WeakPtr<IndexedDBConnection> connection,
       const std::set<int64_t>& object_store_ids,
       blink::WebIDBTransactionMode mode,
-      IndexedDBDatabase* db,
       IndexedDBBackingStore::Transaction* backing_store_transaction);
   virtual ~IndexedDBTransaction();
 
   // May be overridden in tests.
   virtual base::TimeDelta GetInactivityTimeout() const;
 
  private:
   friend class BlobWriteCallbackImpl;
   friend class IndexedDBClassFactory;
   friend class base::RefCounted<IndexedDBTransaction>;
 
   FRIEND_TEST_ALL_PREFIXES(IndexedDBTransactionTestMode, AbortPreemptive);
   FRIEND_TEST_ALL_PREFIXES(IndexedDBTransactionTestMode, AbortTasks);
   FRIEND_TEST_ALL_PREFIXES(IndexedDBTransactionTest, NoTimeoutReadOnly);
   FRIEND_TEST_ALL_PREFIXES(IndexedDBTransactionTest,
                            SchedulePreemptiveTask);
   FRIEND_TEST_ALL_PREFIXES(IndexedDBTransactionTestMode,
                            ScheduleNormalTask);
   FRIEND_TEST_ALL_PREFIXES(IndexedDBTransactionTest, Timeout);
+  FRIEND_TEST_ALL_PREFIXES(IndexedDBTransactionTest, IndexedDBObserver);
 
   void RunTasksIfStarted();
 
   bool IsTaskQueueEmpty() const;
   bool HasPendingTasks() const;
 
   void BlobWriteComplete(bool success);
   void ProcessTaskQueue();
   void CloseOpenCursors();
   leveldb::Status CommitPhaseTwo();
   void Timeout();
 
   const int64_t id_;
   const std::set<int64_t> object_store_ids_;
   const blink::WebIDBTransactionMode mode_;
 
   bool used_;
   State state_;
   bool commit_pending_;
+  base::WeakPtr<IndexedDBConnection> connection_;
+  // TODO(palakj): Eliminate callbacks_ and database_ as we already have

[cmumford, 2016/07/01 18:35:01]

Same on this TODO - it'd be great to consolidate these now before ever landing
in the codebase. I generally try to only add a TODO when I see something that
already exists that needs to be changed. However, if it's new code I try to do
it "right" the first time.

https://google.github.io/styleguide/cppguide.html#TODO_Comments

[palakj1, 2016/07/02 00:48:14]

I am not sure if I can eliminate these. callbacks_ and database_ are
scoped_refptr. 
I have it as a TODO cause I'd need some guidance here.

+  // connection_.
   scoped_refptr<IndexedDBDatabaseCallbacks> callbacks_;
   scoped_refptr<IndexedDBDatabase> database_;
 
+  // These observers do not listen to changes until they are activated.

[cmumford, 2016/07/01 18:35:01]

Nit: delete "They" and "they are".

[palakj1, 2016/07/02 00:48:14]

Done.

+  std::vector<std::unique_ptr<IndexedDBObserver>> pending_observers_;
+
   class TaskQueue {
    public:
     TaskQueue();
     ~TaskQueue();
     bool empty() const { return queue_.empty(); }
     void push(Operation task) { queue_.push(task); }
     Operation pop();
     void clear();
 
    private:
@@ skipping 33 matching lines @@
   // requests are processed before the timer fires, assume the script is
   // unresponsive and abort to unblock the transaction queue.
   base::OneShotTimer timeout_timer_;
 
   Diagnostics diagnostics_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_TRANSACTION_H_