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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include <stdlib.h>
#include "base/logging.h"
#include "gin/array_buffer.h"
#include "gin/per_isolate_data.h"
namespace gin {
namespace {
gin::WrapperInfo g_array_buffer_wrapper_info = {gin::kEmbedderNativeGin};
} // namespace
static_assert(V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT == 2,
"array buffers must have two internal fields");
// ArrayBufferAllocator -------------------------------------------------------
void* ArrayBufferAllocator::Allocate(size_t length) {
return calloc(1, length);
}
void* ArrayBufferAllocator::AllocateUninitialized(size_t length) {
return malloc(length);
}
void ArrayBufferAllocator::Free(void* data, size_t length) {
free(data);
}
ArrayBufferAllocator* ArrayBufferAllocator::SharedInstance() {
static ArrayBufferAllocator* instance = new ArrayBufferAllocator();
return instance;
}
// ArrayBuffer::Private -------------------------------------------------------
// This class exists to solve a tricky lifetime problem. The V8 API doesn't
// want to expose a direct view into the memory behind an array buffer because
// V8 might deallocate that memory during garbage collection. Instead, the V8
// API forces us to externalize the buffer and take ownership of the memory.
// In order to know when to free the memory, we need to figure out both when
// we're done with it and when V8 is done with it.
//
// To determine whether we're done with the memory, every view we have into
// the array buffer takes a reference to the ArrayBuffer::Private object that
// actually owns the memory. To determine when V8 is done with the memory, we
// open a weak handle to the ArrayBuffer object. When we receive the weak
// callback, we know the object is about to be garbage collected and we can
// drop V8's implied reference to the memory.
//
// The final subtlety is that we need every ArrayBuffer into the same array
// buffer to AddRef the same ArrayBuffer::Private. To make that work, we store
// a pointer to the ArrayBuffer::Private object in an internal field of the
// ArrayBuffer object.
//
class ArrayBuffer::Private : public base::RefCounted<ArrayBuffer::Private> {
public:
static scoped_refptr<Private> From(v8::Isolate* isolate,
v8::Local<v8::ArrayBuffer> array);
void* buffer() const { return buffer_; }
size_t length() const { return length_; }
private:
friend class base::RefCounted<Private>;
Private(v8::Isolate* isolate, v8::Local<v8::ArrayBuffer> array);
~Private();
static void FirstWeakCallback(const v8::WeakCallbackInfo<Private>& data);
static void SecondWeakCallback(const v8::WeakCallbackInfo<Private>& data);
v8::Global<v8::ArrayBuffer> array_buffer_;
scoped_refptr<Private> self_reference_;
v8::Isolate* isolate_;
void* buffer_;
size_t length_;
};
scoped_refptr<ArrayBuffer::Private> ArrayBuffer::Private::From(
v8::Isolate* isolate, v8::Local<v8::ArrayBuffer> array) {
if (array->IsExternal()) {
CHECK_EQ(WrapperInfo::From(v8::Local<v8::Object>::Cast(array)),
&g_array_buffer_wrapper_info)
<< "Cannot mix blink and gin ArrayBuffers";
return make_scoped_refptr(static_cast<Private*>(
array->GetAlignedPointerFromInternalField(kEncodedValueIndex)));
}
return make_scoped_refptr(new Private(isolate, array));
}
ArrayBuffer::Private::Private(v8::Isolate* isolate,
v8::Local<v8::ArrayBuffer> array)
: array_buffer_(isolate, array), isolate_(isolate) {
// Take ownership of the array buffer.
CHECK(!array->IsExternal());
v8::ArrayBuffer::Contents contents = array->Externalize();
buffer_ = contents.Data();
length_ = contents.ByteLength();
array->SetAlignedPointerInInternalField(kWrapperInfoIndex,
&g_array_buffer_wrapper_info);
array->SetAlignedPointerInInternalField(kEncodedValueIndex, this);
self_reference_ = this; // Cleared in SecondWeakCallback.
array_buffer_.SetWeak(this, FirstWeakCallback,
v8::WeakCallbackType::kParameter);
}
ArrayBuffer::Private::~Private() {
PerIsolateData::From(isolate_)->allocator()->Free(buffer_, length_);
}
void ArrayBuffer::Private::FirstWeakCallback(
const v8::WeakCallbackInfo<Private>& data) {
Private* parameter = data.GetParameter();
parameter->array_buffer_.Reset();
data.SetSecondPassCallback(SecondWeakCallback);
}
void ArrayBuffer::Private::SecondWeakCallback(
const v8::WeakCallbackInfo<Private>& data) {
Private* parameter = data.GetParameter();
parameter->self_reference_ = NULL;
}
// ArrayBuffer ----------------------------------------------------------------
ArrayBuffer::ArrayBuffer()
: bytes_(0),
num_bytes_(0) {
}
ArrayBuffer::ArrayBuffer(v8::Isolate* isolate,
v8::Local<v8::ArrayBuffer> array) {
private_ = ArrayBuffer::Private::From(isolate, array);
bytes_ = private_->buffer();
num_bytes_ = private_->length();
}
ArrayBuffer::~ArrayBuffer() {
}
ArrayBuffer& ArrayBuffer::operator=(const ArrayBuffer& other) {
private_ = other.private_;
bytes_ = other.bytes_;
num_bytes_ = other.num_bytes_;
return *this;
}
// Converter<ArrayBuffer> -----------------------------------------------------
bool Converter<ArrayBuffer>::FromV8(v8::Isolate* isolate,
v8::Local<v8::Value> val,
ArrayBuffer* out) {
if (!val->IsArrayBuffer())
return false;
*out = ArrayBuffer(isolate, v8::Local<v8::ArrayBuffer>::Cast(val));
return true;
}
// ArrayBufferView ------------------------------------------------------------
ArrayBufferView::ArrayBufferView()
: offset_(0),
num_bytes_(0) {
}
ArrayBufferView::ArrayBufferView(v8::Isolate* isolate,
v8::Local<v8::ArrayBufferView> view)
: array_buffer_(isolate, view->Buffer()),
offset_(view->ByteOffset()),
num_bytes_(view->ByteLength()) {
}
ArrayBufferView::~ArrayBufferView() {
}
ArrayBufferView& ArrayBufferView::operator=(const ArrayBufferView& other) {
array_buffer_ = other.array_buffer_;
offset_ = other.offset_;
num_bytes_ = other.num_bytes_;
return *this;
}
// Converter<ArrayBufferView> -------------------------------------------------
bool Converter<ArrayBufferView>::FromV8(v8::Isolate* isolate,
v8::Local<v8::Value> val,
ArrayBufferView* out) {
if (!val->IsArrayBufferView())
return false;
*out = ArrayBufferView(isolate, v8::Local<v8::ArrayBufferView>::Cast(val));
return true;
}
} // namespace gin
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