110 строки
3.4 KiB
C++
110 строки
3.4 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <mutex>
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#include <thread>
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#include <jsi/jsi.h>
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namespace facebook {
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namespace react {
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/*
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* Takes a function and calls it with a reference to a Runtime. The function
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* will be called when it is safe to do so (i.e. it ensures non-concurrent
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* access) and may be invoked asynchronously, depending on the implementation.
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* If you need to access a Runtime, it's encouraged to use a RuntimeExecutor
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* instead of storing a pointer to the Runtime itself, which makes it more
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* difficult to ensure that the Runtime is being accessed safely.
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*/
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using RuntimeExecutor =
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std::function<void(std::function<void(jsi::Runtime &runtime)> &&callback)>;
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/*
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* The caller can expect that the callback will be executed sometime later on an
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* unspecified thread.
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* Use this method when the caller prefers to not be blocked by executing the
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* `callback`.
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* Note that this method does not provide any guarantees
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* about when the `callback` will be executed (before returning to the caller,
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* after that, or in parallel), the only thing that is guaranteed is that there
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* is no synchronization.
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*/
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inline static void executeAsynchronously(
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RuntimeExecutor const &runtimeExecutor,
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std::function<void(jsi::Runtime &runtime)> &&callback) noexcept {
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std::thread{[callback = std::move(callback), runtimeExecutor]() mutable {
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runtimeExecutor(std::move(callback));
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}};
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}
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/*
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* Executes a `callback` in a *synchronous* manner using given
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* `RuntimeExecutor`.
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* Use this method when the caller needs to *be blocked* by executing the
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* callback but does not concerted about the particular thread on which the
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* `callback` will be executed.
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*/
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inline static void executeSynchronously_CAN_DEADLOCK(
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RuntimeExecutor const &runtimeExecutor,
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std::function<void(jsi::Runtime &runtime)> &&callback) noexcept {
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std::mutex mutex;
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mutex.lock();
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runtimeExecutor(
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[callback = std::move(callback), &mutex](jsi::Runtime &runtime) {
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callback(runtime);
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mutex.unlock();
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});
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mutex.lock();
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}
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/*
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* Executes a `callback` in a *synchronous* manner on the same thread using
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* given `RuntimeExecutor`.
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* Use this method when the caller needs to *be blocked* by executing the
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* `callback` and requires that the callback will be executed on the same
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* thread.
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*/
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inline static void executeSynchronouslyOnSameThread_CAN_DEADLOCK(
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RuntimeExecutor const &runtimeExecutor,
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std::function<void(jsi::Runtime &runtime)> &&callback) noexcept {
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// Note: We need the third mutex to get back to the main thread before
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// the lambda is finished (because all mutexes are allocated on the stack).
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// We use `recursive_mutex` here to not deadlock in case if a
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// `RuntimeExecutor` executes the callback synchronously.
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std::recursive_mutex mutex1;
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std::recursive_mutex mutex2;
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std::recursive_mutex mutex3;
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mutex1.lock();
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mutex2.lock();
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mutex3.lock();
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jsi::Runtime *runtimePtr;
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runtimeExecutor([&](jsi::Runtime &runtime) {
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runtimePtr = &runtime;
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mutex1.unlock();
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// `callback` is called somewhere here.
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mutex2.lock();
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mutex3.unlock();
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});
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mutex1.lock();
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callback(*runtimePtr);
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mutex2.unlock();
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mutex3.lock();
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}
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} // namespace react
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} // namespace facebook
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