content/browser/loader/resource_scheduler.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_LOADER_RESOURCE_SCHEDULER_H_
   6 #define CONTENT_BROWSER_LOADER_RESOURCE_SCHEDULER_H_
   7
   8 #include <map>
   9 #include <set>
  10
  11 #include "base/basictypes.h"
  12 #include "base/compiler_specific.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/threading/non_thread_safe.h"
  15 #include "content/common/content_export.h"
  16 #include "net/base/priority_queue.h"
  17 #include "net/base/request_priority.h"
  18
  19 namespace net {
  20 class HostPortPair;
  21 class URLRequest;
  22 }
  23
  24 namespace content {
  25 class ResourceThrottle;
  26
  27 // There is one ResourceScheduler. All renderer-initiated HTTP requests are
  28 // expected to pass through it.
  29 //
  30 // There are two types of input to the scheduler:
  31 // 1. Requests to start, cancel, or finish fetching a resource.
  32 // 2. Notifications for renderer events, such as new tabs, navigation and
  33 //    painting.
  34 //
  35 // These input come from different threads, so they may not be in sync. The UI
  36 // thread is considered the authority on renderer lifetime, which means some
  37 // IPCs may be meaningless if they arrive after the UI thread signals a renderer
  38 // has been deleted.
  39 //
  40 // The ResourceScheduler tracks many Clients, which should correlate with tabs.
  41 // A client is uniquely identified by its child_id and route_id.
  42 //
  43 // Each Client may have many Requests in flight. Requests are uniquely
  44 // identified within a Client by its ScheduledResourceRequest.
  45 //
  46 // Users should call ScheduleRequest() to notify this ResourceScheduler of a
  47 // new request. The returned ResourceThrottle should be destroyed when the load
  48 // finishes or is canceled.
  49 //
  50 // The scheduler may defer issuing the request via the ResourceThrottle
  51 // interface or it may alter the request's priority by calling set_priority() on
  52 // the URLRequest.
  53 class CONTENT_EXPORT ResourceScheduler : public base::NonThreadSafe {
  54  public:
  55   ResourceScheduler();
  56   ~ResourceScheduler();
  57
  58   // Requests that this ResourceScheduler schedule, and eventually loads, the
  59   // specified |url_request|. Caller should delete the returned ResourceThrottle
  60   // when the load completes or is canceled.
  61   scoped_ptr<ResourceThrottle> ScheduleRequest(
  62       int child_id, int route_id, net::URLRequest* url_request);
  63
  64   // Signals from the UI thread, posted as tasks on the IO thread:
  65
  66   // Called when a renderer is created.
  67   void OnClientCreated(int child_id, int route_id);
  68
  69   // Called when a renderer is destroyed.
  70   void OnClientDeleted(int child_id, int route_id);
  71
  72   // Signals from IPC messages directly from the renderers:
  73
  74   // Called when a client navigates to a new main document.
  75   void OnNavigate(int child_id, int route_id);
  76
  77   // Called when the client has parsed the <body> element. This is a signal that
  78   // resource loads won't interfere with first paint.
  79   void OnWillInsertBody(int child_id, int route_id);
  80
  81   // Signals from the IO thread
  82
  83   // Called when we received a response to a http request that was served
  84   // from a proxy using SPDY.
  85   void OnReceivedSpdyProxiedHttpResponse(int child_id, int route_id);
  86
  87  private:
  88   class RequestQueue;
  89   class ScheduledResourceRequest;
  90   struct RequestPriorityParams;
  91   struct ScheduledResourceSorter {
  92     bool operator()(const ScheduledResourceRequest* a,
  93                     const ScheduledResourceRequest* b) const;
  94   };
  95   class Client;
  96
  97   typedef int64 ClientId;
  98   typedef std::map<ClientId, Client*> ClientMap;
  99   typedef std::set<ScheduledResourceRequest*> RequestSet;
 100
 101   // Called when a ScheduledResourceRequest is destroyed.
 102   void RemoveRequest(ScheduledResourceRequest* request);
 103
 104   // Update the queue position for |request|, possibly causing it to start
 105   // loading.
 106   //
 107   // Queues are maintained for each priority level. When |request| is
 108   // reprioritized, it will move to the end of the queue for that priority
 109   // level.
 110   void ReprioritizeRequest(ScheduledResourceRequest* request,
 111                            net::RequestPriority new_priority,
 112                            int intra_priority_value);
 113
 114   // Returns the client ID for the given |child_id| and |route_id| combo.
 115   ClientId MakeClientId(int child_id, int route_id);
 116
 117   ClientMap client_map_;
 118   RequestSet unowned_requests_;
 119 };
 120
 121 }  // namespace content
 122
 123 #endif  // CONTENT_BROWSER_LOADER_RESOURCE_SCHEDULER_H_