The Tor Browser: js/src/vm/SharedArrayObject.h@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-

     2  * vim: set ts=8 sts=4 et sw=4 tw=99:

     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

     5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     7 #ifndef vm_SharedArrayObject_h

     8 #define vm_SharedArrayObject_h

    10 #include "mozilla/Atomics.h"

    12 #include "jsapi.h"

    13 #include "jsobj.h"

    14 #include "jstypes.h"

    16 #include "gc/Barrier.h"

    17 #include "vm/ArrayBufferObject.h"

    19 typedef struct JSProperty JSProperty;

    21 namespace js {

    23 /*

    24  * SharedArrayRawBuffer

    25  *

    26  * A bookkeeping object always stored immediately before the raw buffer.

    27  * The buffer itself is mmap()'d and refcounted.

    28  * SharedArrayBufferObjects and AsmJS code may hold references.

    29  *

    30  *           |<------ sizeof ------>|<- length ->|

    31  *

    32  *   | waste | SharedArrayRawBuffer | data array | waste |

    33  */

    34 class SharedArrayRawBuffer

    35 {

    36   private:

    37     mozilla::Atomic<uint32_t, mozilla::ReleaseAcquire> refcount;

    38     uint32_t length;

    40   protected:

    41     SharedArrayRawBuffer(uint8_t *buffer, uint32_t length)

    42       : refcount(1), length(length)

    43     {

    44         JS_ASSERT(buffer == dataPointer());

    45     }

    47   public:

    48     static SharedArrayRawBuffer *New(uint32_t length);

    50     inline uint8_t *dataPointer() const {

    51         return ((uint8_t *)this) + sizeof(SharedArrayRawBuffer);

    52     }

    54     inline uint32_t byteLength() const {

    55         return length;

    56     }

    58     void addReference();

    59     void dropReference();

    60 };

    62 /*

    63  * SharedArrayBufferObject

    64  *

    65  * When transferred to a WebWorker, the buffer is not neutered on the parent side,

    66  * and both child and parent reference the same buffer.

    67  */

    68 class SharedArrayBufferObject : public ArrayBufferObject

    69 {

    70     static bool byteLengthGetterImpl(JSContext *cx, CallArgs args);

    72   public:

    73     static const Class class_;

    74     static const Class protoClass;

    76     // Slot used for storing a pointer to the SharedArrayRawBuffer.

    77     static const uint8_t RAWBUF_SLOT = ArrayBufferObject::RESERVED_SLOTS;

    79     static const uint8_t RESERVED_SLOTS = ArrayBufferObject::RESERVED_SLOTS + 1;

    81     static bool class_constructor(JSContext *cx, unsigned argc, Value *vp);

    83     // Create a SharedArrayBufferObject with a new SharedArrayRawBuffer.

    84     static JSObject *New(JSContext *cx, uint32_t length);

    86     // Create a SharedArrayBufferObject using an existing SharedArrayRawBuffer.

    87     static JSObject *New(JSContext *cx, SharedArrayRawBuffer *buffer);

    89     static bool byteLengthGetter(JSContext *cx, unsigned argc, Value *vp);

    91     static void Finalize(FreeOp *fop, JSObject *obj);

    93     void acceptRawBuffer(SharedArrayRawBuffer *buffer);

    94     void dropRawBuffer();

    96     SharedArrayRawBuffer *rawBufferObject() const;

    97     uint8_t *dataPointer() const;

    98     uint32_t byteLength() const;

    99 };

   101 bool

   102 IsSharedArrayBuffer(HandleValue v);

   104 } // namespace js

   106 #endif // vm_SharedArrayObject_h

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