зеркало из https://github.com/mozilla/gecko-dev.git
55 строки
2.1 KiB
C++
55 строки
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* vim: set ts=8 sts=2 et sw=2 tw=80:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef js_WaitCallbacks_h
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#define js_WaitCallbacks_h
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#include <stddef.h>
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#include <stdint.h>
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#include "jstypes.h"
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struct JS_PUBLIC_API JSRuntime;
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namespace JS {
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/**
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* When the JSRuntime is about to block in an Atomics.wait() JS call or in a
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* `wait` instruction in WebAssembly, it can notify the host by means of a call
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* to BeforeWaitCallback. After the wait, it can notify the host by means of a
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* call to AfterWaitCallback. Both callbacks must be null, or neither.
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*
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* (If you change the callbacks from null to not-null or vice versa while some
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* thread on the runtime is in a wait, you will be sorry.)
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*
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* The argument to the BeforeWaitCallback is a pointer to uninitialized
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* stack-allocated working memory of size WAIT_CALLBACK_CLIENT_MAXMEM bytes.
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* The caller of SetWaitCallback() must pass the amount of memory it will need,
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* and this amount will be checked against that limit and the process will crash
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* reliably if the check fails.
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*
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* The value returned by the BeforeWaitCallback will be passed to the
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* AfterWaitCallback.
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*
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* The AfterWaitCallback will be called even if the wakeup is spurious and the
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* thread goes right back to waiting again. Of course the thread will call the
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* BeforeWaitCallback once more before it goes to sleep in this situation.
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*/
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static constexpr size_t WAIT_CALLBACK_CLIENT_MAXMEM = 32;
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using BeforeWaitCallback = void* (*)(uint8_t* memory);
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using AfterWaitCallback = void (*)(void* cookie);
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extern JS_PUBLIC_API void SetWaitCallback(JSRuntime* rt,
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BeforeWaitCallback beforeWait,
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AfterWaitCallback afterWait,
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size_t requiredMemory);
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} // namespace JS
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#endif // js_WaitCallbacks_h
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