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// 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 <map>
#include <set>
#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/memory/scoped_ptr.h"
#include "base/threading/non_thread_safe.h"
#include "base/timer/timer.h"
#include "content/common/content_export.h"
#include "net/base/priority_queue.h"
#include "net/base/request_priority.h"
namespace net {
class HostPortPair;
class URLRequest;
namespace content {
class ResourceThrottle;
// There is one ResourceScheduler. All renderer-initiated HTTP requests are
// expected to pass through it.
// There are two types of input to the scheduler:
// 1. Requests to start, cancel, or finish fetching a resource.
// 2. Notifications for renderer events, such as new tabs, navigation and
// painting.
// These input come from different threads, so they may not be in sync. The UI
// thread is considered the authority on renderer lifetime, which means some
// IPCs may be meaningless if they arrive after the UI thread signals a renderer
// has been deleted.
// The ResourceScheduler tracks many Clients, which should correlate with tabs.
// A client is uniquely identified by its child_id and route_id.
// Each Client may have many Requests in flight. Requests are uniquely
// identified within a Client by its ScheduledResourceRequest.
// Users should call ScheduleRequest() to notify this ResourceScheduler of a
// new request. The returned ResourceThrottle should be destroyed when the load
// finishes or is canceled.
// The scheduler may defer issuing the request via the ResourceThrottle
// interface or it may alter the request's priority by calling set_priority() on
// the URLRequest.
class CONTENT_EXPORT ResourceScheduler : public base::NonThreadSafe {
enum ClientThrottleState {
// TODO(aiolos): Add logic to ShouldStartRequest for PAUSED Clients to only
// issue synchronous requests.
// TODO(aiolos): Add max number of THROTTLED Clients, and logic to set
// subsquent Clients to PAUSED instead. Also add logic to unpause a Client
// when a background Client becomes COALESCED (ie, finishes loading.)
// TODO(aiolos): Add tests for the above mentioned logic.
// Currently being deleted client.
// This state currently follows the same logic for loading requests as
// Loaded background client, all observable clients loaded.
// Background client, an observable client is loading.
// Observable (active) loaded client or
// Loading background client, all observable clients loaded.
// Note that clients which would be COALESCED are UNTHROTTLED until
// coalescing is turned on.
// Observable (active) loading client.
// Use a mock timer when testing.
void set_timer_for_testing(scoped_ptr<base::Timer> timer) {
// TODO(aiolos): Remove when throttling and coalescing have landed
void SetThrottleOptionsForTesting(bool should_throttle, bool should_coalesce);
bool should_coalesce() const { return should_coalesce_; }
bool should_throttle() const { return should_throttle_; }
ClientThrottleState GetClientStateForTesting(int child_id, int route_id);
// Requests that this ResourceScheduler schedule, and eventually loads, the
// specified |url_request|. Caller should delete the returned ResourceThrottle
// when the load completes or is canceled.
scoped_ptr<ResourceThrottle> ScheduleRequest(
int child_id, int route_id, net::URLRequest* url_request);
// Signals from the UI thread, posted as tasks on the IO thread:
// Called when a renderer is created.
void OnClientCreated(int child_id, int route_id);
// Called when a renderer is destroyed.
void OnClientDeleted(int child_id, int route_id);
// Signals from IPC messages directly from the renderers:
// Called when a client navigates to a new main document.
void OnNavigate(int child_id, int route_id);
// Called when the client has parsed the <body> element. This is a signal that
// resource loads won't interfere with first paint.
void OnWillInsertBody(int child_id, int route_id);
// Signals from the IO thread:
// Called when we received a response to a http request that was served
// from a proxy using SPDY.
void OnReceivedSpdyProxiedHttpResponse(int child_id, int route_id);
// Client functions:
// Called to check if all user observable tabs have completed loading.
bool active_clients_loaded() const { return active_clients_loading_ == 0; }
// Called when a Client starts or stops playing audio.
void OnAudibilityChanged(int child_id, int route_id, bool is_audible);
// Called when a Client is shown or hidden.
void OnVisibilityChanged(int child_id, int route_id, bool is_visible);
void OnLoadingStateChanged(int child_id, int route_id, bool is_loaded);
class RequestQueue;
class ScheduledResourceRequest;
struct RequestPriorityParams;
struct ScheduledResourceSorter {
bool operator()(const ScheduledResourceRequest* a,
const ScheduledResourceRequest* b) const;
class Client;
typedef int64 ClientId;
typedef std::map<ClientId, Client*> ClientMap;
typedef std::set<ScheduledResourceRequest*> RequestSet;
// Called when a ScheduledResourceRequest is destroyed.
void RemoveRequest(ScheduledResourceRequest* request);
// These calls may update the ThrottleState of all clients, and have the
// potential to be re-entrant.
// Called when a Client newly becomes active loading.
void IncrementActiveClientsLoading();
// Called when an active and loading Client either completes loading or
// becomes inactive.
void DecrementActiveClientsLoading();
void OnLoadingActiveClientsStateChangedForAllClients();
size_t CountActiveClientsLoading() const;
// Called when a Client becomes coalesced.
void IncrementCoalescedClients();
// Called when a client stops being coalesced.
void DecrementCoalescedClients();
void LoadCoalescedRequests();
size_t CountCoalescedClients() const;
// Update the queue position for |request|, possibly causing it to start
// loading.
// Queues are maintained for each priority level. When |request| is
// reprioritized, it will move to the end of the queue for that priority
// level.
void ReprioritizeRequest(ScheduledResourceRequest* request,
net::RequestPriority new_priority,
int intra_priority_value);
// Returns the client ID for the given |child_id| and |route_id| combo.
ClientId MakeClientId(int child_id, int route_id);
// Returns the client for the given |child_id| and |route_id| combo.
Client* GetClient(int child_id, int route_id);
bool should_coalesce_;
bool should_throttle_;
ClientMap client_map_;
size_t active_clients_loading_;
size_t coalesced_clients_;
// This is a repeating timer to initiate requests on COALESCED Clients.
scoped_ptr<base::Timer> coalescing_timer_;
RequestSet unowned_requests_;
} // namespace content