Refresh policies from DM server periodically

chrome/browser/policy/device_management_policy_provider.cc

Index: chrome/browser/policy/device_management_policy_provider.cc
diff --git a/chrome/browser/policy/device_management_policy_provider.cc b/chrome/browser/policy/device_management_policy_provider.cc
index 25cfc328ca29f2e028ac2395ec5fb8936d7a207d..f19156441e51dd1690269ed6149dae4f892b88f6 100644
--- a/chrome/browser/policy/device_management_policy_provider.cc
+++ b/chrome/browser/policy/device_management_policy_provider.cc
@@ -7,12 +7,11 @@
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
+#include "base/rand_util.h"
 #include "base/task.h"
-#include "base/time.h"
 #include "chrome/browser/browser_thread.h"
 #include "chrome/browser/policy/device_management_backend.h"
 #include "chrome/browser/policy/device_management_policy_cache.h"
-#include "chrome/browser/policy/device_token_fetcher.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/notification_service.h"
@@ -22,7 +21,12 @@ namespace policy {
 
 const char kChromePolicyScope[] = "chromeos/device";
 const char kChromeDevicePolicySettingKey[] = "chrome-policy";
-const int64 kPolicyRefreshRateInMinutes = 3 * 60;  // 3 hours
+const int64 kPolicyRefreshRateInMilliseconds = 3 * 60 * 60 * 1000;  // 3 hours
+const int64 kPolicyRefreshMaxEarlierInMilliseconds = 20 * 60 * 1000;  // 20 mins
+// These are the base values for delays before retrying after an error. They
+// will be doubled each time they are used.
+const int64 kPolicyRefreshErrorDelayInMilliseconds = 3 * 1000;  // 3 seconds
+const int64 kDeviceTokenRefreshErrorDelayInMilliseconds = 3 * 1000;
 
 // Ensures that the portion of the policy provider implementation that requires
 // the IOThread is deferred until the IOThread is fully initialized. The policy
@@ -48,6 +52,22 @@ class DeviceManagementPolicyProvider::InitializeAfterIOThreadExistsTask
   base::WeakPtr<DeviceManagementPolicyProvider> provider_;
 };
 
+class DeviceManagementPolicyProvider::RefreshTask : public Task {
+ public:
+  explicit RefreshTask(base::WeakPtr<DeviceManagementPolicyProvider> provider)
+      : provider_(provider) {}
+
+  // Task implementation:
+  virtual void Run() {
+    DeviceManagementPolicyProvider* provider = provider_.get();
+    if (provider)
+      provider->RefreshTaskExecute();
+  }
+
+ private:
+  base::WeakPtr<DeviceManagementPolicyProvider> provider_;
+};
+
 DeviceManagementPolicyProvider::DeviceManagementPolicyProvider(
     const ConfigurationPolicyProvider::PolicyDefinitionList* policy_list,
     DeviceManagementBackend* backend,
@@ -57,7 +77,12 @@ DeviceManagementPolicyProvider::DeviceManagementPolicyProvider(
       backend_(backend),
       token_service_(token_service),
       storage_dir_(GetOrCreateDeviceManagementDir(storage_dir)),
-      policy_request_pending_(false) {
+      policy_request_pending_(false),
+      refresh_task_pending_(false),
+      policy_refresh_rate_ms_(kPolicyRefreshRateInMilliseconds),
+      policy_refresh_max_earlier_ms_(kPolicyRefreshMaxEarlierInMilliseconds),
+      policy_refresh_error_delay_ms_(kPolicyRefreshErrorDelayInMilliseconds),
+      token_fetch_error_delay_ms_(kDeviceTokenRefreshErrorDelayInMilliseconds) {
   Initialize();
 }
 
@@ -70,34 +95,46 @@ bool DeviceManagementPolicyProvider::Provide(
   return true;
 }
 
-void DeviceManagementPolicyProvider::Observe(
-    NotificationType type,
-    const NotificationSource& source,
-    const NotificationDetails& details) {
-  if (type == NotificationType::DEVICE_TOKEN_AVAILABLE) {
-    if (token_fetcher_.get() == Source<DeviceTokenFetcher>(source).ptr() &&
-        !policy_request_pending_ &&
-        IsPolicyStale()) {
-      SendPolicyRequest();
-    }
-  } else {
-    NOTREACHED();
-  }
-}
-
 void DeviceManagementPolicyProvider::HandlePolicyResponse(
     const em::DevicePolicyResponse& response) {
-  cache_->SetPolicy(response);
-  NotifyStoreOfPolicyChange();
+  if (cache_->SetPolicy(response))
+    NotifyStoreOfPolicyChange();
   policy_request_pending_ = false;
+  // Reset the error delay since policy fetching succeeded this time.
+  policy_refresh_error_delay_ms_ = kPolicyRefreshErrorDelayInMilliseconds;
+  ScheduleRefreshTask(GetRefreshTaskDelay());
 }
 
 void DeviceManagementPolicyProvider::OnError(
     DeviceManagementBackend::ErrorCode code) {
-  LOG(WARNING) << "could not provide policy from the device manager (error = "
-               << code << ")";
   policy_request_pending_ = false;
-  // TODO(danno): do something sensible in the error case, perhaps retry later?
+  LOG(WARNING) << "Could not provide policy from the device manager (error = "
+               << code << "), will retry in "
+               << (policy_refresh_error_delay_ms_/1000) << " seconds.";
+  ScheduleRefreshTask(policy_refresh_error_delay_ms_);
+  policy_refresh_error_delay_ms_ *= 2;
+  if (policy_refresh_rate_ms_ &&
+      policy_refresh_rate_ms_ < policy_refresh_error_delay_ms_) {
+    policy_refresh_error_delay_ms_ = policy_refresh_rate_ms_;
+  }
+}
+
+void DeviceManagementPolicyProvider::OnTokenSuccess() {
+  if (policy_request_pending_)
+    return;
+  SendPolicyRequest();
+}
+
+void DeviceManagementPolicyProvider::OnTokenError() {
+  LOG(WARNING) << "Could not retrieve device token.";
+  ScheduleRefreshTask(token_fetch_error_delay_ms_);
+  token_fetch_error_delay_ms_ *= 2;
+  if (token_fetch_error_delay_ms_ > policy_refresh_rate_ms_)
+    token_fetch_error_delay_ms_ = policy_refresh_rate_ms_;
+}
+
+void DeviceManagementPolicyProvider::OnNotManaged() {
+  VLOG(1) << "This device is not managed.";
 }
 
 void DeviceManagementPolicyProvider::Shutdown() {
@@ -107,10 +144,6 @@ void DeviceManagementPolicyProvider::Shutdown() {
 }
 
 void DeviceManagementPolicyProvider::Initialize() {
-  registrar_.Add(this,
-                 NotificationType::DEVICE_TOKEN_AVAILABLE,
-                 NotificationService::AllSources());
-
   const FilePath policy_path = storage_dir_.Append(
       FILE_PATH_LITERAL("Policy"));
   cache_.reset(new DeviceManagementPolicyCache(policy_path));
@@ -128,12 +161,15 @@ void DeviceManagementPolicyProvider::InitializeAfterIOThreadExists() {
   if (token_service_) {
     token_fetcher_ =
         new DeviceTokenFetcher(backend_.get(), token_service_, token_path);
+    registrar_.Init(token_fetcher_);
+    registrar_.AddObserver(this);
     token_fetcher_->StartFetching();
   }
 }
 
 void DeviceManagementPolicyProvider::SendPolicyRequest() {
   if (!policy_request_pending_) {
+    policy_request_pending_ = true;
     em::DevicePolicyRequest policy_request;
     policy_request.set_policy_scope(kChromePolicyScope);
     em::DevicePolicySettingRequest* setting =
@@ -142,18 +178,44 @@ void DeviceManagementPolicyProvider::SendPolicyRequest() {
     backend_->ProcessPolicyRequest(token_fetcher_->GetDeviceToken(),
                                    token_fetcher_->GetDeviceID(),
                                    policy_request, this);
-    policy_request_pending_ = true;
   }
 }
 
-bool DeviceManagementPolicyProvider::IsPolicyStale() const {
-  base::Time now(base::Time::NowFromSystemTime());
-  base::Time last_policy_refresh_time =
-      cache_->last_policy_refresh_time();
-  base::Time policy_expiration_time =
-      last_policy_refresh_time + base::TimeDelta::FromMinutes(
-          kPolicyRefreshRateInMinutes);
-  return (now > policy_expiration_time);
+void DeviceManagementPolicyProvider::RefreshTaskExecute() {
+  DCHECK(refresh_task_pending_);
+  refresh_task_pending_ = false;
+  // If there is no valid device token, the token_fetcher_ apparently failed,
+  // so it must be restarted.
+  if (!token_fetcher_->IsTokenValid()) {
+    if (token_fetcher_->IsTokenPending()) {
+      NOTREACHED();
+      return;
+    }
+    token_fetcher_->Restart();
+    return;
+  }
+  // If there is a device token, just refresh policies.
+  SendPolicyRequest();
+}
+
+void DeviceManagementPolicyProvider::ScheduleRefreshTask(
+    int64 delay_in_milliseconds) {
+  // This check is simply a safeguard, the situation currently cannot happen.
+  if (refresh_task_pending_) {
+    NOTREACHED();
+    return;
+  }
+  refresh_task_pending_ = true;
+  BrowserThread::PostDelayedTask(BrowserThread::UI, FROM_HERE,
+                                 new RefreshTask(AsWeakPtr()),
+                                 delay_in_milliseconds);
+}
+
+int64 DeviceManagementPolicyProvider::GetRefreshTaskDelay() {
+  int64 delay = policy_refresh_rate_ms_;
+  if (policy_refresh_max_earlier_ms_)
+    delay -= base::RandGenerator(policy_refresh_max_earlier_ms_);
+  return delay;
 }
 
 // static