DatabaseBackend should not post a task to an already terminated database thread

Source/modules/webdatabase/Database.cpp

 /*
  * Copyright (C) 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 241 matching lines @@
 {
     visitor->trace(m_databaseContext);
     visitor->trace(m_sqliteDatabase);
     visitor->trace(m_databaseAuthorizer);
     visitor->trace(m_transactionQueue);
 }
 
 bool Database::openAndVerifyVersion(bool setVersionInNewDatabase, DatabaseError& error, String& errorMessage)
 {
     TaskSynchronizer synchronizer;
-    if (!databaseContext()->databaseThread() || databaseContext()->databaseThread()->terminationRequested(&synchronizer))
+    if (!databaseContext()->databaseThreadAvailable())
         return false;
 
     DatabaseTracker::tracker().prepareToOpenDatabase(this);
     bool success = false;
     OwnPtr<DatabaseOpenTask> task = DatabaseOpenTask::create(this, setVersionInNewDatabase, &synchronizer, error, errorMessage, success);
     databaseContext()->databaseThread()->scheduleTask(task.release());
     synchronizer.waitForTaskCompletion();
 
     return success;
 }
@@ skipping 50 matching lines @@
 }
 
 void Database::scheduleTransaction()
 {
     ASSERT(!m_transactionInProgressMutex.tryLock()); // Locked by caller.
     RefPtrWillBeRawPtr<SQLTransactionBackend> transaction = nullptr;
 
     if (m_isTransactionQueueEnabled && !m_transactionQueue.isEmpty())
         transaction = m_transactionQueue.takeFirst();
 
-    if (transaction && databaseContext()->databaseThread()) {
+    if (transaction && databaseContext()->databaseThreadAvailable()) {
         OwnPtr<DatabaseTransactionTask> task = DatabaseTransactionTask::create(transaction);
         WTF_LOG(StorageAPI, "Scheduling DatabaseTransactionTask %p for transaction %p\n", task.get(), task->transaction());
         m_transactionInProgress = true;
         databaseContext()->databaseThread()->scheduleTask(task.release());
     } else {
         m_transactionInProgress = false;
     }
 }
 
 void Database::scheduleTransactionStep(SQLTransactionBackend* transaction)
 {
-    if (!databaseContext()->databaseThread())
+    if (!databaseContext()->databaseThreadAvailable())
         return;
 
     OwnPtr<DatabaseTransactionTask> task = DatabaseTransactionTask::create(transaction);
     WTF_LOG(StorageAPI, "Scheduling DatabaseTransactionTask %p for the transaction step\n", task.get());
     databaseContext()->databaseThread()->scheduleTask(task.release());
 }
 
 SQLTransactionClient* Database::transactionClient() const
 {
     return databaseContext()->databaseThread()->transactionClient();
@@ skipping 420 matching lines @@
 }
 
 ExecutionContext* Database::executionContext() const
 {
     return databaseContext()->executionContext();
 }
 
 void Database::closeImmediately()
 {
     ASSERT(executionContext()->isContextThread());
-    DatabaseThread* databaseThread = databaseContext()->databaseThread();
-    if (databaseThread && !databaseThread->terminationRequested() && opened()) {
+    if (databaseContext()->databaseThreadAvailable() && opened()) {
         logErrorMessage("forcibly closing database");
-        databaseThread->scheduleTask(DatabaseCloseTask::create(this, 0));
+        databaseContext()->databaseThread()->scheduleTask(DatabaseCloseTask::create(this, 0));
     }
 }
 
 void Database::changeVersion(
     const String& oldVersion,
     const String& newVersion,
     PassOwnPtrWillBeRawPtr<SQLTransactionCallback> callback,
     PassOwnPtrWillBeRawPtr<SQLTransactionErrorCallback> errorCallback,
     PassOwnPtrWillBeRawPtr<VoidCallback> successCallback)
 {
@@ skipping 106 matching lines @@
     return tableNames;
 }
 
 Vector<String> Database::tableNames()
 {
     // FIXME: Not using isolatedCopy on these strings looks ok since threads
     // take strict turns in dealing with them. However, if the code changes,
     // this may not be true anymore.
     Vector<String> result;
     TaskSynchronizer synchronizer;
-    if (!databaseContext()->databaseThread() || databaseContext()->databaseThread()->terminationRequested(&synchronizer))
+    if (!databaseContext()->databaseThreadAvailable())
         return result;
 
     OwnPtr<DatabaseTableNamesTask> task = DatabaseTableNamesTask::create(this, &synchronizer, result);
     databaseContext()->databaseThread()->scheduleTask(task.release());
     synchronizer.waitForTaskCompletion();
 
     return result;
 }
 
 SecurityOrigin* Database::securityOrigin() const
 {
     if (executionContext()->isContextThread())
         return m_contextThreadSecurityOrigin.get();
     if (databaseContext()->databaseThread()->isDatabaseThread())
         return m_databaseThreadSecurityOrigin.get();
     return 0;
 }
 
 } // namespace blink