Changed resource scheduler to block until all critical resources actually load.

content/browser/loader/resource_scheduler.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 <set>
 
 #include "content/browser/loader/resource_scheduler.h"
 
 #include "base/stl_util.h"
 #include "content/common/resource_messages.h"
@@ skipping 107 matching lines @@
  public:
   ScheduledResourceRequest(const ClientId& client_id,
                            net::URLRequest* request,
                            ResourceScheduler* scheduler,
                            const RequestPriorityParams& priority)
       : ResourceMessageDelegate(request),
         client_id_(client_id),
         request_(request),
         ready_(false),
         deferred_(false),
+        critical_(false),
         scheduler_(scheduler),
         priority_(priority),
         fifo_ordering_(0),
         accounted_as_delayable_request_(false) {
     TRACE_EVENT_ASYNC_BEGIN1("net", "URLRequest", request_,
                              "url", request->url().spec());
   }
 
   virtual ~ScheduledResourceRequest() {
     scheduler_->RemoveRequest(this);
@@ skipping 20 matching lines @@
   uint32 fifo_ordering() const { return fifo_ordering_; }
   void set_fifo_ordering(uint32 fifo_ordering) {
     fifo_ordering_ = fifo_ordering;
   }
   bool accounted_as_delayable_request() const {
     return accounted_as_delayable_request_;
   }
   void set_accounted_as_delayable_request(bool accounted) {
     accounted_as_delayable_request_ = accounted;
   }
+  bool critical() const {
+    return critical_;
+  }
+  void set_critical(bool critical) {
+    critical_ = critical;
+  }
 
  private:
   // ResourceMessageDelegate interface:
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE {
     bool handled = true;
     IPC_BEGIN_MESSAGE_MAP(ScheduledResourceRequest, message)
       IPC_MESSAGE_HANDLER(ResourceHostMsg_DidChangePriority, DidChangePriority)
       IPC_MESSAGE_UNHANDLED(handled = false)
     IPC_END_MESSAGE_MAP()
     return handled;
@@ skipping 10 matching lines @@
 
   void DidChangePriority(int request_id, net::RequestPriority new_priority,
                          int intra_priority_value) {
     scheduler_->ReprioritizeRequest(this, new_priority, intra_priority_value);
   }
 
   ClientId client_id_;
   net::URLRequest* request_;
   bool ready_;
   bool deferred_;
+  bool critical_;
   ResourceScheduler* scheduler_;
   RequestPriorityParams priority_;
   uint32 fifo_ordering_;
   // True if the request is delayable in |in_flight_requests_|.
   bool accounted_as_delayable_request_;
 
   DISALLOW_COPY_AND_ASSIGN(ScheduledResourceRequest);
 };
 
 bool ResourceScheduler::ScheduledResourceSorter::operator()(
@@ skipping 23 matching lines @@
 class ResourceScheduler::Client {
  public:
   explicit Client(ResourceScheduler* scheduler)
       : is_audible_(false),
         is_visible_(false),
         is_loaded_(false),
         is_paused_(false),
         has_body_(false),
         using_spdy_proxy_(false),
         total_delayable_count_(0),
+        total_critical_count_(0),
         throttle_state_(ResourceScheduler::THROTTLED) {
     scheduler_ = scheduler;
   }
 
   ~Client() {
     // Update to default state and pause to ensure the scheduler has a
     // correct count of relevant types of clients.
     is_visible_ = false;
     is_audible_ = false;
     is_paused_ = true;
@@ skipping 21 matching lines @@
       LoadAnyStartablePendingRequests();
     }
   }
 
   RequestSet RemoveAllRequests() {
     RequestSet unowned_requests;
     for (RequestSet::iterator it = in_flight_requests_.begin();
          it != in_flight_requests_.end(); ++it) {
       unowned_requests.insert(*it);
       (*it)->set_accounted_as_delayable_request(false);
+      (*it)->set_critical(false);
     }
     ClearInFlightRequests();
     return unowned_requests;
   }
 
   bool is_active() const { return is_visible_ || is_audible_; }
 
   bool is_loaded() const { return is_loaded_; }
 
   void OnAudibilityChanged(bool is_audible) {
@@ skipping 76 matching lines @@
   void ReprioritizeRequest(ScheduledResourceRequest* request,
                            RequestPriorityParams old_priority_params,
                            RequestPriorityParams new_priority_params) {
     request->url_request()->SetPriority(new_priority_params.priority);
     request->set_request_priority_params(new_priority_params);
     if (!pending_requests_.IsQueued(request)) {
       DCHECK(ContainsKey(in_flight_requests_, request));
       // The priority and SPDY support may have changed, so update the
       // delayable count.
       SetRequestDelayable(request, IsDelayableRequest(request));
+      SetRequestCritical(request, IsCriticalRequest(request));

[mmenke, 2014/08/12 17:18:37]

Should we have an enum instead of bools?

[Pat Meenan, 2014/08/13 00:20:12]

Done.

       // Request has already started.
       return;
     }
 
     pending_requests_.Erase(request);
     pending_requests_.Insert(request);
 
     if (new_priority_params.priority > old_priority_params.priority) {
       // Check if this request is now able to load at its new priority.
       LoadAnyStartablePendingRequests();
@@ skipping 48 matching lines @@
   enum ShouldStartReqResult {
     DO_NOT_START_REQUEST_AND_STOP_SEARCHING,
     DO_NOT_START_REQUEST_AND_KEEP_SEARCHING,
     START_REQUEST,
   };
 
   void InsertInFlightRequest(ScheduledResourceRequest* request) {
     in_flight_requests_.insert(request);
     if (IsDelayableRequest(request))
       SetRequestDelayable(request, true);
+    if (IsCriticalRequest(request))
+      SetRequestCritical(request, true);
   }
 
   void EraseInFlightRequest(ScheduledResourceRequest* request) {
     size_t erased = in_flight_requests_.erase(request);
     DCHECK_EQ(1u, erased);
     SetRequestDelayable(request, false);
     DCHECK_LE(total_delayable_count_, in_flight_requests_.size());
+    SetRequestCritical(request, false);
+    DCHECK_LE(total_critical_count_, in_flight_requests_.size());
   }
 
   void ClearInFlightRequests() {
     in_flight_requests_.clear();
     total_delayable_count_ = 0;
+    total_critical_count_ = 0;
   }
 
   bool IsDelayableRequest(ScheduledResourceRequest* request) {
     if (request->url_request()->priority() < net::LOW) {
       net::HostPortPair host_port_pair =
           net::HostPortPair::FromURL(request->url_request()->url());
       net::HttpServerProperties& http_server_properties =
           *request->url_request()->context()->http_server_properties();
       if (!http_server_properties.SupportsSpdy(host_port_pair)) {
         return true;
       }
     }
     return false;
   }
 
   void SetRequestDelayable(ScheduledResourceRequest* request,
                            bool delayable) {
     if (request->accounted_as_delayable_request() == delayable)
       return;
     if (delayable)
       total_delayable_count_++;
     else
       total_delayable_count_--;
     request->set_accounted_as_delayable_request(delayable);
   }
 
+  bool IsCriticalRequest(ScheduledResourceRequest* request) {
+    if (!has_body_ && request->url_request()->priority() >= net::LOW)
+      return true;
+    return false;
+  }
+
+  void SetRequestCritical(ScheduledResourceRequest* request,
+                           bool critical) {
+    if (request->critical() == critical)
+      return;
+    if (critical)
+      total_critical_count_++;
+    else
+      total_critical_count_--;
+    request->set_critical(critical);
+  }
+
   bool ShouldKeepSearching(
       const net::HostPortPair& active_request_host) const {
     size_t same_host_count = 0;
     for (RequestSet::const_iterator it = in_flight_requests_.begin();
          it != in_flight_requests_.end(); ++it) {
       net::HostPortPair host_port_pair =
           net::HostPortPair::FromURL((*it)->url_request()->url());
       if (active_request_host.Equals(host_port_pair)) {
         same_host_count++;
         if (same_host_count >= kMaxNumDelayableRequestsPerHost)
           return true;
       }
     }
     return false;
   }
 
   void StartRequest(ScheduledResourceRequest* request) {
     InsertInFlightRequest(request);
     request->Start();
   }
 
   // ShouldStartRequest is the main scheduling algorithm.
   //
-  // Requests are categorized into three categories:
+  // Requests are categorized into five categories:
   //
   // 1. Non-delayable requests:
   //   * Synchronous requests.
   //   * Non-HTTP[S] requests.
   //
   // 2. Requests to SPDY-capable origin servers.
   //
   // 3. High-priority requests:
   //   * Higher priority requests (>= net::LOW).
   //
-  // 4. Low priority requests
+  // 4. Critical requests:
+  //   * High-priority requests initiated before the renderer has a <body>.
+  //
+  // 5. Low priority requests
   //
   //  The following rules are followed:
   //
   //  ACTIVE_AND_LOADING and UNTHROTTLED Clients follow these rules:
   //   * Non-delayable, High-priority and SDPY capable requests are issued
-  //     immediately
+  //     immediately.
   //   * If no high priority requests are in flight, start loading low priority
   //     requests.
   //   * Low priority requests are delayable.
-  //   * Once the renderer has a <body>, start loading delayable requests.
+  //   * Allow one delayable request toload at a time while critical requests
+  //     are loading.
+  //   * Once all critical requests have finished loading, start loading
+  //     delayable requests.
   //   * Never exceed 10 delayable requests in flight per client.
   //   * Never exceed 6 delayable requests for a given host.
-  //   * Prior to <body>, allow one delayable request to load at a time.
   //
   //  THROTTLED Clients follow these rules:
   //   * Non-delayable and SPDY-capable requests are issued immediately.
   //   * At most one non-SPDY request will be issued per THROTTLED Client
   //   * If no high priority requests are in flight, start loading low priority
   //     requests.
   //
   //  COALESCED Clients never load requests, with the following exceptions:
   //   * Non-delayable requests are issued imediately.
   //   * On a (currently 5 second) heart beat, they load all requests as an
@@ skipping 53 matching lines @@
     }
 
     if (ShouldKeepSearching(host_port_pair)) {
       // There may be other requests for other hosts we'd allow,
       // so keep checking.
       return DO_NOT_START_REQUEST_AND_KEEP_SEARCHING;
     }
 
     bool have_immediate_requests_in_flight =
         in_flight_requests_.size() > num_delayable_requests_in_flight;
-    if (have_immediate_requests_in_flight && !has_body_ &&
+    if (have_immediate_requests_in_flight &&
+        total_critical_count_ != 0 &&
         num_delayable_requests_in_flight != 0) {
       return DO_NOT_START_REQUEST_AND_STOP_SEARCHING;
     }
 
     return START_REQUEST;
   }
 
   void LoadAnyStartablePendingRequests() {
     // We iterate through all the pending requests, starting with the highest
     // priority one. For each entry, one of three things can happen:
@@ skipping 35 matching lines @@
   bool is_visible_;
   bool is_loaded_;
   bool is_paused_;
   bool has_body_;
   bool using_spdy_proxy_;
   RequestQueue pending_requests_;
   RequestSet in_flight_requests_;
   ResourceScheduler* scheduler_;
   // The number of delayable in-flight requests.
   size_t total_delayable_count_;
+  // The number of critical in-flight requests.
+  size_t total_critical_count_;
   ResourceScheduler::ClientThrottleState throttle_state_;
 };
 
 ResourceScheduler::ResourceScheduler()
     : should_coalesce_(false),
       should_throttle_(false),
       active_clients_loading_(0),
       coalesced_clients_(0),
       coalescing_timer_(new base::Timer(true /* retain_user_task */,
                                         true /* is_repeating */)) {
@@ skipping 289 matching lines @@
   client->ReprioritizeRequest(
       request, old_priority_params, new_priority_params);
 }
 
 ResourceScheduler::ClientId ResourceScheduler::MakeClientId(
     int child_id, int route_id) {
   return (static_cast<ResourceScheduler::ClientId>(child_id) << 32) | route_id;
 }
 
 }  // namespace content