Allows prefetch requests to live beyond the renderer by delaying

content/browser/loader/resource_loader.cc

 // Copyright (c) 2012 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 "content/browser/loader/resource_loader.h"
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/time/time.h"
+#include "base/timer/timer.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/loader/cross_site_resource_handler.h"
 #include "content/browser/loader/resource_loader_delegate.h"
 #include "content/browser/loader/resource_request_info_impl.h"
 #include "content/browser/ssl/ssl_client_auth_handler.h"
 #include "content/browser/ssl/ssl_manager.h"
 #include "content/common/ssl_status_serialization.h"
 #include "content/public/browser/cert_store.h"
 #include "content/public/browser/resource_context.h"
 #include "content/public/browser/resource_dispatcher_host_login_delegate.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/process_type.h"
 #include "content/public/common/resource_response.h"
 #include "content/public/common/url_constants.h"
 #include "net/base/io_buffer.h"
 #include "net/base/load_flags.h"
 #include "net/http/http_response_headers.h"
 #include "net/ssl/client_cert_store.h"
 #include "webkit/browser/appcache/appcache_interceptor.h"
 
 using base::TimeDelta;
 using base::TimeTicks;
 
 namespace content {
 namespace {
 
+// TODO(jkarlin): The value is high to reduce the chance of the detachable
+// request timing out, forcing a blocked second request to open a new connection
+// and start over. Reduce this value once we have a better idea of what it
+// should be and once we stop blocking multiple simultaneous requests for the
+// same resource (see bugs 46104 and 31014).
+const int kDefaultDetachableDelayOnCancelMs = 30000;
+
 void PopulateResourceResponse(net::URLRequest* request,
                               ResourceResponse* response) {
   response->head.error_code = request->status().error();
   response->head.request_time = request->request_time();
   response->head.response_time = request->response_time();
   response->head.headers = request->response_headers();
   request->GetCharset(&response->head.charset);
   response->head.content_length = request->GetExpectedContentSize();
   request->GetMimeType(&response->head.mime_type);
   net::HttpResponseInfo response_info = request->response_info();
@@ skipping 18 matching lines @@
 ResourceLoader::ResourceLoader(scoped_ptr<net::URLRequest> request,
                                scoped_ptr<ResourceHandler> handler,
                                ResourceLoaderDelegate* delegate)
     : deferred_stage_(DEFERRED_NONE),
       request_(request.Pass()),
       handler_(handler.Pass()),
       delegate_(delegate),
       last_upload_position_(0),
       waiting_for_upload_progress_ack_(false),
       is_transferring_(false),
+      detachable_delay_on_cancel_ms_(kDefaultDetachableDelayOnCancelMs),
       weak_ptr_factory_(this) {
   request_->set_delegate(this);
   handler_->SetController(this);
 }
 
 ResourceLoader::~ResourceLoader() {
   if (login_delegate_.get())
     login_delegate_->OnRequestCancelled();
   if (ssl_client_auth_handler_.get())
     ssl_client_auth_handler_->OnRequestCancelled();
@@ skipping 335 matching lines @@
   CancelRequest(false);
 }
 
 void ResourceLoader::StartRequestInternal() {
   DCHECK(!request_->is_pending());
   request_->Start();
 
   delegate_->DidStartRequest(this);
 }
 
+void ResourceLoader::Detach() {
+  ResourceRequestInfoImpl* info = GetRequestInfo();
+
+  if (info->is_detached())
+    return;
+  info->set_detached();
+  detached_timer_.reset(new base::OneShotTimer<ResourceLoader>());
+  detached_timer_->Start(
+      FROM_HERE, TimeDelta::FromMilliseconds(detachable_delay_on_cancel_ms_),
+      this, &ResourceLoader::Cancel);
+}
+
 void ResourceLoader::CancelRequestInternal(int error, bool from_renderer) {
   VLOG(1) << "CancelRequestInternal: " << request_->url().spec();
 
   ResourceRequestInfoImpl* info = GetRequestInfo();
 
   // WebKit will send us a cancel for downloads since it no longer handles
   // them.  In this case, ignore the cancel since we handle downloads in the
   // browser.
   if (from_renderer && (info->is_download() || info->is_stream()))
     return;
 
+  if (from_renderer && info->is_detachable()) {
+    Detach();
+    return;
+  }
+
   // TODO(darin): Perhaps we should really be looking to see if the status is
   // IO_PENDING?
   bool was_pending = request_->is_pending();
 
   if (login_delegate_.get()) {
     login_delegate_->OnRequestCancelled();
     login_delegate_ = NULL;
   }
   if (ssl_client_auth_handler_.get()) {
     ssl_client_auth_handler_->OnRequestCancelled();
@@ skipping 171 matching lines @@
     // we resume.
     deferred_stage_ = DEFERRED_FINISH;
   }
 }
 
 void ResourceLoader::CallDidFinishLoading() {
   delegate_->DidFinishLoading(this);
 }
 
 }  // namespace content