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