Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set sw=2 ts=8 et ft=cpp : */
       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 file,
       5             :  * You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : #include "mozilla/Assertions.h"
       8             : #include "mozilla/Logging.h"
       9             : #include "mozilla/ShmemPool.h"
      10             : #include "mozilla/Move.h"
      11             : 
      12             : namespace mozilla {
      13             : 
      14           0 : ShmemPool::ShmemPool(size_t aPoolSize)
      15             :   : mMutex("mozilla::ShmemPool"),
      16             :     mPoolFree(aPoolSize)
      17             : #ifdef DEBUG
      18           0 :     ,mMaxPoolUse(0)
      19             : #endif
      20             : {
      21           0 :   mShmemPool.SetLength(aPoolSize);
      22           0 : }
      23             : 
      24           0 : mozilla::ShmemBuffer ShmemPool::GetIfAvailable(size_t aSize)
      25             : {
      26           0 :   MutexAutoLock lock(mMutex);
      27             : 
      28             :   // Pool is empty, don't block caller.
      29           0 :   if (mPoolFree == 0) {
      30             :     // This isn't initialized, so will be understood as an error.
      31           0 :     return ShmemBuffer();
      32             :   }
      33             : 
      34           0 :   ShmemBuffer& res = mShmemPool[mPoolFree - 1];
      35             : 
      36           0 :   if (!res.mInitialized) {
      37           0 :     LOG(("No free preallocated Shmem"));
      38           0 :     return ShmemBuffer();
      39             :   }
      40             : 
      41           0 :   MOZ_ASSERT(res.mShmem.IsWritable(), "Pool in Shmem is not writable?");
      42             : 
      43           0 :   if (res.mShmem.Size<uint8_t>() < aSize) {
      44           0 :     LOG(("Free Shmem but not of the right size"));
      45           0 :     return ShmemBuffer();
      46             :   }
      47             : 
      48           0 :   mPoolFree--;
      49             : #ifdef DEBUG
      50           0 :   size_t poolUse = mShmemPool.Length() - mPoolFree;
      51           0 :   if (poolUse > mMaxPoolUse) {
      52           0 :     mMaxPoolUse = poolUse;
      53           0 :     LOG(("Maximum ShmemPool use increased: %" PRIuSIZE " buffers", mMaxPoolUse));
      54             :   }
      55             : #endif
      56           0 :   return Move(res);
      57             : }
      58             : 
      59           0 : void ShmemPool::Put(ShmemBuffer&& aShmem)
      60             : {
      61           0 :   MutexAutoLock lock(mMutex);
      62           0 :   MOZ_ASSERT(mPoolFree < mShmemPool.Length());
      63           0 :   mShmemPool[mPoolFree] = Move(aShmem);
      64           0 :   mPoolFree++;
      65             : #ifdef DEBUG
      66           0 :   size_t poolUse = mShmemPool.Length() - mPoolFree;
      67           0 :   if (poolUse > 0) {
      68           0 :     LOG_VERBOSE(("ShmemPool usage reduced to %" PRIuSIZE " buffers", poolUse));
      69             :   }
      70             : #endif
      71           0 : }
      72             : 
      73           0 : ShmemPool::~ShmemPool()
      74             : {
      75             : #ifdef DEBUG
      76           0 :   for (size_t i = 0; i < mShmemPool.Length(); i++) {
      77           0 :     MOZ_ASSERT(!mShmemPool[i].Valid());
      78             :   }
      79             : #endif
      80           0 : }
      81             : 
      82             : } // namespace mozilla