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Code Issues Releases Wiki Activity

Safer locking of id() to prevent deadlocks

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This commit is contained in:
Leo Franchi 2012-06-16 11:14:20 +02:00
parent cd3eeb2951
commit 3f2906d4d1
2 changed files with 28 additions and 9 deletions
src/libtomahawk
Album.cppArtist.cpp

19
src/libtomahawk/Album.cpp

@ -29,6 +29,8 @@
#include "utils/Logger.h"
#include <QReadWriteLock>
using namespace Tomahawk;
QHash< QString, album_ptr > Album::s_albumsByName = QHash< QString, album_ptr >();
@ -36,7 +38,7 @@ QHash< unsigned int, album_ptr > Album::s_albumsById = QHash< unsigned int, albu
static QMutex s_nameCacheMutex;
static QMutex s_idCacheMutex;
static QMutex s_idMutex;
static QReadWriteLock s_idMutex;
Album::~Album()
{
@ -155,18 +157,25 @@ Album::loadId( bool autoCreate )
unsigned int
Album::id() const
{
QMutexLocker l( &s_idMutex );
s_idMutex.lockForRead();
const bool waiting = m_waitingForId;
unsigned int finalId = m_id;
s_idMutex.unlock();
if ( m_waitingForId )
if ( waiting )
{
m_id = m_idFuture.get();
finalId = m_idFuture.get();
s_idMutex.lockForWrite();
m_id = finalId;
m_waitingForId = false;
if ( m_id > 0 )
s_albumsById[ m_id ] = m_ownRef.toStrongRef();
s_idMutex.unlock();
}
return m_id;
return finalId;
}

18
src/libtomahawk/Artist.cpp

@ -30,6 +30,8 @@
#include "utils/Logger.h"
#include <QReadWriteLock>
using namespace Tomahawk;
QHash< QString, artist_ptr > Artist::s_artistsByName = QHash< QString, artist_ptr >();
@ -37,7 +39,7 @@ QHash< unsigned int, artist_ptr > Artist::s_artistsById = QHash< unsigned int, a
static QMutex s_nameCacheMutex;
static QMutex s_idCacheMutex;
static QMutex s_idMutex;
static QReadWriteLock s_idMutex;
Artist::~Artist()
{
@ -235,14 +237,22 @@ Artist::loadId( bool autoCreate )
unsigned int
Artist::id() const
{
QMutexLocker l( &s_idMutex );
if ( m_waitingForFuture )
s_idMutex.lockForRead();
const bool waiting = m_waitingForFuture;
unsigned int finalid = m_id;
s_idMutex.unlock();
if ( waiting )
{
m_id = m_idFuture.get();
finalid = m_idFuture.get();
s_idMutex.lockForWrite();
m_id = finalid;
m_waitingForFuture = false;
if ( m_id > 0 )
s_artistsById[ m_id ] = m_ownRef.toStrongRef();
s_idMutex.unlock();
}
return m_id;