Oilpan: Prepare to move SQLTransactionBackendSync and SQLTransactionSync to Oilpan heap.

Source/modules/webdatabase/SQLTransactionBackendSync.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 44 matching lines @@
     : m_database(db)
     , m_callback(callback)
     , m_readOnly(readOnly)
     , m_hasVersionMismatch(false)
     , m_modifiedDatabase(false)
     , m_transactionClient(adoptPtr(new SQLTransactionClient()))
 {
     ASSERT(m_database->executionContext()->isContextThread());
 }
 
+void SQLTransactionBackendSync::rollbackIfInProgress()
+{
+    ASSERT(!m_database->executionContext() || m_database->executionContext()->isContextThread());
+    if (m_sqliteTransaction && m_sqliteTransaction->inProgress())
+        rollback();
+}
+
 SQLTransactionBackendSync::~SQLTransactionBackendSync()
 {
-    ASSERT(m_database->executionContext()->isContextThread());
-    if (m_sqliteTransaction && m_sqliteTransaction->inProgress())
-        rollback();
+#if ENABLE(OILPAN)
+    ASSERT(!m_sqliteTransaction || !m_sqliteTransaction->inProgress());
+#else
+    rollbackIfInProgress();
+#endif
+}
+
+void SQLTransactionBackendSync::trace(Visitor* visitor)
+{
+    visitor->trace(m_database);
 }
 
 PassRefPtr<SQLResultSet> SQLTransactionBackendSync::executeSQL(const String& sqlStatement, const Vector<SQLValue>& arguments, ExceptionState& exceptionState)
 {
     ASSERT(m_database->executionContext()->isContextThread());
 
     m_database->setLastErrorMessage("");
 
     if (!m_database->opened()) {
         m_database->setLastErrorMessage("cannot executeSQL because the database is not open");
@@ skipping 142 matching lines @@
     if (m_database->hadDeletes())
         m_database->incrementalVacuumIfNeeded();
 
     // The commit was successful. If the transaction modified this database, notify the delegates.
     if (m_modifiedDatabase)
         m_transactionClient->didCommitWriteTransaction(database());
 
     m_database->reportCommitTransactionResult(0, -1, 0); // OK
 }
 
+// This can be called during GC. Do not allocate new on-heap objects.

[Vyacheslav Egorov (Google), 2014/03/18 07:54:55]

I don't think comments like this scale as long you call more than one function
inside because they should also essentially have the same comment.

Sadly I don't see any good way to handle this.

We can consider annotating functions that can be called during GC with a special
attribute and checking their bodies transitively but that would soon turn into a
mess probably.

 void SQLTransactionBackendSync::rollback()
 {
-    ASSERT(m_database->executionContext()->isContextThread());
+    ASSERT(!m_database->executionContext() || m_database->executionContext()->isContextThread());
     m_database->disableAuthorizer();
     if (m_sqliteTransaction) {

[Vyacheslav Egorov (Google), 2014/03/18 07:54:55]

from my reading of the code this whole if can be just replaced with
m_sqliteTransaction.clear() because destructor does rollback.

SQLiteTransaction::~SQLiteTransaction()
{
    if (m_inProgress)
        rollback();
}

         m_sqliteTransaction->rollback();
         m_sqliteTransaction.clear();
     }
     m_database->enableAuthorizer();
 
     ASSERT(!m_database->sqliteDatabase().transactionInProgress());
 }
 
 } // namespace WebCore