src/components/policy/core/common/cloud/cloud_policy_refresh_scheduler.cc

   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 #include "components/policy/core/common/cloud/cloud_policy_refresh_scheduler.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/bind.h"
  10 #include "base/bind_helpers.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "base/metrics/histogram.h"
  13 #include "base/sequenced_task_runner.h"
  14 #include "base/time/default_tick_clock.h"
  15 #include "base/time/tick_clock.h"
  16 #include "components/policy/core/common/cloud/cloud_policy_constants.h"
  17
  18 namespace policy {
  19
  20 namespace {
  21
  22 // The maximum rate at which to refresh policies.
  23 const size_t kMaxRefreshesPerHour = 5;
  24
  25 // The maximum time to wait for the invalidations service to become available
  26 // before starting to issue requests.
  27 const int kWaitForInvalidationsTimeoutSeconds = 5;
  28
  29 }  // namespace
  30
  31 #if defined(OS_ANDROID) || defined(OS_IOS)
  32
  33 const int64 CloudPolicyRefreshScheduler::kDefaultRefreshDelayMs =
  34     24 * 60 * 60 * 1000;  // 1 day.
  35 const int64 CloudPolicyRefreshScheduler::kUnmanagedRefreshDelayMs =
  36     24 * 60 * 60 * 1000;  // 1 day.
  37 // Delay for periodic refreshes when the invalidations service is available,
  38 // in milliseconds.
  39 // TODO(joaodasilva): increase this value once we're confident that the
  40 // invalidations channel works as expected.
  41 const int64 CloudPolicyRefreshScheduler::kWithInvalidationsRefreshDelayMs =
  42     24 * 60 * 60 * 1000;  // 1 day.
  43 const int64 CloudPolicyRefreshScheduler::kInitialErrorRetryDelayMs =
  44     5 * 60 * 1000;  // 5 minutes.
  45 const int64 CloudPolicyRefreshScheduler::kRefreshDelayMinMs =
  46     30 * 60 * 1000;  // 30 minutes.
  47 const int64 CloudPolicyRefreshScheduler::kRefreshDelayMaxMs =
  48     7 * 24 * 60 * 60 * 1000;  // 1 week.
  49
  50 #else
  51
  52 const int64 CloudPolicyRefreshScheduler::kDefaultRefreshDelayMs =
  53     3 * 60 * 60 * 1000;  // 3 hours.
  54 const int64 CloudPolicyRefreshScheduler::kUnmanagedRefreshDelayMs =
  55     24 * 60 * 60 * 1000;  // 1 day.
  56 // Delay for periodic refreshes when the invalidations service is available,
  57 // in milliseconds.
  58 // TODO(joaodasilva): increase this value once we're confident that the
  59 // invalidations channel works as expected.
  60 const int64 CloudPolicyRefreshScheduler::kWithInvalidationsRefreshDelayMs =
  61     3 * 60 * 60 * 1000;  // 3 hours.
  62 const int64 CloudPolicyRefreshScheduler::kInitialErrorRetryDelayMs =
  63     5 * 60 * 1000;  // 5 minutes.
  64 const int64 CloudPolicyRefreshScheduler::kRefreshDelayMinMs =
  65     30 * 60 * 1000;  // 30 minutes.
  66 const int64 CloudPolicyRefreshScheduler::kRefreshDelayMaxMs =
  67     24 * 60 * 60 * 1000;  // 1 day.
  68
  69 #endif
  70
  71 CloudPolicyRefreshScheduler::CloudPolicyRefreshScheduler(
  72     CloudPolicyClient* client,
  73     CloudPolicyStore* store,
  74     const scoped_refptr<base::SequencedTaskRunner>& task_runner)
  75     : client_(client),
  76       store_(store),
  77       task_runner_(task_runner),
  78       error_retry_delay_ms_(kInitialErrorRetryDelayMs),
  79       refresh_delay_ms_(kDefaultRefreshDelayMs),
  80       rate_limiter_(kMaxRefreshesPerHour,
  81                     base::TimeDelta::FromHours(1),
  82                     base::Bind(&CloudPolicyRefreshScheduler::RefreshNow,
  83                                base::Unretained(this)),
  84                     task_runner_,
  85                     scoped_ptr<base::TickClock>(new base::DefaultTickClock())),
  86       invalidations_available_(false),
  87       creation_time_(base::Time::NowFromSystemTime()) {
  88   client_->AddObserver(this);
  89   store_->AddObserver(this);
  90   net::NetworkChangeNotifier::AddIPAddressObserver(this);
  91
  92   UpdateLastRefreshFromPolicy();
  93
  94   // Give some time for the invalidation service to become available before the
  95   // first refresh if there is already policy present.
  96   if (store->has_policy())
  97     WaitForInvalidationService();
  98   else
  99     ScheduleRefresh();
 100 }
 101
 102 CloudPolicyRefreshScheduler::~CloudPolicyRefreshScheduler() {
 103   store_->RemoveObserver(this);
 104   client_->RemoveObserver(this);
 105   net::NetworkChangeNotifier::RemoveIPAddressObserver(this);
 106 }
 107
 108 void CloudPolicyRefreshScheduler::SetRefreshDelay(int64 refresh_delay) {
 109   refresh_delay_ms_ = std::min(std::max(refresh_delay, kRefreshDelayMinMs),
 110                                kRefreshDelayMaxMs);
 111   ScheduleRefresh();
 112 }
 113
 114 void CloudPolicyRefreshScheduler::RefreshSoon() {
 115   // An external consumer needs a policy update now (e.g. a new extension, or
 116   // the InvalidationService received a policy invalidation), so don't wait
 117   // before fetching anymore.
 118   wait_for_invalidations_timeout_callback_.Cancel();
 119   rate_limiter_.PostRequest();
 120 }
 121
 122 void CloudPolicyRefreshScheduler::SetInvalidationServiceAvailability(
 123     bool is_available) {
 124   if (!creation_time_.is_null()) {
 125     base::TimeDelta elapsed = base::Time::NowFromSystemTime() - creation_time_;
 126     UMA_HISTOGRAM_MEDIUM_TIMES("Enterprise.PolicyInvalidationsStartupTime",
 127                                elapsed);
 128     creation_time_ = base::Time();
 129   }
 130
 131   if (is_available == invalidations_available_) {
 132     // No change in state. If we're currently WaitingForInvalidationService
 133     // then the timeout task will eventually execute and trigger a reschedule;
 134     // let the InvalidationService keep retrying until that happens.
 135     return;
 136   }
 137
 138   wait_for_invalidations_timeout_callback_.Cancel();
 139   invalidations_available_ = is_available;
 140
 141   // Schedule a refresh since the refresh delay has been updated; however, allow
 142   // some time for the invalidation service to update. If it is now online, the
 143   // wait allows pending invalidations to be delivered. If it is now offline,
 144   // then the wait allows for the service to recover from transient failure
 145   // before falling back on the polling behavior.
 146   WaitForInvalidationService();
 147 }
 148
 149 void CloudPolicyRefreshScheduler::OnPolicyFetched(CloudPolicyClient* client) {
 150   error_retry_delay_ms_ = kInitialErrorRetryDelayMs;
 151
 152   // Schedule the next refresh.
 153   last_refresh_ = base::Time::NowFromSystemTime();
 154   ScheduleRefresh();
 155 }
 156
 157 void CloudPolicyRefreshScheduler::OnRegistrationStateChanged(
 158     CloudPolicyClient* client) {
 159   error_retry_delay_ms_ = kInitialErrorRetryDelayMs;
 160
 161   // The client might have registered, so trigger an immediate refresh.
 162   RefreshNow();
 163 }
 164
 165 void CloudPolicyRefreshScheduler::OnClientError(CloudPolicyClient* client) {
 166   // Save the status for below.
 167   DeviceManagementStatus status = client_->status();
 168
 169   // Schedule an error retry if applicable.
 170   last_refresh_ = base::Time::NowFromSystemTime();
 171   ScheduleRefresh();
 172
 173   // Update the retry delay.
 174   if (client->is_registered() &&
 175       (status == DM_STATUS_REQUEST_FAILED ||
 176        status == DM_STATUS_TEMPORARY_UNAVAILABLE)) {
 177     error_retry_delay_ms_ = std::min(error_retry_delay_ms_ * 2,
 178                                      refresh_delay_ms_);
 179   } else {
 180     error_retry_delay_ms_ = kInitialErrorRetryDelayMs;
 181   }
 182 }
 183
 184 void CloudPolicyRefreshScheduler::OnStoreLoaded(CloudPolicyStore* store) {
 185   UpdateLastRefreshFromPolicy();
 186
 187   // Re-schedule the next refresh in case the is_managed bit changed.
 188   ScheduleRefresh();
 189 }
 190
 191 void CloudPolicyRefreshScheduler::OnStoreError(CloudPolicyStore* store) {
 192   // If |store_| fails, the is_managed bit that it provides may become stale.
 193   // The best guess in that situation is to assume is_managed didn't change and
 194   // continue using the stale information. Thus, no specific response to a store
 195   // error is required. NB: Changes to is_managed fire OnStoreLoaded().
 196 }
 197
 198 void CloudPolicyRefreshScheduler::OnIPAddressChanged() {
 199   if (client_->status() == DM_STATUS_REQUEST_FAILED)
 200     RefreshSoon();
 201 }
 202
 203 void CloudPolicyRefreshScheduler::UpdateLastRefreshFromPolicy() {
 204   if (!last_refresh_.is_null())
 205     return;
 206
 207   // If the client has already fetched policy, assume that happened recently. If
 208   // that assumption ever breaks, the proper thing to do probably is to move the
 209   // |last_refresh_| bookkeeping to CloudPolicyClient.
 210   if (!client_->responses().empty()) {
 211     last_refresh_ = base::Time::NowFromSystemTime();
 212     return;
 213   }
 214
 215 #if defined(OS_ANDROID) || defined(OS_IOS)
 216   // Refreshing on mobile platforms:
 217   // - if no user is signed-in then the |client_| is never registered and
 218   //   nothing happens here.
 219   // - if the user is signed-in but isn't enterprise then the |client_| is
 220   //   never registered and nothing happens here.
 221   // - if the user is signed-in but isn't registered for policy yet then the
 222   //   |client_| isn't registered either; the UserPolicySigninService will try
 223   //   to register, and OnRegistrationStateChanged() will be invoked later.
 224   // - if the client is signed-in and has policy then its timestamp is used to
 225   //   determine when to perform the next fetch, which will be once the cached
 226   //   version is considered "old enough".
 227   //
 228   // If there is an old policy cache then a fetch will be performed "soon"; if
 229   // that fetch fails then a retry is attempted after a delay, with exponential
 230   // backoff. If those fetches keep failing then the cached timestamp is *not*
 231   // updated, and another fetch (and subsequent retries) will be attempted
 232   // again on the next startup.
 233   //
 234   // But if the cached policy is considered fresh enough then we try to avoid
 235   // fetching again on startup; the Android logic differs from the desktop in
 236   // this aspect.
 237   if (store_->has_policy() && store_->policy()->has_timestamp()) {
 238     last_refresh_ =
 239         base::Time::UnixEpoch() +
 240         base::TimeDelta::FromMilliseconds(store_->policy()->timestamp());
 241   }
 242 #else
 243   // If there is a cached non-managed response, make sure to only re-query the
 244   // server after kUnmanagedRefreshDelayMs. NB: For existing policy, an
 245   // immediate refresh is intentional.
 246   if (store_->has_policy() && store_->policy()->has_timestamp() &&
 247       !store_->is_managed()) {
 248     last_refresh_ =
 249         base::Time::UnixEpoch() +
 250         base::TimeDelta::FromMilliseconds(store_->policy()->timestamp());
 251   }
 252 #endif
 253 }
 254
 255 void CloudPolicyRefreshScheduler::RefreshNow() {
 256   last_refresh_ = base::Time();
 257   ScheduleRefresh();
 258 }
 259
 260 void CloudPolicyRefreshScheduler::ScheduleRefresh() {
 261   // If the client isn't registered, there is nothing to do.
 262   if (!client_->is_registered()) {
 263     refresh_callback_.Cancel();
 264     return;
 265   }
 266
 267   // Don't schedule anything yet if we're still waiting for the invalidations
 268   // service.
 269   if (WaitingForInvalidationService())
 270     return;
 271
 272   // If policy invalidations are available then periodic updates are done at
 273   // a much lower rate; otherwise use the |refresh_delay_ms_| value.
 274   int64 refresh_delay_ms =
 275       invalidations_available_ ? kWithInvalidationsRefreshDelayMs
 276                                : refresh_delay_ms_;
 277
 278   // If there is a registration, go by the client's status. That will tell us
 279   // what the appropriate refresh delay should be.
 280   switch (client_->status()) {
 281     case DM_STATUS_SUCCESS:
 282       if (store_->is_managed())
 283         RefreshAfter(refresh_delay_ms);
 284       else
 285         RefreshAfter(kUnmanagedRefreshDelayMs);
 286       return;
 287     case DM_STATUS_SERVICE_ACTIVATION_PENDING:
 288     case DM_STATUS_SERVICE_POLICY_NOT_FOUND:
 289       RefreshAfter(refresh_delay_ms);
 290       return;
 291     case DM_STATUS_REQUEST_FAILED:
 292     case DM_STATUS_TEMPORARY_UNAVAILABLE:
 293       RefreshAfter(error_retry_delay_ms_);
 294       return;
 295     case DM_STATUS_REQUEST_INVALID:
 296     case DM_STATUS_HTTP_STATUS_ERROR:
 297     case DM_STATUS_RESPONSE_DECODING_ERROR:
 298     case DM_STATUS_SERVICE_MANAGEMENT_NOT_SUPPORTED:
 299       RefreshAfter(kUnmanagedRefreshDelayMs);
 300       return;
 301     case DM_STATUS_SERVICE_MANAGEMENT_TOKEN_INVALID:
 302     case DM_STATUS_SERVICE_DEVICE_NOT_FOUND:
 303     case DM_STATUS_SERVICE_INVALID_SERIAL_NUMBER:
 304     case DM_STATUS_SERVICE_DEVICE_ID_CONFLICT:
 305     case DM_STATUS_SERVICE_MISSING_LICENSES:
 306     case DM_STATUS_SERVICE_DEPROVISIONED:
 307     case DM_STATUS_SERVICE_DOMAIN_MISMATCH:
 308       // Need a re-registration, no use in retrying.
 309       refresh_callback_.Cancel();
 310       return;
 311   }
 312
 313   NOTREACHED() << "Invalid client status " << client_->status();
 314   RefreshAfter(kUnmanagedRefreshDelayMs);
 315 }
 316
 317 void CloudPolicyRefreshScheduler::PerformRefresh() {
 318   if (client_->is_registered()) {
 319     // Update |last_refresh_| so another fetch isn't triggered inadvertently.
 320     last_refresh_ = base::Time::NowFromSystemTime();
 321
 322     // The result of this operation will be reported through a callback, at
 323     // which point the next refresh will be scheduled.
 324     client_->FetchPolicy();
 325     return;
 326   }
 327
 328   // This should never happen, as the registration change should have been
 329   // handled via OnRegistrationStateChanged().
 330   NOTREACHED();
 331 }
 332
 333 void CloudPolicyRefreshScheduler::RefreshAfter(int delta_ms) {
 334   base::TimeDelta delta(base::TimeDelta::FromMilliseconds(delta_ms));
 335   refresh_callback_.Cancel();
 336
 337   // Schedule the callback.
 338   base::TimeDelta delay =
 339       std::max((last_refresh_ + delta) - base::Time::NowFromSystemTime(),
 340                base::TimeDelta());
 341   refresh_callback_.Reset(
 342       base::Bind(&CloudPolicyRefreshScheduler::PerformRefresh,
 343                  base::Unretained(this)));
 344   task_runner_->PostDelayedTask(FROM_HERE, refresh_callback_.callback(), delay);
 345 }
 346
 347 void CloudPolicyRefreshScheduler::WaitForInvalidationService() {
 348   DCHECK(!WaitingForInvalidationService());
 349   wait_for_invalidations_timeout_callback_.Reset(
 350       base::Bind(
 351           &CloudPolicyRefreshScheduler::OnWaitForInvalidationServiceTimeout,
 352           base::Unretained(this)));
 353   base::TimeDelta delay =
 354       base::TimeDelta::FromSeconds(kWaitForInvalidationsTimeoutSeconds);
 355   task_runner_->PostDelayedTask(
 356       FROM_HERE,
 357       wait_for_invalidations_timeout_callback_.callback(),
 358       delay);
 359 }
 360
 361 void CloudPolicyRefreshScheduler::OnWaitForInvalidationServiceTimeout() {
 362   wait_for_invalidations_timeout_callback_.Cancel();
 363   ScheduleRefresh();
 364 }
 365
 366 bool CloudPolicyRefreshScheduler::WaitingForInvalidationService() const {
 367   return !wait_for_invalidations_timeout_callback_.IsCancelled();
 368 }
 369
 370 }  // namespace policy