Add a ResourceScheduler to ResourceDispatcherHost.

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 "content/browser/loader/resource_scheduler.h"
+
+#include "base/stl_util.h"
+#include "net/base/load_flags.h"
+#include "net/base/request_priority.h"
+#include "net/url_request/url_request.h"
+
+namespace content {
+
+namespace {
+
+ResourceScheduler::ClientId MakeClientId(int child_id, int route_id) {
+  return (static_cast<ResourceScheduler::ClientId>(child_id) << 32) | route_id;
+}
+
+}  // unnamed namespace
+
+class LoadHandleImpl : public ResourceScheduler::LoadHandle {
+ public:
+  LoadHandleImpl(ResourceScheduler::SchedulerId scheduler_id,
+                 ResourceScheduler::ClientId client_id,
+                 ResourceScheduler* scheduler)
+      : scheduler_id_(scheduler_id),
+        client_id_(client_id),
+        scheduler_(scheduler) {
+  }
+
+  virtual ~LoadHandleImpl() {
+    scheduler_->RemoveLoad(scheduler_id_, client_id_);
+  }
+
+ private:
+  ResourceScheduler::SchedulerId scheduler_id_;
+  ResourceScheduler::ClientId client_id_;
+  ResourceScheduler* scheduler_;
+
+  DISALLOW_COPY_AND_ASSIGN(LoadHandleImpl);
+};
+
+ResourceScheduler::ResourceScheduler()
+    : next_scheduler_id_(0) {
+}
+
+ResourceScheduler::~ResourceScheduler() {
+}
+
+scoped_ptr<ResourceScheduler::LoadHandle> ResourceScheduler::ScheduleLoad(
+    int child_id,
+    int route_id,
+    Loadable* loadable) {
+  SchedulerId scheduler_id = ++next_scheduler_id_;
+  ClientId client_id = MakeClientId(child_id, route_id);
+  scoped_ptr<LoadHandle> handle(new LoadHandleImpl(
+      scheduler_id, client_id, this));
+
+  if (route_id == 0 || !ContainsKey(client_map_, client_id)) {
+    // <a ping> requests don't belong to a specific page. Most tests don't call
+    // OnCreate et. al. as needed to register Clients either.
+    unowned_requests_.insert(scheduler_id);
+    loadable->StartRequest();
+    return handle.Pass();
+  }
+
+  Client* client = client_map_[client_id];
+  DCHECK(!client->has_closed);
+  Request request = { scheduler_id, loadable };
+
+  // Treat synchronous requests as high priority.
+  bool is_low_priority = loadable->url_request().priority() < net::MEDIUM &&
+      !(loadable->url_request().load_flags() & net::LOAD_IGNORE_LIMITS);
+
+  if (is_low_priority && !client->in_flight_requests.empty() &&
+      !client->has_painted) {
+    client->pending_requests.push_back(request);
+  } else {
+    StartRequest(request, client);
+  }
+  return handle.Pass();
+}
+
+void ResourceScheduler::RemoveLoad(SchedulerId scheduler_id,
+                                   ClientId client_id) {
+  if (ContainsKey(unowned_requests_, scheduler_id)) {
+    unowned_requests_.erase(scheduler_id);
+    return;
+  }
+
+  DCHECK(ContainsKey(client_map_, client_id));
+  Client* client = client_map_[client_id];
+  SchedulerIdSet::iterator it = client->in_flight_requests.find(scheduler_id);
+  if (it == client->in_flight_requests.end()) {
+    bool removed = false;
+    RequestQueue::iterator queue_it;
+    for (queue_it = client->pending_requests.begin();
+         queue_it != client->pending_requests.end(); ++queue_it) {
+      if (queue_it->scheduler_id == scheduler_id) {
+        client->pending_requests.erase(queue_it);
+        removed = true;
+        break;
+      }
+    }
+    DCHECK(removed);
+    DCHECK(!ContainsKey(client->in_flight_requests, scheduler_id));
+  } else {
+    size_t erased = client->in_flight_requests.erase(scheduler_id);
+    DCHECK(erased);
+  }
+
+  if (client->has_closed) {
+    if (client->in_flight_requests.empty()
+        && client->pending_requests.empty()) {
+      delete client;
+      client_map_.erase(client_id);
+    }
+  } else if (client->in_flight_requests.empty()) {
+    LoadPendingRequests(client);
+  }
+}
+
+void ResourceScheduler::OnCreate(int child_id, int route_id) {
+  ClientId client_id = MakeClientId(child_id, route_id);
+  DCHECK(!ContainsKey(client_map_, client_id));
+  client_map_[client_id] = new Client;
+}
+
+void ResourceScheduler::OnNavigate(int child_id, int route_id) {
+  ClientId client_id = MakeClientId(child_id, route_id);
+  if (!ContainsKey(client_map_, client_id)) {
+    return;
+  }
+
+  Client* client = client_map_[client_id];
+  client->has_painted = false;
+}
+
+void ResourceScheduler::OnPaint(int child_id, int route_id) {
+  ClientId client_id = MakeClientId(child_id, route_id);
+  if (!ContainsKey(client_map_, client_id)) {
+    return;
+  }
+
+  Client* client = client_map_[client_id];
+  if (!client->has_painted) {
+    client->has_painted = true;
+    LoadPendingRequests(client);
+  }
+}
+
+void ResourceScheduler::OnDestroy(int child_id, int route_id) {
+  ClientId client_id = MakeClientId(child_id, route_id);
+  if (!ContainsKey(client_map_, client_id)) {
+    return;
+  }
+
+  Client* client = client_map_[client_id];
+  if (client->pending_requests.empty() && client->in_flight_requests.empty()) {
+    delete client;
+    client_map_.erase(client_id);
+  } else {
+    client->has_closed = true;
+  }
+}
+
+void ResourceScheduler::StartRequest(Request request, Client* client) {
+  client->in_flight_requests.insert(request.scheduler_id);
+  request.loadable->StartRequest();
+}
+
+void ResourceScheduler::LoadPendingRequests(Client* client) {
+  RequestQueue::iterator it;
+  for (it = client->pending_requests.begin();
+       it != client->pending_requests.end(); ++it) {
+    StartRequest(*it, client);
+  }
+  client->pending_requests.clear();
+}
+
+ResourceScheduler::Client::Client()
+    : has_painted(false),
+      has_closed(false) {
+}
+
+ResourceScheduler::Client::~Client() {
+}
+
+}  // namespace content