Re-try variations seed fetch earlier if it fails the first time.

Makes it so that if a variations seed fetch fails the first time due
to an error in the network stack (not a bad response from the server),
that we'll re-try again after 5 minutes instead of waiting for the full
fetch interval to elapse (5 hours).

Also applies to mobile platforms, where we'll also re-try in 5 minutes
in such cases, rather than on the next browser startup.

BUG=247820

Review URL: https://chromiumcodereview.appspot.com/15675019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@205575 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 36 insertions, 10 deletions

diff --git a/chrome/browser/metrics/variations/variations_request_scheduler.cc b/chrome/browser/metrics/variations/variations_request_scheduler.cc
index 0eac6b7..091e522 100644
--- a/chrome/browser/metrics/variations/variations_request_scheduler.cc
+++ b/chrome/browser/metrics/variations/variations_request_scheduler.cc
@@ -6,13 +6,6 @@
 
 namespace chrome_variations {
 
-namespace {
-
-// Time between seed fetches, in hours.
-const int kSeedFetchPeriodHours = 5;
-
-}  // namespace
-
 VariationsRequestScheduler::VariationsRequestScheduler(
     const base::Closure& task) : task_(task) {
 }
@@ -21,15 +14,26 @@ VariationsRequestScheduler::~VariationsRequestScheduler() {
 }
 
 void VariationsRequestScheduler::Start() {
-  // Call the task and repeat it periodically.
+  // Time between regular seed fetches, in hours.
+  const int kFetchPeriodHours = 5;
   task_.Run();
-  timer_.Start(FROM_HERE, base::TimeDelta::FromHours(kSeedFetchPeriodHours),
-               task_);
+  timer_.Start(FROM_HERE, base::TimeDelta::FromHours(kFetchPeriodHours), task_);
 }
 
 void VariationsRequestScheduler::Reset() {
   if (timer_.IsRunning())
     timer_.Reset();
+  one_shot_timer_.Stop();
+}
+
+void VariationsRequestScheduler::ScheduleFetchShortly() {
+  // The delay before attempting a fetch shortly, in minutes.
+  const int kFetchShortlyDelayMinutes = 5;
+  one_shot_timer_.Start(FROM_HERE,
+                        base::TimeDelta::FromMinutes(kFetchShortlyDelayMinutes),
+                        task_);
+  // Reset the regular timer to avoid it triggering soon after.
+  Reset();
 }
 
 base::Closure VariationsRequestScheduler::task() const {
diff --git a/chrome/browser/metrics/variations/variations_request_scheduler.h b/chrome/browser/metrics/variations/variations_request_scheduler.h
index 897983c..e6113ed 100644
--- a/chrome/browser/metrics/variations/variations_request_scheduler.h
+++ b/chrome/browser/metrics/variations/variations_request_scheduler.h
@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_REQUEST_SCHEDULER_H_
 
 #include "base/bind.h"
+#include "base/time.h"
 #include "base/timer.h"
 
 class PrefService;
@@ -23,6 +24,10 @@ class VariationsRequestScheduler {
   // Resets the scheduler if it is currently on a timer.
   virtual void Reset();
 
+  // Schedules a fetch shortly, for example to re-try the initial request which
+  // may have failed.
+  void ScheduleFetchShortly();
+
   // Factory method for this class.
   static VariationsRequestScheduler* Create(const base::Closure& task,
                                             PrefService* local_state);
@@ -43,6 +48,9 @@ class VariationsRequestScheduler {
   // automatically canceled.
   base::RepeatingTimer<VariationsRequestScheduler> timer_;
 
+  // A one-shot timer used for scheduling out-of-band fetches.
+  base::OneShotTimer<VariationsRequestScheduler> one_shot_timer_;
+
   DISALLOW_COPY_AND_ASSIGN(VariationsRequestScheduler);
 };
 
diff --git a/chrome/browser/metrics/variations/variations_service.cc b/chrome/browser/metrics/variations/variations_service.cc
index 24f74ca..2b1bb3b 100644
--- a/chrome/browser/metrics/variations/variations_service.cc
+++ b/chrome/browser/metrics/variations/variations_service.cc
@@ -176,6 +176,7 @@ VariationsService::VariationsService(PrefService* local_state)
     : local_state_(local_state),
       variations_server_url_(GetVariationsServerURL(local_state)),
       create_trials_from_seed_called_(false),
+      initial_request_completed_(false),
       resource_request_allowed_notifier_(
           new ResourceRequestAllowedNotifier) {
   resource_request_allowed_notifier_->Init(this);
@@ -186,6 +187,7 @@ VariationsService::VariationsService(ResourceRequestAllowedNotifier* notifier,
     : local_state_(local_state),
       variations_server_url_(GetVariationsServerURL(NULL)),
       create_trials_from_seed_called_(false),
+      initial_request_completed_(false),
       resource_request_allowed_notifier_(notifier) {
   resource_request_allowed_notifier_->Init(this);
 }
@@ -357,6 +359,10 @@ void VariationsService::FetchVariationsSeed() {
 
 void VariationsService::OnURLFetchComplete(const net::URLFetcher* source) {
   DCHECK_EQ(pending_seed_request_.get(), source);
+
+  const bool is_first_request = !initial_request_completed_;
+  initial_request_completed_ = true;
+
   // The fetcher will be deleted when the request is handled.
   scoped_ptr<const net::URLFetcher> request(pending_seed_request_.release());
   const net::URLRequestStatus& request_status = request->GetStatus();
@@ -366,6 +372,11 @@ void VariationsService::OnURLFetchComplete(const net::URLFetcher* source) {
     DVLOG(1) << "Variations server request failed with error: "
              << request_status.error() << ": "
              << net::ErrorToString(request_status.error());
+    // It's common for the very first fetch attempt to fail (e.g. the network
+    // may not yet be available). In such a case, try again soon, rather than
+    // waiting the full time interval.
+    if (is_first_request)
+      request_scheduler_->ScheduleFetchShortly();
     return;
   }
 
diff --git a/chrome/browser/metrics/variations/variations_service.h b/chrome/browser/metrics/variations/variations_service.h
index 4392337..35c2723 100644
--- a/chrome/browser/metrics/variations/variations_service.h
+++ b/chrome/browser/metrics/variations/variations_service.h
@@ -196,6 +196,9 @@ class VariationsService
   // it gets called prior to |StartRepeatedVariationsSeedFetch|.
   bool create_trials_from_seed_called_;
 
+  // Tracks whether the initial request to the variations server had completed.
+  bool initial_request_completed_;
+
   // Helper class used to tell this service if it's allowed to make network
   // resource requests.
   scoped_ptr<ResourceRequestAllowedNotifier> resource_request_allowed_notifier_;