[mojo] Ports EDK

mojo/edk/system/ports/message_queue.cc

+// 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.
+
+#include "mojo/edk/system/ports/message_queue.h"
+
+#include <algorithm>
+
+#include "base/logging.h"
+#include "mojo/edk/system/ports/event.h"
+
+namespace mojo {
+namespace edk {
+namespace ports {
+
+inline uint64_t GetSequenceNum(const ScopedMessage& message) {
+  return GetEventData<UserEventData>(*message)->sequence_num;
+}
+
+// Used by std::{push,pop}_heap functions
+inline bool operator<(const ScopedMessage& a, const ScopedMessage& b) {
+  return GetSequenceNum(a) > GetSequenceNum(b);
+}
+
+MessageQueue::MessageQueue() : MessageQueue(kInitialSequenceNum) {}
+
+MessageQueue::MessageQueue(uint64_t next_sequence_num)
+    : next_sequence_num_(next_sequence_num) {
+  // The message queue is blocked waiting for a message with sequence number
+  // equal to |next_sequence_num|.
+}
+
+MessageQueue::~MessageQueue() {
+#ifndef NDEBUG
+  size_t num_leaked_ports = 0;
+  for (const auto& message : heap_)
+    num_leaked_ports += message->num_ports();
+  DLOG_IF(WARNING, num_leaked_ports > 0)
+      << "Leaking " << num_leaked_ports << " ports in unreceived messages";
+#endif
+}
+
+bool MessageQueue::HasNextMessage() const {
+  return !heap_.empty() && GetSequenceNum(heap_[0]) == next_sequence_num_;
+}
+
+void MessageQueue::GetNextMessageIf(
+    std::function<bool(const Message&)> selector,
+    ScopedMessage* message) {
+  if (!HasNextMessage() || (selector && !selector(*heap_[0].get()))) {
+    message->reset();
+    return;
+  }
+
+  std::pop_heap(heap_.begin(), heap_.end());
+  *message = std::move(heap_.back());
+  heap_.pop_back();
+
+  next_sequence_num_++;
+}
+
+void MessageQueue::AcceptMessage(ScopedMessage message,
+                                 bool* has_next_message) {
+  DCHECK(GetEventHeader(*message)->type == EventType::kUser);
+
+  // TODO: Handle sequence number roll-over.
+
+  heap_.emplace_back(std::move(message));
+  std::push_heap(heap_.begin(), heap_.end());
+
+  if (!signalable_) {
+    *has_next_message = false;
+  } else {
+    *has_next_message = (GetSequenceNum(heap_[0]) == next_sequence_num_);
+  }
+}
+
+void MessageQueue::GetReferencedPorts(std::deque<PortName>* port_names) {
+  for (const auto& message : heap_) {
+    for (size_t i = 0; i < message->num_ports(); ++i)
+      port_names->push_back(message->ports()[i]);
+  }
+}
+
+}  // namespace ports
+}  // namespace edk
+}  // namespace mojo