[Chromecast] Add connectivity checking for Chromecast.

chromecast/net/connectivity_checker.cc

+// Copyright 2015 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 "chromecast/net/connectivity_checker.h"
+
+#include "base/command_line.h"
+#include "base/logging.h"
+#include "base/message_loop/message_loop.h"
+#include "chromecast/net/net_switches.h"
+#include "net/base/request_priority.h"
+#include "net/http/http_response_headers.h"
+#include "net/http/http_response_info.h"
+#include "net/http/http_status_code.h"
+#include "net/proxy/proxy_config.h"
+#include "net/proxy/proxy_config_service_fixed.h"
+#include "net/url_request/url_request_context.h"
+#include "net/url_request/url_request_context_builder.h"
+
+namespace chromecast {
+
+namespace {
+
+// How often we perform connectivity checks in seconds

[gunsch, 2015/02/20 01:56:03]

nit: avoid first-person references in comments, here and line 27

[derekjchow1, 2015/02/20 02:24:16]

Done.

+const unsigned int kConnectivityPeriodSeconds = 1;
+
+// Number of consecutive bad responses we receive before we change connectivity
+// to offline
+const unsigned int kNumBadResponses = 3;
+
+// Default url for connectivity checking.
+const char kDefaultConnectivityCheckUrl[] =
+    "https://clients3.google.com/generate_204";
+
+}  // namespace
+
+ConnectivityChecker::ConnectivityChecker(
+    const scoped_refptr<base::MessageLoopProxy>& loop_proxy)
+    : connectivity_observer_list_(
+          new ObserverListThreadSafe<ConnectivityObserver>()),
+      loop_proxy_(loop_proxy),
+      connected_(false),
+      bad_responses_(0) {
+  DCHECK(loop_proxy_.get());
+  loop_proxy->PostTask(FROM_HERE,
+                       base::Bind(&ConnectivityChecker::Initialize, this));
+}
+
+void ConnectivityChecker::Initialize() {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  base::CommandLine::StringType check_url_str =
+      command_line->GetSwitchValueNative(switches::kConnectivityCheckUrl);
+  connectivity_check_url_.reset(new GURL(
+      check_url_str.empty() ? kDefaultConnectivityCheckUrl : check_url_str));
+
+  net::URLRequestContextBuilder builder;
+  builder.set_proxy_config_service(
+      new net::ProxyConfigServiceFixed(net::ProxyConfig::CreateDirect()));
+  builder.DisableHttpCache();
+  url_request_context_.reset(builder.Build());
+
+  net::NetworkChangeNotifier::AddConnectionTypeObserver(this);
+  if (!net::NetworkChangeNotifier::IsOffline()) {
+    loop_proxy_->PostTask(FROM_HERE,
+                          base::Bind(&ConnectivityChecker::Check, this));
+  }
+}
+
+ConnectivityChecker::~ConnectivityChecker() {
+  DCHECK(loop_proxy_.get());
+  loop_proxy_->DeleteSoon(FROM_HERE, url_request_context_.release());
+}
+
+void ConnectivityChecker::AddConnectivityObserver(
+    ConnectivityObserver* observer) {
+  connectivity_observer_list_->AddObserver(observer);
+}
+
+void ConnectivityChecker::RemoveConnectivityObserver(
+    ConnectivityObserver* observer) {
+  connectivity_observer_list_->RemoveObserver(observer);
+}
+
+bool ConnectivityChecker::Connected() const {
+  return connected_;
+}
+
+void ConnectivityChecker::SetConnectivity(bool connected) {
+  if (connected)
+    bad_responses_ = 0;

[gunsch, 2015/02/20 01:57:28]

how about moving "bad_responses_ = 0" to "OnResponseStarted"? Then all the logic
involving the bad-response counting is in one single method.

[derekjchow1, 2015/02/20 02:24:16]

Done.

+
+  if (connected_ == connected)
+    return;
+
+  connected_ = connected;
+  connectivity_observer_list_->Notify(
+      FROM_HERE, &ConnectivityObserver::OnConnectivityChanged, connected);
+  LOG(INFO) << "Global connection is: " << (connected ? "Up" : "Down");
+}
+
+void ConnectivityChecker::Check() {
+  if (!loop_proxy_->BelongsToCurrentThread()) {
+    loop_proxy_->PostTask(FROM_HERE,
+                          base::Bind(&ConnectivityChecker::Check, this));
+    return;
+  }
+  DCHECK(url_request_context_.get());
+
+  // If url_request_ is non-null, there is already a check going on. Don't
+  // start another.
+  if (url_request_.get())
+    return;
+
+  VLOG(2) << "Connectivity check: url=" << *connectivity_check_url_;
+  url_request_ = url_request_context_->CreateRequest(
+      *connectivity_check_url_, net::MAXIMUM_PRIORITY, this, NULL);
+  url_request_->set_method("HEAD");
+  url_request_->Start();
+}
+
+void ConnectivityChecker::OnConnectionTypeChanged(
+    net::NetworkChangeNotifier::ConnectionType type) {
+  Cancel();
+
+  // If there is no connection, set connectivity to false. Otherwise retest
+  // connectivity
+  if (type == net::NetworkChangeNotifier::CONNECTION_NONE) {
+    SetConnectivity(false);
+  } else {
+    Check();
+  }
+}
+
+void ConnectivityChecker::OnResponseStarted(net::URLRequest* request) {
+  int http_response_code =
+      (request->status().is_success() &&
+       request->response_info().headers.get() != NULL)
+          ? request->response_info().headers->response_code()
+          : net::HTTP_BAD_REQUEST;
+
+  // Clears resources.
+  url_request_.reset(NULL);  // URLRequest::Cancel() is called in destructor.
+
+  if (http_response_code < 400) {
+    SetConnectivity(true);
+    return;
+  }
+
+  ++bad_responses_;
+  if (bad_responses_ > kNumBadResponses) {
+    bad_responses_ = kNumBadResponses;
+    SetConnectivity(false);
+  }
+
+  // Check again
+  if (!net::NetworkChangeNotifier::IsOffline()) {
+    loop_proxy_->PostDelayedTask(
+        FROM_HERE, base::Bind(&ConnectivityChecker::Check, this),
+        base::TimeDelta::FromSeconds(kConnectivityPeriodSeconds));
+  }
+}
+
+void ConnectivityChecker::OnReadCompleted(net::URLRequest* request,
+                                          int bytes_read) {
+  NOTREACHED();
+}
+
+void ConnectivityChecker::Cancel() {
+  if (url_request_.get()) {
+    VLOG(2) << "Cancel connectivity check in progress";
+    url_request_.reset(NULL);  // URLRequest::Cancel() is called in destructor.
+  }
+}
+
+}  // namespace chromecast