Reland: Add GCMChannelStatusSyncer to schedule requests and enable/disable GCM

components/gcm_driver/gcm_channel_status_syncer.cc

+// Copyright 2014 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 "components/gcm_driver/gcm_channel_status_syncer.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/message_loop/message_loop.h"
+#include "base/prefs/pref_registry_simple.h"
+#include "base/prefs/pref_service.h"
+#include "base/rand_util.h"
+#include "components/gcm_driver/gcm_channel_status_request.h"
+#include "components/gcm_driver/gcm_driver.h"
+
+namespace gcm {
+
+namespace {
+
+// The GCM channel's enabled state.
+const char kGCMChannelStatus[] = "gcm.channel_status";
+
+// The GCM channel's polling interval (in seconds).
+const char kGCMChannelPollIntervalSeconds[] = "gcm.poll_interval";
+
+// Last time when checking with the GCM channel status server is done.
+const char kGCMChannelLastCheckTime[] = "gcm.check_time";
+
+// A small delay to avoid sending request at browser startup time for first-time
+// request.
+const int kFirstTimeDelaySeconds = 1 * 60;  // 1 minute.
+
+// The fuzzing variation added to the polling delay.
+const int kGCMChannelRequestTimeJitterSeconds = 15 * 60;  // 15 minues.
+
+}  // namespace
+
+// static
+void GCMChannelStatusSyncer::RegisterPrefs(PrefRegistrySimple* registry) {
+  registry->RegisterBooleanPref(kGCMChannelStatus, true);
+  registry->RegisterIntegerPref(
+      kGCMChannelPollIntervalSeconds,
+      GCMChannelStatusRequest::default_poll_interval_seconds());
+  registry->RegisterInt64Pref(kGCMChannelLastCheckTime, 0);
+}
+
+// static
+void GCMChannelStatusSyncer::RegisterProfilePrefs(
+    user_prefs::PrefRegistrySyncable* registry) {
+  registry->RegisterBooleanPref(
+      kGCMChannelStatus,
+      true,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterIntegerPref(
+      kGCMChannelPollIntervalSeconds,
+      GCMChannelStatusRequest::default_poll_interval_seconds(),
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterInt64Pref(
+      kGCMChannelLastCheckTime,
+      0,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+}
+
+// static
+int GCMChannelStatusSyncer::first_time_delay_seconds() {
+  return kFirstTimeDelaySeconds;
+}
+
+GCMChannelStatusSyncer::GCMChannelStatusSyncer(
+    GCMDriver* driver,
+    PrefService* prefs,
+    scoped_refptr<net::URLRequestContextGetter> request_context)
+    : driver_(driver),
+      prefs_(prefs),
+      request_context_(request_context),
+      gcm_enabled_(true),
+      poll_interval_seconds_(
+          GCMChannelStatusRequest::default_poll_interval_seconds()),
+      delay_removed_for_testing_(false),
+      weak_ptr_factory_(this) {
+  gcm_enabled_ = prefs_->GetBoolean(kGCMChannelStatus);
+  poll_interval_seconds_ = prefs_->GetInteger(kGCMChannelPollIntervalSeconds);
+  if (poll_interval_seconds_ <
+      GCMChannelStatusRequest::min_poll_interval_seconds()) {
+    poll_interval_seconds_ =
+        GCMChannelStatusRequest::min_poll_interval_seconds();
+  }
+  last_check_time_ = base::Time::FromInternalValue(
+      prefs_->GetInt64(kGCMChannelLastCheckTime));
+}
+
+GCMChannelStatusSyncer::~GCMChannelStatusSyncer() {
+}
+
+void GCMChannelStatusSyncer::EnsureStarted() {
+  // Bail out if already started.
+  if (request_)
+    return;
+
+  ScheduleRequest();
+}
+
+void GCMChannelStatusSyncer::Stop() {
+  request_.reset();
+  weak_ptr_factory_.InvalidateWeakPtrs();
+}
+
+void GCMChannelStatusSyncer::OnRequestCompleted(bool enabled,
+                                                int poll_interval_seconds) {
+  DCHECK(request_);
+  request_.reset();
+
+  // Persist the current time as the last request complete time.
+  last_check_time_ = base::Time::Now();

[fgorski, 2014/09/11 18:24:35]

injected clock is typically more useful for testing, but I see what you are
doing below.

[jianli, 2014/09/11 21:04:30]

Agreed. For now, testing with real clock seems to work fine. If in the future,
there is something that can't be covered with real clock, I will do the switch.

+  prefs_->SetInt64(kGCMChannelLastCheckTime,
+                   last_check_time_.ToInternalValue());
+
+  if (gcm_enabled_ != enabled) {
+    gcm_enabled_ = enabled;
+    prefs_->SetBoolean(kGCMChannelStatus, enabled);
+    if (gcm_enabled_)
+      driver_->Enable();
+    else
+      driver_->Disable();
+  }
+
+  if (poll_interval_seconds_ != poll_interval_seconds) {
+    poll_interval_seconds_ = poll_interval_seconds;

[fgorski, 2014/09/11 18:24:35]

this code should check for min poll interval.

try to extract method from 83-88 and call it from here as well.

[jianli, 2014/09/11 21:04:30]

OnRequestCompleted is called with min value enforced for poll_interval_seconds.
I added a DCHECK for this.

+    prefs_->SetInteger(kGCMChannelPollIntervalSeconds, poll_interval_seconds_);
+  }
+
+  ScheduleRequest();
+}
+
+void GCMChannelStatusSyncer::ScheduleRequest() {
+  current_request_delay_interval_ = GetRequestDelayInterval();
+  base::MessageLoop::current()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&GCMChannelStatusSyncer::StartRequest,
+                 weak_ptr_factory_.GetWeakPtr()),
+      current_request_delay_interval_);
+}
+
+void GCMChannelStatusSyncer::StartRequest() {
+  DCHECK(!request_);
+
+  request_.reset(new GCMChannelStatusRequest(
+      request_context_,
+      base::Bind(&GCMChannelStatusSyncer::OnRequestCompleted,
+                 weak_ptr_factory_.GetWeakPtr())));
+  request_->Start();
+}
+
+base::TimeDelta GCMChannelStatusSyncer::GetRequestDelayInterval() const {
+  // No delay during testing.
+  if (delay_removed_for_testing_)
+    return base::TimeDelta();
+
+  // Make sure that checking with server occurs at polling interval, regardless
+  // whether the browser restarts.
+  int delay_seconds = static_cast<int>(poll_interval_seconds_ -
+      (base::Time::Now() - last_check_time_).InSeconds());
+  if (delay_seconds < 0)
+    delay_seconds = 0;
+
+  if (last_check_time_.is_null()) {
+    // For the first-time request, add a small delay to avoid sending request at
+    // browser startup time.
+    DCHECK(!delay_seconds);
+    delay_seconds = kFirstTimeDelaySeconds;
+  } else {
+    // Otherwise, add a fuzzing variation to the delay.
+    delay_seconds += base::RandInt(0, kGCMChannelRequestTimeJitterSeconds);
+  }
+
+  return base::TimeDelta::FromSeconds(delay_seconds);
+}
+
+}  // namespace gcm