Implement a traffic policer in the simulator

net/quic/test_tools/simulator/traffic_policer.cc

Index: net/quic/test_tools/simulator/traffic_policer.cc
diff --git a/net/quic/test_tools/simulator/traffic_policer.cc b/net/quic/test_tools/simulator/traffic_policer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..84ea4db0f24389cb3c2d7fad94bd6cbcd67b02ca
--- /dev/null
+++ b/net/quic/test_tools/simulator/traffic_policer.cc
@@ -0,0 +1,86 @@
+// Copyright (c) 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 "net/quic/test_tools/simulator/traffic_policer.h"
+
+#include <algorithm>
+
+namespace net {
+namespace simulator {
+
+TrafficPolicer::TrafficPolicer(Simulator* simulator,
+                               std::string name,
+                               QuicByteCount initial_bucket_size,
+                               QuicByteCount max_bucket_size,
+                               QuicBandwidth target_bandwidth,
+                               Endpoint* input)
+    : Actor(simulator, name),
+      initial_bucket_size_(initial_bucket_size),
+      max_bucket_size_(max_bucket_size),
+      target_bandwidth_(target_bandwidth),
+      last_refill_time_(clock_->Now()),
+      input_(input),
+      output_(this) {
+  input_->SetTxPort(this);
+}
+
+TrafficPolicer::~TrafficPolicer() {}
+
+void TrafficPolicer::Act() {}
+
+void TrafficPolicer::Refill() {
+  QuicTime::Delta time_passed = clock_->Now() - last_refill_time_;
+  QuicByteCount refill_size = time_passed * target_bandwidth_;
+
+  for (auto& bucket : token_buckets_) {
+    bucket.second = std::min(bucket.second + refill_size, max_bucket_size_);
+  }
+
+  last_refill_time_ = clock_->Now();
+}
+
+void TrafficPolicer::AcceptPacket(std::unique_ptr<Packet> packet) {
+  // Refill existing buckets.
+  Refill();
+
+  // Create a new bucket if one does not exist.
+  if (token_buckets_.count(packet->destination) == 0) {
+    token_buckets_.insert(
+        std::make_pair(packet->destination, initial_bucket_size_));
+  }
+
+  auto bucket = token_buckets_.find(packet->destination);
+  DCHECK(bucket != token_buckets_.end());
+
+  // Silently drop the packet on the floor if out of tokens
+  if (bucket->second < packet->size) {
+    return;
+  }
+
+  bucket->second -= packet->size;
+  output_tx_port_->AcceptPacket(std::move(packet));
+}
+
+QuicTime::Delta TrafficPolicer::TimeUntilAvailable() {
+  return output_tx_port_->TimeUntilAvailable();
+}
+
+TrafficPolicer::Output::Output(TrafficPolicer* policer)
+    : Endpoint(policer->simulator(), policer->name() + " (output port)"),
+      policer_(policer) {}
+
+TrafficPolicer::Output::~Output() {}
+
+UnconstrainedPortInterface* TrafficPolicer::Output::GetRxPort() {
+  return policer_->input_->GetRxPort();
+}
+
+void TrafficPolicer::Output::SetTxPort(ConstrainedPortInterface* port) {
+  policer_->output_tx_port_ = port;
+}
+
+void TrafficPolicer::Output::Act() {}
+
+}  // namespace simulator
+}  // namespace net