1 files changed, 175 insertions, 0 deletions
diff --git a/src/shrpx_downstream_queue.cc b/src/shrpx_downstream_queue.cc
new file mode 100644
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+++ b/src/shrpx_downstream_queue.cc
@@ -0,0 +1,175 @@
+/*
+ * nghttp2 - HTTP/2 C Library
+ *
+ * Copyright (c) 2012 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_downstream_queue.h"
+
+#include <cassert>
+#include <limits>
+
+#include "shrpx_downstream.h"
+
+namespace shrpx {
+
+DownstreamQueue::HostEntry::HostEntry(ImmutableString &&key)
+    : key(std::move(key)), num_active(0) {}
+
+DownstreamQueue::DownstreamQueue(size_t conn_max_per_host, bool unified_host)
+    : conn_max_per_host_(conn_max_per_host == 0
+                             ? std::numeric_limits<size_t>::max()
+                             : conn_max_per_host),
+      unified_host_(unified_host) {}
+
+DownstreamQueue::~DownstreamQueue() {
+  dlist_delete_all(downstreams_);
+  for (auto &p : host_entries_) {
+    auto &ent = p.second;
+    dlist_delete_all(ent.blocked);
+  }
+}
+
+void DownstreamQueue::add_pending(std::unique_ptr<Downstream> downstream) {
+  downstream->set_dispatch_state(DispatchState::PENDING);
+  downstreams_.append(downstream.release());
+}
+
+void DownstreamQueue::mark_failure(Downstream *downstream) {
+  downstream->set_dispatch_state(DispatchState::FAILURE);
+}
+
+DownstreamQueue::HostEntry &
+DownstreamQueue::find_host_entry(const StringRef &host) {
+  auto itr = host_entries_.find(host);
+  if (itr == std::end(host_entries_)) {
+    auto key = ImmutableString{std::begin(host), std::end(host)};
+    auto key_ref = StringRef{key};
+#ifdef HAVE_STD_MAP_EMPLACE
+    std::tie(itr, std::ignore) =
+        host_entries_.emplace(key_ref, HostEntry(std::move(key)));
+#else  // !HAVE_STD_MAP_EMPLACE
+    // for g++-4.7
+    std::tie(itr, std::ignore) = host_entries_.insert(
+        std::make_pair(key_ref, HostEntry(std::move(key))));
+#endif // !HAVE_STD_MAP_EMPLACE
+  }
+  return (*itr).second;
+}
+
+StringRef DownstreamQueue::make_host_key(const StringRef &host) const {
+  return unified_host_ ? StringRef{} : host;
+}
+
+StringRef DownstreamQueue::make_host_key(Downstream *downstream) const {
+  return make_host_key(downstream->request().authority);
+}
+
+void DownstreamQueue::mark_active(Downstream *downstream) {
+  auto &ent = find_host_entry(make_host_key(downstream));
+  ++ent.num_active;
+
+  downstream->set_dispatch_state(DispatchState::ACTIVE);
+}
+
+void DownstreamQueue::mark_blocked(Downstream *downstream) {
+  auto &ent = find_host_entry(make_host_key(downstream));
+
+  downstream->set_dispatch_state(DispatchState::BLOCKED);
+
+  auto link = new BlockedLink{};
+  downstream->attach_blocked_link(link);
+  ent.blocked.append(link);
+}
+
+bool DownstreamQueue::can_activate(const StringRef &host) const {
+  auto itr = host_entries_.find(make_host_key(host));
+  if (itr == std::end(host_entries_)) {
+    return true;
+  }
+  auto &ent = (*itr).second;
+  return ent.num_active < conn_max_per_host_;
+}
+
+namespace {
+bool remove_host_entry_if_empty(const DownstreamQueue::HostEntry &ent,
+                                DownstreamQueue::HostEntryMap &host_entries,
+                                const StringRef &host) {
+  if (ent.blocked.empty() && ent.num_active == 0) {
+    host_entries.erase(host);
+    return true;
+  }
+  return false;
+}
+} // namespace
+
+Downstream *DownstreamQueue::remove_and_get_blocked(Downstream *downstream,
+                                                    bool next_blocked) {
+  // Delete downstream when this function returns.
+  auto delptr = std::unique_ptr<Downstream>(downstream);
+
+  downstreams_.remove(downstream);
+
+  auto host = make_host_key(downstream);
+  auto &ent = find_host_entry(host);
+
+  if (downstream->get_dispatch_state() == DispatchState::ACTIVE) {
+    --ent.num_active;
+  } else {
+    // For those downstreams deleted while in blocked state
+    auto link = downstream->detach_blocked_link();
+    if (link) {
+      ent.blocked.remove(link);
+      delete link;
+    }
+  }
+
+  if (remove_host_entry_if_empty(ent, host_entries_, host)) {
+    return nullptr;
+  }
+
+  if (!next_blocked || ent.num_active >= conn_max_per_host_) {
+    return nullptr;
+  }
+
+  auto link = ent.blocked.head;
+
+  if (!link) {
+    return nullptr;
+  }
+
+  auto next_downstream = link->downstream;
+  auto link2 = next_downstream->detach_blocked_link();
+  // This is required with --disable-assert.
+  (void)link2;
+  assert(link2 == link);
+  ent.blocked.remove(link);
+  delete link;
+  remove_host_entry_if_empty(ent, host_entries_, host);
+
+  return next_downstream;
+}
+
+Downstream *DownstreamQueue::get_downstreams() const {
+  return downstreams_.head;
+}
+
+} // namespace shrpx