WriteBlockedList for QUIC that prioritizes Crypto and Headers streams

net/quic/quic_write_blocked_list.h

+// Copyright (c) 2014 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_QUIC_QUIC_WRITE_BLOCKED_LIST_H_
+#define NET_QUIC_QUIC_WRITE_BLOCKED_LIST_H_
+
+#include "net/base/net_export.h"
+#include "net/quic/quic_protocol.h"
+#include "net/spdy/write_blocked_list.h"
+
+namespace net {
+
+// Keeps tracks of the QUIC streams that have data to write, sorted by
+// priority.  QUIC stream priority order is:
+// Crypto stream > Headers stream > Data streams by requested priority.
+class NET_EXPORT_PRIVATE QuicWriteBlockedList {
+ private:
+  typedef WriteBlockedList<QuicStreamId> QuicWriteBlockedListBase;
+
+ public:
+  static const QuicPriority kHighestPriority;
+  static const QuicPriority kLowestPriority;
+
+  QuicWriteBlockedList();
+  ~QuicWriteBlockedList();
+
+  bool HasWriteBlockedStreams() const {
+    return crypto_stream_blocked_ ||
+        headers_stream_blocked_ ||
+        base_write_blocked_list_.HasWriteBlockedStreams();
+  }
+
+  size_t NumBlockedStreams() const {
+    int num_blocked = base_write_blocked_list_.NumBlockedStreams();
+    if (crypto_stream_blocked_) {
+      ++num_blocked;
+    }
+    if (headers_stream_blocked_) {
+      ++num_blocked;
+    }
+
+    return num_blocked;
+  }
+
+  QuicStreamId PopFront() {
+    if (crypto_stream_blocked_) {
+      crypto_stream_blocked_ = false;
+      return kCryptoStreamId;
+    } else if (headers_stream_blocked_) {
+      headers_stream_blocked_ = false;
+      return kHeadersStreamId;
+    } else {
+      SpdyPriority priority =
+          base_write_blocked_list_.GetHighestPriorityWriteBlockedList();
+      return base_write_blocked_list_.PopFront(priority);
+    }
+  }
+
+  // TODO(avd) Remove version argument when QUIC_VERSION_12 is deprecated.
+  void PushBack(QuicStreamId stream_id,
+                QuicPriority priority,
+                QuicVersion version) {
+    if (stream_id == kCryptoStreamId) {
+      DCHECK_EQ(kHighestPriority, priority);
+      // TODO(avd) Add DCHECK(!crypto_stream_blocked_)
+      crypto_stream_blocked_ = true;
+    } else if (version > QUIC_VERSION_12 &&
+               stream_id == kHeadersStreamId) {
+      DCHECK_EQ(kHighestPriority, priority);
+      // TODO(avd) Add DCHECK(!headers_stream_blocked_);
+      headers_stream_blocked_ = true;
+    } else {
+      base_write_blocked_list_.PushBack(
+          stream_id, static_cast<SpdyPriority>(priority));
+    }
+  }
+
+ private:
+  QuicWriteBlockedListBase base_write_blocked_list_;
+  bool crypto_stream_blocked_;
+  bool headers_stream_blocked_;
+
+  DISALLOW_COPY_AND_ASSIGN(QuicWriteBlockedList);
+};
+
+}  // namespace net
+
+
+#endif  // NET_QUIC_QUIC_WRITE_BLOCKED_LIST_H_