Make the DatabaseTracker thread-safe.

WebCore/storage/DatabaseTracker.h

 /*
  * Copyright (C) 2007, 2008 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 42 matching lines @@
 #if !PLATFORM(CHROMIUM)
 class DatabaseTrackerClient;
 class OriginQuotaManager;
 
 struct SecurityOriginTraits;
 #endif // !PLATFORM(CHROMIUM)
 
 class DatabaseTracker : public Noncopyable {
 public:
     static DatabaseTracker& tracker();
-    // FIXME: Due to workers having multiple threads in a single process sharing
-    // a DatabaseTracker, this singleton will have to be synchronized or moved
-    // to TLS.
+    // This singleton will potentially be used from multiple worker threads and the page's context thread simultaneously.  To keep this safe, it's
+    // currently using 4 locks.  In order to avoid deadlock when taking multiple locks, you must take them in the correct order:
+    // originQuotaManager() before m_databaseGuard or m_openDatabaseMapGuard
+    // m_databaseGuard before m_openDatabaseMapGuard
+    // notificationMutex() is currently independent of the other locks.
 
     bool canEstablishDatabase(ScriptExecutionContext*, const String& name, const String& displayName, unsigned long estimatedSize);
     void setDatabaseDetails(SecurityOrigin*, const String& name, const String& displayName, unsigned long estimatedSize);
     String fullPathForDatabase(SecurityOrigin*, const String& name, bool createIfDoesNotExist = true);
 
     void addOpenDatabase(Database*);
     void removeOpenDatabase(Database*);
     void getOpenDatabases(SecurityOrigin* origin, const String& name, HashSet<RefPtr<Database> >* databases);
 
     unsigned long long getMaxSizeForDatabase(const Database*);
 
 private:
     DatabaseTracker();
 
     typedef HashSet<Database*> DatabaseSet;
     typedef HashMap<String, DatabaseSet*> DatabaseNameMap;
     typedef HashMap<RefPtr<SecurityOrigin>, DatabaseNameMap*, SecurityOriginHash> DatabaseOriginMap;
 
     Mutex m_openDatabaseMapGuard;
     mutable OwnPtr<DatabaseOriginMap> m_openDatabaseMap;
 
 #if !PLATFORM(CHROMIUM)
 public:
     void setDatabaseDirectoryPath(const String&);
-    const String& databaseDirectoryPath() const;
+    String databaseDirectoryPath() const;
 
     void origins(Vector<RefPtr<SecurityOrigin> >& result);
     bool databaseNamesForOrigin(SecurityOrigin*, Vector<String>& result);
 
     DatabaseDetails detailsForNameAndOrigin(const String&, SecurityOrigin*);
 
     unsigned long long usageForDatabase(const String&, SecurityOrigin*);
     unsigned long long usageForOrigin(SecurityOrigin*);
     unsigned long long quotaForOrigin(SecurityOrigin*);
     void setQuota(SecurityOrigin*, unsigned long long);
 
     void deleteAllDatabases();
     void deleteOrigin(SecurityOrigin*);
     void deleteDatabase(SecurityOrigin*, const String& name);
 
     void setClient(DatabaseTrackerClient*);
 
     // From a secondary thread, must be thread safe with its data
     void scheduleNotifyDatabaseChanged(SecurityOrigin*, const String& name);
 
     OriginQuotaManager& originQuotaManager();
 
 
     bool hasEntryForOrigin(SecurityOrigin*);
 
 private:
+    OriginQuotaManager& originQuotaManagerNoLock();
+    bool hasEntryForOriginNoLock(SecurityOrigin* origin);
+    String fullPathForDatabaseNoLock(SecurityOrigin*, const String& name, bool createIfDoesNotExist);
+    bool databaseNamesForOriginNoLock(SecurityOrigin* origin, Vector<String>& resultVector);
+    unsigned long long usageForOriginNoLock(SecurityOrigin* origin);
+    unsigned long long quotaForOriginNoLock(SecurityOrigin* origin);
+
     String trackerDatabasePath() const;
     void openTrackerDatabase(bool createIfDoesNotExist);
 
     String originPath(SecurityOrigin*) const;
 
     bool hasEntryForDatabase(SecurityOrigin*, const String& databaseIdentifier);
 
     bool addDatabase(SecurityOrigin*, const String& name, const String& path);
     void populateOrigins();
 
     bool deleteDatabaseFile(SecurityOrigin*, const String& name);
 
+    // This lock protects m_database, m_quotaMap, and m_proposedDatabases.
+    Mutex m_databaseGuard;
     SQLiteDatabase m_database;
 
     typedef HashMap<RefPtr<SecurityOrigin>, unsigned long long, SecurityOriginHash> QuotaMap;
-    Mutex m_quotaMapGuard;
     mutable OwnPtr<QuotaMap> m_quotaMap;
 
     OwnPtr<OriginQuotaManager> m_quotaManager;
 
     String m_databaseDirectoryPath;
 
     DatabaseTrackerClient* m_client;
 
-    std::pair<SecurityOrigin*, DatabaseDetails>* m_proposedDatabase;
-
-#ifndef NDEBUG
-    ThreadIdentifier m_thread;
-#endif
+    typedef std::pair<SecurityOrigin*, DatabaseDetails> ProposedDatabase;
+    HashSet<ProposedDatabase*> m_proposedDatabases;
 
     static void scheduleForNotification();
     static void notifyDatabasesChanged(void*);
 #endif // !PLATFORM(CHROMIUM)
 };
 
 } // namespace WebCore
 
 #endif // ENABLE(DATABASE)
 #endif // DatabaseTracker_h