1 files changed, 143 insertions, 0 deletions
diff --git a/src/shrpx_connect_blocker.cc b/src/shrpx_connect_blocker.cc
new file mode 100644
index 0000000..ff767b0
--- /dev/null
+++ b/src/shrpx_connect_blocker.cc
@@ -0,0 +1,143 @@
+/*
+ * 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"
+#include "shrpx_config.h"
+#include "shrpx_log.h"
+
+namespace shrpx {
+
+namespace {
+void connect_blocker_cb(struct ev_loop *loop, ev_timer *w, int revents) {
+  auto connect_blocker = static_cast<ConnectBlocker *>(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<void()> block_func,
+                               std::function<void()> unblock_func)
+    : gen_(gen),
+      block_func_(std::move(block_func)),
+      unblock_func_(std::move(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 =
+      util::int_pow(MULTIPLIER, std::min(MAX_BACKOFF_EXP, fail_count_));
+  auto dist = std::uniform_real_distribution<>(-JITTER * base_backoff,
+                                               JITTER * base_backoff);
+
+  auto &downstreamconf = *get_config()->conn.downstream;
+
+  auto backoff =
+      std::min(downstreamconf.timeout.max_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<double>::max(), 0.);
+  ev_timer_start(loop_, &timer_);
+}
+
+void ConnectBlocker::online() {
+  ev_timer_stop(loop_, &timer_);
+
+  call_unblock_func();
+
+  fail_count_ = 0;
+
+  offline_ = false;
+}
+
+bool ConnectBlocker::in_offline() const { return offline_; }
+
+void ConnectBlocker::call_block_func() {
+  if (block_func_) {
+    block_func_();
+  }
+}
+
+void ConnectBlocker::call_unblock_func() {
+  if (unblock_func_) {
+    unblock_func_();
+  }
+}
+
+} // namespace shrpx