/* 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 "VolatileBuffer.h" #include "mozilla/Assertions.h" #include "mozilla/DebugOnly.h" #include "mozilla/mozalloc.h" #include <mach/mach.h> #include <sys/mman.h> #include <unistd.h> #define MIN_VOLATILE_ALLOC_SIZE 8192 namespace mozilla { VolatileBuffer::VolatileBuffer() : mMutex("VolatileBuffer"), mBuf(nullptr), mSize(0), mLockCount(0), mHeap(false) {} bool VolatileBuffer::Init(size_t aSize, size_t aAlignment) { MOZ_ASSERT(!mSize && !mBuf, "Init called twice"); MOZ_ASSERT(!(aAlignment % sizeof(void*)), "Alignment must be multiple of pointer size"); mSize = aSize; kern_return_t ret = 0; if (aSize < MIN_VOLATILE_ALLOC_SIZE) { goto heap_alloc; } ret = vm_allocate(mach_task_self(), (vm_address_t*)&mBuf, mSize, VM_FLAGS_PURGABLE | VM_FLAGS_ANYWHERE); if (ret == KERN_SUCCESS) { return true; } heap_alloc: (void)posix_memalign(&mBuf, aAlignment, aSize); mHeap = true; return !!mBuf; } VolatileBuffer::~VolatileBuffer() { MOZ_ASSERT(mLockCount == 0, "Being destroyed with non-zero lock count?"); if (OnHeap()) { free(mBuf); } else { vm_deallocate(mach_task_self(), (vm_address_t)mBuf, mSize); } } bool VolatileBuffer::Lock(void** aBuf) { MutexAutoLock lock(mMutex); MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer"); *aBuf = mBuf; if (++mLockCount > 1 || OnHeap()) { return true; } int state = VM_PURGABLE_NONVOLATILE; kern_return_t ret = vm_purgable_control(mach_task_self(), (vm_address_t)mBuf, VM_PURGABLE_SET_STATE, &state); return ret == KERN_SUCCESS && !(state & VM_PURGABLE_EMPTY); } void VolatileBuffer::Unlock() { MutexAutoLock lock(mMutex); MOZ_ASSERT(mLockCount > 0, "VolatileBuffer unlocked too many times!"); if (--mLockCount || OnHeap()) { return; } int state = VM_PURGABLE_VOLATILE | VM_VOLATILE_GROUP_DEFAULT; DebugOnly<kern_return_t> ret = vm_purgable_control( mach_task_self(), (vm_address_t)mBuf, VM_PURGABLE_SET_STATE, &state); MOZ_ASSERT(ret == KERN_SUCCESS, "Failed to set buffer as purgable"); } bool VolatileBuffer::OnHeap() const { return mHeap; } size_t VolatileBuffer::HeapSizeOfExcludingThis( MallocSizeOf aMallocSizeOf) const { return OnHeap() ? aMallocSizeOf(mBuf) : 0; } size_t VolatileBuffer::NonHeapSizeOfExcludingThis() const { if (OnHeap()) { return 0; } unsigned long pagemask = getpagesize() - 1; return (mSize + pagemask) & ~pagemask; } } // namespace mozilla