This CL will introduce a new way to do exponential back-off on failure within

Chromium. It is a network level implementation and should constitute a good 
enough bottleneck to manage every outgoing http request.

Committing for malavv@google.com.
Original review: http://codereview.chromium.org/2487001/show

BUG=none
TEST=unit tests


Review URL: http://codereview.chromium.org/3005049

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@56376 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 29 insertions, 9 deletions

diff --git a/net/url_request/url_request_http_job.cc b/net/url_request/url_request_http_job.cc
index cbccff2..5564628 100644
--- a/net/url_request/url_request_http_job.cc
+++ b/net/url_request/url_request_http_job.cc
@@ -27,6 +27,7 @@
 #include "net/http/http_transaction.h"
 #include "net/http/http_transaction_factory.h"
 #include "net/http/http_util.h"
+#include "net/request_throttler/request_throttler_header_adapter.h"
 #include "net/url_request/https_prober.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context.h"
@@ -91,6 +92,8 @@ URLRequestHttpJob::URLRequestHttpJob(URLRequest* request)
           this, &URLRequestHttpJob::OnReadCompleted)),
       read_in_progress_(false),
       transaction_(NULL),
+      throttling_entry_(Singleton<RequestThrottlerManager>::get()->
+           RegisterRequestUrl(request->url())),
       sdch_dictionary_advertised_(false),
       sdch_test_activated_(false),
       sdch_test_control_(false),
@@ -569,6 +572,11 @@ void URLRequestHttpJob::NotifyHeadersComplete() {
   // also need this info.
   is_cached_content_ = response_info_->was_cached;
 
+  if (!is_cached_content_) {
+    RequestThrottlerHeaderAdapter response_adapter(response_info_->headers);
+    throttling_entry_->UpdateWithResponse(&response_adapter);
+  }
+
   ProcessStrictTransportSecurityHeader();
 
   if (SdchManager::Global() &&
@@ -616,30 +624,37 @@ void URLRequestHttpJob::StartTransaction() {
   // If we already have a transaction, then we should restart the transaction
   // with auth provided by username_ and password_.
 
-  int rv;
+  int return_value;
+
   if (transaction_.get()) {
-    rv = transaction_->RestartWithAuth(username_, password_, &start_callback_);
+    return_value = transaction_->RestartWithAuth(username_,
+        password_, &start_callback_);
     username_.clear();
     password_.clear();
   } else {
     DCHECK(request_->context());
     DCHECK(request_->context()->http_transaction_factory());
 
-    rv = request_->context()->http_transaction_factory()->CreateTransaction(
-        &transaction_);
-    if (rv == net::OK) {
-      rv = transaction_->Start(
-          &request_info_, &start_callback_, request_->net_log());
+    return_value = request_->context()->http_transaction_factory()->
+        CreateTransaction(&transaction_);
+    if (return_value == net::OK) {
+      if (throttling_entry_->IsRequestAllowed()) {
+        return_value = transaction_->Start(
+            &request_info_, &start_callback_, request_->net_log());
+      } else {
+        // Special error code for the exponential back-off module.
+        return_value = net::ERR_TEMPORARILY_THROTTLED_BY_DDOS;
+      }
     }
   }
 
-  if (rv == net::ERR_IO_PENDING)
+  if (return_value == net::ERR_IO_PENDING)
     return;
 
   // The transaction started synchronously, but we need to notify the
   // URLRequest delegate via the message loop.
   MessageLoop::current()->PostTask(FROM_HERE, NewRunnableMethod(
-      this, &URLRequestHttpJob::OnStartCompleted, rv));
+      this, &URLRequestHttpJob::OnStartCompleted, return_value));
 }
 
 void URLRequestHttpJob::AddExtraHeaders() {
diff --git a/net/url_request/url_request_http_job.h b/net/url_request/url_request_http_job.h
index ea2e544..79511f2 100644
--- a/net/url_request/url_request_http_job.h
+++ b/net/url_request/url_request_http_job.h
@@ -11,10 +11,12 @@
 #include <vector>
 
 #include "base/scoped_ptr.h"
+#include "base/string_util.h"
 #include "base/string16.h"
 #include "net/base/auth.h"
 #include "net/base/completion_callback.h"
 #include "net/http/http_request_info.h"
+#include "net/request_throttler/request_throttler_manager.h"
 #include "net/url_request/url_request_job.h"
 
 namespace net {
@@ -113,6 +115,9 @@ class URLRequestHttpJob : public URLRequestJob {
 
   scoped_ptr<net::HttpTransaction> transaction_;
 
+  // This is used to supervise traffic and enforce exponential back-off.
+  scoped_refptr<RequestThrottlerEntryInterface> throttling_entry_;
+
   // Indicated if an SDCH dictionary was advertised, and hence an SDCH
   // compressed response is expected.  We use this to help detect (accidental?)
   // proxy corruption of a response, which sometimes marks SDCH content as