| // Copyright (c) 2015 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef NET_SPDY_PRIORITY_WRITE_SCHEDULER_H_ |
| #define NET_SPDY_PRIORITY_WRITE_SCHEDULER_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include <algorithm> |
| #include <deque> |
| #include <tuple> |
| #include <unordered_map> |
| #include <utility> |
| #include <vector> |
| |
| #include "base/logging.h" |
| #include "net/spdy/spdy_bug_tracker.h" |
| #include "net/spdy/spdy_protocol.h" |
| #include "net/spdy/write_scheduler.h" |
| |
| namespace net { |
| |
| namespace test { |
| template <typename StreamIdType> |
| class PriorityWriteSchedulerPeer; |
| } |
| |
| // WriteScheduler implementation that manages the order in which streams are |
| // written using the SPDY priority scheme described at: |
| // https://www.chromium.org/spdy/spdy-protocol/spdy-protocol-draft3-1#TOC-2.3.3-Stream-priority |
| // |
| // Internally, PriorityWriteScheduler consists of 8 PriorityInfo objects, one |
| // for each priority value. Each PriorityInfo contains a list of streams of |
| // that priority that are ready to write, as well as a timestamp of the last |
| // I/O event that occurred for a stream of that priority. |
| template <typename StreamIdType> |
| class PriorityWriteScheduler : public WriteScheduler<StreamIdType> { |
| public: |
| using typename WriteScheduler<StreamIdType>::StreamPrecedenceType; |
| |
| // Creates scheduler with no streams. |
| PriorityWriteScheduler() = default; |
| |
| void RegisterStream(StreamIdType stream_id, |
| const StreamPrecedenceType& precedence) override { |
| SPDY_BUG_IF(!precedence.is_spdy3_priority()) << "Expected SPDY priority"; |
| |
| // parent_id not used here, but may as well validate it. However, |
| // parent_id may legitimately not be registered yet--see b/15676312. |
| StreamIdType parent_id = precedence.parent_id(); |
| DVLOG_IF(1, parent_id != kHttp2RootStreamId && !StreamRegistered(parent_id)) |
| << "Parent stream " << parent_id << " not registered"; |
| |
| if (stream_id == kHttp2RootStreamId) { |
| SPDY_BUG << "Stream " << kHttp2RootStreamId << " already registered"; |
| return; |
| } |
| StreamInfo stream_info = {precedence.spdy3_priority(), stream_id, false}; |
| bool inserted = |
| stream_infos_.insert(std::make_pair(stream_id, stream_info)).second; |
| SPDY_BUG_IF(!inserted) << "Stream " << stream_id << " already registered"; |
| } |
| |
| void UnregisterStream(StreamIdType stream_id) override { |
| auto it = stream_infos_.find(stream_id); |
| if (it == stream_infos_.end()) { |
| SPDY_BUG << "Stream " << stream_id << " not registered"; |
| return; |
| } |
| StreamInfo& stream_info = it->second; |
| if (stream_info.ready) { |
| bool erased = |
| Erase(&priority_infos_[stream_info.priority].ready_list, stream_info); |
| DCHECK(erased); |
| } |
| stream_infos_.erase(it); |
| } |
| |
| bool StreamRegistered(StreamIdType stream_id) const override { |
| return stream_infos_.find(stream_id) != stream_infos_.end(); |
| } |
| |
| StreamPrecedenceType GetStreamPrecedence( |
| StreamIdType stream_id) const override { |
| auto it = stream_infos_.find(stream_id); |
| if (it == stream_infos_.end()) { |
| DVLOG(1) << "Stream " << stream_id << " not registered"; |
| return StreamPrecedenceType(kV3LowestPriority); |
| } |
| return StreamPrecedenceType(it->second.priority); |
| } |
| |
| void UpdateStreamPrecedence(StreamIdType stream_id, |
| const StreamPrecedenceType& precedence) override { |
| SPDY_BUG_IF(!precedence.is_spdy3_priority()) << "Expected SPDY priority"; |
| |
| // parent_id not used here, but may as well validate it. However, |
| // parent_id may legitimately not be registered yet--see b/15676312. |
| StreamIdType parent_id = precedence.parent_id(); |
| DVLOG_IF(1, parent_id != kHttp2RootStreamId && !StreamRegistered(parent_id)) |
| << "Parent stream " << parent_id << " not registered"; |
| |
| auto it = stream_infos_.find(stream_id); |
| if (it == stream_infos_.end()) { |
| // TODO(mpw): add to stream_infos_ on demand--see b/15676312. |
| DVLOG(1) << "Stream " << stream_id << " not registered"; |
| return; |
| } |
| StreamInfo& stream_info = it->second; |
| SpdyPriority new_priority = precedence.spdy3_priority(); |
| if (stream_info.priority == new_priority) { |
| return; |
| } |
| if (stream_info.ready) { |
| bool erased = |
| Erase(&priority_infos_[stream_info.priority].ready_list, stream_info); |
| DCHECK(erased); |
| priority_infos_[new_priority].ready_list.push_back(&stream_info); |
| ++num_ready_streams_; |
| } |
| stream_info.priority = new_priority; |
| } |
| |
| std::vector<StreamIdType> GetStreamChildren( |
| StreamIdType stream_id) const override { |
| return std::vector<StreamIdType>(); |
| } |
| |
| void RecordStreamEventTime(StreamIdType stream_id, |
| int64_t now_in_usec) override { |
| auto it = stream_infos_.find(stream_id); |
| if (it == stream_infos_.end()) { |
| SPDY_BUG << "Stream " << stream_id << " not registered"; |
| return; |
| } |
| PriorityInfo& priority_info = priority_infos_[it->second.priority]; |
| priority_info.last_event_time_usec = |
| std::max(priority_info.last_event_time_usec, now_in_usec); |
| } |
| |
| int64_t GetLatestEventWithPrecedence(StreamIdType stream_id) const override { |
| auto it = stream_infos_.find(stream_id); |
| if (it == stream_infos_.end()) { |
| SPDY_BUG << "Stream " << stream_id << " not registered"; |
| return 0; |
| } |
| int64_t last_event_time_usec = 0; |
| const StreamInfo& stream_info = it->second; |
| for (SpdyPriority p = kV3HighestPriority; p < stream_info.priority; ++p) { |
| last_event_time_usec = std::max(last_event_time_usec, |
| priority_infos_[p].last_event_time_usec); |
| } |
| return last_event_time_usec; |
| } |
| |
| StreamIdType PopNextReadyStream() override { |
| return std::get<0>(PopNextReadyStreamAndPrecedence()); |
| } |
| |
| // Returns the next ready stream and its precedence. |
| std::tuple<StreamIdType, StreamPrecedenceType> |
| PopNextReadyStreamAndPrecedence() override { |
| for (SpdyPriority p = kV3HighestPriority; p <= kV3LowestPriority; ++p) { |
| ReadyList& ready_list = priority_infos_[p].ready_list; |
| if (!ready_list.empty()) { |
| StreamInfo* info = ready_list.front(); |
| ready_list.pop_front(); |
| --num_ready_streams_; |
| |
| DCHECK(stream_infos_.find(info->stream_id) != stream_infos_.end()); |
| info->ready = false; |
| return std::make_tuple(info->stream_id, |
| StreamPrecedenceType(info->priority)); |
| } |
| } |
| SPDY_BUG << "No ready streams available"; |
| return std::make_tuple(0, StreamPrecedenceType(kV3LowestPriority)); |
| } |
| |
| bool ShouldYield(StreamIdType stream_id) const override { |
| auto it = stream_infos_.find(stream_id); |
| if (it == stream_infos_.end()) { |
| SPDY_BUG << "Stream " << stream_id << " not registered"; |
| return false; |
| } |
| |
| // If there's a higher priority stream, this stream should yield. |
| const StreamInfo& stream_info = it->second; |
| for (SpdyPriority p = kV3HighestPriority; p < stream_info.priority; ++p) { |
| if (!priority_infos_[p].ready_list.empty()) { |
| return true; |
| } |
| } |
| |
| // If this priority level is empty, or this stream is the next up, there's |
| // no need to yield. |
| const auto& ready_list = priority_infos_[it->second.priority].ready_list; |
| if (ready_list.empty() || ready_list.front()->stream_id == stream_id) { |
| return false; |
| } |
| |
| // There are other streams in this priority level which take precedence. |
| // Yield. |
| return true; |
| } |
| |
| void MarkStreamReady(StreamIdType stream_id, bool add_to_front) override { |
| auto it = stream_infos_.find(stream_id); |
| if (it == stream_infos_.end()) { |
| SPDY_BUG << "Stream " << stream_id << " not registered"; |
| return; |
| } |
| StreamInfo& stream_info = it->second; |
| if (stream_info.ready) { |
| return; |
| } |
| ReadyList& ready_list = priority_infos_[stream_info.priority].ready_list; |
| if (add_to_front) { |
| ready_list.push_front(&stream_info); |
| } else { |
| ready_list.push_back(&stream_info); |
| } |
| ++num_ready_streams_; |
| stream_info.ready = true; |
| } |
| |
| void MarkStreamNotReady(StreamIdType stream_id) override { |
| auto it = stream_infos_.find(stream_id); |
| if (it == stream_infos_.end()) { |
| SPDY_BUG << "Stream " << stream_id << " not registered"; |
| return; |
| } |
| StreamInfo& stream_info = it->second; |
| if (!stream_info.ready) { |
| return; |
| } |
| bool erased = |
| Erase(&priority_infos_[stream_info.priority].ready_list, stream_info); |
| DCHECK(erased); |
| stream_info.ready = false; |
| } |
| |
| // Returns true iff the number of ready streams is non-zero. |
| bool HasReadyStreams() const override { return num_ready_streams_ > 0; } |
| |
| // Returns the number of ready streams. |
| size_t NumReadyStreams() const override { return num_ready_streams_; } |
| |
| private: |
| friend class test::PriorityWriteSchedulerPeer<StreamIdType>; |
| |
| // State kept for all registered streams. All ready streams have ready = true |
| // and should be present in priority_infos_[priority].ready_list. |
| struct StreamInfo { |
| SpdyPriority priority; |
| StreamIdType stream_id; |
| bool ready; |
| }; |
| |
| // 0(1) size lookup, 0(1) insert at front or back. |
| typedef std::deque<StreamInfo*> ReadyList; |
| |
| // State kept for each priority level. |
| struct PriorityInfo { |
| // IDs of streams that are ready to write. |
| ReadyList ready_list; |
| // Time of latest write event for stream of this priority, in microseconds. |
| int64_t last_event_time_usec = 0; |
| }; |
| |
| typedef std::unordered_map<StreamIdType, StreamInfo> StreamInfoMap; |
| |
| // Erases first occurrence (which should be the only one) of |info| in |
| // |ready_list|, returning true if found (and erased), or false otherwise. |
| // Decrements |num_ready_streams_| if an entry is erased. |
| bool Erase(ReadyList* ready_list, const StreamInfo& info) { |
| auto it = std::find(ready_list->begin(), ready_list->end(), &info); |
| if (it == ready_list->end()) { |
| return false; |
| } |
| ready_list->erase(it); |
| --num_ready_streams_; |
| return true; |
| } |
| |
| // Number of ready streams. |
| size_t num_ready_streams_ = 0; |
| // Per-priority state, including ready lists. |
| PriorityInfo priority_infos_[kV3LowestPriority + 1]; |
| // StreamInfos for all registered streams. |
| StreamInfoMap stream_infos_; |
| }; |
| |
| } // namespace net |
| |
| #endif // NET_SPDY_PRIORITY_WRITE_SCHEDULER_H_ |