gecko/storage/src/SQLiteMutex.h
Shawn Wilsher 2d8562eff5 Bug 494828 - Stop using our own mutexes and use SQLite's where possible.
Part 1: Create helper objects to make using sqlite3_mutex safer and easier.
r=cjones
2009-07-22 15:18:33 -07:00

208 lines
5.4 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Mozilla Corporation.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Shawn Wilsher <me@shawnwilsher.com> (Original Author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#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.
*/
SQLiteMutex(const char *aName)
: BlockingResourceBase(aName, eMutex)
, mMutex(NULL)
{
}
/**
* 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;
}
#ifndef 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.
CallStack callContext = CallStack();
CheckAcquire(callContext);
sqlite3_mutex_enter(mMutex);
Acquire(callContext); // 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 NS_STACK_CLASS SQLiteMutexAutoLock
{
public:
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 NS_STACK_CLASS SQLiteMutexAutoUnlock
{
public:
SQLiteMutexAutoUnlock(SQLiteMutex &aMutex)
: mMutex(aMutex)
{
mMutex.unlock();
}
~SQLiteMutexAutoUnlock()
{
mMutex.lock();
}
private:
SQLiteMutex &mMutex;
};
} // namespace storage
} // namespace mozilla
#endif // mozilla_storage_SQLiteMutex_h_