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ShmemRecycleAllocator.h (2935B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 #ifndef include_dom_media_ipc_ShmemRecycleAllocator_h
      7 #define include_dom_media_ipc_ShmemRecycleAllocator_h
      8 
      9 #include "mozilla/ShmemPool.h"
     10 
     11 namespace mozilla {
     12 
     13 // When used with ShmemRecycleAllocator instances, it allows for preventing a
     14 // subset of shmems from being recycled until a transaction is complete. This is
     15 // useful in cases such as encoding, where an arbitrary number of frames may be
     16 // sent for encoding before any others complete. This instead allows us to
     17 // recycle shmems as individual transactions complete without waiting for all
     18 // outstanding to be complete first.
     19 class ShmemRecycleTicket {
     20 public:
     21  NS_INLINE_DECL_REFCOUNTING_ONEVENTTARGET(ShmemRecycleTicket)
     22 
     23  ShmemRecycleTicket() = default;
     24 
     25 private:
     26  template <class T>
     27  friend class ShmemRecycleAllocator;
     28 
     29  ~ShmemRecycleTicket() { MOZ_DIAGNOSTIC_ASSERT(mUsedShmems.IsEmpty()); }
     30 
     31  AutoTArray<ShmemBuffer, 4> mUsedShmems;
     32 };
     33 
     34 template <class T>
     35 class ShmemRecycleAllocator {
     36 public:
     37  explicit ShmemRecycleAllocator(T* aActor)
     38      : mActor(aActor), mPool(1, ShmemPool::PoolType::DynamicPool) {}
     39  ShmemBuffer AllocateBuffer(size_t aSize,
     40                             ShmemRecycleTicket* aTicket = nullptr,
     41                             ShmemPool::AllocationPolicy aPolicy =
     42                                 ShmemPool::AllocationPolicy::Unsafe) {
     43    ShmemBuffer buffer = mPool.Get(mActor, aSize, aPolicy);
     44    if (!buffer.Valid()) {
     45      return buffer;
     46    }
     47    MOZ_DIAGNOSTIC_ASSERT(aSize <= buffer.Get().Size<uint8_t>());
     48    if (aTicket) {
     49      aTicket->mUsedShmems.AppendElement(buffer.Get());
     50    } else {
     51      mUsedShmems.AppendElement(buffer.Get());
     52    }
     53    mNeedCleanup = true;
     54    return buffer;
     55  }
     56 
     57  void ReleaseBuffer(ShmemBuffer&& aBuffer) { mPool.Put(std::move(aBuffer)); }
     58 
     59  void ReleaseAllBuffers() {
     60    for (auto&& mem : mUsedShmems) {
     61      ReleaseBuffer(ShmemBuffer(mem.Get()));
     62    }
     63    mUsedShmems.Clear();
     64  }
     65 
     66  void ReleaseTicket(ShmemRecycleTicket* aTicket) {
     67    for (auto&& mem : aTicket->mUsedShmems) {
     68      ReleaseBuffer(ShmemBuffer(mem.Get()));
     69    }
     70    aTicket->mUsedShmems.Clear();
     71  }
     72 
     73  void CleanupShmemRecycleAllocator() {
     74    ReleaseAllBuffers();
     75    mPool.Cleanup(mActor);
     76    mNeedCleanup = false;
     77  }
     78 
     79  ~ShmemRecycleAllocator() {
     80    MOZ_DIAGNOSTIC_ASSERT(mUsedShmems.IsEmpty() && !mNeedCleanup,
     81                          "Shmems not all deallocated");
     82  }
     83 
     84 private:
     85  T* const mActor;
     86  ShmemPool mPool;
     87  AutoTArray<ShmemBuffer, 4> mUsedShmems;
     88  bool mNeedCleanup = false;
     89 };
     90 
     91 }  // namespace mozilla
     92 
     93 #endif  // include_dom_media_ipc_ShmemRecycleAllocator_h