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/*
* Copyright 2011-present Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Simple timeout queue. Call user-specified callbacks when their timeouts
* expire.
*
* This class assumes that "time" is an int64_t and doesn't care about time
* units (seconds, milliseconds, etc). You call runOnce() / runLoop() using
* the same time units that you use to specify callbacks.
*
* @author Tudor Bosman (tudorb@fb.com)
*/
#pragma once
#include <cstdint>
#include <functional>
#include <boost/multi_index/indexed_by.hpp>
#include <boost/multi_index/member.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/multi_index_container.hpp>
namespace folly {
class TimeoutQueue {
public:
typedef int64_t Id;
typedef std::function<void(Id, int64_t)> Callback;
TimeoutQueue() : nextId_(1) { }
/**
* Add a one-time timeout event that will fire "delay" time units from "now"
* (that is, the first time that run*() is called with a time value >= now
* + delay).
*/
Id add(int64_t now, int64_t delay, Callback callback);
/**
* Add a repeating timeout event that will fire every "interval" time units
* (it will first fire when run*() is called with a time value >=
* now + interval).
*
* run*() will always invoke each repeating event at most once, even if
* more than one "interval" period has passed.
*/
Id addRepeating(int64_t now, int64_t interval, Callback callback);
/**
* Erase a given timeout event, returns true if the event was actually
* erased and false if it didn't exist in our queue.
*/
bool erase(Id id);
/**
* Process all events that are due at times <= "now" by calling their
* callbacks.
*
* Callbacks are allowed to call back into the queue and add / erase events;
* they might create more events that are already due. In this case,
* runOnce() will only go through the queue once, and return a "next
* expiration" time in the past or present (<= now); runLoop()
* will process the queue again, until there are no events already due.
*
* Note that it is then possible for runLoop to never return if
* callbacks re-add themselves to the queue (or if you have repeating
* callbacks with an interval of 0).
*
* Return the time that the next event will be due (same as
* nextExpiration(), below)
*/
int64_t runOnce(int64_t now) { return runInternal(now, true); }
int64_t runLoop(int64_t now) { return runInternal(now, false); }
/**
* Return the time that the next event will be due.
*/
int64_t nextExpiration() const;
private:
int64_t runInternal(int64_t now, bool runOnce);
// noncopyable
TimeoutQueue(const TimeoutQueue&) = delete;
TimeoutQueue& operator=(const TimeoutQueue&) = delete;
struct Event {
Id id;
int64_t expiration;
int64_t repeatInterval;
Callback callback;
};
typedef boost::multi_index_container<
Event,
boost::multi_index::indexed_by<
boost::multi_index::ordered_unique<boost::multi_index::member<
Event, Id, &Event::id
>>,
boost::multi_index::ordered_non_unique<boost::multi_index::member<
Event, int64_t, &Event::expiration
>>
>
> Set;
enum {
BY_ID=0,
BY_EXPIRATION=1
};
Set timeouts_;
Id nextId_;
};
} // namespace folly