Run load state update timer only when needed

content/browser/loader/resource_dispatcher_host_impl.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.
 
 // See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading
 
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
 
 #include <algorithm>
 #include <set>
@@ skipping 97 matching lines @@
 
 // ----------------------------------------------------------------------------
 
 namespace content {
 
 namespace {
 
 static ResourceDispatcherHostImpl* g_resource_dispatcher_host;
 
 // The interval for calls to ResourceDispatcherHostImpl::UpdateLoadStates
-const int kUpdateLoadStatesIntervalMsec = 100;
+const int kUpdateLoadStatesIntervalMsec = 250;
 
 // Maximum byte "cost" of all the outstanding requests for a renderer.
 // See delcaration of |max_outstanding_requests_cost_per_process_| for details.
 // This bound is 25MB, which allows for around 6000 outstanding requests.
 const int kMaxOutstandingRequestsCostPerProcess = 26214400;
 
 // The number of milliseconds after noting a user gesture that we will
 // tag newly-created URLRequest objects with the
 // net::LOAD_MAYBE_USER_GESTURE load flag. This is a fairly arbitrary
 // guess at how long to expect direct impact from a user gesture, but
@@ skipping 652 matching lines @@
       info->GetContext()->GetRequestContext()->job_factory();
   if (job_factory->IsHandledURL(url))
     return false;
 
   return delegate_->HandleExternalProtocol(
       url, info->GetChildID(), info->GetRouteID(), info->IsMainFrame(),
       info->GetPageTransition(), info->HasUserGesture());
 }
 
 void ResourceDispatcherHostImpl::DidStartRequest(ResourceLoader* loader) {
-  // Make sure we have the load state monitor running
-  if (!update_load_states_timer_->IsRunning()) {
+  // Make sure we have the load state monitor running.
+  if (!update_load_states_timer_->IsRunning() &&
+      scheduler_->HasLoadingClients()) {
     update_load_states_timer_->Start(
         FROM_HERE, TimeDelta::FromMilliseconds(kUpdateLoadStatesIntervalMsec),
         this, &ResourceDispatcherHostImpl::UpdateLoadInfo);
   }
 }
 
 void ResourceDispatcherHostImpl::DidReceiveRedirect(ResourceLoader* loader,
                                                     const GURL& new_url) {
   ResourceRequestInfoImpl* info = loader->GetRequestInfo();
 
@@ skipping 971 matching lines @@
 
 void ResourceDispatcherHostImpl::RemovePendingLoader(
     const LoaderMap::iterator& iter) {
   ResourceRequestInfoImpl* info = iter->second->GetRequestInfo();
 
   // Remove the memory credit that we added when pushing the request onto
   // the pending list.
   IncrementOutstandingRequestsMemory(-1, *info);
 
   pending_loaders_.erase(iter);
-
-  // If we have no more pending requests, then stop the load state monitor
-  if (pending_loaders_.empty() && update_load_states_timer_)
-    update_load_states_timer_->Stop();
 }
 
 void ResourceDispatcherHostImpl::CancelRequest(int child_id,
                                                int request_id) {
   ResourceLoader* loader = GetLoader(child_id, request_id);
   if (!loader) {
     // We probably want to remove this warning eventually, but I wanted to be
     // able to notice when this happens during initial development since it
     // should be rare and may indicate a bug.
     DVLOG(1) << "Canceling a request that wasn't found";
@@ skipping 401 matching lines @@
         LoadInfoIsMoreInteresting(load_info, existing->second)) {
       (*info_map)[id] = load_info;
     }
   }
   return info_map.Pass();
 }
 
 void ResourceDispatcherHostImpl::UpdateLoadInfo() {
   scoped_ptr<LoadInfoMap> info_map(GetLoadInfoForAllRoutes());
 
-  if (info_map->empty())
+  // Stop the timer if there are no more pending requests. Future new requests
+  // will restart it as necessary.
+  // Also stop the timer if there are no loading clients, to avoid waking up
+  // unnecessarily when there is a long running (hanging get) request like when
+  // on a Google Docs document.

[mmenke, 2015/05/22 15:19:24]

nit:  Shouldn't mention Google Docs, think it's fine just to end at request, or
could say "like many chat widgits use."

[Andre, 2015/05/22 17:30:21]

Done.

+  if (info_map->empty() || !scheduler_->HasLoadingClients()) {
+    update_load_states_timer_->Stop();
     return;
+  }
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&ResourceDispatcherHostImpl::UpdateLoadInfoOnUIThread,
                  base::Passed(&info_map)));
 }
 
 void ResourceDispatcherHostImpl::BlockRequestsForRoute(int child_id,
                                                        int route_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
@@ skipping 148 matching lines @@
 
   // Add a flag to selectively bypass the data reduction proxy if the resource
   // type is not an image.
   if (request_data.resource_type != RESOURCE_TYPE_IMAGE)
     load_flags |= net::LOAD_BYPASS_DATA_REDUCTION_PROXY;
 
   return load_flags;
 }
 
 }  // namespace content