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MemoryManager.cpp
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MemoryManager.cpp
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/*
* MemoryManager.cpp - A lightweight, generic memory manager for LMMS
*
* Copyright (c) 2014 Vesa Kivimäki
* Copyright (c) 2007-2014 Tobias Doerffel <tobydox/at/users.sourceforge.net>
*
* This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program (see COPYING); if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA.
*
*/
#include "MemoryManager.h"
#include <QtGlobal>
#include <QReadWriteLock>
#include <stdint.h>
MemoryPoolVector MemoryManager::s_memoryPools;
QReadWriteLock MemoryManager::s_poolMutex;
PointerInfoMap MemoryManager::s_pointerInfo;
QMutex MemoryManager::s_pointerMutex;
bool MemoryManager::init()
{
s_memoryPools.reserve( 64 );
s_pointerInfo.reserve( 4096 );
// construct first MemoryPool and allocate memory
MemoryPool m ( MM_INITIAL_CHUNKS );
m.m_pool = MemoryHelper::alignedMalloc( MM_INITIAL_CHUNKS * MM_CHUNK_SIZE );
s_memoryPools.append( m );
return true;
}
void * MemoryManager::alloc( size_t size )
{
int requiredChunks = size / MM_CHUNK_SIZE + ( size % MM_CHUNK_SIZE > 0 ? 1 : 0 );
MemoryPool * mp = NULL;
void * ptr = NULL;
MemoryPoolVector::iterator it = s_memoryPools.begin();
s_poolMutex.lockForRead();
while( it != s_memoryPools.end() && !ptr )
{
ptr = ( *it ).getChunks( requiredChunks );
if( ptr )
{
mp = &( *it );
}
++it;
}
s_poolMutex.unlock();
if( ptr )
{
s_pointerMutex.lock();
PtrInfo p;
p.chunks = requiredChunks;
p.memPool = mp;
s_pointerInfo[ptr] = p;
s_pointerMutex.unlock();
return ptr;
}
// can't find enough chunks in existing pools, so
// create a new pool that is guaranteed to have enough chunks
int moreChunks = qMax( requiredChunks, MM_INCREMENT_CHUNKS );
int i = MemoryManager::extend( moreChunks );
mp = &s_memoryPools[i];
ptr = s_memoryPools[i].getChunks( requiredChunks );
if( ptr )
{
s_pointerMutex.lock();
PtrInfo p;
p.chunks = requiredChunks;
p.memPool = mp;
s_pointerInfo[ptr] = p;
s_pointerMutex.unlock();
return ptr;
}
// still no luck? something is horribly wrong
qFatal( "MemoryManager.cpp: Couldn't allocate memory: %d chunks asked", requiredChunks );
return NULL;
}
void MemoryManager::free( void * ptr )
{
if( ptr == NULL )
{
qDebug( "MemoryManager: Null pointer deallocation attempted" );
return; // let's not try to deallocate null pointers, ok?
}
// fetch info on the ptr and remove
s_pointerMutex.lock();
if( ! s_pointerInfo.contains( ptr ) ) // if we have no info on ptr, fail loudly
{
qFatal( "MemoryManager: Couldn't find pointer info for pointer: %p", ptr );
}
PtrInfo p = s_pointerInfo[ptr];
s_pointerInfo.remove( ptr );
s_pointerMutex.unlock();
p.memPool->releaseChunks( ptr, p.chunks );
}
int MemoryManager::extend( int chunks )
{
MemoryPool m ( chunks );
m.m_pool = MemoryHelper::alignedMalloc( chunks * MM_CHUNK_SIZE );
s_poolMutex.lockForWrite();
s_memoryPools.append( m );
int i = s_memoryPools.size() - 1;
s_poolMutex.unlock();
return i;
}
void MemoryManager::cleanup()
{
for( MemoryPoolVector::iterator it = s_memoryPools.begin(); it != s_memoryPools.end(); ++it )
{
MemoryHelper::alignedFree( ( *it ).m_pool );
MemoryHelper::alignedFree( ( *it ).m_free );
}
}
void * MemoryPool::getChunks( int chunksNeeded )
{
if( chunksNeeded > m_chunks ) // not enough chunks in this pool?
{
return NULL;
}
m_mutex.lock();
// now find out if we have a long enough sequence of chunks in this pool
char last = 0;
intptr_t n = 0;
intptr_t index = -1;
bool found = false;
for( int i = 0; i < m_chunks; ++i )
{
if( m_free[i] )
{
if( !last )
{
index = i;
}
++n;
if( n >= chunksNeeded )
{
found = true;
break;
}
}
else
{
n = 0;
}
last = m_free[i];
}
if( found ) // if enough chunks found, return pointer to chunks
{
// set chunk flags to false so we know the chunks are in use
for( intptr_t i = 0; i < chunksNeeded; ++i )
{
m_free[ index + i ] = 0;
}
m_mutex.unlock();
return (char*)m_pool + ( index * MM_CHUNK_SIZE );
}
m_mutex.unlock();
return NULL; // out of stock, come again tomorrow!
}
void MemoryPool::releaseChunks( void * ptr, int chunks )
{
m_mutex.lock();
intptr_t start = ( (intptr_t)ptr - (intptr_t)m_pool ) / MM_CHUNK_SIZE;
if( start < 0 )
{
qFatal( "MemoryManager: error at releaseChunks() - corrupt pointer info?" );
}
memset( &m_free[ start ], 1, chunks );
m_mutex.unlock();
}