[IndexedDB] Adding transaction and value support to observers

content/browser/indexed_db/indexed_db_connection.cc

 // 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.
 
 #include "content/browser/indexed_db/indexed_db_connection.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "content/browser/indexed_db/indexed_db_class_factory.h"
 #include "content/browser/indexed_db/indexed_db_database_callbacks.h"
 #include "content/browser/indexed_db/indexed_db_observer.h"
 #include "content/browser/indexed_db/indexed_db_tracing.h"
 #include "content/browser/indexed_db/indexed_db_transaction.h"
 
 namespace content {
 
 namespace {
-
+static const int64_t kMaxObserverTransactionId = -1ll;
 static int32_t next_id;
 
 }  // namespace
 
 IndexedDBConnection::IndexedDBConnection(
     int child_process_id,
     scoped_refptr<IndexedDBDatabase> database,
     scoped_refptr<IndexedDBDatabaseCallbacks> callbacks)
     : id_(next_id++),
       child_process_id_(child_process_id),
@@ skipping 122 matching lines @@
   base::WeakPtr<IndexedDBTransaction> transaction_ptr =
       transaction->ptr_factory_.GetWeakPtr();
   transactions_[transaction->id()] = std::move(transaction);
   return transaction_ptr;
 }
 
 void IndexedDBConnection::RemoveTransaction(int64_t id) {
   transactions_.erase(id);
 }
 
+int64_t IndexedDBConnection::NewObserverTransactionId() {
+  // If we ever overflow, just reset the ID.

[jsbell, 2017/01/13 00:14:12]

At 1000 transaction/sec that's 285000 years. But good to be safe. :)

[dmurph, 2017/01/13 01:50:42]

haha sgtm.

+  if (next_observer_transaction_id_ == kMaxObserverTransactionId) {

[jsbell, 2017/01/13 00:14:12]

nit: no need for {}

[dmurph, 2017/01/13 01:50:42]

Done.

+    next_observer_transaction_id_ = 1ll << 32;
+  }
+  return next_observer_transaction_id_++;

[jsbell, 2017/01/13 00:14:12]

Maybe DCHECK that the high bits are not 0 ?

(which is the critical thing here)

[dmurph, 2017/01/13 01:50:42]

Done.

+}
+
 }  // namespace content