| // Copyright 2016 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_HTTP2_PRIORITY_DEPENDENCIES_H_ |
| #define NET_HTTP2_PRIORITY_DEPENDENCIES_H_ |
| |
| #include <list> |
| #include <map> |
| |
| #include "net/base/net_export.h" |
| #include "net/spdy/spdy_protocol.h" |
| |
| namespace net { |
| |
| // A helper class encapsulating the state and logic to set dependencies of |
| // HTTP2 streams based on their SpdyPriority and the ordering |
| // of creation and deletion of the streams. |
| class NET_EXPORT_PRIVATE Http2PriorityDependencies { |
| public: |
| Http2PriorityDependencies(); |
| ~Http2PriorityDependencies(); |
| |
| // Called when a stream SYN is sent to the server. Note that in the |
| // case of server push, a stream may be created without this routine |
| // being called. In such cases, the client ignores the stream's priority |
| // (as the server is effectively overriding the client's notions of |
| // priority anyway). |
| // On return, |*dependent_stream_id| is set to the stream id that |
| // this stream should be made dependent on, and |*exclusive| set to |
| // whether that dependency should be exclusive. |
| void OnStreamSynSent(SpdyStreamId id, |
| SpdyPriority priority, |
| SpdyStreamId* dependent_stream_id, |
| bool* exclusive); |
| |
| void OnStreamDestruction(SpdyStreamId id); |
| |
| private: |
| // The requirements for the internal data structure for this class are: |
| // a) Constant time insertion of entries at the end of the list, |
| // b) Fast removal of any entry based on its id. |
| // c) Constant time lookup of the entry at the end of the list. |
| // std::list would satisfy (a) & (c), but some form of map is |
| // needed for (b). The priority must be included in the map |
| // entries so that deletion can determine which list in id_priority_lists_ |
| // to erase from. |
| using IdList = std::list<std::pair<SpdyStreamId, SpdyPriority>>; |
| using EntryMap = std::map<SpdyStreamId, IdList::iterator>; |
| |
| IdList id_priority_lists_[kV3LowestPriority + 1]; |
| |
| // Tracks the location of an id anywhere in the above vector of lists. |
| // Iterators to list elements remain valid until those particular elements |
| // are erased. |
| EntryMap entry_by_stream_id_; |
| }; |
| |
| } // namespace net |
| |
| #endif // NET_HTTP2_PRIORITY_DEPENDENCIES_H_ |