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      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 #include "net/spdy/spdy_protocol.h"
     13 
     14 namespace net {
     15 
     16 const int kHighestPriority = 0;
     17 const int kLowestPriority = 7;
     18 
     19 template <typename IdType>
     20 class WriteBlockedList {
     21  public:
     22   // 0(1) size lookup.  0(1) insert at front or back.
     23   typedef std::deque<IdType> BlockedList;
     24   typedef typename BlockedList::iterator iterator;
     25 
     26   static SpdyPriority ClampPriority(SpdyPriority priority) {
     27     if (priority < kHighestPriority) {
     28       LOG(DFATAL) << "Invalid priority: " << static_cast<int>(priority);
     29       return kHighestPriority;
     30     }
     31     if (priority > kLowestPriority) {
     32       LOG(DFATAL) << "Invalid priority: " << static_cast<int>(priority);
     33       return kLowestPriority;
     34     }
     35     return priority;
     36   }
     37 
     38   // Returns the priority of the highest priority list with sessions on it.
     39   SpdyPriority GetHighestPriorityWriteBlockedList() const {
     40     for (SpdyPriority i = 0; i <= kLowestPriority; ++i) {
     41       if (write_blocked_lists_[i].size() > 0)
     42         return i;
     43     }
     44     LOG(DFATAL) << "No blocked streams";
     45     return kHighestPriority;
     46   }
     47 
     48   IdType PopFront(SpdyPriority priority) {
     49     priority = ClampPriority(priority);
     50     DCHECK(!write_blocked_lists_[priority].empty());
     51     IdType stream_id = write_blocked_lists_[priority].front();
     52     write_blocked_lists_[priority].pop_front();
     53     return stream_id;
     54   }
     55 
     56   bool HasWriteBlockedStreamsGreaterThanPriority(SpdyPriority priority) const {
     57     priority = ClampPriority(priority);
     58     for (SpdyPriority i = kHighestPriority; i < priority; ++i) {
     59       if (!write_blocked_lists_[i].empty()) {
     60         return true;
     61       }
     62     }
     63     return false;
     64   }
     65 
     66   bool HasWriteBlockedStreams() const {
     67     for (SpdyPriority i = kHighestPriority; i <= kLowestPriority; ++i) {
     68       if (!write_blocked_lists_[i].empty()) {
     69         return true;
     70       }
     71     }
     72     return false;
     73   }
     74 
     75   void PushBack(IdType stream_id, SpdyPriority priority) {
     76     write_blocked_lists_[ClampPriority(priority)].push_back(stream_id);
     77   }
     78 
     79   void RemoveStreamFromWriteBlockedList(IdType stream_id,
     80                                         SpdyPriority priority) {
     81     iterator it = std::find(write_blocked_lists_[priority].begin(),
     82                             write_blocked_lists_[priority].end(),
     83                             stream_id);
     84     while (it != write_blocked_lists_[priority].end()) {
     85       write_blocked_lists_[priority].erase(it);
     86       it = std::find(write_blocked_lists_[priority].begin(),
     87                      write_blocked_lists_[priority].end(),
     88                      stream_id);
     89     }
     90   }
     91 
     92   size_t NumBlockedStreams() const {
     93     size_t num_blocked_streams = 0;
     94     for (SpdyPriority i = kHighestPriority; i <= kLowestPriority; ++i) {
     95       num_blocked_streams += write_blocked_lists_[i].size();
     96     }
     97     return num_blocked_streams;
     98   }
     99 
    100  private:
    101   BlockedList write_blocked_lists_[kLowestPriority + 1];
    102 };
    103 
    104 }  // namespace net
    105 
    106 #endif  // NET_SPDY_WRITE_BLOCKED_LIST_H_
    107