Source/WebKitLegacy/Storage/StorageTracker.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2011 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
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "StorageTracker.h"

 #include "StorageThread.h"
 #include "StorageTrackerClient.h"
 #include "WebStorageNamespaceProvider.h"
 #include <WebCore/PageGroup.h>
 #include <WebCore/SQLiteDatabaseTracker.h>
 #include <WebCore/SQLiteStatement.h>
 #include <WebCore/SecurityOrigin.h>
 #include <WebCore/SecurityOriginData.h>
 #include <WebCore/TextEncoding.h>
 #include <wtf/FileSystem.h>
 #include <wtf/MainThread.h>
 #include <wtf/StdLibExtras.h>
 #include <wtf/Vector.h>
 #include <wtf/text/CString.h>

 #if PLATFORM(IOS_FAMILY)
 #include <pal/spi/ios/SQLite3SPI.h>
 #endif

 using namespace WebCore;

 namespace WebKit {

 static StorageTracker* storageTracker = nullptr;

 // If there is no document referencing a storage database, close the underlying database
 // after it has been idle for m_StorageDatabaseIdleInterval seconds.
 static const Seconds defaultStorageDatabaseIdleInterval { 300_s };

 void StorageTracker::initializeTracker(const String& storagePath, StorageTrackerClient* client)
 {
     ASSERT(isMainThread());
     ASSERT(!storageTracker || !storageTracker->m_client);

     if (!storageTracker)
         storageTracker = new StorageTracker(storagePath);

     storageTracker->m_client = client;
     storageTracker->m_needsInitialization = true;
 }

 void StorageTracker::internalInitialize()
 {
     m_needsInitialization = false;

     ASSERT(isMainThread());

     // Make sure text encoding maps have been built on the main thread, as the StorageTracker thread might try to do it there instead.
     // FIXME (<rdar://problem/9127819>): Is there a more explicit way of doing this besides accessing the UTF8Encoding?
     UTF8Encoding();

     storageTracker->setIsActive(true);
     storageTracker->m_thread->start();
     storageTracker->importOriginIdentifiers();

     m_thread->dispatch([this] {
         FileSystem::deleteFile(FileSystem::pathByAppendingComponent(m_storageDirectoryPath, "StorageTracker.db"));
     });
 }

 StorageTracker& StorageTracker::tracker()
 {
     if (!storageTracker)
         storageTracker = new StorageTracker("");
     if (storageTracker->m_needsInitialization)
         storageTracker->internalInitialize();

     return *storageTracker;
 }

 StorageTracker::StorageTracker(const String& storagePath)
     : m_storageDirectoryPath(storagePath.isolatedCopy())
     , m_client(0)
     , m_thread(makeUnique<StorageThread>())
     , m_isActive(false)
     , m_needsInitialization(false)
     , m_StorageDatabaseIdleInterval(defaultStorageDatabaseIdleInterval)
 {
 }

 String StorageTracker::trackerDatabasePath()
 {
     ASSERT(!m_databaseMutex.tryLock());
     return FileSystem::pathByAppendingComponent(m_storageDirectoryPath, "LegacyStorageTracker.db");
 }

 static bool ensureDatabaseFileExists(const String& fileName, bool createIfDoesNotExist)
 {
     if (createIfDoesNotExist)
         return FileSystem::makeAllDirectories(FileSystem::directoryName(fileName));

     return FileSystem::fileExists(fileName);
 }

 void StorageTracker::openTrackerDatabase(bool createIfDoesNotExist)
 {
     ASSERT(m_isActive);
     ASSERT(!isMainThread());

     SQLiteTransactionInProgressAutoCounter transactionCounter;

     ASSERT(!m_databaseMutex.tryLock());

     if (m_database.isOpen())
         return;

     String databasePath = trackerDatabasePath();

     if (!ensureDatabaseFileExists(databasePath, createIfDoesNotExist)) {
         if (createIfDoesNotExist)
             LOG_ERROR("Failed to create database file '%s'", databasePath.ascii().data());
         return;
     }

     if (!m_database.open(databasePath)) {
         LOG_ERROR("Failed to open databasePath %s.", databasePath.ascii().data());
         return;
     }

     m_database.disableThreadingChecks();

     if (!m_database.tableExists("Origins")) {
         if (!m_database.executeCommand("CREATE TABLE Origins (origin TEXT UNIQUE ON CONFLICT REPLACE, path TEXT);"))
             LOG_ERROR("Failed to create Origins table.");
     }
 }

 void StorageTracker::importOriginIdentifiers()
 {
     if (!m_isActive)
         return;

     ASSERT(isMainThread());
     ASSERT(m_thread);

     m_thread->dispatch([this] {
         syncImportOriginIdentifiers();
     });
 }

 void StorageTracker::finishedImportingOriginIdentifiers()
 {
     LockHolder locker(m_databaseMutex);
     if (m_client)
         m_client->didFinishLoadingOrigins();
 }

 void StorageTracker::syncImportOriginIdentifiers()
 {
     ASSERT(m_isActive);

     ASSERT(!isMainThread());

     {
         LockHolder locker(m_databaseMutex);

         // Don't force creation of StorageTracker's db just because a tracker
         // was initialized. It will be created if local storage dbs are found
         // by syncFileSystemAndTrackerDatabse() or the next time a local storage
         // db is created by StorageAreaSync.
         openTrackerDatabase(false);

         if (m_database.isOpen()) {
             SQLiteTransactionInProgressAutoCounter transactionCounter;

             SQLiteStatement statement(m_database, "SELECT origin FROM Origins");
             if (statement.prepare() != SQLITE_OK) {
                 LOG_ERROR("Failed to prepare statement.");
                 return;
             }

             int result;

             {
                 LockHolder lockOrigins(m_originSetMutex);
                 while ((result = statement.step()) == SQLITE_ROW)
                     m_originSet.add(statement.getColumnText(0).isolatedCopy());
             }

             if (result != SQLITE_DONE) {
                 LOG_ERROR("Failed to read in all origins from the database.");
                 return;
             }
         }
     }

     syncFileSystemAndTrackerDatabase();

     {
         LockHolder locker(m_clientMutex);

         if (m_client) {
             LockHolder locker(m_originSetMutex);
             OriginSet::const_iterator end = m_originSet.end();
             for (OriginSet::const_iterator it = m_originSet.begin(); it != end; ++it)
                 m_client->dispatchDidModifyOrigin(*it);
         }
     }

     callOnMainThread([this] {
         finishedImportingOriginIdentifiers();
     });
 }

 void StorageTracker::syncFileSystemAndTrackerDatabase()
 {
     ASSERT(!isMainThread());

     SQLiteTransactionInProgressAutoCounter transactionCounter;

     ASSERT(m_isActive);

     Vector<String> paths;
     {
         LockHolder locker(m_databaseMutex);
         paths = FileSystem::listDirectory(m_storageDirectoryPath, "*.localstorage");
     }

     // Use a copy of m_originSet to find expired entries and to schedule their
     // deletions from disk and from m_originSet.
     OriginSet originSetCopy;
     {
         LockHolder locker(m_originSetMutex);
         for (OriginSet::const_iterator it = m_originSet.begin(), end = m_originSet.end(); it != end; ++it)
             originSetCopy.add((*it).isolatedCopy());
     }

     // Add missing StorageTracker records.
     OriginSet foundOrigins;
     String fileExtension = ".localstorage"_s;

     for (Vector<String>::const_iterator it = paths.begin(), end = paths.end(); it != end; ++it) {
         const String& path = *it;

         if (path.length() > fileExtension.length() && path.endsWith(fileExtension)) {
             String file = FileSystem::pathGetFileName(path);
             String originIdentifier = file.substring(0, file.length() - fileExtension.length());
             if (!originSetCopy.contains(originIdentifier))
                 syncSetOriginDetails(originIdentifier, path);

             foundOrigins.add(originIdentifier);
         }
     }

     // Delete stale StorageTracker records.
     for (OriginSet::const_iterator it = originSetCopy.begin(), end = originSetCopy.end(); it != end; ++it) {
         const String& originIdentifier = *it;
         if (foundOrigins.contains(originIdentifier))
             continue;

         callOnMainThread([this, originIdentifier = originIdentifier.isolatedCopy()] {
             deleteOriginWithIdentifier(originIdentifier);
         });
     }
 }

 void StorageTracker::setOriginDetails(const String& originIdentifier, const String& databaseFile)
 {
     if (!m_isActive)
         return;

     {
         LockHolder locker(m_originSetMutex);

         if (m_originSet.contains(originIdentifier))
             return;

         m_originSet.add(originIdentifier);
     }

     auto function = [this, originIdentifier = originIdentifier.isolatedCopy(), databaseFile = databaseFile.isolatedCopy()] {
         syncSetOriginDetails(originIdentifier, databaseFile);
     };

     if (isMainThread()) {
         ASSERT(m_thread);
         m_thread->dispatch(WTFMove(function));
     } else {
         // FIXME: This weird ping-ponging was done to fix a deadlock. We should figure out a cleaner way to avoid it instead.
         callOnMainThread([this, function = WTFMove(function)]() mutable {
             m_thread->dispatch(WTFMove(function));
         });
     }
 }

 void StorageTracker::syncSetOriginDetails(const String& originIdentifier, const String& databaseFile)
 {
     ASSERT(!isMainThread());

     SQLiteTransactionInProgressAutoCounter transactionCounter;

     LockHolder locker(m_databaseMutex);

     openTrackerDatabase(true);

     if (!m_database.isOpen())
         return;

     SQLiteStatement statement(m_database, "INSERT INTO Origins VALUES (?, ?)");
     if (statement.prepare() != SQLITE_OK) {
         LOG_ERROR("Unable to establish origin '%s' in the tracker", originIdentifier.ascii().data());
         return;
     }

     statement.bindText(1, originIdentifier);
     statement.bindText(2, databaseFile);

     if (statement.step() != SQLITE_DONE)
         LOG_ERROR("Unable to establish origin '%s' in the tracker", originIdentifier.ascii().data());

     {
         LockHolder locker(m_originSetMutex);
         if (!m_originSet.contains(originIdentifier))
             m_originSet.add(originIdentifier);
     }

     {
         LockHolder locker(m_clientMutex);
         if (m_client)
             m_client->dispatchDidModifyOrigin(originIdentifier);
     }
 }

 Vector<SecurityOriginData> StorageTracker::origins()
 {
     ASSERT(m_isActive);

     if (!m_isActive)
         return { };

     LockHolder locker(m_originSetMutex);

     Vector<SecurityOriginData> result;
     result.reserveInitialCapacity(m_originSet.size());
     for (auto& identifier : m_originSet) {
         auto origin = SecurityOriginData::fromDatabaseIdentifier(identifier);
         if (!origin) {
             ASSERT_NOT_REACHED();
             continue;
         }
         result.uncheckedAppend(origin.value());
     }
     return result;
 }

 void StorageTracker::deleteAllOrigins()
 {
     ASSERT(m_isActive);
     ASSERT(isMainThread());
     ASSERT(m_thread);

     if (!m_isActive)
         return;

     {
         LockHolder locker(m_originSetMutex);
         willDeleteAllOrigins();
         m_originSet.clear();
     }

     WebStorageNamespaceProvider::clearLocalStorageForAllOrigins();

     m_thread->dispatch([this] {
         syncDeleteAllOrigins();
     });
 }

 #if PLATFORM(IOS_FAMILY)
 static void truncateDatabaseFile(SQLiteDatabase& database)
 {
     sqlite3_file_control(database.sqlite3Handle(), 0, SQLITE_TRUNCATE_DATABASE, 0);
 }
 #endif

 void StorageTracker::syncDeleteAllOrigins()
 {
     ASSERT(!isMainThread());

     SQLiteTransactionInProgressAutoCounter transactionCounter;

     LockHolder locker(m_databaseMutex);

     openTrackerDatabase(false);
     if (!m_database.isOpen())
         return;

     SQLiteStatement statement(m_database, "SELECT origin, path FROM Origins");
     if (statement.prepare() != SQLITE_OK) {
         LOG_ERROR("Failed to prepare statement.");
         return;
     }

     int result;
     while ((result = statement.step()) == SQLITE_ROW) {
         if (!canDeleteOrigin(statement.getColumnText(0)))
             continue;

         FileSystem::deleteFile(statement.getColumnText(1));

         {
             LockHolder locker(m_clientMutex);
             if (m_client)
                 m_client->dispatchDidModifyOrigin(statement.getColumnText(0));
         }
     }

     if (result != SQLITE_DONE)
         LOG_ERROR("Failed to read in all origins from the database.");

     if (m_database.isOpen()) {
 #if PLATFORM(IOS_FAMILY)
         truncateDatabaseFile(m_database);
 #endif
         m_database.close();
     }

 #if !PLATFORM(IOS_FAMILY)
     if (!FileSystem::deleteFile(trackerDatabasePath())) {
         // In the case where it is not possible to delete the database file (e.g some other program
         // like a virus scanner is accessing it), make sure to remove all entries.
         openTrackerDatabase(false);
         if (!m_database.isOpen())
             return;
         SQLiteStatement deleteStatement(m_database, "DELETE FROM Origins");
         if (deleteStatement.prepare() != SQLITE_OK) {
             LOG_ERROR("Unable to prepare deletion of all origins");
             return;
         }
         if (!deleteStatement.executeCommand()) {
             LOG_ERROR("Unable to execute deletion of all origins");
             return;
         }
     }
     FileSystem::deleteEmptyDirectory(m_storageDirectoryPath);
 #endif
 }

 void StorageTracker::deleteOriginWithIdentifier(const String& originIdentifier)
 {
     auto origin = SecurityOriginData::fromDatabaseIdentifier(originIdentifier);
     if (!origin) {
         ASSERT_NOT_REACHED();
         return;
     }
     deleteOrigin(origin.value());
 }

 void StorageTracker::deleteOrigin(const SecurityOriginData& origin)
 {
     ASSERT(m_isActive);
     ASSERT(isMainThread());
     ASSERT(m_thread);

     if (!m_isActive)
         return;

     // Before deleting database, we need to clear in-memory local storage data
     // in StorageArea, and to close the StorageArea db. It's possible for an
     // item to be added immediately after closing the db and cause StorageAreaSync
     // to reopen the db before the db is deleted by a StorageTracker thread.
     // In this case, reopening the db in StorageAreaSync will cancel a pending
     // StorageTracker db deletion.
     WebStorageNamespaceProvider::clearLocalStorageForOrigin(origin);

     String originId = origin.databaseIdentifier();

     {
         LockHolder locker(m_originSetMutex);
         willDeleteOrigin(originId);
         m_originSet.remove(originId);
     }

     m_thread->dispatch([this, originId = originId.isolatedCopy()] {
         syncDeleteOrigin(originId);
     });
 }

 void StorageTracker::syncDeleteOrigin(const String& originIdentifier)
 {
     ASSERT(!isMainThread());

     SQLiteTransactionInProgressAutoCounter transactionCounter;

     LockHolder locker(m_databaseMutex);

     if (!canDeleteOrigin(originIdentifier)) {
         LOG_ERROR("Attempted to delete origin '%s' while it was being created\n", originIdentifier.ascii().data());
         return;
     }

     openTrackerDatabase(false);
     if (!m_database.isOpen())
         return;

     String path = databasePathForOrigin(originIdentifier);
     if (path.isEmpty()) {
         // It is possible to get a request from the API to delete the storage for an origin that
         // has no such storage.
         return;
     }

     SQLiteStatement deleteStatement(m_database, "DELETE FROM Origins where origin=?");
     if (deleteStatement.prepare() != SQLITE_OK) {
         LOG_ERROR("Unable to prepare deletion of origin '%s'", originIdentifier.ascii().data());
         return;
     }
     deleteStatement.bindText(1, originIdentifier);
     if (!deleteStatement.executeCommand()) {
         LOG_ERROR("Unable to execute deletion of origin '%s'", originIdentifier.ascii().data());
         return;
     }

     FileSystem::deleteFile(path);

     bool shouldDeleteTrackerFiles = false;
     {
         LockHolder locker(m_originSetMutex);
         m_originSet.remove(originIdentifier);
         shouldDeleteTrackerFiles = m_originSet.isEmpty();
     }

     if (shouldDeleteTrackerFiles) {
 #if PLATFORM(IOS_FAMILY)
         truncateDatabaseFile(m_database);
 #endif
         m_database.close();
 #if !PLATFORM(IOS_FAMILY)
         FileSystem::deleteFile(trackerDatabasePath());
         FileSystem::deleteEmptyDirectory(m_storageDirectoryPath);
 #endif
     }

     {
         LockHolder locker(m_clientMutex);
         if (m_client)
             m_client->dispatchDidModifyOrigin(originIdentifier);
     }
 }

 void StorageTracker::willDeleteAllOrigins()
 {
     ASSERT(!m_originSetMutex.tryLock());

     OriginSet::const_iterator end = m_originSet.end();
     for (OriginSet::const_iterator it = m_originSet.begin(); it != end; ++it)
         m_originsBeingDeleted.add((*it).isolatedCopy());
 }

 void StorageTracker::willDeleteOrigin(const String& originIdentifier)
 {
     ASSERT(isMainThread());
     ASSERT(!m_originSetMutex.tryLock());

     m_originsBeingDeleted.add(originIdentifier);
 }

 bool StorageTracker::canDeleteOrigin(const String& originIdentifier)
 {
     ASSERT(!m_databaseMutex.tryLock());
     LockHolder locker(m_originSetMutex);
     return m_originsBeingDeleted.contains(originIdentifier);
 }

 void StorageTracker::cancelDeletingOrigin(const String& originIdentifier)
 {
     if (!m_isActive)
         return;

     LockHolder locker(m_databaseMutex);
     {
         LockHolder locker(m_originSetMutex);
         if (!m_originsBeingDeleted.isEmpty())
             m_originsBeingDeleted.remove(originIdentifier);
     }
 }

 bool StorageTracker::isActive()
 {
     return m_isActive;
 }

 void StorageTracker::setIsActive(bool flag)
 {
     m_isActive = flag;
 }

 String StorageTracker::databasePathForOrigin(const String& originIdentifier)
 {
     ASSERT(!m_databaseMutex.tryLock());
     ASSERT(m_isActive);

     if (!m_database.isOpen())
         return String();

     SQLiteTransactionInProgressAutoCounter transactionCounter;

     SQLiteStatement pathStatement(m_database, "SELECT path FROM Origins WHERE origin=?");
     if (pathStatement.prepare() != SQLITE_OK) {
         LOG_ERROR("Unable to prepare selection of path for origin '%s'", originIdentifier.ascii().data());
         return String();
     }
     pathStatement.bindText(1, originIdentifier);
     int result = pathStatement.step();
     if (result != SQLITE_ROW)
         return String();

     return pathStatement.getColumnText(0);
 }

 long long StorageTracker::diskUsageForOrigin(SecurityOrigin* origin)
 {
     if (!m_isActive)
         return 0;

     LockHolder locker(m_databaseMutex);

     String path = databasePathForOrigin(origin->data().databaseIdentifier());
     if (path.isEmpty())
         return 0;

     long long size;
     return FileSystem::getFileSize(path, size) ? size : 0;
 }

 } // namespace WebCore
	/*
	* Copyright (C) 2011 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
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
	* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
	* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	* THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "StorageTracker.h"

	#include "StorageThread.h"
	#include "StorageTrackerClient.h"
	#include "WebStorageNamespaceProvider.h"
	#include <WebCore/PageGroup.h>
	#include <WebCore/SQLiteDatabaseTracker.h>
	#include <WebCore/SQLiteStatement.h>
	#include <WebCore/SecurityOrigin.h>
	#include <WebCore/SecurityOriginData.h>
	#include <WebCore/TextEncoding.h>
	#include <wtf/FileSystem.h>
	#include <wtf/MainThread.h>
	#include <wtf/StdLibExtras.h>
	#include <wtf/Vector.h>
	#include <wtf/text/CString.h>

	#if PLATFORM(IOS_FAMILY)
	#include <pal/spi/ios/SQLite3SPI.h>
	#endif

	using namespace WebCore;

	namespace WebKit {

	static StorageTracker* storageTracker = nullptr;

	// If there is no document referencing a storage database, close the underlying database
	// after it has been idle for m_StorageDatabaseIdleInterval seconds.
	static const Seconds defaultStorageDatabaseIdleInterval { 300_s };

	void StorageTracker::initializeTracker(const String& storagePath, StorageTrackerClient* client)
	{
	ASSERT(isMainThread());
	ASSERT(!storageTracker \|\| !storageTracker->m_client);

	if (!storageTracker)
	storageTracker = new StorageTracker(storagePath);

	storageTracker->m_client = client;
	storageTracker->m_needsInitialization = true;
	}

	void StorageTracker::internalInitialize()
	{
	m_needsInitialization = false;

	ASSERT(isMainThread());

	// Make sure text encoding maps have been built on the main thread, as the StorageTracker thread might try to do it there instead.
	// FIXME (<rdar://problem/9127819>): Is there a more explicit way of doing this besides accessing the UTF8Encoding?
	UTF8Encoding();

	storageTracker->setIsActive(true);
	storageTracker->m_thread->start();
	storageTracker->importOriginIdentifiers();

	m_thread->dispatch([this] {
	FileSystem::deleteFile(FileSystem::pathByAppendingComponent(m_storageDirectoryPath, "StorageTracker.db"));
	});
	}

	StorageTracker& StorageTracker::tracker()
	{
	if (!storageTracker)
	storageTracker = new StorageTracker("");
	if (storageTracker->m_needsInitialization)
	storageTracker->internalInitialize();

	return *storageTracker;
	}

	StorageTracker::StorageTracker(const String& storagePath)
	: m_storageDirectoryPath(storagePath.isolatedCopy())
	, m_client(0)
	, m_thread(makeUnique<StorageThread>())
	, m_isActive(false)
	, m_needsInitialization(false)
	, m_StorageDatabaseIdleInterval(defaultStorageDatabaseIdleInterval)
	{
	}

	String StorageTracker::trackerDatabasePath()
	{
	ASSERT(!m_databaseMutex.tryLock());
	return FileSystem::pathByAppendingComponent(m_storageDirectoryPath, "LegacyStorageTracker.db");
	}

	static bool ensureDatabaseFileExists(const String& fileName, bool createIfDoesNotExist)
	{
	if (createIfDoesNotExist)
	return FileSystem::makeAllDirectories(FileSystem::directoryName(fileName));

	return FileSystem::fileExists(fileName);
	}

	void StorageTracker::openTrackerDatabase(bool createIfDoesNotExist)
	{
	ASSERT(m_isActive);
	ASSERT(!isMainThread());

	SQLiteTransactionInProgressAutoCounter transactionCounter;

	ASSERT(!m_databaseMutex.tryLock());

	if (m_database.isOpen())
	return;

	String databasePath = trackerDatabasePath();

	if (!ensureDatabaseFileExists(databasePath, createIfDoesNotExist)) {
	if (createIfDoesNotExist)
	LOG_ERROR("Failed to create database file '%s'", databasePath.ascii().data());
	return;
	}

	if (!m_database.open(databasePath)) {
	LOG_ERROR("Failed to open databasePath %s.", databasePath.ascii().data());
	return;
	}

	m_database.disableThreadingChecks();

	if (!m_database.tableExists("Origins")) {
	if (!m_database.executeCommand("CREATE TABLE Origins (origin TEXT UNIQUE ON CONFLICT REPLACE, path TEXT);"))
	LOG_ERROR("Failed to create Origins table.");
	}
	}

	void StorageTracker::importOriginIdentifiers()
	{
	if (!m_isActive)
	return;

	ASSERT(isMainThread());
	ASSERT(m_thread);

	m_thread->dispatch([this] {
	syncImportOriginIdentifiers();
	});
	}

	void StorageTracker::finishedImportingOriginIdentifiers()
	{
	LockHolder locker(m_databaseMutex);
	if (m_client)
	m_client->didFinishLoadingOrigins();
	}

	void StorageTracker::syncImportOriginIdentifiers()
	{
	ASSERT(m_isActive);

	ASSERT(!isMainThread());

	{
	LockHolder locker(m_databaseMutex);

	// Don't force creation of StorageTracker's db just because a tracker
	// was initialized. It will be created if local storage dbs are found
	// by syncFileSystemAndTrackerDatabse() or the next time a local storage
	// db is created by StorageAreaSync.
	openTrackerDatabase(false);

	if (m_database.isOpen()) {
	SQLiteTransactionInProgressAutoCounter transactionCounter;

	SQLiteStatement statement(m_database, "SELECT origin FROM Origins");
	if (statement.prepare() != SQLITE_OK) {
	LOG_ERROR("Failed to prepare statement.");
	return;
	}

	int result;

	{
	LockHolder lockOrigins(m_originSetMutex);
	while ((result = statement.step()) == SQLITE_ROW)
	m_originSet.add(statement.getColumnText(0).isolatedCopy());
	}

	if (result != SQLITE_DONE) {
	LOG_ERROR("Failed to read in all origins from the database.");
	return;
	}
	}
	}

	syncFileSystemAndTrackerDatabase();

	{
	LockHolder locker(m_clientMutex);

	if (m_client) {
	LockHolder locker(m_originSetMutex);
	OriginSet::const_iterator end = m_originSet.end();
	for (OriginSet::const_iterator it = m_originSet.begin(); it != end; ++it)
	m_client->dispatchDidModifyOrigin(*it);
	}
	}

	callOnMainThread([this] {
	finishedImportingOriginIdentifiers();
	});
	}

	void StorageTracker::syncFileSystemAndTrackerDatabase()
	{
	ASSERT(!isMainThread());

	SQLiteTransactionInProgressAutoCounter transactionCounter;

	ASSERT(m_isActive);

	Vector<String> paths;
	{
	LockHolder locker(m_databaseMutex);
	paths = FileSystem::listDirectory(m_storageDirectoryPath, "*.localstorage");
	}

	// Use a copy of m_originSet to find expired entries and to schedule their
	// deletions from disk and from m_originSet.
	OriginSet originSetCopy;
	{
	LockHolder locker(m_originSetMutex);
	for (OriginSet::const_iterator it = m_originSet.begin(), end = m_originSet.end(); it != end; ++it)
	originSetCopy.add((*it).isolatedCopy());
	}

	// Add missing StorageTracker records.
	OriginSet foundOrigins;
	String fileExtension = ".localstorage"_s;

	for (Vector<String>::const_iterator it = paths.begin(), end = paths.end(); it != end; ++it) {
	const String& path = *it;

	if (path.length() > fileExtension.length() && path.endsWith(fileExtension)) {
	String file = FileSystem::pathGetFileName(path);
	String originIdentifier = file.substring(0, file.length() - fileExtension.length());
	if (!originSetCopy.contains(originIdentifier))
	syncSetOriginDetails(originIdentifier, path);

	foundOrigins.add(originIdentifier);
	}
	}

	// Delete stale StorageTracker records.
	for (OriginSet::const_iterator it = originSetCopy.begin(), end = originSetCopy.end(); it != end; ++it) {
	const String& originIdentifier = *it;
	if (foundOrigins.contains(originIdentifier))
	continue;

	callOnMainThread([this, originIdentifier = originIdentifier.isolatedCopy()] {
	deleteOriginWithIdentifier(originIdentifier);
	});
	}
	}

	void StorageTracker::setOriginDetails(const String& originIdentifier, const String& databaseFile)
	{
	if (!m_isActive)
	return;

	{
	LockHolder locker(m_originSetMutex);

	if (m_originSet.contains(originIdentifier))
	return;

	m_originSet.add(originIdentifier);
	}

	auto function = [this, originIdentifier = originIdentifier.isolatedCopy(), databaseFile = databaseFile.isolatedCopy()] {
	syncSetOriginDetails(originIdentifier, databaseFile);
	};

	if (isMainThread()) {
	ASSERT(m_thread);
	m_thread->dispatch(WTFMove(function));
	} else {
	// FIXME: This weird ping-ponging was done to fix a deadlock. We should figure out a cleaner way to avoid it instead.
	callOnMainThread([this, function = WTFMove(function)]() mutable {
	m_thread->dispatch(WTFMove(function));
	});
	}
	}

	void StorageTracker::syncSetOriginDetails(const String& originIdentifier, const String& databaseFile)
	{
	ASSERT(!isMainThread());

	SQLiteTransactionInProgressAutoCounter transactionCounter;

	LockHolder locker(m_databaseMutex);

	openTrackerDatabase(true);

	if (!m_database.isOpen())
	return;

	SQLiteStatement statement(m_database, "INSERT INTO Origins VALUES (?, ?)");
	if (statement.prepare() != SQLITE_OK) {
	LOG_ERROR("Unable to establish origin '%s' in the tracker", originIdentifier.ascii().data());
	return;
	}

	statement.bindText(1, originIdentifier);
	statement.bindText(2, databaseFile);

	if (statement.step() != SQLITE_DONE)
	LOG_ERROR("Unable to establish origin '%s' in the tracker", originIdentifier.ascii().data());

	{
	LockHolder locker(m_originSetMutex);
	if (!m_originSet.contains(originIdentifier))
	m_originSet.add(originIdentifier);
	}

	{
	LockHolder locker(m_clientMutex);
	if (m_client)
	m_client->dispatchDidModifyOrigin(originIdentifier);
	}
	}

	Vector<SecurityOriginData> StorageTracker::origins()
	{
	ASSERT(m_isActive);

	if (!m_isActive)
	return { };

	LockHolder locker(m_originSetMutex);

	Vector<SecurityOriginData> result;
	result.reserveInitialCapacity(m_originSet.size());
	for (auto& identifier : m_originSet) {
	auto origin = SecurityOriginData::fromDatabaseIdentifier(identifier);
	if (!origin) {
	ASSERT_NOT_REACHED();
	continue;
	}
	result.uncheckedAppend(origin.value());
	}
	return result;
	}

	void StorageTracker::deleteAllOrigins()
	{
	ASSERT(m_isActive);
	ASSERT(isMainThread());
	ASSERT(m_thread);

	if (!m_isActive)
	return;

	{
	LockHolder locker(m_originSetMutex);
	willDeleteAllOrigins();
	m_originSet.clear();
	}

	WebStorageNamespaceProvider::clearLocalStorageForAllOrigins();

	m_thread->dispatch([this] {
	syncDeleteAllOrigins();
	});
	}

	#if PLATFORM(IOS_FAMILY)
	static void truncateDatabaseFile(SQLiteDatabase& database)
	{
	sqlite3_file_control(database.sqlite3Handle(), 0, SQLITE_TRUNCATE_DATABASE, 0);
	}
	#endif

	void StorageTracker::syncDeleteAllOrigins()
	{
	ASSERT(!isMainThread());

	SQLiteTransactionInProgressAutoCounter transactionCounter;

	LockHolder locker(m_databaseMutex);

	openTrackerDatabase(false);
	if (!m_database.isOpen())
	return;

	SQLiteStatement statement(m_database, "SELECT origin, path FROM Origins");
	if (statement.prepare() != SQLITE_OK) {
	LOG_ERROR("Failed to prepare statement.");
	return;
	}

	int result;
	while ((result = statement.step()) == SQLITE_ROW) {
	if (!canDeleteOrigin(statement.getColumnText(0)))
	continue;

	FileSystem::deleteFile(statement.getColumnText(1));

	{
	LockHolder locker(m_clientMutex);
	if (m_client)
	m_client->dispatchDidModifyOrigin(statement.getColumnText(0));
	}
	}

	if (result != SQLITE_DONE)
	LOG_ERROR("Failed to read in all origins from the database.");

	if (m_database.isOpen()) {
	#if PLATFORM(IOS_FAMILY)
	truncateDatabaseFile(m_database);
	#endif
	m_database.close();
	}

	#if !PLATFORM(IOS_FAMILY)
	if (!FileSystem::deleteFile(trackerDatabasePath())) {
	// In the case where it is not possible to delete the database file (e.g some other program
	// like a virus scanner is accessing it), make sure to remove all entries.
	openTrackerDatabase(false);
	if (!m_database.isOpen())
	return;
	SQLiteStatement deleteStatement(m_database, "DELETE FROM Origins");
	if (deleteStatement.prepare() != SQLITE_OK) {
	LOG_ERROR("Unable to prepare deletion of all origins");
	return;
	}
	if (!deleteStatement.executeCommand()) {
	LOG_ERROR("Unable to execute deletion of all origins");
	return;
	}
	}
	FileSystem::deleteEmptyDirectory(m_storageDirectoryPath);
	#endif
	}

	void StorageTracker::deleteOriginWithIdentifier(const String& originIdentifier)
	{
	auto origin = SecurityOriginData::fromDatabaseIdentifier(originIdentifier);
	if (!origin) {
	ASSERT_NOT_REACHED();
	return;
	}
	deleteOrigin(origin.value());
	}

	void StorageTracker::deleteOrigin(const SecurityOriginData& origin)
	{
	ASSERT(m_isActive);
	ASSERT(isMainThread());
	ASSERT(m_thread);

	if (!m_isActive)
	return;

	// Before deleting database, we need to clear in-memory local storage data
	// in StorageArea, and to close the StorageArea db. It's possible for an
	// item to be added immediately after closing the db and cause StorageAreaSync
	// to reopen the db before the db is deleted by a StorageTracker thread.
	// In this case, reopening the db in StorageAreaSync will cancel a pending
	// StorageTracker db deletion.
	WebStorageNamespaceProvider::clearLocalStorageForOrigin(origin);

	String originId = origin.databaseIdentifier();

	{
	LockHolder locker(m_originSetMutex);
	willDeleteOrigin(originId);
	m_originSet.remove(originId);
	}

	m_thread->dispatch([this, originId = originId.isolatedCopy()] {
	syncDeleteOrigin(originId);
	});
	}

	void StorageTracker::syncDeleteOrigin(const String& originIdentifier)
	{
	ASSERT(!isMainThread());

	SQLiteTransactionInProgressAutoCounter transactionCounter;

	LockHolder locker(m_databaseMutex);

	if (!canDeleteOrigin(originIdentifier)) {
	LOG_ERROR("Attempted to delete origin '%s' while it was being created\n", originIdentifier.ascii().data());
	return;
	}

	openTrackerDatabase(false);
	if (!m_database.isOpen())
	return;

	String path = databasePathForOrigin(originIdentifier);
	if (path.isEmpty()) {
	// It is possible to get a request from the API to delete the storage for an origin that
	// has no such storage.
	return;
	}

	SQLiteStatement deleteStatement(m_database, "DELETE FROM Origins where origin=?");
	if (deleteStatement.prepare() != SQLITE_OK) {
	LOG_ERROR("Unable to prepare deletion of origin '%s'", originIdentifier.ascii().data());
	return;
	}
	deleteStatement.bindText(1, originIdentifier);
	if (!deleteStatement.executeCommand()) {
	LOG_ERROR("Unable to execute deletion of origin '%s'", originIdentifier.ascii().data());
	return;
	}

	FileSystem::deleteFile(path);

	bool shouldDeleteTrackerFiles = false;
	{
	LockHolder locker(m_originSetMutex);
	m_originSet.remove(originIdentifier);
	shouldDeleteTrackerFiles = m_originSet.isEmpty();
	}

	if (shouldDeleteTrackerFiles) {
	#if PLATFORM(IOS_FAMILY)
	truncateDatabaseFile(m_database);
	#endif
	m_database.close();
	#if !PLATFORM(IOS_FAMILY)
	FileSystem::deleteFile(trackerDatabasePath());
	FileSystem::deleteEmptyDirectory(m_storageDirectoryPath);
	#endif
	}

	{
	LockHolder locker(m_clientMutex);
	if (m_client)
	m_client->dispatchDidModifyOrigin(originIdentifier);
	}
	}

	void StorageTracker::willDeleteAllOrigins()
	{
	ASSERT(!m_originSetMutex.tryLock());

	OriginSet::const_iterator end = m_originSet.end();
	for (OriginSet::const_iterator it = m_originSet.begin(); it != end; ++it)
	m_originsBeingDeleted.add((*it).isolatedCopy());
	}

	void StorageTracker::willDeleteOrigin(const String& originIdentifier)
	{
	ASSERT(isMainThread());
	ASSERT(!m_originSetMutex.tryLock());

	m_originsBeingDeleted.add(originIdentifier);
	}

	bool StorageTracker::canDeleteOrigin(const String& originIdentifier)
	{
	ASSERT(!m_databaseMutex.tryLock());
	LockHolder locker(m_originSetMutex);
	return m_originsBeingDeleted.contains(originIdentifier);
	}

	void StorageTracker::cancelDeletingOrigin(const String& originIdentifier)
	{
	if (!m_isActive)
	return;

	LockHolder locker(m_databaseMutex);
	{
	LockHolder locker(m_originSetMutex);
	if (!m_originsBeingDeleted.isEmpty())
	m_originsBeingDeleted.remove(originIdentifier);
	}
	}

	bool StorageTracker::isActive()
	{
	return m_isActive;
	}

	void StorageTracker::setIsActive(bool flag)
	{
	m_isActive = flag;
	}

	String StorageTracker::databasePathForOrigin(const String& originIdentifier)
	{
	ASSERT(!m_databaseMutex.tryLock());
	ASSERT(m_isActive);

	if (!m_database.isOpen())
	return String();

	SQLiteTransactionInProgressAutoCounter transactionCounter;

	SQLiteStatement pathStatement(m_database, "SELECT path FROM Origins WHERE origin=?");
	if (pathStatement.prepare() != SQLITE_OK) {
	LOG_ERROR("Unable to prepare selection of path for origin '%s'", originIdentifier.ascii().data());
	return String();
	}
	pathStatement.bindText(1, originIdentifier);
	int result = pathStatement.step();
	if (result != SQLITE_ROW)
	return String();

	return pathStatement.getColumnText(0);
	}

	long long StorageTracker::diskUsageForOrigin(SecurityOrigin* origin)
	{
	if (!m_isActive)
	return 0;

	LockHolder locker(m_databaseMutex);

	String path = databasePathForOrigin(origin->data().databaseIdentifier());
	if (path.isEmpty())
	return 0;

	long long size;
	return FileSystem::getFileSize(path, size) ? size : 0;
	}

	} // namespace WebCore