1/*
2 * Copyright 2011-present Facebook, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/**
18 * Simple timeout queue. Call user-specified callbacks when their timeouts
19 * expire.
20 *
21 * This class assumes that "time" is an int64_t and doesn't care about time
22 * units (seconds, milliseconds, etc). You call runOnce() / runLoop() using
23 * the same time units that you use to specify callbacks.
24 *
25 * @author Tudor Bosman (tudorb@fb.com)
26 */
27
28#pragma once
29
30#include <cstdint>
31#include <functional>
32
33#include <boost/multi_index/indexed_by.hpp>
34#include <boost/multi_index/member.hpp>
35#include <boost/multi_index/ordered_index.hpp>
36#include <boost/multi_index_container.hpp>
37
38namespace folly {
39
40class TimeoutQueue {
41 public:
42 typedef int64_t Id;
43 typedef std::function<void(Id, int64_t)> Callback;
44
45 TimeoutQueue() : nextId_(1) {}
46
47 /**
48 * Add a one-time timeout event that will fire "delay" time units from "now"
49 * (that is, the first time that run*() is called with a time value >= now
50 * + delay).
51 */
52 Id add(int64_t now, int64_t delay, Callback callback);
53
54 /**
55 * Add a repeating timeout event that will fire every "interval" time units
56 * (it will first fire when run*() is called with a time value >=
57 * now + interval).
58 *
59 * run*() will always invoke each repeating event at most once, even if
60 * more than one "interval" period has passed.
61 */
62 Id addRepeating(int64_t now, int64_t interval, Callback callback);
63
64 /**
65 * Erase a given timeout event, returns true if the event was actually
66 * erased and false if it didn't exist in our queue.
67 */
68 bool erase(Id id);
69
70 /**
71 * Process all events that are due at times <= "now" by calling their
72 * callbacks.
73 *
74 * Callbacks are allowed to call back into the queue and add / erase events;
75 * they might create more events that are already due. In this case,
76 * runOnce() will only go through the queue once, and return a "next
77 * expiration" time in the past or present (<= now); runLoop()
78 * will process the queue again, until there are no events already due.
79 *
80 * Note that it is then possible for runLoop to never return if
81 * callbacks re-add themselves to the queue (or if you have repeating
82 * callbacks with an interval of 0).
83 *
84 * Return the time that the next event will be due (same as
85 * nextExpiration(), below)
86 */
87 int64_t runOnce(int64_t now) {
88 return runInternal(now, true);
89 }
90 int64_t runLoop(int64_t now) {
91 return runInternal(now, false);
92 }
93
94 /**
95 * Return the time that the next event will be due.
96 */
97 int64_t nextExpiration() const;
98
99 private:
100 int64_t runInternal(int64_t now, bool runOnce);
101 // noncopyable
102 TimeoutQueue(const TimeoutQueue&) = delete;
103 TimeoutQueue& operator=(const TimeoutQueue&) = delete;
104
105 struct Event {
106 Id id;
107 int64_t expiration;
108 int64_t repeatInterval;
109 Callback callback;
110 };
111
112 typedef boost::multi_index_container<
113 Event,
114 boost::multi_index::indexed_by<
115 boost::multi_index::ordered_unique<
116 boost::multi_index::member<Event, Id, &Event::id>>,
117 boost::multi_index::ordered_non_unique<
118 boost::multi_index::member<Event, int64_t, &Event::expiration>>>>
119 Set;
120
121 enum {
122 BY_ID = 0,
123 BY_EXPIRATION = 1,
124 };
125
126 Set timeouts_;
127 Id nextId_;
128};
129
130} // namespace folly
131