michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "VolatileBuffer.h"
michael@0: #include "mozilla/Assertions.h"
michael@0: #include "mozilla/DebugOnly.h"
michael@0: #include "mozilla/mozalloc.h"
michael@0: 
michael@0: #include <mach/mach.h>
michael@0: #include <sys/mman.h>
michael@0: #include <unistd.h>
michael@0: 
michael@0: #define MIN_VOLATILE_ALLOC_SIZE 8192
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: VolatileBuffer::VolatileBuffer()
michael@0:   : mBuf(nullptr)
michael@0:   , mSize(0)
michael@0:   , mLockCount(0)
michael@0:   , mHeap(false)
michael@0: {
michael@0: }
michael@0: 
michael@0: bool
michael@0: VolatileBuffer::Init(size_t aSize, size_t aAlignment)
michael@0: {
michael@0:   MOZ_ASSERT(!mSize && !mBuf, "Init called twice");
michael@0:   MOZ_ASSERT(!(aAlignment % sizeof(void *)),
michael@0:              "Alignment must be multiple of pointer size");
michael@0: 
michael@0:   mSize = aSize;
michael@0: 
michael@0:   kern_return_t ret = 0;
michael@0:   if (aSize < MIN_VOLATILE_ALLOC_SIZE) {
michael@0:     goto heap_alloc;
michael@0:   }
michael@0: 
michael@0:   ret = vm_allocate(mach_task_self(),
michael@0:                     (vm_address_t*)&mBuf,
michael@0:                     mSize,
michael@0:                     VM_FLAGS_PURGABLE | VM_FLAGS_ANYWHERE);
michael@0:   if (ret == KERN_SUCCESS) {
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0: heap_alloc:
michael@0:   (void)moz_posix_memalign(&mBuf, aAlignment, aSize);
michael@0:   mHeap = true;
michael@0:   return !!mBuf;
michael@0: }
michael@0: 
michael@0: VolatileBuffer::~VolatileBuffer()
michael@0: {
michael@0:   if (OnHeap()) {
michael@0:     free(mBuf);
michael@0:   } else {
michael@0:     vm_deallocate(mach_task_self(), (vm_address_t)mBuf, mSize);
michael@0:   }
michael@0: }
michael@0: 
michael@0: bool
michael@0: VolatileBuffer::Lock(void** aBuf)
michael@0: {
michael@0:   MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer");
michael@0: 
michael@0:   *aBuf = mBuf;
michael@0:   if (++mLockCount > 1 || OnHeap()) {
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   int state = VM_PURGABLE_NONVOLATILE;
michael@0:   kern_return_t ret =
michael@0:     vm_purgable_control(mach_task_self(),
michael@0:                         (vm_address_t)mBuf,
michael@0:                         VM_PURGABLE_SET_STATE,
michael@0:                         &state);
michael@0:   return ret == KERN_SUCCESS && !(state & VM_PURGABLE_EMPTY);
michael@0: }
michael@0: 
michael@0: void
michael@0: VolatileBuffer::Unlock()
michael@0: {
michael@0:   MOZ_ASSERT(mLockCount > 0, "VolatileBuffer unlocked too many times!");
michael@0:   if (--mLockCount || OnHeap()) {
michael@0:     return;
michael@0:   }
michael@0: 
michael@0:   int state = VM_PURGABLE_VOLATILE | VM_VOLATILE_GROUP_DEFAULT;
michael@0:   DebugOnly<kern_return_t> ret =
michael@0:     vm_purgable_control(mach_task_self(),
michael@0:                         (vm_address_t)mBuf,
michael@0:                         VM_PURGABLE_SET_STATE,
michael@0:                         &state);
michael@0:   MOZ_ASSERT(ret == KERN_SUCCESS, "Failed to set buffer as purgable");
michael@0: }
michael@0: 
michael@0: bool
michael@0: VolatileBuffer::OnHeap() const
michael@0: {
michael@0:   return mHeap;
michael@0: }
michael@0: 
michael@0: size_t
michael@0: VolatileBuffer::HeapSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
michael@0: {
michael@0:   return OnHeap() ? aMallocSizeOf(mBuf) : 0;
michael@0: }
michael@0: 
michael@0: size_t
michael@0: VolatileBuffer::NonHeapSizeOfExcludingThis() const
michael@0: {
michael@0:   if (OnHeap()) {
michael@0:     return 0;
michael@0:   }
michael@0: 
michael@0:   unsigned long pagemask = getpagesize() - 1;
michael@0:   return (mSize + pagemask) & ~pagemask;
michael@0: }
michael@0: 
michael@0: } // namespace mozilla