Implement exponential back-off mechanism.

net/url_request/url_request_http_job.cc

 // Copyright (c) 2010 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/url_request/url_request_http_job.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/file_util.h"
@@ skipping 15 matching lines @@
 #include "net/http/http_response_headers.h"
 #include "net/http/http_response_info.h"
 #include "net/http/http_transaction.h"
 #include "net/http/http_transaction_factory.h"
 #include "net/http/http_util.h"
 #include "net/url_request/https_prober.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_error_job.h"
 #include "net/url_request/url_request_redirect_job.h"
+#include "net/url_request/url_request_throttler_header_adapter.h"
+#include "net/url_request/url_request_throttler_manager.h"
 
 static const char kAvailDictionaryHeader[] = "Avail-Dictionary";
 
 // TODO(darin): make sure the port blocking code is not lost
 // static
 URLRequestJob* URLRequestHttpJob::Factory(URLRequest* request,
                                           const std::string& scheme) {
   DCHECK(scheme == "http" || scheme == "https");
 
   int port = request->url().IntPort();
@@ skipping 38 matching lines @@
       ALLOW_THIS_IN_INITIALIZER_LIST(can_get_cookies_callback_(
           this, &URLRequestHttpJob::OnCanGetCookiesCompleted)),
       ALLOW_THIS_IN_INITIALIZER_LIST(can_set_cookie_callback_(
           this, &URLRequestHttpJob::OnCanSetCookieCompleted)),
       ALLOW_THIS_IN_INITIALIZER_LIST(start_callback_(
           this, &URLRequestHttpJob::OnStartCompleted)),
       ALLOW_THIS_IN_INITIALIZER_LIST(read_callback_(
           this, &URLRequestHttpJob::OnReadCompleted)),
       read_in_progress_(false),
       transaction_(NULL),
+      throttling_entry_(net::URLRequestThrottlerManager::GetInstance()->
+          RegisterRequestUrl(request->url())),
       sdch_dictionary_advertised_(false),
       sdch_test_activated_(false),
       sdch_test_control_(false),
       is_cached_content_(false) {
 }
 
 URLRequestHttpJob::~URLRequestHttpJob() {
   DCHECK(!sdch_test_control_ || !sdch_test_activated_);
   if (!IsCachedContent()) {
     if (sdch_test_control_)
@@ skipping 458 matching lines @@
 
 void URLRequestHttpJob::NotifyHeadersComplete() {
   DCHECK(!response_info_);
 
   response_info_ = transaction_->GetResponseInfo();
 
   // Save boolean, as we'll need this info at destruction time, and filters may
   // also need this info.
   is_cached_content_ = response_info_->was_cached;
 
+  if (!is_cached_content_) {
+    net::URLRequestThrottlerHeaderAdapter response_adapter(
+        response_info_->headers);
+    throttling_entry_->UpdateWithResponse(&response_adapter);
+  }
+
   ProcessStrictTransportSecurityHeader();
 
   if (SdchManager::Global() &&
       SdchManager::Global()->IsInSupportedDomain(request_->url())) {
     static const std::string name = "Get-Dictionary";
     std::string url_text;
     void* iter = NULL;
     // TODO(jar): We need to not fetch dictionaries the first time they are
     // seen, but rather wait until we can justify their usefulness.
     // For now, we will only fetch the first dictionary, which will at least
@@ skipping 29 matching lines @@
   context_ = NULL;
 }
 
 void URLRequestHttpJob::StartTransaction() {
   // NOTE: This method assumes that request_info_ is already setup properly.
 
   // If we already have a transaction, then we should restart the transaction
   // with auth provided by username_ and password_.
 
   int rv;
+
   if (transaction_.get()) {
     rv = 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());
+      if (!throttling_entry_->IsDuringExponentialBackoff()) {
+        rv = transaction_->Start(
+            &request_info_, &start_callback_, request_->net_log());
+      } else {
+        // Special error code for the exponential back-off module.
+        rv = net::ERR_TEMPORARILY_THROTTLED;
+      }
       // Make sure the context is alive for the duration of the
       // transaction.
       context_ = request_->context();
     }
   }
 
   if (rv == net::ERR_IO_PENDING)
     return;
 
   // The transaction started synchronously, but we need to notify the
@@ skipping 272 matching lines @@
     HTTPSProberDelegate* delegate =
         new HTTPSProberDelegate(request_info_.url.host(), max_age,
                                 include_subdomains,
                                 ctx->transport_security_state());
     if (!prober->ProbeHost(request_info_.url.host(), request()->context(),
                            delegate)) {
       delete delegate;
     }
   }
 }