michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef mozilla_storage_SQLiteMutex_h_
michael@0: #define mozilla_storage_SQLiteMutex_h_
michael@0: 
michael@0: #include "mozilla/BlockingResourceBase.h"
michael@0: #include "sqlite3.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace storage {
michael@0: 
michael@0: /**
michael@0:  * Wrapper class for sqlite3_mutexes.  To be used whenever we want to use a
michael@0:  * sqlite3_mutex.
michael@0:  *
michael@0:  * @warning Never EVER wrap the same sqlite3_mutex with a different SQLiteMutex.
michael@0:  *          If you do this, you void the deadlock detector's warranty!
michael@0:  */
michael@0: class SQLiteMutex : private BlockingResourceBase
michael@0: {
michael@0: public:
michael@0:   /**
michael@0:    * Constructs a wrapper for a sqlite3_mutex that has deadlock detecting.
michael@0:    *
michael@0:    * @param aName
michael@0:    *        A name which can be used to reference this mutex.
michael@0:    */
michael@0:   SQLiteMutex(const char *aName)
michael@0:   : BlockingResourceBase(aName, eMutex)
michael@0:   , mMutex(nullptr)
michael@0:   {
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Sets the mutex that we are wrapping.  We generally do not have access to
michael@0:    * our mutex at class construction, so we have to set it once we get access to
michael@0:    * it.
michael@0:    *
michael@0:    * @param aMutex
michael@0:    *        The sqlite3_mutex that we are going to wrap.
michael@0:    */
michael@0:   void initWithMutex(sqlite3_mutex *aMutex)
michael@0:   {
michael@0:     NS_ASSERTION(aMutex, "You must pass in a valid mutex!");
michael@0:     NS_ASSERTION(!mMutex, "A mutex has already been set for this!");
michael@0:     mMutex = aMutex;
michael@0:   }
michael@0: 
michael@0: #if !defined(DEBUG) || defined(MOZ_NATIVE_SQLITE)
michael@0:   /**
michael@0:    * Acquires the mutex.
michael@0:    */
michael@0:   void lock()
michael@0:   {
michael@0:     sqlite3_mutex_enter(mMutex);
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Releases the mutex.
michael@0:    */
michael@0:   void unlock()
michael@0:   {
michael@0:     sqlite3_mutex_leave(mMutex);
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Asserts that the current thread owns the mutex.
michael@0:    */
michael@0:   void assertCurrentThreadOwns()
michael@0:   {
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Asserts that the current thread does not own the mutex.
michael@0:    */
michael@0:   void assertNotCurrentThreadOwns()
michael@0:   {
michael@0:   }
michael@0: 
michael@0: #else
michael@0:   void lock()
michael@0:   {
michael@0:     NS_ASSERTION(mMutex, "No mutex associated with this wrapper!");
michael@0: 
michael@0:     // While SQLite Mutexes may be recursive, in our own code we do not want to
michael@0:     // treat them as such.
michael@0:     CallStack callContext = CallStack();
michael@0: 
michael@0:     CheckAcquire(callContext);
michael@0:     sqlite3_mutex_enter(mMutex);
michael@0:     Acquire(callContext); // Call is protected by us holding the mutex.
michael@0:   }
michael@0: 
michael@0:   void unlock()
michael@0:   {
michael@0:     NS_ASSERTION(mMutex, "No mutex associated with this wrapper!");
michael@0: 
michael@0:     // While SQLite Mutexes may be recursive, in our own code we do not want to
michael@0:     // treat them as such.
michael@0:     Release(); // Call is protected by us holding the mutex.
michael@0:     sqlite3_mutex_leave(mMutex);
michael@0:   }
michael@0: 
michael@0:   void assertCurrentThreadOwns()
michael@0:   {
michael@0:     NS_ASSERTION(mMutex, "No mutex associated with this wrapper!");
michael@0:     NS_ASSERTION(sqlite3_mutex_held(mMutex),
michael@0:                  "Mutex is not held, but we expect it to be!");
michael@0:   }
michael@0: 
michael@0:   void assertNotCurrentThreadOwns()
michael@0:   {
michael@0:     NS_ASSERTION(mMutex, "No mutex associated with this wrapper!");
michael@0:     NS_ASSERTION(sqlite3_mutex_notheld(mMutex),
michael@0:                  "Mutex is held, but we expect it to not be!");
michael@0:   }
michael@0: #endif // ifndef DEBUG
michael@0: 
michael@0: private:
michael@0:   sqlite3_mutex *mMutex;
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * Automatically acquires the mutex when it enters scope, and releases it when
michael@0:  * it leaves scope.
michael@0:  */
michael@0: class MOZ_STACK_CLASS SQLiteMutexAutoLock
michael@0: {
michael@0: public:
michael@0:   SQLiteMutexAutoLock(SQLiteMutex &aMutex)
michael@0:   : mMutex(aMutex)
michael@0:   {
michael@0:     mMutex.lock();
michael@0:   }
michael@0: 
michael@0:   ~SQLiteMutexAutoLock()
michael@0:   {
michael@0:     mMutex.unlock();
michael@0:   }
michael@0: 
michael@0: private:
michael@0:   SQLiteMutex &mMutex;
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * Automatically releases the mutex when it enters scope, and acquires it when
michael@0:  * it leaves scope.
michael@0:  */
michael@0: class MOZ_STACK_CLASS SQLiteMutexAutoUnlock
michael@0: {
michael@0: public:
michael@0:   SQLiteMutexAutoUnlock(SQLiteMutex &aMutex)
michael@0:   : mMutex(aMutex)
michael@0:   {
michael@0:     mMutex.unlock();
michael@0:   }
michael@0: 
michael@0:   ~SQLiteMutexAutoUnlock()
michael@0:   {
michael@0:     mMutex.lock();
michael@0:   }
michael@0: 
michael@0: private:
michael@0:   SQLiteMutex &mMutex;
michael@0: };
michael@0: 
michael@0: } // namespace storage
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif // mozilla_storage_SQLiteMutex_h_