153 lines
4.0 KiB
C++
153 lines
4.0 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_ShmemPool_h
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#define mozilla_ShmemPool_h
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#include "mozilla/ipc/Shmem.h"
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#include "mozilla/Mutex.h"
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#undef LOG
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#undef LOG_ENABLED
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extern mozilla::LazyLogModule gCamerasParentLog;
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#define LOG(args) MOZ_LOG(gCamerasParentLog, mozilla::LogLevel::Debug, args)
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#define LOG_ENABLED() MOZ_LOG_TEST(gCamerasParentLog, mozilla::LogLevel::Debug)
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namespace mozilla {
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class ShmemPool;
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class ShmemBuffer {
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public:
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ShmemBuffer() : mInitialized(false) {}
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explicit ShmemBuffer(mozilla::ipc::Shmem aShmem) {
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mInitialized = true;
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mShmem = aShmem;
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}
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ShmemBuffer(ShmemBuffer&& rhs) {
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mInitialized = rhs.mInitialized;
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mShmem = Move(rhs.mShmem);
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}
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ShmemBuffer& operator=(ShmemBuffer&& rhs) {
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MOZ_ASSERT(&rhs != this, "self-moves are prohibited");
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mInitialized = rhs.mInitialized;
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mShmem = Move(rhs.mShmem);
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return *this;
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}
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// No copies allowed
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ShmemBuffer(const ShmemBuffer&) = delete;
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ShmemBuffer& operator=(const ShmemBuffer&) = delete;
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bool Valid() {
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return mInitialized;
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}
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char* GetBytes() {
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return mShmem.get<char>();
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}
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mozilla::ipc::Shmem& Get() {
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return mShmem;
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}
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private:
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friend class ShmemPool;
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bool mInitialized;
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mozilla::ipc::Shmem mShmem;
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};
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class ShmemPool {
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public:
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explicit ShmemPool(size_t aPoolSize);
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~ShmemPool();
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// Get/GetIfAvailable differ in what thread they can run on. GetIfAvailable
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// can run anywhere but won't allocate if the right size isn't available.
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ShmemBuffer GetIfAvailable(size_t aSize);
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void Put(ShmemBuffer&& aShmem);
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// We need to use the allocation/deallocation functions
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// of a specific IPC child/parent instance.
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template <class T>
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void Cleanup(T* aInstance)
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{
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MutexAutoLock lock(mMutex);
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for (size_t i = 0; i < mShmemPool.Length(); i++) {
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if (mShmemPool[i].mInitialized) {
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aInstance->DeallocShmem(mShmemPool[i].Get());
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mShmemPool[i].mInitialized = false;
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}
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}
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}
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template <class T>
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ShmemBuffer Get(T* aInstance, size_t aSize)
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{
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MutexAutoLock lock(mMutex);
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// Pool is empty, don't block caller.
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if (mPoolFree == 0) {
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// This isn't initialized, so will be understood as an error.
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return ShmemBuffer();
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}
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ShmemBuffer& res = mShmemPool[mPoolFree - 1];
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if (!res.mInitialized) {
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LOG(("Initializing new Shmem in pool"));
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if (!aInstance->AllocShmem(aSize, ipc::SharedMemory::TYPE_BASIC, &res.mShmem)) {
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LOG(("Failure allocating new Shmem buffer"));
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return ShmemBuffer();
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}
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res.mInitialized = true;
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}
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MOZ_ASSERT(res.mShmem.IsWritable(), "Shmem in Pool is not writable?");
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// Prepare buffer, increase size if needed (we never shrink as we don't
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// maintain seperate sized pools and we don't want to keep reallocating)
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if (res.mShmem.Size<char>() < aSize) {
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LOG(("Size change/increase in Shmem Pool"));
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aInstance->DeallocShmem(res.mShmem);
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res.mInitialized = false;
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// this may fail; always check return value
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if (!aInstance->AllocShmem(aSize, ipc::SharedMemory::TYPE_BASIC, &res.mShmem)) {
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LOG(("Failure allocating resized Shmem buffer"));
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return ShmemBuffer();
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} else {
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res.mInitialized = true;
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}
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}
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MOZ_ASSERT(res.mShmem.IsWritable(), "Shmem in Pool is not writable post resize?");
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mPoolFree--;
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#ifdef DEBUG
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size_t poolUse = mShmemPool.Length() - mPoolFree;
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if (poolUse > mMaxPoolUse) {
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mMaxPoolUse = poolUse;
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LOG(("Maximum ShmemPool use increased: %d buffers", mMaxPoolUse));
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}
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#endif
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return Move(res);
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}
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private:
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Mutex mMutex;
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size_t mPoolFree;
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#ifdef DEBUG
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size_t mMaxPoolUse;
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#endif
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nsTArray<ShmemBuffer> mShmemPool;
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};
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} // namespace mozilla
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#endif // mozilla_ShmemPool_h
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