Revert of DatabaseBackend objects should be destructed in the originator thread

Source/modules/webdatabase/DatabaseThread.cpp

 /*
  * Copyright (C) 2007, 2008, 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 30 matching lines @@
 DatabaseThread::DatabaseThread()
     : m_transactionClient(adoptPtr(new SQLTransactionClient()))
     , m_transactionCoordinator(adoptPtr(new SQLTransactionCoordinator()))
     , m_cleanupSync(0)
     , m_terminationRequested(false)
 {
 }
 
 DatabaseThread::~DatabaseThread()
 {
-    ASSERT(m_thread);
-    ASSERT(!isDatabaseThread());
     bool terminationRequested;
     {
         MutexLocker lock(m_terminationRequestedMutex);
         terminationRequested = m_terminationRequested;
     }
     if (!terminationRequested)
         requestTermination(0);
     m_thread.clear();
 }
 
@@ skipping 28 matching lines @@
 void DatabaseThread::cleanupDatabaseThread()
 {
     WTF_LOG(StorageAPI, "Cleaning up DatabaseThread %p", this);
 
     // Clean up the list of all pending transactions on this database thread
     m_transactionCoordinator->shutdown();
 
     // Close the databases that we ran transactions on. This ensures that if any transactions are still open, they are rolled back and we don't leave the database in an
     // inconsistent or locked state.
     if (m_openDatabaseSet.size() > 0) {
-        DatabaseSet::iterator end = m_openDatabaseSet.end();
-        for (DatabaseSet::iterator it = m_openDatabaseSet.begin(); it != end; ++it)
+        // As the call to close will modify the original set, we must take a copy to iterate over.
+        DatabaseSet openSetCopy;
+        openSetCopy.swap(m_openDatabaseSet);
+        DatabaseSet::iterator end = openSetCopy.end();
+        for (DatabaseSet::iterator it = openSetCopy.begin(); it != end; ++it)
             (*it).get()->close();
     }
 
     if (m_cleanupSync) // Someone wanted to know when we were done cleaning up.
         m_thread->postTask(new Task(WTF::bind(&DatabaseTaskSynchronizer::taskCompleted, m_cleanupSync)));
 }
 
 void DatabaseThread::recordDatabaseOpen(DatabaseBackend* database)
 {
     ASSERT(isDatabaseThread());
     ASSERT(database);
     ASSERT(!m_openDatabaseSet.contains(database));
     m_openDatabaseSet.add(database);
 }
 
 void DatabaseThread::recordDatabaseClosed(DatabaseBackend* database)
 {
 #ifndef ASSERT_DISABLED
     MutexLocker lock(m_terminationRequestedMutex);
 #endif
     ASSERT(isDatabaseThread());
-    ASSERT_UNUSED(database, database);
+    ASSERT(database);
     ASSERT(m_terminationRequested || m_openDatabaseSet.contains(database));
-    // We'll clear m_openDatabaseSet in the destructor.
+    m_openDatabaseSet.remove(database);
+}
+
+bool DatabaseThread::isDatabaseOpen(DatabaseBackend* database)
+{
+    ASSERT(isDatabaseThread());
+    ASSERT(database);
+    MutexLocker lock(m_terminationRequestedMutex);
+    return !m_terminationRequested && m_openDatabaseSet.contains(database);
 }
 
 void DatabaseThread::scheduleTask(PassOwnPtr<DatabaseTask> task)
 {
     ASSERT(m_thread);
     ASSERT(!task->hasSynchronizer() || task->hasCheckedForTermination());
     // WebThread takes ownership of the task.
     m_thread->postTask(task.leakPtr());
 }
 
 } // namespace WebCore