Allows prefetch requests to live beyond the renderer by delaying

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 <set>
 #include <vector>
@@ skipping 109 matching lines @@
 // 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
 // this should be OK as the load flag is a best-effort thing only,
 // rather than being intended as fully accurate.
 const int kUserGestureWindowMs = 3500;
 
 // Ratio of |max_num_in_flight_requests_| that any one renderer is allowed to
 // use. Arbitrarily chosen.
 const double kMaxRequestsPerProcessRatio = 0.45;
 
+bool IsDetachableResourceType(const ResourceType::Type type) {

[mmenke, 2013/10/24 20:27:21]

nit:  const not needed.

[jkarlin2, 2013/10/25 14:10:21]

Done.

+  switch (type) {
+    case ResourceType::PREFETCH:
+      return true;
+    default:
+      return false;
+  }
+}
+
 // Aborts a request before an URLRequest has actually been created.
 void AbortRequestBeforeItStarts(ResourceMessageFilter* filter,
                                 IPC::Message* sync_result,
                                 int request_id) {
   if (sync_result) {
     SyncLoadResult result;
     result.error_code = net::ERR_ABORTED;
     ResourceHostMsg_SyncLoad::WriteReplyParams(sync_result, result);
     filter->Send(sync_result);
   } else {
@@ skipping 259 matching lines @@
       delete loaders;
     } else {
       ++i;
     }
   }
 
 #ifndef NDEBUG
   for (LoaderList::iterator i = loaders_to_cancel.begin();
        i != loaders_to_cancel.end(); ++i) {
     // There is no strict requirement that this be the case, but currently
-    // downloads, streams  and transferred requests are the only requests that
-    // aren't cancelled when the associated processes go away. It may be OK for
-    // this invariant to change in the future, but if this assertion fires
-    // without the invariant changing, then it's indicative of a leak.
-    DCHECK((*i)->GetRequestInfo()->is_download() ||
-           (*i)->GetRequestInfo()->is_stream() ||
-           (*i)->is_transferring());
+    // downloads, streams, detachable requests, and transferred requests are the
+    // only requests that aren't cancelled when the associated processes go
+    // away. It may be OK for this invariant to change in the future, but if
+    // this assertion fires without the invariant changing, then it's indicative
+    // of a leak.
+    DCHECK(
+        (*i)->GetRequestInfo()->is_download() ||
+        (*i)->GetRequestInfo()->is_stream() ||
+        (*i)->GetRequestInfo()->is_detachable() ||
+        (*i)->is_transferring());
   }
 #endif
 
   loaders_to_cancel.clear();
 
   // Validate that no more requests for this context were added.
   for (LoaderMap::const_iterator i = pending_loaders_.begin();
        i != pending_loaders_.end(); ++i) {
     // http://crbug.com/90971
     CHECK_NE(i->second->GetRequestInfo()->GetContext(), context);
@@ skipping 261 matching lines @@
       new_url));
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(
           &NotifyRedirectOnUI,
           render_process_id, render_view_id, base::Passed(&detail)));
 }
 
 void ResourceDispatcherHostImpl::DidReceiveResponse(ResourceLoader* loader) {
   ResourceRequestInfoImpl* info = loader->GetRequestInfo();
+
   // There should be an entry in the map created when we dispatched the
-  // request.
+  // request unless it's been detached and the renderer has died.
   OfflineMap::iterator policy_it(
       offline_policy_map_.find(info->GetGlobalRoutingID()));
   if (offline_policy_map_.end() != policy_it) {
     policy_it->second->UpdateStateForSuccessfullyStartedRequest(
         loader->request()->response_info());
-  } else {
+  } else if (!info->is_detachable()) {

[mmenke, 2013/10/24 20:27:21]

optional nit:  I suggest:

} else {
  ...
  DCHECK(info->is_detachable());
}

Think it's a little simpler.

[jkarlin2, 2013/10/25 14:10:21]

Done.

     // We should always have an entry in offline_policy_map_ from when
     // this request traversed Begin{Download,SaveFile,Request}.
     // TODO(rdsmith): This isn't currently true; see http://crbug.com/241176.
     NOTREACHED();
   }
 
   int render_process_id, render_view_id;
   if (!info->GetAssociatedRenderView(&render_process_id, &render_view_id))
     return;
 
@@ skipping 351 matching lines @@
           request_data.origin_pid,
           request_id,
           request_data.is_main_frame,
           request_data.frame_id,
           request_data.parent_is_main_frame,
           request_data.parent_frame_id,
           request_data.resource_type,
           request_data.transition_type,
           false,  // is download
           false,  // is stream
+          false,  // is detachable
           allow_download,
           request_data.has_user_gesture,
           request_data.referrer_policy,
           resource_context,
           filter_->GetWeakPtr(),
           !is_sync_load);
   extra_info->AssociateWithRequest(request);  // Request takes ownership.
 
   if (request->url().SchemeIs(chrome::kBlobScheme)) {
     // Hang on to a reference to ensure the blob is not released prior
     // to the job being started.
     webkit_blob::BlobProtocolHandler::SetRequestedBlobDataHandle(
         request,
         filter_->blob_storage_context()->context()->
             GetBlobDataFromPublicURL(request->url()));
   }
 
   // Have the appcache associate its extra info with the request.
   appcache::AppCacheInterceptor::SetExtraRequestInfo(
       request, filter_->appcache_service(), child_id,
       request_data.appcache_host_id, request_data.resource_type);
 
   // Construct the IPC resource handler.
   scoped_ptr<ResourceHandler> handler;
   if (sync_result) {
     handler.reset(new SyncResourceHandler(request, sync_result, this));
   } else {
     handler.reset(new AsyncResourceHandler(request, this));
+    if (IsDetachableResourceType(request_data.resource_type))
+      extra_info->set_is_detachable(true);
   }
 
   // The RedirectToFileResourceHandler depends on being next in the chain.
   if (request_data.download_to_file) {
     handler.reset(
         new RedirectToFileResourceHandler(handler.Pass(), request, this));
   }
 
   // Install a CrossSiteResourceHandler for all main frame requests.  This will
   // let us check whether a transfer is required and pause for the unload
@@ skipping 98 matching lines @@
       route_id,
       0,
       request_id_,
       false,     // is_main_frame
       -1,        // frame_id
       false,     // parent_is_main_frame
       -1,        // parent_frame_id
       ResourceType::SUB_RESOURCE,
       PAGE_TRANSITION_LINK,
       download,  // is_download
-      false,  // is_stream
+      false,     // is_stream
+      false,     // is_detachable
       download,  // allow_download
       false,     // has_user_gesture
       WebKit::WebReferrerPolicyDefault,
       context,
       base::WeakPtr<ResourceMessageFilter>(),  // filter
       true);     // is_async
 }
 
 void ResourceDispatcherHostImpl::OnRenderViewHostCreated(
     int child_id,
@@ skipping 75 matching lines @@
   ResourceLoader* loader = GetLoader(id);
   if (loader) {
     // The response we were meant to resume could have already been canceled.
     ResourceRequestInfoImpl* info = loader->GetRequestInfo();
     if (info->cross_site_handler())
       info->cross_site_handler()->ResumeResponse();
   }
 }
 
 // The object died, so cancel and detach all requests associated with it except
-// for downloads, which belong to the browser process even if initiated via a
-// renderer.
+// for downloads and detachable resources, which belong to the browser process
+// even if initiated via a renderer.
 void ResourceDispatcherHostImpl::CancelRequestsForProcess(int child_id) {
   CancelRequestsForRoute(child_id, -1 /* cancel all */);
   registered_temp_files_.erase(child_id);
 }
 
 void ResourceDispatcherHostImpl::CancelRequestsForRoute(int child_id,
                                                         int route_id) {
   // Since pending_requests_ is a map, we first build up a list of all of the
   // matching requests to be cancelled, and then we cancel them.  Since there
   // may be more than one request to cancel, we cannot simply hold onto the map
   // iterators found in the first loop.
 
   // Find the global ID of all matching elements.
   bool any_requests_transferring = false;
   std::vector<GlobalRequestID> matching_requests;
   for (LoaderMap::const_iterator i = pending_loaders_.begin();
        i != pending_loaders_.end(); ++i) {
     if (i->first.child_id != child_id)
       continue;
 
     ResourceRequestInfoImpl* info = i->second->GetRequestInfo();
 
     GlobalRequestID id(child_id, i->first.request_id);
     DCHECK(id == i->first);
+    // Don't cancel navigations that are expected to live beyond this process.
+    if (IsTransferredNavigation(id)) any_requests_transferring = true;
 
-    // Don't cancel navigations that are transferring to another process,
-    // since they belong to another process now.
-    if (IsTransferredNavigation(id))
-      any_requests_transferring = true;
-    if (!info->is_download() && !info->is_stream() &&
-        !IsTransferredNavigation(id) &&
-        (route_id == -1 || route_id == info->GetRouteID())) {
+    if (info->is_detachable()) {
+      i->second->CancelAfterTimeout();
+    } else if (!info->is_download() && !info->is_stream() &&
+               !IsTransferredNavigation(id) &&
+               (route_id == -1 || route_id == info->GetRouteID())) {
       matching_requests.push_back(id);
     }
   }
 
   // Remove matches.
   for (size_t i = 0; i < matching_requests.size(); ++i) {
     LoaderMap::iterator iter = pending_loaders_.find(matching_requests[i]);
     // Although every matching request was in pending_requests_ when we built
     // matching_requests, it is normal for a matching request to be not found
     // in pending_requests_ after we have removed some matching requests from
@@ skipping 550 matching lines @@
   if ((load_flags & net::LOAD_REPORT_RAW_HEADERS)
       && !policy->CanReadRawCookies(child_id)) {
     VLOG(1) << "Denied unauthorized request for raw headers";
     load_flags &= ~net::LOAD_REPORT_RAW_HEADERS;
   }
 
   return load_flags;
 }
 
 }  // namespace content