1 /*
2 * nghttp2 - HTTP/2 C Library
3 *
4 * Copyright (c) 2014 Tatsuhiro Tsujikawa
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining
7 * a copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sublicense, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be
15 * included in all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
21 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
22 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
23 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24 */
25 #include "shrpx_connect_blocker.h"
26 #include "shrpx_config.h"
27 #include "shrpx_log.h"
28
29 namespace shrpx {
30
31 namespace {
connect_blocker_cb(struct ev_loop * loop,ev_timer * w,int revents)32 void connect_blocker_cb(struct ev_loop *loop, ev_timer *w, int revents) {
33 auto connect_blocker = static_cast<ConnectBlocker *>(w->data);
34 if (LOG_ENABLED(INFO)) {
35 LOG(INFO) << "Unblock";
36 }
37
38 connect_blocker->call_unblock_func();
39 }
40 } // namespace
41
ConnectBlocker(std::mt19937 & gen,struct ev_loop * loop,std::function<void ()> block_func,std::function<void ()> unblock_func)42 ConnectBlocker::ConnectBlocker(std::mt19937 &gen, struct ev_loop *loop,
43 std::function<void()> block_func,
44 std::function<void()> unblock_func)
45 : gen_(gen),
46 block_func_(block_func),
47 unblock_func_(unblock_func),
48 loop_(loop),
49 fail_count_(0),
50 offline_(false) {
51 ev_timer_init(&timer_, connect_blocker_cb, 0., 0.);
52 timer_.data = this;
53 }
54
~ConnectBlocker()55 ConnectBlocker::~ConnectBlocker() { ev_timer_stop(loop_, &timer_); }
56
blocked() const57 bool ConnectBlocker::blocked() const { return ev_is_active(&timer_); }
58
on_success()59 void ConnectBlocker::on_success() {
60 if (ev_is_active(&timer_)) {
61 return;
62 }
63
64 fail_count_ = 0;
65 }
66
67 // Use the similar backoff algorithm described in
68 // https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md
69 namespace {
70 constexpr size_t MAX_BACKOFF_EXP = 10;
71 constexpr auto MULTIPLIER = 1.6;
72 constexpr auto JITTER = 0.2;
73 } // namespace
74
on_failure()75 void ConnectBlocker::on_failure() {
76 if (ev_is_active(&timer_)) {
77 return;
78 }
79
80 call_block_func();
81
82 ++fail_count_;
83
84 auto base_backoff =
85 util::int_pow(MULTIPLIER, std::min(MAX_BACKOFF_EXP, fail_count_));
86 auto dist = std::uniform_real_distribution<>(-JITTER * base_backoff,
87 JITTER * base_backoff);
88
89 auto &downstreamconf = *get_config()->conn.downstream;
90
91 auto backoff =
92 std::min(downstreamconf.timeout.max_backoff, base_backoff + dist(gen_));
93
94 LOG(WARN) << "Could not connect " << fail_count_
95 << " times in a row; sleep for " << backoff << " seconds";
96
97 ev_timer_set(&timer_, backoff, 0.);
98 ev_timer_start(loop_, &timer_);
99 }
100
get_fail_count() const101 size_t ConnectBlocker::get_fail_count() const { return fail_count_; }
102
offline()103 void ConnectBlocker::offline() {
104 if (offline_) {
105 return;
106 }
107
108 if (!ev_is_active(&timer_)) {
109 call_block_func();
110 }
111
112 offline_ = true;
113
114 ev_timer_stop(loop_, &timer_);
115 ev_timer_set(&timer_, std::numeric_limits<double>::max(), 0.);
116 ev_timer_start(loop_, &timer_);
117 }
118
online()119 void ConnectBlocker::online() {
120 ev_timer_stop(loop_, &timer_);
121
122 call_unblock_func();
123
124 fail_count_ = 0;
125
126 offline_ = false;
127 }
128
in_offline() const129 bool ConnectBlocker::in_offline() const { return offline_; }
130
call_block_func()131 void ConnectBlocker::call_block_func() {
132 if (block_func_) {
133 block_func_();
134 }
135 }
136
call_unblock_func()137 void ConnectBlocker::call_unblock_func() {
138 if (unblock_func_) {
139 unblock_func_();
140 }
141 }
142
143 } // namespace shrpx
144