Upgrade V8 to version 4.9.385.28
https://chromium.googlesource.com/v8/v8/+/4.9.385.28
FPIIM-449
Change-Id: I4b2e74289d4bf3667f2f3dc8aa2e541f63e26eb4
diff --git a/src/futex-emulation.h b/src/futex-emulation.h
new file mode 100644
index 0000000..9949bdf
--- /dev/null
+++ b/src/futex-emulation.h
@@ -0,0 +1,131 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_FUTEX_EMULATION_H_
+#define V8_FUTEX_EMULATION_H_
+
+#include <stdint.h>
+
+#include "src/allocation.h"
+#include "src/base/atomicops.h"
+#include "src/base/lazy-instance.h"
+#include "src/base/macros.h"
+#include "src/base/platform/condition-variable.h"
+#include "src/base/platform/mutex.h"
+#include "src/handles.h"
+
+// Support for emulating futexes, a low-level synchronization primitive. They
+// are natively supported by Linux, but must be emulated for other platforms.
+// This library emulates them on all platforms using mutexes and condition
+// variables for consistency.
+//
+// This is used by the Futex API defined in the SharedArrayBuffer draft spec,
+// found here: https://github.com/lars-t-hansen/ecmascript_sharedmem
+
+namespace v8 {
+
+namespace base {
+class TimeDelta;
+} // base
+
+namespace internal {
+
+class Isolate;
+class JSArrayBuffer;
+
+class FutexWaitListNode {
+ public:
+ FutexWaitListNode()
+ : prev_(nullptr),
+ next_(nullptr),
+ backing_store_(nullptr),
+ wait_addr_(0),
+ waiting_(false),
+ interrupted_(false) {}
+
+ void NotifyWake();
+
+ private:
+ friend class FutexEmulation;
+ friend class FutexWaitList;
+
+ base::ConditionVariable cond_;
+ FutexWaitListNode* prev_;
+ FutexWaitListNode* next_;
+ void* backing_store_;
+ size_t wait_addr_;
+ bool waiting_;
+ bool interrupted_;
+
+ DISALLOW_COPY_AND_ASSIGN(FutexWaitListNode);
+};
+
+
+class FutexWaitList {
+ public:
+ FutexWaitList();
+
+ void AddNode(FutexWaitListNode* node);
+ void RemoveNode(FutexWaitListNode* node);
+
+ private:
+ friend class FutexEmulation;
+
+ FutexWaitListNode* head_;
+ FutexWaitListNode* tail_;
+
+ DISALLOW_COPY_AND_ASSIGN(FutexWaitList);
+};
+
+
+class FutexEmulation : public AllStatic {
+ public:
+ // These must match the values in src/harmony-atomics.js
+ enum Result {
+ kOk = 0,
+ kNotEqual = -1,
+ kTimedOut = -2,
+ };
+
+ // Check that array_buffer[addr] == value, and return kNotEqual if not. If
+ // they are equal, block execution on |isolate|'s thread until woken via
+ // |Wake|, or when the time given in |rel_timeout_ms| elapses. Note that
+ // |rel_timeout_ms| can be Infinity.
+ // If woken, return kOk, otherwise return kTimedOut. The initial check and
+ // the decision to wait happen atomically.
+ static Object* Wait(Isolate* isolate, Handle<JSArrayBuffer> array_buffer,
+ size_t addr, int32_t value, double rel_timeout_ms);
+
+ // Wake |num_waiters_to_wake| threads that are waiting on the given |addr|.
+ // The rest of the waiters will continue to wait. The return value is the
+ // number of woken waiters.
+ static Object* Wake(Isolate* isolate, Handle<JSArrayBuffer> array_buffer,
+ size_t addr, int num_waiters_to_wake);
+
+ // Check that array_buffer[addr] == value, and return kNotEqual if not. If
+ // they are equal, wake |num_waiters_to_wake| threads that are waiting on the
+ // given |addr|. The rest of the waiters will continue to wait, but will now
+ // be waiting on |addr2| instead of |addr|. The return value is the number of
+ // woken waiters or kNotEqual as described above.
+ static Object* WakeOrRequeue(Isolate* isolate,
+ Handle<JSArrayBuffer> array_buffer, size_t addr,
+ int num_waiters_to_wake, int32_t value,
+ size_t addr2);
+
+ // Return the number of threads waiting on |addr|. Should only be used for
+ // testing.
+ static Object* NumWaitersForTesting(Isolate* isolate,
+ Handle<JSArrayBuffer> array_buffer,
+ size_t addr);
+
+ private:
+ friend class FutexWaitListNode;
+
+ static base::LazyMutex mutex_;
+ static base::LazyInstance<FutexWaitList>::type wait_list_;
+};
+} // namespace internal
+} // namespace v8
+
+#endif // V8_FUTEX_EMULATION_H_