136 lines
3.6 KiB
C++
136 lines
3.6 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <functional>
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#include <vector>
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#include <folly/Optional.h>
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#include <folly/Try.h>
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#include <folly/fibers/FiberManagerInternal.h>
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#include <folly/fibers/Promise.h>
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namespace folly {
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namespace fibers {
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template <typename T>
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class TaskIterator;
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/**
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* Schedules several tasks and immediately returns an iterator, that
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* allow one to traverse tasks in the order of their completion. All results
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* and exceptions thrown are stored alongside with the task id and are
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* accessible via iterator.
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*
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* @param first Range of tasks to be scheduled
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* @param last
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*
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* @return movable, non-copyable iterator
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*/
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template <class InputIterator>
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TaskIterator<invoke_result_t<
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typename std::iterator_traits<InputIterator>::
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value_type>> inline addTasks(InputIterator first, InputIterator last);
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template <typename T>
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class TaskIterator {
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public:
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typedef T value_type;
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TaskIterator() : fm_(FiberManager::getFiberManager()) {}
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// not copyable
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TaskIterator(const TaskIterator& other) = delete;
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TaskIterator& operator=(const TaskIterator& other) = delete;
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// movable
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TaskIterator(TaskIterator&& other) noexcept;
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TaskIterator& operator=(TaskIterator&& other) = delete;
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/**
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* Add one more task to the TaskIterator.
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*
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* @param func task to be added, will be scheduled on current FiberManager
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*/
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template <typename F>
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void addTask(F&& func);
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/**
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* @return True if there are tasks immediately available to be consumed (no
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* need to await on them).
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*/
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bool hasCompleted() const;
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/**
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* @return True if there are tasks pending execution (need to awaited on).
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*/
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bool hasPending() const;
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/**
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* @return True if there are any tasks (hasCompleted() || hasPending()).
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*/
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bool hasNext() const;
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/**
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* Await for another task to complete. Will not await if the result is
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* already available.
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*
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* @return result of the task completed.
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* @throw exception thrown by the task.
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*/
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T awaitNext();
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/**
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* Await until the specified number of tasks completes or there are no
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* tasks left to await for.
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* Note: Will not await if there are already the specified number of tasks
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* available.
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*
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* @param n Number of tasks to await for completition.
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*/
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void reserve(size_t n);
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/**
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* @return id of the last task that was processed by awaitNext().
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*/
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size_t getTaskID() const;
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private:
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template <class InputIterator>
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friend TaskIterator<
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invoke_result_t<typename std::iterator_traits<InputIterator>::value_type>>
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addTasks(InputIterator first, InputIterator last);
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struct Context {
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std::vector<std::pair<size_t, folly::Try<T>>> results;
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folly::Optional<Promise<void>> promise;
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size_t totalTasks{0};
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size_t tasksConsumed{0};
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size_t tasksToFulfillPromise{0};
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};
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std::shared_ptr<Context> context_{std::make_shared<Context>()};
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size_t id_{std::numeric_limits<size_t>::max()};
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FiberManager& fm_;
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folly::Try<T> awaitNextResult();
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};
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} // namespace fibers
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} // namespace folly
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#include <folly/fibers/AddTasks-inl.h>
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