/* * nghttp2 - HTTP/2 C Library * * Copyright (c) 2014 Tatsuhiro Tsujikawa * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include "shrpx_connect_blocker.h" namespace shrpx { namespace { void connect_blocker_cb(struct ev_loop *loop, ev_timer *w, int revents) { auto connect_blocker = static_cast(w->data); if (LOG_ENABLED(INFO)) { LOG(INFO) << "Unblock"; } connect_blocker->call_unblock_func(); } } // namespace ConnectBlocker::ConnectBlocker(std::mt19937 &gen, struct ev_loop *loop, std::function block_func, std::function unblock_func) : gen_(gen), block_func_(block_func), unblock_func_(unblock_func), loop_(loop), fail_count_(0), offline_(false) { ev_timer_init(&timer_, connect_blocker_cb, 0., 0.); timer_.data = this; } ConnectBlocker::~ConnectBlocker() { ev_timer_stop(loop_, &timer_); } bool ConnectBlocker::blocked() const { return ev_is_active(&timer_); } void ConnectBlocker::on_success() { if (ev_is_active(&timer_)) { return; } fail_count_ = 0; } // Use the similar backoff algorithm described in // https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md namespace { constexpr size_t MAX_BACKOFF_EXP = 10; constexpr auto MULTIPLIER = 1.6; constexpr auto JITTER = 0.2; } // namespace void ConnectBlocker::on_failure() { if (ev_is_active(&timer_)) { return; } call_block_func(); ++fail_count_; auto base_backoff = pow(MULTIPLIER, std::min(MAX_BACKOFF_EXP, fail_count_)); auto dist = std::uniform_real_distribution<>(-JITTER * base_backoff, JITTER * base_backoff); auto backoff = base_backoff + dist(gen_); LOG(WARN) << "Could not connect " << fail_count_ << " times in a row; sleep for " << backoff << " seconds"; ev_timer_set(&timer_, backoff, 0.); ev_timer_start(loop_, &timer_); } size_t ConnectBlocker::get_fail_count() const { return fail_count_; } void ConnectBlocker::offline() { if (offline_) { return; } if (!ev_is_active(&timer_)) { call_block_func(); } offline_ = true; ev_timer_stop(loop_, &timer_); ev_timer_set(&timer_, std::numeric_limits::max(), 0.); ev_timer_start(loop_, &timer_); } void ConnectBlocker::online() { ev_timer_stop(loop_, &timer_); fail_count_ = 0; offline_ = false; } bool ConnectBlocker::in_offline() const { return offline_; } void ConnectBlocker::call_block_func() { block_func_(); } void ConnectBlocker::call_unblock_func() { unblock_func_(); } } // namespace shrpx