130 lines
3.8 KiB
C++
130 lines
3.8 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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/**
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* Simple timeout queue. Call user-specified callbacks when their timeouts
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* expire.
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*
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* This class assumes that "time" is an int64_t and doesn't care about time
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* units (seconds, milliseconds, etc). You call runOnce() / runLoop() using
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* the same time units that you use to specify callbacks.
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*
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* @author Tudor Bosman (tudorb@fb.com)
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*/
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#pragma once
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#include <cstdint>
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#include <functional>
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#include <boost/multi_index/indexed_by.hpp>
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#include <boost/multi_index/member.hpp>
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#include <boost/multi_index/ordered_index.hpp>
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#include <boost/multi_index_container.hpp>
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namespace folly {
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class TimeoutQueue {
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public:
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typedef int64_t Id;
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typedef std::function<void(Id, int64_t)> Callback;
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TimeoutQueue() : nextId_(1) {}
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/**
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* Add a one-time timeout event that will fire "delay" time units from "now"
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* (that is, the first time that run*() is called with a time value >= now
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* + delay).
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*/
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Id add(int64_t now, int64_t delay, Callback callback);
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/**
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* Add a repeating timeout event that will fire every "interval" time units
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* (it will first fire when run*() is called with a time value >=
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* now + interval).
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*
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* run*() will always invoke each repeating event at most once, even if
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* more than one "interval" period has passed.
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*/
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Id addRepeating(int64_t now, int64_t interval, Callback callback);
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/**
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* Erase a given timeout event, returns true if the event was actually
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* erased and false if it didn't exist in our queue.
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*/
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bool erase(Id id);
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/**
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* Process all events that are due at times <= "now" by calling their
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* callbacks.
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*
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* Callbacks are allowed to call back into the queue and add / erase events;
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* they might create more events that are already due. In this case,
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* runOnce() will only go through the queue once, and return a "next
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* expiration" time in the past or present (<= now); runLoop()
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* will process the queue again, until there are no events already due.
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*
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* Note that it is then possible for runLoop to never return if
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* callbacks re-add themselves to the queue (or if you have repeating
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* callbacks with an interval of 0).
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*
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* Return the time that the next event will be due (same as
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* nextExpiration(), below)
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*/
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int64_t runOnce(int64_t now) {
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return runInternal(now, true);
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}
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int64_t runLoop(int64_t now) {
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return runInternal(now, false);
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}
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/**
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* Return the time that the next event will be due.
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*/
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int64_t nextExpiration() const;
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private:
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int64_t runInternal(int64_t now, bool onceOnly);
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TimeoutQueue(const TimeoutQueue&) = delete;
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TimeoutQueue& operator=(const TimeoutQueue&) = delete;
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struct Event {
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Id id;
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int64_t expiration;
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int64_t repeatInterval;
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Callback callback;
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};
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typedef boost::multi_index_container<
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Event,
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boost::multi_index::indexed_by<
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boost::multi_index::ordered_unique<
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boost::multi_index::member<Event, Id, &Event::id>>,
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boost::multi_index::ordered_non_unique<
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boost::multi_index::member<Event, int64_t, &Event::expiration>>>>
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Set;
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enum {
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BY_ID = 0,
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BY_EXPIRATION = 1,
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};
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Set timeouts_;
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Id nextId_;
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};
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} // namespace folly
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