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 * modification, are permitted provided that the following conditions
 * are met:
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 * 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
 *     documentation and/or other materials provided with the distribution.
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "modules/webdatabase/DatabaseThread.h"

#include "modules/webdatabase/Database.h"
#include "modules/webdatabase/DatabaseTask.h"
#include "modules/webdatabase/SQLTransactionClient.h"
#include "modules/webdatabase/SQLTransactionCoordinator.h"
#include "modules/webdatabase/StorageLog.h"
#include "platform/CrossThreadFunctional.h"
#include "platform/WaitableEvent.h"
#include "platform/WebThreadSupportingGC.h"
#include "public/platform/Platform.h"
#include "wtf/PtrUtil.h"
#include <memory>

namespace blink {

DatabaseThread::DatabaseThread()
    : m_transactionClient(WTF::makeUnique<SQLTransactionClient>()),
      m_cleanupSync(nullptr),
      m_terminationRequested(false) {
  DCHECK(isMainThread());
}

DatabaseThread::~DatabaseThread() {
  ASSERT(m_openDatabaseSet.isEmpty());
  ASSERT(!m_thread);
}

DEFINE_TRACE(DatabaseThread) {}

void DatabaseThread::start() {
  ASSERT(isMainThread());
  if (m_thread)
    return;
  m_thread = WebThreadSupportingGC::create("WebCore: Database");
  m_thread->postTask(BLINK_FROM_HERE,
                     crossThreadBind(&DatabaseThread::setupDatabaseThread,
                                     wrapCrossThreadPersistent(this)));
}

void DatabaseThread::setupDatabaseThread() {
  m_thread->initialize();
  m_transactionCoordinator = new SQLTransactionCoordinator();
}

void DatabaseThread::terminate() {
  ASSERT(isMainThread());
  WaitableEvent sync;
  {
    MutexLocker lock(m_terminationRequestedMutex);
    ASSERT(!m_terminationRequested);
    m_terminationRequested = true;
    m_cleanupSync = &sync;
    STORAGE_DVLOG(1) << "DatabaseThread " << this << " was asked to terminate";
    m_thread->postTask(BLINK_FROM_HERE,
                       crossThreadBind(&DatabaseThread::cleanupDatabaseThread,
                                       wrapCrossThreadPersistent(this)));
  }
  sync.wait();
  // The WebThread destructor blocks until all the tasks of the database
  // thread are processed. However, it shouldn't block at all because
  // the database thread has already finished processing the cleanup task.
  m_thread.reset();
}

void DatabaseThread::cleanupDatabaseThread() {
  DCHECK(isDatabaseThread());

  STORAGE_DVLOG(1) << "Cleaning up DatabaseThread " << 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) {
    // As the call to close will modify the original set, we must take a copy to
    // iterate over.
    HashSet<CrossThreadPersistent<Database>> openSetCopy;
    openSetCopy.swap(m_openDatabaseSet);
    HashSet<CrossThreadPersistent<Database>>::iterator end = openSetCopy.end();
    for (HashSet<CrossThreadPersistent<Database>>::iterator it =
             openSetCopy.begin();
         it != end; ++it)
      (*it)->close();
  }
  m_openDatabaseSet.clear();

  m_thread->postTask(BLINK_FROM_HERE,
                     WTF::bind(&DatabaseThread::cleanupDatabaseThreadCompleted,
                               wrapCrossThreadPersistent(this)));
}

void DatabaseThread::cleanupDatabaseThreadCompleted() {
  m_thread->shutdown();
  if (m_cleanupSync)  // Someone wanted to know when we were done cleaning up.
    m_cleanupSync->signal();
}

void DatabaseThread::recordDatabaseOpen(Database* database) {
  ASSERT(isDatabaseThread());
  ASSERT(database);
  ASSERT(!m_openDatabaseSet.contains(database));
  MutexLocker lock(m_terminationRequestedMutex);
  if (!m_terminationRequested)
    m_openDatabaseSet.add(database);
}

void DatabaseThread::recordDatabaseClosed(Database* database) {
  ASSERT(isDatabaseThread());
  ASSERT(database);
#if DCHECK_IS_ON()
  {
    MutexLocker lock(m_terminationRequestedMutex);
    ASSERT(m_terminationRequested || m_openDatabaseSet.contains(database));
  }
#endif
  m_openDatabaseSet.remove(database);
}

bool DatabaseThread::isDatabaseOpen(Database* database) {
  ASSERT(isDatabaseThread());
  ASSERT(database);
  MutexLocker lock(m_terminationRequestedMutex);
  return !m_terminationRequested && m_openDatabaseSet.contains(database);
}

bool DatabaseThread::isDatabaseThread() const {
  // This function is called only from the main thread or the database
  // thread. If we are not in the main thread, we are in the database thread.
  return !isMainThread();
}

void DatabaseThread::scheduleTask(std::unique_ptr<DatabaseTask> task) {
  ASSERT(m_thread);
#if DCHECK_IS_ON()
  {
    MutexLocker lock(m_terminationRequestedMutex);
    ASSERT(!m_terminationRequested);
  }
#endif
  // WebThread takes ownership of the task.
  m_thread->postTask(BLINK_FROM_HERE,
                     crossThreadBind(&DatabaseTask::run, std::move(task)));
}

}  // namespace blink