memory/volatile/VolatileBufferFallback.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #include "VolatileBuffer.h"
   6 #include "mozilla/Assertions.h"
   7 #include "mozilla/mozalloc.h"
   8
   9 #ifdef MOZ_MEMORY
  10 int posix_memalign(void** memptr, size_t alignment, size_t size);
  11 #endif
  12
  13 namespace mozilla {
  14
  15 VolatileBuffer::VolatileBuffer()
  16     : mMutex("VolatileBuffer"), mBuf(nullptr), mSize(0), mLockCount(0) {}
  17
  18 bool VolatileBuffer::Init(size_t aSize, size_t aAlignment) {
  19   MOZ_ASSERT(!mSize && !mBuf, "Init called twice");
  20   MOZ_ASSERT(!(aAlignment % sizeof(void*)),
  21              "Alignment must be multiple of pointer size");
  22
  23   mSize = aSize;
  24 #if defined(MOZ_MEMORY) || defined(HAVE_POSIX_MEMALIGN)
  25   if (posix_memalign(&mBuf, aAlignment, aSize) != 0) {
  26     return false;
  27   }
  28 #else
  29 #  error "No memalign implementation found"
  30 #endif
  31   return !!mBuf;
  32 }
  33
  34 VolatileBuffer::~VolatileBuffer() {
  35   MOZ_ASSERT(mLockCount == 0, "Being destroyed with non-zero lock count?");
  36
  37   free(mBuf);
  38 }
  39
  40 bool VolatileBuffer::Lock(void** aBuf) {
  41   MutexAutoLock lock(mMutex);
  42
  43   MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer");
  44
  45   *aBuf = mBuf;
  46   mLockCount++;
  47
  48   return true;
  49 }
  50
  51 void VolatileBuffer::Unlock() {
  52   MutexAutoLock lock(mMutex);
  53
  54   mLockCount--;
  55   MOZ_ASSERT(mLockCount >= 0, "VolatileBuffer unlocked too many times!");
  56 }
  57
  58 bool VolatileBuffer::OnHeap() const { return true; }
  59
  60 size_t VolatileBuffer::HeapSizeOfExcludingThis(
  61     MallocSizeOf aMallocSizeOf) const {
  62   return aMallocSizeOf(mBuf);
  63 }
  64
  65 size_t VolatileBuffer::NonHeapSizeOfExcludingThis() const { return 0; }
  66
  67 }  // namespace mozilla