Allow policy refresh rate to be configured through policy.

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 8b9d9b49a7e72af478b224503ad5f434d274cce8..22bbc4c717117f657845a781bf1bfc039d1c0724 100644
--- a/chrome/browser/policy/device_management_policy_provider.cc
+++ b/chrome/browser/policy/device_management_policy_provider.cc
@@ -12,6 +12,7 @@
 #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/profile_policy_context.h"
 #include "chrome/browser/policy/proto/device_management_constants.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_paths.h"
@@ -23,8 +24,12 @@ namespace policy {
 
 namespace em = enterprise_management;
 
-const int64 kPolicyRefreshRateInMilliseconds = 3 * 60 * 60 * 1000;  // 3 hours
-const int64 kPolicyRefreshMaxEarlierInMilliseconds = 20 * 60 * 1000;  // 20 mins
+// The maximum ratio in percent of the policy refresh rate we use for fuzzing

[danno, 2011/01/06 19:16:26]

I like random deviation here, too.

[Mattias Nissler (ping if slow), 2011/01/07 11:15:33]

Done.

+// the policy refresh time instant.
+const int kPolicyRefreshFuzzFactorPercent = 10;
+// Maximum preemption resulting from fuzzing we are willing to accept.
+const int64 kPolicyRefreshFuzzMaxInMilliseconds = 30 * 60 * 1000;
+
 // 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
@@ -35,44 +40,25 @@ const int64 kPolicyRefreshUnmanagedDeviceInMilliseconds = 24 * 60 * 60 * 1000;
 const FilePath::StringType kDeviceTokenFilename = FILE_PATH_LITERAL("Token");
 const FilePath::StringType kPolicyFilename = FILE_PATH_LITERAL("Policy");
 
-// Ensures that the portion of the policy provider implementation that requires
-// the IOThread is deferred until the IOThread is fully initialized. The policy
-// provider posts this task on the UI thread during its constructor, thereby
-// guaranteeing that the code won't get executed until after the UI and IO
-// threads are fully constructed.
-class DeviceManagementPolicyProvider::InitializeAfterIOThreadExistsTask
-    : public Task {
+// Calls back into the provider to refresh policy.
+class DeviceManagementPolicyProvider::RefreshTask : public CancelableTask {
  public:
-  explicit InitializeAfterIOThreadExistsTask(
-      base::WeakPtr<DeviceManagementPolicyProvider> provider)
-      : provider_(provider) {
-  }
+  explicit RefreshTask(DeviceManagementPolicyProvider* provider)
+      : provider_(provider) {}
 
   // Task implementation:
   virtual void Run() {
-    DeviceManagementPolicyProvider* provider = provider_.get();
-    if (provider)
-      provider->InitializeAfterIOThreadExists();
+    if (provider_)
+      provider_->RefreshTaskExecute();
   }
 
- private:
-  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();
+  // CancelableTask implementation:
+  virtual void Cancel() {
+    provider_ = NULL;
   }
 
  private:
-  base::WeakPtr<DeviceManagementPolicyProvider> provider_;
+  DeviceManagementPolicyProvider* provider_;
 };
 
 DeviceManagementPolicyProvider::DeviceManagementPolicyProvider(
@@ -82,36 +68,19 @@ DeviceManagementPolicyProvider::DeviceManagementPolicyProvider(
     : ConfigurationPolicyProvider(policy_list) {
   Initialize(backend,
              profile,
-             kPolicyRefreshRateInMilliseconds,
-             kPolicyRefreshMaxEarlierInMilliseconds,
+             ProfilePolicyContext::kDefaultPolicyRefreshRateInMilliseconds,
+             kPolicyRefreshFuzzFactorPercent,
+             kPolicyRefreshFuzzMaxInMilliseconds,
              kPolicyRefreshErrorDelayInMilliseconds,
              kDeviceTokenRefreshErrorDelayInMilliseconds,
              kPolicyRefreshUnmanagedDeviceInMilliseconds);
 }
 
-DeviceManagementPolicyProvider::DeviceManagementPolicyProvider(
-    const PolicyDefinitionList* policy_list,
-    DeviceManagementBackend* backend,
-    Profile* profile,
-    int64 policy_refresh_rate_ms,
-    int64 policy_refresh_max_earlier_ms,
-    int64 policy_refresh_error_delay_ms,
-    int64 token_fetch_error_delay_ms,
-    int64 unmanaged_device_refresh_rate_ms)
-    : ConfigurationPolicyProvider(policy_list) {
-  Initialize(backend,
-             profile,
-             policy_refresh_rate_ms,
-             policy_refresh_max_earlier_ms,
-             policy_refresh_error_delay_ms,
-             token_fetch_error_delay_ms,
-             unmanaged_device_refresh_rate_ms);
-}
-
 DeviceManagementPolicyProvider::~DeviceManagementPolicyProvider() {
   FOR_EACH_OBSERVER(ConfigurationPolicyProvider::Observer,
                     observer_list_,
                     OnProviderGoingAway());
+  CancelRefreshTask();
 }
 
 bool DeviceManagementPolicyProvider::Provide(
@@ -122,156 +91,135 @@ bool DeviceManagementPolicyProvider::Provide(
 }
 
 bool DeviceManagementPolicyProvider::IsInitializationComplete() const {
-  return !waiting_for_initial_policies_;
+  return !cache_->last_policy_refresh_time().is_null();
 }
 
 void DeviceManagementPolicyProvider::HandlePolicyResponse(
     const em::DevicePolicyResponse& response) {
+  DCHECK(TokenAvailable());
   if (cache_->SetPolicy(response))
     NotifyCloudPolicyUpdate();
-  policy_request_pending_ = false;
-  // Reset the error delay since policy fetching succeeded this time.
-  policy_refresh_error_delay_ms_ = kPolicyRefreshErrorDelayInMilliseconds;
-  ScheduleRefreshTask(GetRefreshTaskDelay());
-  // Update this provider's internal waiting state, but don't notify anyone
-  // else yet (that's done by the PrefValueStore that receives the policy).
-  waiting_for_initial_policies_ = false;
+  SetState(STATE_POLICY_VALID);
 }
 
 void DeviceManagementPolicyProvider::OnError(
     DeviceManagementBackend::ErrorCode code) {
-  policy_request_pending_ = false;
+  DCHECK(TokenAvailable());
   if (code == DeviceManagementBackend::kErrorServiceDeviceNotFound ||
       code == DeviceManagementBackend::kErrorServiceManagementTokenInvalid) {
     LOG(WARNING) << "The device token was either invalid or unknown to the "
                  << "device manager, re-registering device.";
-    token_fetcher_->Restart();
+    SetState(STATE_TOKEN_RESET);
   } else if (code ==
              DeviceManagementBackend::kErrorServiceManagementNotSupported) {
     VLOG(1) << "The device is no longer managed, resetting device token.";
-    token_fetcher_->Restart();
+    SetState(STATE_TOKEN_RESET);
   } else {
     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_;
-    }
+                 << (effective_policy_refresh_error_delay_ms_ / 1000)
+                 << " seconds.";
+    SetState(STATE_POLICY_ERROR);
   }
-  StopWaitingForInitialPolicies();
 }
 
 void DeviceManagementPolicyProvider::OnTokenSuccess() {
-  if (policy_request_pending_)
-    return;
+  DCHECK(!TokenAvailable());
   cache_->SetDeviceUnmanaged(false);
-  SendPolicyRequest();
+  SetState(STATE_TOKEN_VALID);
 }
 
 void DeviceManagementPolicyProvider::OnTokenError() {
+  DCHECK(!TokenAvailable());
   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_;
-  StopWaitingForInitialPolicies();
+  SetState(STATE_TOKEN_ERROR);
 }
 
 void DeviceManagementPolicyProvider::OnNotManaged() {
+  DCHECK(!TokenAvailable());
   VLOG(1) << "This device is not managed.";
   cache_->SetDeviceUnmanaged(true);
-  ScheduleRefreshTask(unmanaged_device_refresh_rate_ms_);
-  StopWaitingForInitialPolicies();
+  SetState(STATE_UNMANAGED);
 }
 
-void DeviceManagementPolicyProvider::AddObserver(
-    ConfigurationPolicyProvider::Observer* observer) {
-  observer_list_.AddObserver(observer);
+void DeviceManagementPolicyProvider::SetRefreshRate(
+    int64 refresh_rate_milliseconds) {

[Jakob Kummerow, 2011/01/07 09:48:51]

missing line:
policy_refresh_rate_ms_ = refresh_rate_milliseconds;

+  // Reschedule the refresh task if necessary.
+  if (state_ == STATE_POLICY_VALID)
+    SetState(STATE_POLICY_VALID);
 }
 
-void DeviceManagementPolicyProvider::RemoveObserver(
-    ConfigurationPolicyProvider::Observer* observer) {
-  observer_list_.RemoveObserver(observer);
-}
-
-void DeviceManagementPolicyProvider::NotifyCloudPolicyUpdate() {
-  FOR_EACH_OBSERVER(ConfigurationPolicyProvider::Observer,
-                    observer_list_,
-                    OnUpdatePolicy());
+DeviceManagementPolicyProvider::DeviceManagementPolicyProvider(
+    const PolicyDefinitionList* policy_list,
+    DeviceManagementBackend* backend,
+    Profile* profile,
+    int64 policy_refresh_rate_ms,
+    int policy_refresh_fuzz_factor_percent,
+    int64 policy_refresh_fuzz_max_ms,
+    int64 policy_refresh_error_delay_ms,
+    int64 token_fetch_error_delay_ms,
+    int64 unmanaged_device_refresh_rate_ms)
+    : ConfigurationPolicyProvider(policy_list) {
+  Initialize(backend,
+             profile,
+             policy_refresh_rate_ms,
+             policy_refresh_fuzz_factor_percent,
+             policy_refresh_fuzz_max_ms,
+             policy_refresh_error_delay_ms,
+             token_fetch_error_delay_ms,
+             unmanaged_device_refresh_rate_ms);
 }
 
 void DeviceManagementPolicyProvider::Initialize(
     DeviceManagementBackend* backend,
     Profile* profile,
     int64 policy_refresh_rate_ms,
-    int64 policy_refresh_max_earlier_ms,
+    int policy_refresh_fuzz_factor_percent,
+    int64 policy_refresh_fuzz_max_ms,
     int64 policy_refresh_error_delay_ms,
     int64 token_fetch_error_delay_ms,
     int64 unmanaged_device_refresh_rate_ms) {
+  DCHECK(profile);
   backend_.reset(backend);
   profile_ = profile;
   storage_dir_ = GetOrCreateDeviceManagementDir(profile_->GetPath());
-  policy_request_pending_ = false;
-  refresh_task_pending_ = false;
-  waiting_for_initial_policies_ = true;
+  state_ = STATE_INITIALIZING;
+  refresh_task_ = NULL;
   policy_refresh_rate_ms_ = policy_refresh_rate_ms;
-  policy_refresh_max_earlier_ms_ = policy_refresh_max_earlier_ms;
+  policy_refresh_fuzz_factor_percent_ = policy_refresh_fuzz_factor_percent;
+  policy_refresh_fuzz_max_ms_ = policy_refresh_fuzz_max_ms;
   policy_refresh_error_delay_ms_ = policy_refresh_error_delay_ms;
+  effective_policy_refresh_error_delay_ms_ = policy_refresh_error_delay_ms;
   token_fetch_error_delay_ms_ = token_fetch_error_delay_ms;
+  effective_token_fetch_error_delay_ms_ = token_fetch_error_delay_ms;
   unmanaged_device_refresh_rate_ms_ = unmanaged_device_refresh_rate_ms;
 
   const FilePath policy_path = storage_dir_.Append(kPolicyFilename);
   cache_.reset(new DeviceManagementPolicyCache(policy_path));
   cache_->LoadPolicyFromFile();
 
+  SetDeviceTokenFetcher(new DeviceTokenFetcher(backend_.get(), profile,
+                                               GetTokenPath()));
+
   if (cache_->is_device_unmanaged()) {
     // This is a non-first login on an unmanaged device.
-    waiting_for_initial_policies_ = false;
-    // Defer token_fetcher_ initialization until this device should ask for
-    // a device token again.
-    base::Time unmanaged_timestamp = cache_->last_policy_refresh_time();
-    int64 delay = unmanaged_device_refresh_rate_ms_ -
-        (base::Time::NowFromSystemTime().ToInternalValue() -
-            unmanaged_timestamp.ToInternalValue());
-    if (delay < 0)
-      delay = 0;
-    BrowserThread::PostDelayedTask(
-        BrowserThread::UI, FROM_HERE,
-        new InitializeAfterIOThreadExistsTask(AsWeakPtr()),
-        delay);
+    SetState(STATE_UNMANAGED);
   } else {
-    if (file_util::PathExists(
-        storage_dir_.Append(kDeviceTokenFilename))) {
-      // This is a non-first login on a managed device.
-      waiting_for_initial_policies_ = false;
-    }
-    // Defer initialization that requires the IOThread until after the IOThread
-    // has been initialized.
-    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-                            new InitializeAfterIOThreadExistsTask(AsWeakPtr()));
+    SetState(STATE_INITIALIZING);
   }
 }
 
-void DeviceManagementPolicyProvider::InitializeAfterIOThreadExists() {
-  if (profile_) {
-    if (!token_fetcher_) {
-      token_fetcher_ = new DeviceTokenFetcher(
-          backend_.get(), profile_, GetTokenPath());
-    }
-    registrar_.Init(token_fetcher_);
-    registrar_.AddObserver(this);
-    token_fetcher_->StartFetching();
-  }
+void DeviceManagementPolicyProvider::AddObserver(
+    ConfigurationPolicyProvider::Observer* observer) {
+  observer_list_.AddObserver(observer);
 }
 
-void DeviceManagementPolicyProvider::SendPolicyRequest() {
-  if (policy_request_pending_)
-    return;
+void DeviceManagementPolicyProvider::RemoveObserver(
+    ConfigurationPolicyProvider::Observer* observer) {
+  observer_list_.RemoveObserver(observer);
+}
 
-  policy_request_pending_ = true;
+void DeviceManagementPolicyProvider::SendPolicyRequest() {
   em::DevicePolicyRequest policy_request;
   policy_request.set_policy_scope(kChromePolicyScope);
   em::DevicePolicySettingRequest* setting =
@@ -284,40 +232,39 @@ void DeviceManagementPolicyProvider::SendPolicyRequest() {
 }
 
 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();
+  DCHECK(refresh_task_);
+  refresh_task_ = NULL;
+
+  switch (state_) {
+    case STATE_INITIALIZING:
+      token_fetcher_->StartFetching();
+      return;
+    case STATE_TOKEN_VALID:
+    case STATE_POLICY_VALID:
+    case STATE_POLICY_ERROR:
+      SendPolicyRequest();
+      return;
+    case STATE_UNMANAGED:
+    case STATE_TOKEN_ERROR:
+    case STATE_TOKEN_RESET:
+      token_fetcher_->Restart();
       return;
-    }
-    token_fetcher_->Restart();
-    return;
   }
-  // If there is a device token, just refresh policies.
-  SendPolicyRequest();
+
+  NOTREACHED() << "Unhandled state";
 }
 
-void DeviceManagementPolicyProvider::ScheduleRefreshTask(
-    int64 delay_in_milliseconds) {
-  // This check is simply a safeguard, the situation currently cannot happen.
-  if (refresh_task_pending_) {
-    NOTREACHED();
-    return;
+void DeviceManagementPolicyProvider::CancelRefreshTask() {
+  if (refresh_task_) {
+    refresh_task_->Cancel();
+    refresh_task_ = NULL;
   }
-  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;
+void DeviceManagementPolicyProvider::NotifyCloudPolicyUpdate() {
+  FOR_EACH_OBSERVER(ConfigurationPolicyProvider::Observer,
+                    observer_list_,
+                    OnUpdatePolicy());
 }
 
 FilePath DeviceManagementPolicyProvider::GetTokenPath() {
@@ -326,14 +273,85 @@ FilePath DeviceManagementPolicyProvider::GetTokenPath() {
 
 void DeviceManagementPolicyProvider::SetDeviceTokenFetcher(
     DeviceTokenFetcher* token_fetcher) {
-  DCHECK(!token_fetcher_);
+  registrar_.Init(token_fetcher);
+  registrar_.AddObserver(this);
   token_fetcher_ = token_fetcher;
 }
 
-void DeviceManagementPolicyProvider::StopWaitingForInitialPolicies() {
-  waiting_for_initial_policies_ = false;
-  // Notify observers that initial policy fetch is complete.
-  NotifyCloudPolicyUpdate();
+void DeviceManagementPolicyProvider::SetState(
+    DeviceManagementPolicyProvider::ProviderState new_state) {
+  if (!IsInitializationComplete() &&

[danno, 2011/01/06 19:16:26]

I am confused here. If !IsInitializationComplete you notify the observers that
the initial policy fetch is complete? Perhaps an explanatory comment.

[Mattias Nissler (ping if slow), 2011/01/07 11:15:33]

The idea is to notify observers once we switch to a state where policy is
available. The code here was indeed wrong. I changed the tests to validate that
this notification actually gets sent.

+      state_ != STATE_INITIALIZING &&
+      state_ != STATE_TOKEN_VALID) {
+    // Notify observers that initial policy fetch is complete.
+    NotifyCloudPolicyUpdate();

[danno, 2011/01/06 19:16:26]

I found the old code much more readable, it was clear that the notification
happened when there was an error, when the device isn't managed, etc. Perhaps it
would be clearer if this call was included in the individual state transitions.

[Mattias Nissler (ping if slow), 2011/01/07 11:15:33]

I disagree. We now have a central point that detects whether we switch from an
initializing state to a steady state. That gives much more confidence that we
didn't miss some code path.

+  }
+  state_ = new_state;
+
+  base::Time now(base::Time::NowFromSystemTime());
+  base::Time refresh_at;
+  base::Time last_refresh(cache_->last_policy_refresh_time());
+  if (last_refresh.is_null())
+    last_refresh = now;
+
+  // Determine when to take the next step.
+  switch (state_) {
+    case STATE_INITIALIZING:
+      refresh_at = now;
+      break;
+    case STATE_TOKEN_VALID:
+      cache_->SetDeviceUnmanaged(false);
+      effective_token_fetch_error_delay_ms_ = token_fetch_error_delay_ms_;
+      refresh_at = now;
+      break;
+    case STATE_TOKEN_RESET:
+      refresh_at = now;
+      break;
+    case STATE_UNMANAGED:
+      refresh_at = last_refresh +
+          base::TimeDelta::FromMilliseconds(unmanaged_device_refresh_rate_ms_);
+      break;
+    case STATE_POLICY_VALID:
+      effective_policy_refresh_error_delay_ms_ = policy_refresh_error_delay_ms_;
+      refresh_at =
+          last_refresh + base::TimeDelta::FromMilliseconds(GetRefreshDelay());
+      break;
+    case STATE_TOKEN_ERROR:
+      refresh_at = now + base::TimeDelta::FromMilliseconds(
+                             effective_token_fetch_error_delay_ms_);
+      effective_token_fetch_error_delay_ms_ *= 2;
+      if (effective_token_fetch_error_delay_ms_ > policy_refresh_rate_ms_)
+        effective_token_fetch_error_delay_ms_ = policy_refresh_rate_ms_;
+      break;
+    case STATE_POLICY_ERROR:
+      refresh_at = now + base::TimeDelta::FromMilliseconds(
+                             effective_policy_refresh_error_delay_ms_);
+      effective_policy_refresh_error_delay_ms_ *= 2;
+      if (effective_policy_refresh_error_delay_ms_ > policy_refresh_rate_ms_)
+        effective_policy_refresh_error_delay_ms_ = policy_refresh_rate_ms_;
+      break;
+  }
+
+  // Update the refresh task.
+  CancelRefreshTask();
+  if (!refresh_at.is_null()) {
+    refresh_task_ = new RefreshTask(this);
+    int64 delay = std::max<int64>((refresh_at - now).InMilliseconds(), 0);
+    BrowserThread::PostDelayedTask(BrowserThread::UI, FROM_HERE, refresh_task_,
+                                   delay);
+  }
+}
+
+int64 DeviceManagementPolicyProvider::GetRefreshDelay() {
+  int64 fuzz = policy_refresh_fuzz_factor_percent_ * policy_refresh_rate_ms_;
+  fuzz = std::min(fuzz, policy_refresh_fuzz_max_ms_);
+  return policy_refresh_rate_ms_ - base::RandGenerator(fuzz + 1);
+}
+
+bool DeviceManagementPolicyProvider::TokenAvailable() const {
+  return state_ == STATE_TOKEN_VALID ||
+         state_ == STATE_POLICY_VALID ||
+         state_ == STATE_POLICY_ERROR;
 }
 
 // static