content::ResourceDispatcherHostImpl changes for stale-while-revalidate

content/browser/loader/resource_dispatcher_host_impl.cc

Index: content/browser/loader/resource_dispatcher_host_impl.cc
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index ade6e5d1648e01c3304f968789c526f469e63511..e24c17ad04ffee3e544d24aba406722a85d67cb7 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -19,6 +19,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/profiler/scoped_tracker.h"
@@ -41,6 +42,7 @@
 #include "content/browser/loader/detachable_resource_handler.h"
 #include "content/browser/loader/navigation_resource_handler.h"
 #include "content/browser/loader/navigation_url_loader_impl_core.h"
+#include "content/browser/loader/null_resource_handler.h"
 #include "content/browser/loader/power_save_block_resource_throttle.h"
 #include "content/browser/loader/redirect_to_file_resource_handler.h"
 #include "content/browser/loader/resource_message_filter.h"
@@ -89,6 +91,8 @@
 #include "net/cookies/cookie_monster.h"
 #include "net/http/http_response_headers.h"
 #include "net/http/http_response_info.h"
+#include "net/http/http_transaction_factory.h"
+#include "net/http/http_util.h"
 #include "net/ssl/ssl_cert_request_info.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context.h"
@@ -416,6 +420,31 @@ void LogResourceRequestTimeOnUI(
   }
 }
 
+bool QualifiesForAsyncRevalidation(const ResourceHostMsg_Request& request) {
+  if (request.load_flags &
+      (net::LOAD_BYPASS_CACHE | net::LOAD_DISABLE_CACHE |
+       net::LOAD_VALIDATE_CACHE | net::LOAD_PREFERRING_CACHE |
+       net::LOAD_ONLY_FROM_CACHE)) {
+    return false;
+  }
+  if (request.method != "GET")
+    return false;
+  // A GET request should not have a body, but don't leave it to chance.
+  if (request.request_body.get())
+    return false;
+  if (!request.url.SchemeIsHTTPOrHTTPS())
+    return false;
+  return true;
+}
+
+std::pair<net::HttpCache*, std::string> AsyncRevalidationKey(
+    net::HttpTransactionFactory* http_transaction_factory,
+    const GURL& url) {
+  net::HttpCache* http_cache = http_transaction_factory->GetCache();
+  std::string url_key = net::HttpUtil::SpecForRequest(url);
+  return std::make_pair(http_cache, url_key);
+}
+
 }  // namespace
 
 // static
@@ -429,14 +458,14 @@ ResourceDispatcherHostImpl::ResourceDispatcherHostImpl()
       is_shutdown_(false),
       num_in_flight_requests_(0),
       max_num_in_flight_requests_(base::SharedMemory::GetHandleLimit()),
-      max_num_in_flight_requests_per_process_(
-          static_cast<int>(
-              max_num_in_flight_requests_ * kMaxRequestsPerProcessRatio)),
+      max_num_in_flight_requests_per_process_(static_cast<int>(
+          max_num_in_flight_requests_ * kMaxRequestsPerProcessRatio)),
       max_outstanding_requests_cost_per_process_(
           kMaxOutstandingRequestsCostPerProcess),
       filter_(NULL),
       delegate_(NULL),
-      allow_cross_origin_auth_prompt_(false) {
+      allow_cross_origin_auth_prompt_(false),
+      async_revalidation_enabled_(false) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(!g_resource_dispatcher_host);
   g_resource_dispatcher_host = this;
@@ -454,6 +483,12 @@ ResourceDispatcherHostImpl::ResourceDispatcherHostImpl()
 
   update_load_states_timer_.reset(
       new base::RepeatingTimer<ResourceDispatcherHostImpl>());
+
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (base::FieldTrialList::FindFullName("StaleWhileRevalidate") == "Enabled" ||
+      command_line->HasSwitch(switches::kEnableStaleWhileRevalidate)) {
+    async_revalidation_enabled_ = true;
+  }
 }
 
 ResourceDispatcherHostImpl::~ResourceDispatcherHostImpl() {
@@ -819,22 +854,25 @@ void ResourceDispatcherHostImpl::DidReceiveRedirect(ResourceLoader* loader,
 
 void ResourceDispatcherHostImpl::DidReceiveResponse(ResourceLoader* loader) {
   ResourceRequestInfoImpl* info = loader->GetRequestInfo();
-
-  if (loader->request()->was_fetched_via_proxy() &&
-      loader->request()->was_fetched_via_spdy() &&
-      loader->request()->url().SchemeIs(url::kHttpScheme)) {
+  net::URLRequest* request = loader->request();
+  if (request->was_fetched_via_proxy() &&
+      request->was_fetched_via_spdy() &&
+      request->url().SchemeIs(url::kHttpScheme)) {
     scheduler_->OnReceivedSpdyProxiedHttpResponse(
         info->GetChildID(), info->GetRouteID());
   }
 
+  if (request->response_info().async_revalidation_required)
+    BeginAsyncRevalidation(request);
+
   int render_process_id, render_frame_host;
   if (!info->GetAssociatedRenderFrame(&render_process_id, &render_frame_host))
     return;
 
   // Notify the observers on the UI thread.
   scoped_ptr<ResourceRequestDetails> detail(new ResourceRequestDetails(
-      loader->request(),
-      GetCertID(loader->request(), info->GetChildID())));
+      request,
+      GetCertID(request, info->GetChildID())));
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(
@@ -1186,7 +1224,22 @@ void ResourceDispatcherHostImpl::BeginRequest(
     AbortRequestBeforeItStarts(filter_, sync_result, request_id);
     return;
   }
+  bool is_async_revalidation = false;
+  BeginRequestFromData(request_id, request_data, sync_result, process_type,
+                       child_id, route_id, is_async_revalidation,
+                       request_context, resource_context);
+}
 
+void ResourceDispatcherHostImpl::BeginRequestFromData(
+    int request_id,
+    const ResourceHostMsg_Request& request_data,
+    IPC::Message* sync_result,
+    int process_type,
+    int child_id,
+    int route_id,
+    bool is_async_revalidation,
+    net::URLRequestContext* request_context,
+    ResourceContext* resource_context) {
   // Construct the request.
   scoped_ptr<net::URLRequest> new_request;
   new_request = request_context->CreateRequest(
@@ -1259,6 +1312,13 @@ void ResourceDispatcherHostImpl::BeginRequest(
     load_flags |= net::LOAD_DO_NOT_USE_EMBEDDED_IDENTITY;
   }
 
+  // Check if request is eligible for async revalidation.
+  bool support_async_revalidation =
+      (async_revalidation_enabled_ && !is_sync_load && !is_async_revalidation &&
+       QualifiesForAsyncRevalidation(request_data));
+  if (support_async_revalidation)
+    load_flags |= net::LOAD_SUPPORT_ASYNC_REVALIDATION;
+
   // Sync loads should have maximum priority and should be the only
   // requets that have the ignore limits flag set.
   if (is_sync_load) {
@@ -1292,7 +1352,9 @@ void ResourceDispatcherHostImpl::BeginRequest(
       request_data.referrer_policy,
       request_data.visiblity_state,
       resource_context, filter_->GetWeakPtr(),
-      !is_sync_load);
+      !is_sync_load,
+      is_async_revalidation,
+      support_async_revalidation ? &request_data : NULL);
   // Request takes ownership.
   extra_info->AssociateWithRequest(new_request.get());
 
@@ -1327,11 +1389,9 @@ void ResourceDispatcherHostImpl::BeginRequest(
       request_data.appcache_host_id, request_data.resource_type,
       request_data.should_reset_appcache);
 
-  scoped_ptr<ResourceHandler> handler(
-       CreateResourceHandler(
-           new_request.get(),
-           request_data, sync_result, route_id, process_type, child_id,
-           resource_context));
+  scoped_ptr<ResourceHandler> handler(CreateResourceHandler(
+      new_request.get(), request_data, sync_result, route_id, process_type,
+      child_id, is_async_revalidation, resource_context));
 
   if (handler)
     BeginRequestInternal(new_request.Pass(), handler.Pass());
@@ -1344,6 +1404,7 @@ scoped_ptr<ResourceHandler> ResourceDispatcherHostImpl::CreateResourceHandler(
     int route_id,
     int process_type,
     int child_id,
+    bool is_async_revalidation,
     ResourceContext* resource_context) {
   // TODO(pkasting): Remove ScopedTracker below once crbug.com/456331 is fixed.
   tracked_objects::ScopedTracker tracking_profile(
@@ -1360,6 +1421,10 @@ scoped_ptr<ResourceHandler> ResourceDispatcherHostImpl::CreateResourceHandler(
     }
 
     handler.reset(new SyncResourceHandler(request, sync_result, this));
+  } else if (is_async_revalidation) {
+    handler.reset(new NullResourceHandler(
+        request, this, base::TimeDelta::FromSeconds(
+                           kNullResourceHandlerDefaultReadTimeoutSecs)));
   } else {
     handler.reset(new AsyncResourceHandler(request, this));
 
@@ -1400,29 +1465,39 @@ scoped_ptr<ResourceHandler> ResourceDispatcherHostImpl::CreateResourceHandler(
       handler.reset(new CrossSiteResourceHandler(handler.Pass(), request));
   }
 
+  // The BufferedResourceHandler performs mime-type sniffing and redirecting of
+  // downloads and plugin-handled content. The first we don't need for an
+  // async_revalidation, and the second is dangerous.
+  if (!is_async_revalidation) {
+    handler = AddBufferedResourceHandler(request, handler.Pass());
+  }
+
   return AddStandardHandlers(request, request_data.resource_type,
                              resource_context, filter_->appcache_service(),
                              child_id, route_id, handler.Pass());
 }
 
-scoped_ptr<ResourceHandler> ResourceDispatcherHostImpl::AddStandardHandlers(
+scoped_ptr<ResourceHandler>
+ResourceDispatcherHostImpl::AddBufferedResourceHandler(
     net::URLRequest* request,
-    ResourceType resource_type,
-    ResourceContext* resource_context,
-    AppCacheService* appcache_service,
-    int child_id,
-    int route_id,
     scoped_ptr<ResourceHandler> handler) {
-
   PluginService* plugin_service = nullptr;
 #if defined(ENABLE_PLUGINS)
   plugin_service = PluginService::GetInstance();
 #endif
   // Insert a buffered event handler before the actual one.
-  handler.reset(
-      new BufferedResourceHandler(
-          handler.Pass(), this, plugin_service, request));
+  return make_scoped_ptr(new BufferedResourceHandler(handler.Pass(), this,
+                                                     plugin_service, request));
+}
 
+scoped_ptr<ResourceHandler> ResourceDispatcherHostImpl::AddStandardHandlers(

[tyoshino (SeeGerritForStatus), 2015/06/12 08:20:44]

now this should be called e.g. AddThrottlingResourceHandler? though it also
contains RequestBeginning call.

[Adam Rice, 2015/06/12 14:20:09]

I tentatively renamed it AddThrottlesAndSchedule(). I'm welcome to other
suggestions.

+    net::URLRequest* request,
+    ResourceType resource_type,
+    ResourceContext* resource_context,
+    AppCacheService* appcache_service,
+    int child_id,
+    int route_id,
+    scoped_ptr<ResourceHandler> handler) {
   ScopedVector<ResourceThrottle> throttles;
   if (delegate_) {
     delegate_->RequestBeginning(request,
@@ -1553,7 +1628,9 @@ ResourceRequestInfoImpl* ResourceDispatcherHostImpl::CreateRequestInfo(
       blink::WebPageVisibilityStateVisible,
       context,
       base::WeakPtr<ResourceMessageFilter>(),  // filter
-      true);                                   // is_async
+      true,                                    // is_async
+      false,                                   // is_async_revalidation
+      NULL);                                   // original_message
 }
 
 void ResourceDispatcherHostImpl::OnRenderViewHostCreated(int child_id,
@@ -1704,7 +1781,8 @@ void ResourceDispatcherHostImpl::CancelRequestsForRoute(int child_id,
       any_requests_transferring = true;
     if (info->detachable_handler()) {
       info->detachable_handler()->Detach();
-    } else if (!info->IsDownload() && !info->is_stream() &&
+    } else if (!info->IsDownload() &&
+               !info->is_stream() && !info->IsAsyncRevalidation() &&
                !IsTransferredNavigation(id) &&
                (route_id == -1 || route_id == info->GetRouteID())) {
       matching_requests.push_back(id);
@@ -1774,6 +1852,15 @@ void ResourceDispatcherHostImpl::RemovePendingRequest(int child_id,
 void ResourceDispatcherHostImpl::RemovePendingLoader(
     const LoaderMap::iterator& iter) {
   ResourceRequestInfoImpl* info = iter->second->GetRequestInfo();
+  if (info->IsAsyncRevalidation()) {
+    net::URLRequest* request = iter->second->request();
+    auto async_revalidation_key =
+        AsyncRevalidationKey(request->context()->http_transaction_factory(),
+                             request->original_url());
+    bool erased =
+        in_progress_async_revalidations_.erase(async_revalidation_key);
+    DCHECK(erased);
+  }
 
   // Remove the memory credit that we added when pushing the request onto
   // the pending list.
@@ -1999,7 +2086,9 @@ void ResourceDispatcherHostImpl::BeginNavigationRequest(
       blink::WebPageVisibilityStateVisible,
       resource_context,
       base::WeakPtr<ResourceMessageFilter>(),  // filter
-      true);
+      true,                                    // is_async
+      false,                                   // is_async_revalidation
+      NULL);                                   // original_message
   // Request takes ownership.
   extra_info->AssociateWithRequest(new_request.get());
 
@@ -2023,12 +2112,12 @@ void ResourceDispatcherHostImpl::BeginNavigationRequest(
   // TODO(davidben): Pass in the appropriate appcache_service. Also fix the
   // dependency on child_id/route_id. Those are used by the ResourceScheduler;
   // currently it's a no-op.
-  handler = AddStandardHandlers(new_request.get(), resource_type,
-                                resource_context,
-                                nullptr,  // appcache_service
-                                -1,  // child_id
-                                -1,  // route_id
-                                handler.Pass());
+  handler = AddStandardHandlers(
+      new_request.get(), resource_type, resource_context,
+      nullptr,  // appcache_service
+      -1,       // child_id
+      -1,       // route_id
+      AddBufferedResourceHandler(new_request.get(), handler.Pass()));
 
   BeginRequestInternal(new_request.Pass(), handler.Pass());
 }
@@ -2372,4 +2461,52 @@ int ResourceDispatcherHostImpl::BuildLoadFlagsForRequest(
   return load_flags;
 }
 
+void ResourceDispatcherHostImpl::BeginAsyncRevalidation(
+    net::URLRequest* for_request) {
+  ResourceRequestInfoImpl* info =
+      ResourceRequestInfoImpl::ForRequest(for_request);
+  DCHECK(info);
+  DCHECK(!info->IsAsyncRevalidation());
+  ResourceHostMsg_Request* original_request = info->original_request();

[tyoshino (SeeGerritForStatus), 2015/06/12 08:20:44]

original_request_data?

[Adam Rice, 2015/06/12 14:20:09]

Done.

+  DCHECK(original_request);

[tyoshino (SeeGerritForStatus), 2015/06/12 08:20:43]

blank line

[Adam Rice, 2015/06/12 14:20:09]

Done.

+  ResourceHostMsg_Request new_request = *original_request;

[tyoshino (SeeGerritForStatus), 2015/06/12 08:20:44]

new_request_data?

[Adam Rice, 2015/06/12 14:20:09]

Done.

+  new_request.do_not_prompt_for_login = true;
+  new_request.allow_download = false;
+  new_request.enable_load_timing = false;
+  new_request.download_to_file = false;
+  new_request.transferred_request_child_id = -1;
+  new_request.transferred_request_request_id = -1;
+  new_request.priority = net::MINIMUM_PRIORITY;

[tyoshino (SeeGerritForStatus), 2015/06/12 08:20:44]

blank line

[Adam Rice, 2015/06/12 14:20:09]

Done.

+  int process_type = PROCESS_TYPE_BROWSER;
+  int child_id = info->GetChildID();
+  int route_id = info->GetRouteID();
+  int request_id = --request_id_;
+  bool is_async_revalidation = true;

[tyoshino (SeeGerritForStatus), 2015/06/12 08:20:44]

blink line

[Adam Rice, 2015/06/12 14:20:09]

Done.

+  ResourceContext* resource_context = NULL;
+  net::URLRequestContext* request_context = NULL;
+  // TODO(ricea): How can we ensure that resource_context and request_context
+  // live long enough to service the request?
+  info->filter()->GetContexts(new_request, &resource_context, &request_context);
+  if (is_shutdown_ || (delegate_ &&
+                       !delegate_->ShouldBeginRequest(
+                           new_request.method, new_request.url,
+                           new_request.resource_type, resource_context))) {
+    return;
+  }

[tyoshino (SeeGerritForStatus), 2015/06/12 08:20:44]

blank line

[Adam Rice, 2015/06/12 14:20:09]

Done.

+  auto async_revalidation_key = AsyncRevalidationKey(
+      request_context->http_transaction_factory(), original_request->url);
+  if (!in_progress_async_revalidations_.insert(async_revalidation_key).second) {
+    // A matching async revalidation is already in progress for this cache; we
+    // don't need another one.
+    return;
+  }
+  CHECK(ContainsKey(active_resource_contexts_, resource_context));

[tyoshino (SeeGerritForStatus), 2015/06/12 08:20:44]

blank line

[Adam Rice, 2015/06/12 14:20:09]

Done.

+  // TODO(ricea): Make filter_ be passed around in a sane way.
+  filter_ = info->filter();
+  BeginRequestFromData(request_id, new_request, NULL, process_type, child_id,
+                       route_id, is_async_revalidation, request_context,
+                       resource_context);
+  filter_ = NULL;
+}
+
 }  // namespace content