net/spdy/write_blocked_list.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_SPDY_WRITE_BLOCKED_LIST_H_
   6 #define NET_SPDY_WRITE_BLOCKED_LIST_H_
   7
   8 #include <algorithm>
   9 #include <deque>
  10
  11 #include "base/logging.h"
  12
  13 namespace net {
  14
  15 const int kHighestPriority = 0;
  16 const int kLowestPriority = 7;
  17
  18 template <typename IdType>
  19 class WriteBlockedList {
  20  public:
  21   // 0(1) size lookup.  0(1) insert at front or back.
  22   typedef std::deque<IdType> BlockedList;
  23   typedef typename BlockedList::iterator iterator;
  24
  25   // Returns the priority of the highest priority list with sessions on it, or
  26   // -1 if none of the lists have pending sessions.
  27   int GetHighestPriorityWriteBlockedList() const {
  28     for (int i = 0; i <= kLowestPriority; ++i) {
  29       if (write_blocked_lists_[i].size() > 0)
  30         return i;
  31     }
  32     return -1;
  33   }
  34
  35   int PopFront(int priority) {
  36     DCHECK(!write_blocked_lists_[priority].empty());
  37     IdType stream_id = write_blocked_lists_[priority].front();
  38     write_blocked_lists_[priority].pop_front();
  39     return stream_id;
  40   }
  41
  42   bool HasWriteBlockedStreamsGreaterThanPriority(int priority) const {
  43     for (int i = kHighestPriority; i < priority; ++i) {
  44       if (!write_blocked_lists_[i].empty()) {
  45         return true;
  46       }
  47     }
  48     return false;
  49   }
  50
  51   bool HasWriteBlockedStreams() const {
  52     return HasWriteBlockedStreamsGreaterThanPriority(kLowestPriority + 1);
  53   }
  54
  55   void PushBack(IdType stream_id, int priority) {
  56     write_blocked_lists_[priority].push_back(stream_id);
  57   }
  58
  59   void RemoveStreamFromWriteBlockedList(IdType stream_id, int priority) {
  60     iterator it = std::find(write_blocked_lists_[priority].begin(),
  61                             write_blocked_lists_[priority].end(),
  62                             stream_id);
  63     while (it != write_blocked_lists_[priority].end()) {
  64       write_blocked_lists_[priority].erase(it);
  65       it = std::find(write_blocked_lists_[priority].begin(),
  66                      write_blocked_lists_[priority].end(),
  67                      stream_id);
  68     }
  69   }
  70
  71   int NumBlockedStreams() {
  72     int num_blocked_streams = 0;
  73     for (int i = kHighestPriority; i <= kLowestPriority; ++i) {
  74       num_blocked_streams += write_blocked_lists_[i].size();
  75     }
  76     return num_blocked_streams;
  77   }
  78
  79  private:
  80   // Priority ranges from 0 to 7
  81   BlockedList write_blocked_lists_[8];
  82 };
  83
  84 }  // namespace net
  85
  86 #endif  // NET_SPDY_WRITE_BLOCKED_LIST_H_