Add histograms to gather ResourceScheduler information.

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/metrics/field_trial.h"
+#include "base/metrics/histogram.h"
 #include "base/stl_util.h"
+#include "base/time/time.h"
 #include "content/common/resource_messages.h"
 #include "content/browser/loader/resource_message_delegate.h"
 #include "content/public/browser/resource_controller.h"
 #include "content/public/browser/resource_request_info.h"
 #include "content/public/browser/resource_throttle.h"
 #include "ipc/ipc_message_macros.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/load_flags.h"
 #include "net/base/request_priority.h"
 #include "net/http/http_server_properties.h"
@@ skipping 90 matching lines @@
   PointerMap pointers_;
 };
 
 // This is the handle we return to the ResourceDispatcherHostImpl so it can
 // interact with the request.
 class ResourceScheduler::ScheduledResourceRequest
     : public ResourceMessageDelegate,
       public ResourceThrottle {
  public:
   ScheduledResourceRequest(const ClientId& client_id,
+                           ResourceScheduler::ClientState client_state,

[mmenke, 2014/11/03 16:05:55]

Optional nit:  Suggest not taking this as an argument, but instead calling
scheduler->GetClientState here - think that, as implemented, when the request
wants the client state and what it does with it is more a feature of the request
than something the scheduler should care about.

[aiolos (Not reviewing), 2014/11/03 17:50:25]

Done.

                            net::URLRequest* request,
                            ResourceScheduler* scheduler,
                            const RequestPriorityParams& priority)
       : ResourceMessageDelegate(request),
         client_id_(client_id),
+        client_state_on_creation_(client_state),
         request_(request),
         ready_(false),
         deferred_(false),
         classification_(NORMAL_REQUEST),
         scheduler_(scheduler),
         priority_(priority),
         fifo_ordering_(0) {
     TRACE_EVENT_ASYNC_BEGIN1("net", "URLRequest", request_,
                              "url", request->url().spec());
   }
 
   ~ScheduledResourceRequest() override { scheduler_->RemoveRequest(this); }
 
   void Start() {
     TRACE_EVENT_ASYNC_STEP_PAST0("net", "URLRequest", request_, "Queued");
     ready_ = true;
-    if (deferred_ && request_->status().is_success()) {
-      deferred_ = false;
-      controller()->Resume();
+    if (request_->status().is_success()) {

[mmenke, 2014/11/03 16:05:55]

nit:  Suggest making this an early return - early returns are generally
preferred, particularly when there's a bunch of code below them, making
indentation a little harder to follow.

[aiolos (Not reviewing), 2014/11/03 17:50:26]

Done.

+      base::TimeTicks time = base::TimeTicks::Now();
+      ClientState current_state = scheduler_->GetClientState(client_id_);
+      const char* client_state =
+          current_state == UNKNOWN || current_state != client_state_on_creation_
+              ? "Other"
+              : current_state == ACTIVE ? "Active" : "Background";

[mmenke, 2014/11/03 16:05:54]

Suggest a method or function for this, or splitting this into multiple
statements.  As-is, it's pretty hard to follow.

[aiolos (Not reviewing), 2014/11/03 17:50:25]

Done.

+      if (deferred_) {
+        deferred_ = false;
+        controller()->Resume();
+        scheduler_->PostHistogram(
+            "RequestTimeDeferred", client_state, time - time_deferred_);

[mmenke, 2014/11/03 16:05:55]

If !deferred_, we should be recording a 0, I believe.

[aiolos (Not reviewing), 2014/11/03 17:50:25]

Done.

+      }
+      // TODO(aiolos): Remove one of these histograms after gaining an
+      // understanding of the difference between them and which one is more
+      // interesting.
+      scheduler_->PostHistogram("RequestTimeThrottled",
+                                client_state,
+                                time - request_->creation_time());
     }
   }
 
   void set_request_priority_params(const RequestPriorityParams& priority) {
     priority_ = priority;
   }
   const RequestPriorityParams& get_request_priority_params() const {
     return priority_;
   }
   const ClientId& client_id() const { return client_id_; }
@@ skipping 15 matching lines @@
   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;
   }
 
   // ResourceThrottle interface:
-  void WillStartRequest(bool* defer) override { deferred_ = *defer = !ready_; }
+  void WillStartRequest(bool* defer) override {
+    deferred_ = *defer = !ready_;
+    time_deferred_ = base::TimeTicks::Now();
+  }
 
   const char* GetNameForLogging() const override { return "ResourceScheduler"; }
 
   void DidChangePriority(int request_id, net::RequestPriority new_priority,
                          int intra_priority_value) {
     scheduler_->ReprioritizeRequest(this, new_priority, intra_priority_value);
   }
 
   ClientId client_id_;
+  ResourceScheduler::ClientState client_state_on_creation_;
   net::URLRequest* request_;
   bool ready_;
   bool deferred_;
   RequestClassification classification_;
   ResourceScheduler* scheduler_;
   RequestPriorityParams priority_;
   uint32 fifo_ordering_;
+  base::TimeTicks time_deferred_;
 
   DISALLOW_COPY_AND_ASSIGN(ScheduledResourceRequest);
 };
 
 bool ResourceScheduler::ScheduledResourceSorter::operator()(
     const ScheduledResourceRequest* a,
     const ScheduledResourceRequest* b) const {
   // Want the set to be ordered first by decreasing priority, then by
   // decreasing intra_priority.
   // ie. with (priority, intra_priority)
@@ skipping 540 matching lines @@
   DCHECK(client);
   return client->throttle_state();
 }
 
 scoped_ptr<ResourceThrottle> ResourceScheduler::ScheduleRequest(
     int child_id,
     int route_id,
     net::URLRequest* url_request) {
   DCHECK(CalledOnValidThread());
   ClientId client_id = MakeClientId(child_id, route_id);
-  scoped_ptr<ScheduledResourceRequest> request(
-      new ScheduledResourceRequest(client_id, url_request, this,
-          RequestPriorityParams(url_request->priority(), 0)));
+  scoped_ptr<ScheduledResourceRequest> request(new ScheduledResourceRequest(
+      client_id,
+      GetClientState(client_id),
+      url_request,
+      this,
+      RequestPriorityParams(url_request->priority(), 0)));
 
   ClientMap::iterator it = client_map_.find(client_id);
   if (it == client_map_.end()) {
     // There are several ways this could happen:
     // 1. <a ping> requests don't have a route_id.
     // 2. Most unittests don't send the IPCs needed to register Clients.
     // 3. The tab is closed while a RequestResource IPC is in flight.
     unowned_requests_.insert(request.get());
     request->Start();
     return request.Pass();
@@ skipping 221 matching lines @@
 void ResourceScheduler::LoadCoalescedRequests() {
   DCHECK(should_coalesce_);
   ClientMap::iterator client_it = client_map_.begin();
   while (client_it != client_map_.end()) {
     Client* client = client_it->second;
     client->LoadCoalescedRequests();
     ++client_it;
   }
 }
 
+ResourceScheduler::ClientState ResourceScheduler::GetClientState(
+    ClientId client_id) const {
+  ClientMap::const_iterator client_it = client_map_.find(client_id);
+  if (client_it == client_map_.end())
+    return UNKNOWN;
+  return client_it->second->is_active() ? ACTIVE : BACKGROUND;
+}
+
 void ResourceScheduler::ReprioritizeRequest(ScheduledResourceRequest* request,
                                             net::RequestPriority new_priority,
                                             int new_intra_priority_value) {
   if (request->url_request()->load_flags() & net::LOAD_IGNORE_LIMITS) {
     // We should not be re-prioritizing requests with the
     // IGNORE_LIMITS flag.
     NOTREACHED();
     return;
   }
   RequestPriorityParams new_priority_params(new_priority,
@@ skipping 17 matching lines @@
   Client *client = client_it->second;
   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;
 }
 
+void ResourceScheduler::PostHistogram(const char* base_name,

[mmenke, 2014/11/03 16:05:55]

This should be in an anonymous namespace up top.

[aiolos (Not reviewing), 2014/11/03 17:50:26]

Done.

+                                      const char* suffix,
+                                      base::TimeDelta time) {
+  std::string histogram_name =
+      base::StringPrintf("ResourceScheduler.%s_%s", base_name, suffix);
+  base::HistogramBase* histogram_counter = base::Histogram::FactoryTimeGet(
+      histogram_name,
+      base::TimeDelta::FromMilliseconds(1),
+      base::TimeDelta::FromMinutes(5),
+      50,
+      base::Histogram::kUmaTargetedHistogramFlag);
+  histogram_counter->AddTime(time);
+}
 }  // namespace content