gecko-dev/dom/media/systemservices/ShmemPool.cpp

153 lines
4.0 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set sw=2 ts=8 et ft=cpp : */
/* 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/. */
#include "mozilla/Assertions.h"
#include "mozilla/Logging.h"
#include "mozilla/ShmemPool.h"
#include "mozilla/Move.h"
#undef LOG
#undef LOG_ENABLED
extern mozilla::LazyLogModule gCamerasParentLog;
#define LOG(args) MOZ_LOG(gCamerasParentLog, mozilla::LogLevel::Debug, args)
#define LOG_ENABLED() MOZ_LOG_TEST(gCamerasParentLog, mozilla::LogLevel::Debug)
namespace mozilla {
ShmemPool::ShmemPool(size_t aPoolSize)
: mMutex("mozilla::ShmemPool"),
mPoolFree(aPoolSize)
#ifdef DEBUG
,mMaxPoolUse(0)
#endif
{
mShmemPool.SetLength(aPoolSize);
}
mozilla::ShmemBuffer ShmemPool::GetIfAvailable(size_t aSize)
{
MutexAutoLock lock(mMutex);
// Pool is empty, don't block caller.
if (mPoolFree == 0) {
// This isn't initialized, so will be understood as an error.
return ShmemBuffer();
}
ShmemBuffer& res = mShmemPool[mPoolFree - 1];
if (!res.mInitialized) {
LOG(("No free preallocated Shmem"));
return ShmemBuffer();
}
MOZ_ASSERT(res.mShmem.IsWritable(), "Pool in Shmem is not writable?");
if (res.mShmem.Size<char>() < aSize) {
LOG(("Free Shmem but not of the right size"));
return ShmemBuffer();
}
mPoolFree--;
#ifdef DEBUG
size_t poolUse = mShmemPool.Length() - mPoolFree;
if (poolUse > mMaxPoolUse) {
mMaxPoolUse = poolUse;
LOG(("Maximum ShmemPool use increased: %d buffers", mMaxPoolUse));
}
#endif
return Move(res);
}
template <class T>
mozilla::ShmemBuffer ShmemPool::Get(T* aInstance, size_t aSize)
{
MutexAutoLock lock(mMutex);
// Pool is empty, don't block caller.
if (mPoolFree == 0) {
// This isn't initialized, so will be understood as an error.
return ShmemBuffer();
}
ShmemBuffer& res = mShmemPool[mPoolFree - 1];
if (!res.mInitialized) {
LOG(("Initializing new Shmem in pool"));
if (!aInstance->AllocShmem(aSize, SharedMemory::TYPE_BASIC, &res.mShmem)) {
LOG(("Failure allocating new Shmem buffer"));
return ShmemBuffer();
}
res.mInitialized = true;
}
MOZ_ASSERT(res.mShmem.IsWritable(), "Shmem in Pool is not writable?");
// Prepare buffer, increase size if needed (we never shrink as we don't
// maintain seperate sized pools and we don't want to keep reallocating)
if (res.mShmem.Size<char>() < aSize) {
LOG(("Size change/increase in Shmem Pool"));
aInstance->DeallocShmem(res.mShmem);
res.mInitialized = false;
// this may fail; always check return value
if (!aInstance->AllocShmem(aSize, SharedMemory::TYPE_BASIC, &res.mShmem)) {
LOG(("Failure allocating resized Shmem buffer"));
return ShmemBuffer();
} else {
res.mInitialized = true;
}
}
MOZ_ASSERT(res.mShmem.IsWritable(), "Shmem in Pool is not writable post resize?");
mPoolFree--;
#ifdef DEBUG
size_t poolUse = mShmemPool.Length() - mPoolFree;
if (poolUse > mMaxPoolUse) {
mMaxPoolUse = poolUse;
LOG(("Maximum ShmemPool use increased: %d buffers", mMaxPoolUse));
}
#endif
return Move(res);
}
void ShmemPool::Put(ShmemBuffer&& aShmem)
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mPoolFree < mShmemPool.Length());
mShmemPool[mPoolFree] = Move(aShmem);
mPoolFree++;
#ifdef DEBUG
size_t poolUse = mShmemPool.Length() - mPoolFree;
if (poolUse > 0) {
LOG(("ShmemPool usage reduced to %d buffers", poolUse));
}
#endif
}
template <class T>
void ShmemPool::Cleanup(T* aInstance)
{
MutexAutoLock lock(mMutex);
for (size_t i = 0; i < mShmemPool.Length(); i++) {
if (mShmemPool[i].mInitialized) {
aInstance->DeallocShmem(mShmemPool[i].Get());
mShmemPool[i].mInitialized = false;
}
}
}
ShmemPool::~ShmemPool()
{
#ifdef DEBUG
for (size_t i = 0; i < mShmemPool.Length(); i++) {
MOZ_ASSERT(!mShmemPool[i].Valid());
}
#endif
}
} // namespace mozilla