DevTools: make network conditions emulation scoped (browser)

chrome/browser/devtools/devtools_network_realm.cc

+// Copyright 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.
+
+#include "chrome/browser/devtools/devtools_network_realm.h"
+
+#include "base/time/time.h"
+#include "chrome/browser/devtools/devtools_network_conditions.h"
+#include "chrome/browser/devtools/devtools_network_transaction.h"
+
+namespace {
+
+int64_t kPacketSize = 1500;
+
+}  // namespace
+
+DevToolsNetworkRealm::DevToolsNetworkRealm() {
+}
+
+DevToolsNetworkRealm::~DevToolsNetworkRealm() {
+  DCHECK(!conditions_);
+}
+
+void DevToolsNetworkRealm::RemoveTransaction(
+    DevToolsNetworkTransaction* transaction) {
+  if (!conditions_ || !conditions_->IsThrottling())
+    return;
+
+  UpdateThrottles();
+  throttled_transactions_.erase(std::remove(throttled_transactions_.begin(),
+      throttled_transactions_.end(), transaction),
+      throttled_transactions_.end());
+  ArmTimer();
+}
+
+void DevToolsNetworkRealm::UpdateConditions(
+    const scoped_refptr<DevToolsNetworkConditions> conditions) {
+  if (conditions_ && conditions_->IsThrottling())
+    UpdateThrottles();
+
+  conditions_ = conditions;
+  if (!conditions || !(conditions->IsThrottling() || conditions->IsOffline())) {
+    timer_.Stop();
+    int64_t length = throttled_transactions_.size();
+    for (int64_t i = 0; i < length; ++i)
+        throttled_transactions_[i]->FireThrottledCallback();
+    throttled_transactions_.clear();
+  }
+
+  if (!conditions)
+    return;
+
+  if (conditions_->IsThrottling()) {
+    DCHECK(conditions_->download_throughput() != 0);
+    offset_ = base::TimeTicks::Now();
+    last_tick_ = 0;
+    int64_t us_tick_length =
+        (1000000L * kPacketSize) / conditions_->download_throughput();
+    DCHECK(us_tick_length != 0);
+    if (us_tick_length == 0)
+      us_tick_length = 1;
+    tick_length_ = base::TimeDelta::FromMicroseconds(us_tick_length);
+    ArmTimer();
+  }
+}
+
+void DevToolsNetworkRealm::UpdateThrottles() {
+  int64_t last_tick = (base::TimeTicks::Now() - offset_) / tick_length_;
+  int64_t ticks = last_tick - last_tick_;
+  last_tick_ = last_tick;
+
+  int64_t length = throttled_transactions_.size();
+  if (!length)
+    return;
+
+  int64_t shift = ticks % length;
+  for (int64_t i = 0; i < length; ++i) {
+    throttled_transactions_[i]->DecreaseThrottledByteCount(
+        (ticks / length) * kPacketSize + (i < shift ? kPacketSize : 0));
+  }
+  std::rotate(throttled_transactions_.begin(),
+      throttled_transactions_.begin() + shift, throttled_transactions_.end());
+}
+
+void DevToolsNetworkRealm::OnTimer() {
+  UpdateThrottles();
+
+  std::vector<DevToolsNetworkTransaction*> active_transactions;
+  std::vector<DevToolsNetworkTransaction*> finished_transactions;
+  size_t length = throttled_transactions_.size();
+  for (size_t i = 0; i < length; ++i) {
+    if (throttled_transactions_[i]->throttled_byte_count() < 0)
+      finished_transactions.push_back(throttled_transactions_[i]);
+    else
+      active_transactions.push_back(throttled_transactions_[i]);
+  }
+  throttled_transactions_.swap(active_transactions);
+
+  length = finished_transactions.size();
+  for (size_t i = 0; i < length; ++i)
+      finished_transactions[i]->FireThrottledCallback();
+
+  ArmTimer();
+}
+
+void DevToolsNetworkRealm::ArmTimer() {
+  size_t length = throttled_transactions_.size();
+  if (!length)
+    return;
+  int64_t min_ticks_left = 0x10000L;
+  for (size_t i = 0; i < length; ++i) {
+    int64_t packets_left = (throttled_transactions_[i]->throttled_byte_count() +
+        kPacketSize - 1) / kPacketSize;
+    int64_t ticks_left = (i + 1) + length * (packets_left - 1);
+    if (i == 0 || ticks_left < min_ticks_left)
+      min_ticks_left = ticks_left;
+  }
+  base::TimeTicks desired_time =
+      offset_ + tick_length_ * (last_tick_ + min_ticks_left);
+  timer_.Start(
+      FROM_HERE,
+      desired_time - base::TimeTicks::Now(),
+      base::Bind(
+          &DevToolsNetworkRealm::OnTimer,
+          base::Unretained(this)));
+}
+
+void DevToolsNetworkRealm::ThrottleTransaction(
+    DevToolsNetworkTransaction* transaction) {
+  UpdateThrottles();
+  throttled_transactions_.push_back(transaction);
+  ArmTimer();
+}