Anti-DDoS enhancements: Log to net log, UMA stats, improved policy.

net/url_request/url_request_throttler_manager.h

Index: net/url_request/url_request_throttler_manager.h
diff --git a/net/url_request/url_request_throttler_manager.h b/net/url_request/url_request_throttler_manager.h
index 4b9b21f316ee3ad53f60e9b49371e4c2531edfb7..846b682ad612f724f9b0d45de68e94cd0b8ef93d 100644
--- a/net/url_request/url_request_throttler_manager.h
+++ b/net/url_request/url_request_throttler_manager.h
@@ -16,10 +16,14 @@
 #include "base/threading/non_thread_safe.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/net_api.h"
+#include "net/base/network_change_notifier.h"
 #include "net/url_request/url_request_throttler_entry.h"
 
 namespace net {
 
+class BoundNetLog;
+class NetLog;
+
 // Class that registers URL request throttler entries for URLs being accessed
 // in order to supervise traffic. URL requests for HTTP contents should
 // register their URLs in this manager on each request.
@@ -34,7 +38,9 @@ namespace net {
 // although to allow it to be used as a singleton, construction and destruction
 // can occur on a separate thread.
 class NET_API URLRequestThrottlerManager
-    : NON_EXPORTED_BASE(public base::NonThreadSafe) {
+    : NON_EXPORTED_BASE(public base::NonThreadSafe),
+      public NetworkChangeNotifier::IPAddressObserver,
+      public NetworkChangeNotifier::OnlineStateObserver {
  public:
   static URLRequestThrottlerManager* GetInstance();
 
@@ -71,6 +77,16 @@ class NET_API URLRequestThrottlerManager
   void set_enforce_throttling(bool enforce);
   bool enforce_throttling();
 
+  // Sets the NetLog instance to use.
+  void set_net_log(NetLog* net_log);
+  NetLog* net_log() const;
+
+  // IPAddressObserver interface.
+  virtual void OnIPAddressChanged() OVERRIDE;
+
+  // OnlineStateObserver interface.
+  virtual void OnOnlineStateChanged(bool online) OVERRIDE;
+
  protected:
   URLRequestThrottlerManager();
   ~URLRequestThrottlerManager();
@@ -90,6 +106,15 @@ class NET_API URLRequestThrottlerManager
   // Method that does the actual work of garbage collecting.
   void GarbageCollectEntries();
 
+  // When we switch from online to offline or change IP addresses, we
+  // clear all back-off history. This is a precaution in case the change in
+  // online state now lets us communicate without error with servers that
+  // we were previously getting 500 or 503 responses from (perhaps the
+  // responses are from a badly-written proxy that should have returned a
+  // 502 or 504 because it's upstream connection was down or it had no route
+  // to the server).
+  void OnNetworkChange();
+
   // Used by tests.
   int GetNumberOfEntriesForTests() const { return url_entries_.size(); }
 
@@ -136,6 +161,13 @@ class NET_API URLRequestThrottlerManager
   // workaround.
   bool enable_thread_checks_;
 
+  // Initially false, switches to true once we have logged because of back-off
+  // being disabled for localhost.
+  bool logged_for_localhost_disabled_;
+
+  // NetLog to use, or NULL if none configured.
+  scoped_ptr<BoundNetLog> net_log_;
+
   DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerManager);
 };