1 files changed, 173 insertions, 0 deletions
diff --git a/chrome/browser/net/url_fetcher_protect.cc b/chrome/browser/net/url_fetcher_protect.cc
new file mode 100644
index 0000000..5b7b208
--- /dev/null
+++ b/chrome/browser/net/url_fetcher_protect.cc
@@ -0,0 +1,173 @@
+// Copyright (c) 2006-2008 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/net/url_fetcher_protect.h"
+
+// URLFetcherProtectEntry ----------------------------------------------------
+
+using base::TimeDelta;
+using base::TimeTicks;
+
+// Default parameters.  Time is in milliseconds.
+// static
+const int URLFetcherProtectEntry::kDefaultSlidingWindowPeriod = 2000;
+
+const int URLFetcherProtectEntry::kDefaultMaxSendThreshold = 20;
+const int URLFetcherProtectEntry::kDefaultMaxRetries = 0;
+
+const int URLFetcherProtectEntry::kDefaultInitialTimeout = 100;
+const double URLFetcherProtectEntry::kDefaultMultiplier = 2.0;
+const int URLFetcherProtectEntry::kDefaultConstantFactor = 100;
+const int URLFetcherProtectEntry::kDefaultMaximumTimeout = 60000;
+
+
+URLFetcherProtectEntry::URLFetcherProtectEntry()
+    : sliding_window_period_(kDefaultSlidingWindowPeriod),
+      max_send_threshold_(kDefaultMaxSendThreshold),
+      max_retries_(kDefaultMaxRetries),
+      initial_timeout_(kDefaultInitialTimeout),
+      multiplier_(kDefaultMultiplier),
+      constant_factor_(kDefaultConstantFactor),
+      maximum_timeout_(kDefaultMaximumTimeout) {
+  ResetBackoff();
+}
+
+URLFetcherProtectEntry::URLFetcherProtectEntry(int sliding_window_period,
+                                               int max_send_threshold,
+                                               int max_retries,
+                                               int initial_timeout,
+                                               double multiplier,
+                                               int constant_factor,
+                                               int maximum_timeout)
+    : sliding_window_period_(sliding_window_period),
+      max_send_threshold_(max_send_threshold),
+      max_retries_(max_retries),
+      initial_timeout_(initial_timeout),
+      multiplier_(multiplier),
+      constant_factor_(constant_factor),
+      maximum_timeout_(maximum_timeout) {
+  ResetBackoff();
+}
+
+int URLFetcherProtectEntry::UpdateBackoff(EventType event_type) {
+  // request may be sent in different threads
+  AutoLock lock(lock_);
+
+  TimeDelta t;
+  switch (event_type) {
+    case SEND:
+      t = AntiOverload();
+      break;
+    case SUCCESS:
+      t = ResetBackoff();
+      break;
+    case FAILURE:
+      t = IncreaseBackoff();
+      break;
+    default:
+      NOTREACHED();
+  }
+
+  int wait = static_cast<int>(t.InMilliseconds());
+  DCHECK(wait >= 0);
+  return wait;
+}
+
+TimeDelta URLFetcherProtectEntry::AntiOverload() {
+  TimeDelta sw = TimeDelta::FromMilliseconds(sliding_window_period_);
+  TimeTicks now = TimeTicks::Now();
+  // Estimate when the next request will be sent.
+  release_time_ = now;
+  if (send_log_.size() > 0) {
+    release_time_ = std::max(release_time_, send_log_.back());
+  }
+  // Checks if there are too many send events in recent time.
+  if (send_log_.size() >= static_cast<unsigned>(max_send_threshold_)) {
+    release_time_ = std::max(release_time_, send_log_.front() + sw);
+  }
+  // Logs the new send event.
+  send_log_.push(release_time_);
+  // Drops the out-of-date events in the event list.
+  while (!send_log_.empty() &&
+         (send_log_.front() + sw <= send_log_.back())) {
+    send_log_.pop();
+  }
+  return release_time_ - now;
+}
+
+TimeDelta URLFetcherProtectEntry::ResetBackoff() {
+  timeout_period_ = initial_timeout_;
+  release_time_ = TimeTicks::Now();
+  return TimeDelta::FromMilliseconds(0);
+}
+
+TimeDelta URLFetcherProtectEntry::IncreaseBackoff() {
+  TimeTicks now = TimeTicks::Now();
+
+  release_time_ = std::max(release_time_, now) +
+                  TimeDelta::FromMilliseconds(timeout_period_);
+
+  // Calculates the new backoff time.
+  timeout_period_ = static_cast<int>
+      (multiplier_ * timeout_period_ + constant_factor_);
+  if (maximum_timeout_ && timeout_period_ > maximum_timeout_)
+    timeout_period_ = maximum_timeout_;
+
+  return release_time_ - now;
+}
+
+// URLFetcherProtectManager --------------------------------------------------
+
+// static
+scoped_ptr<URLFetcherProtectManager> URLFetcherProtectManager::protect_manager_;
+Lock URLFetcherProtectManager::lock_;
+
+URLFetcherProtectManager::~URLFetcherProtectManager() {
+  // Deletes all entries
+  ProtectService::iterator i;
+  for (i = services_.begin(); i != services_.end(); ++i) {
+    if (i->second)
+      delete i->second;
+  }
+}
+
+// static
+URLFetcherProtectManager* URLFetcherProtectManager::GetInstance() {
+  AutoLock lock(lock_);
+
+  if (protect_manager_.get() == NULL) {
+    protect_manager_.reset(new URLFetcherProtectManager());
+  }
+  return protect_manager_.get();
+}
+
+URLFetcherProtectEntry* URLFetcherProtectManager::Register(std::string id) {
+  AutoLock lock(lock_);
+
+  ProtectService::iterator i = services_.find(id);
+
+  if (i != services_.end()) {
+    // The entry exists.
+    return i->second;
+  }
+
+  // Creates a new entry.
+  URLFetcherProtectEntry* entry = new URLFetcherProtectEntry();
+  services_[id] = entry;
+  return entry;
+}
+
+URLFetcherProtectEntry* URLFetcherProtectManager::Register(
+    std::string id, URLFetcherProtectEntry* entry) {
+  AutoLock lock(lock_);
+
+  ProtectService::iterator i = services_.find(id);
+  if (i != services_.end()) {
+    // The entry exists.
+    delete i->second;
+  }
+
+  services_[id] = entry;
+  return entry;
+}