Retries with exponential backoff for dismissals

chrome/browser/resources/google_now/background.js

Index: chrome/browser/resources/google_now/background.js
diff --git a/chrome/browser/resources/google_now/background.js b/chrome/browser/resources/google_now/background.js
index 3c4bf8f5c5e95148f1d39da830bb396fc8de8779..0fdbd6724c10e7292d530e9fbf3dc12adacdf8ec 100644
--- a/chrome/browser/resources/google_now/background.js
+++ b/chrome/browser/resources/google_now/background.js
@@ -53,22 +53,21 @@ var INITIAL_POLLING_PERIOD_SECONDS = 5 * 60;  // 5 minutes
  */
 var MAXIMUM_POLLING_PERIOD_SECONDS = 60 * 60;  // 1 hour
 
-var UPDATE_NOTIFICATIONS_ALARM_NAME = 'UPDATE';
-
 /**
- * Period for retrying the server request for dismissing cards.
+ * Initial period for retrying the server request for dismissing cards.
  */
-var RETRY_DISMISS_PERIOD_SECONDS = 60;  // 1 minute
+var INITIAL_RETRY_DISMISS_PERIOD_SECONDS = 60;  // 1 minute
 
-var RETRY_DISMISS_ALARM_NAME = 'RETRY_DISMISS';
+/**
+ * Maximum period for retrying the server request for dismissing cards.
+ */
+var MAXIMUM_RETRY_DISMISS_PERIOD_SECONDS = 60 * 60;  // 1 hour
 
 /**
  * Time we keep dismissals after successful server dismiss requests.
  */
 var DISMISS_RETENTION_TIME_MS = 20 * 60 * 1000;  // 20 minutes
 
-var storage = chrome.storage.local;
-
 /**
  * Names for tasks that can be created by the extension.
  */
@@ -121,6 +120,17 @@ tasks.instrumentApiFunction(chrome.runtime.onStartup, 'addListener', 0);
 tasks.instrumentApiFunction(chrome.tabs, 'create', 1);
 tasks.instrumentApiFunction(storage, 'get', 1);
 
+var updateCardsAttempts = buildAttemptManager(
+    'cards-update',
+    requestLocation,
+    INITIAL_POLLING_PERIOD_SECONDS,
+    MAXIMUM_POLLING_PERIOD_SECONDS);
+var dismissalAttempts = buildAttemptManager(
+    'dismiss',
+    retryPendingDismissals,
+    INITIAL_RETRY_DISMISS_PERIOD_SECONDS,
+    MAXIMUM_RETRY_DISMISS_PERIOD_SECONDS);
+
 /**
  * Diagnostic event identifier.
  * @enum {number}
@@ -293,13 +303,9 @@ function parseAndShowNotificationCards(response, callback) {
       }
     }
 
-    scheduleNextUpdate(parsedResponse.expiration_timestamp_seconds);
+    updateCardsAttempts.start(parsedResponse.expiration_timestamp_seconds);

[skare_, 2013/05/14 02:03:52]

just as an opinion as a first-time reader, name for these is slightly hard to
read but I don't have a great suggestion --
s/updateCardsAttempts/updateCardsRequest?

[vadimt, 2013/05/14 18:47:50]

'Request' has connotations with a single network request. 'Attempts' stresses
the repeating nature of this beast.

 
-    // Now that we got a valid response from the server, reset the retry period
-    // to the initial value. This retry period will be used the next time we
-    // fail to get the server-provided period.
     storage.set({
-      retryDelaySeconds: INITIAL_POLLING_PERIOD_SECONDS,
       activeNotifications: notificationsData,
       recentDismissals: updatedRecentDismissals
     });
@@ -372,23 +378,7 @@ function updateNotificationsCards(position) {
       ' @' + new Date());
   tasks.add(UPDATE_CARDS_TASK_NAME, function(callback) {
     console.log('updateNotificationsCards-task-begin');
-    tasks.debugSetStepName('updateNotificationsCards-get-retryDelaySeconds');
-    storage.get('retryDelaySeconds', function(items) {
-      console.log('updateNotificationsCards-get-retryDelaySeconds ' +
-                  JSON.stringify(items));
-      // Immediately schedule the update after the current retry period. Then,
-      // we'll use update time from the server if available.
-      scheduleNextUpdate(items.retryDelaySeconds);
-
-      // TODO(vadimt): Consider interrupting waiting for the next update if we
-      // detect that the network conditions have changed. Also, decide whether
-      // the exponential backoff is needed both when we are offline and when
-      // there are failures on the server side.
-      var newRetryDelaySeconds =
-          Math.min(items.retryDelaySeconds * 2 * (1 + 0.2 * Math.random()),
-                   MAXIMUM_POLLING_PERIOD_SECONDS);
-      storage.set({retryDelaySeconds: newRetryDelaySeconds});
-
+    updateCardsAttempts.planForNext(function() {
       processPendingDismissals(function(success) {
         if (success) {
           // The cards are requested only if there are no unsent dismissals.
@@ -460,7 +450,7 @@ function processPendingDismissals(callbackBoolean) {
 
     function doProcessDismissals() {
       if (items.pendingDismissals.length == 0) {
-        chrome.alarms.clear(RETRY_DISMISS_ALARM_NAME);
+        dismissalAttempts.stop();
         onFinish(true);
         return;
       }
@@ -490,7 +480,9 @@ function processPendingDismissals(callbackBoolean) {
  */
 function retryPendingDismissals() {
   tasks.add(RETRY_DISMISS_TASK_NAME, function(callback) {
-    processPendingDismissals(function(success) { callback(); });
+    dismissalAttempts.planForNext(function() {
+      processPendingDismissals(function(success) { callback(); });
+     });
   });
 }
 
@@ -538,15 +530,7 @@ function onNotificationClosed(notificationId, byUser) {
   chrome.metricsPrivate.recordUserAction('GoogleNow.Dismissed');
 
   tasks.add(DISMISS_CARD_TASK_NAME, function(callback) {
-    // Schedule retrying dismissing until all dismissals go through.
-    // TODO(vadimt): Implement exponential backoff and unify it with getting
-    // cards.
-    var alarmInfo = {
-      delayInMinutes: RETRY_DISMISS_PERIOD_SECONDS / 60,
-      periodInMinutes: RETRY_DISMISS_PERIOD_SECONDS / 60
-    };
-
-    chrome.alarms.create(RETRY_DISMISS_ALARM_NAME, alarmInfo);
+    dismissalAttempts.start();
 
     // Deleting the notification in case it was re-added while this task was
     // scheduled, waiting for execution.
@@ -568,37 +552,19 @@ function onNotificationClosed(notificationId, byUser) {
 }
 
 /**
- * Schedules next update for notification cards.
- * @param {int} delaySeconds Length of time in seconds after which the alarm
- *     event should fire.
- */
-function scheduleNextUpdate(delaySeconds) {
-  console.log('scheduleNextUpdate ' + delaySeconds);
-  // Schedule an alarm after the specified delay. 'periodInMinutes' is for the
-  // case when we fail to re-register the alarm.
-  var alarmInfo = {
-    delayInMinutes: delaySeconds / 60,
-    periodInMinutes: MAXIMUM_POLLING_PERIOD_SECONDS / 60
-  };
-
-  chrome.alarms.create(UPDATE_NOTIFICATIONS_ALARM_NAME, alarmInfo);
-}
-
-/**
  * Initializes the event page on install or on browser startup.
  */
 function initialize() {
+  // Create an update timer for a case when for some reason location request
+  // gets stuck.
+  updateCardsAttempts.start(MAXIMUM_POLLING_PERIOD_SECONDS);
+
   var initialStorage = {
     activeNotifications: {},
-    recentDismissals: {},
-    retryDelaySeconds: INITIAL_POLLING_PERIOD_SECONDS
+    recentDismissals: {}
   };
   storage.set(initialStorage);
 
-  // Create an update timer for a case when for some reason location request
-  // gets stuck.
-  scheduleNextUpdate(MAXIMUM_POLLING_PERIOD_SECONDS);
-
   requestLocation();
 }
 
@@ -615,13 +581,6 @@ chrome.runtime.onStartup.addListener(function() {
   initialize();
 });
 
-chrome.alarms.onAlarm.addListener(function(alarm) {
-  if (alarm.name == UPDATE_NOTIFICATIONS_ALARM_NAME)
-    requestLocation();
-  else if (alarm.name == RETRY_DISMISS_ALARM_NAME)
-    retryPendingDismissals();
-});
-
 chrome.notifications.onClicked.addListener(
     function(notificationId) {
       chrome.metricsPrivate.recordUserAction('GoogleNow.MessageClicked');