Bug 914481 - Patch 4 - Track why we fail to deliver notifications to Service Workers. r=kitcambridge

--HG--
extra : rebase_source : 66bb02452a4b5ffb77157d0f7a44d56b327c360c

dom/push/PushService.jsm

@@ -52,6 +52,16 @@ const PUSH_SERVICE_CONNECTION_DISABLE = 3;
 const PUSH_SERVICE_ACTIVE_OFFLINE = 4;
 const PUSH_SERVICE_RUNNING = 5;
 
+// Telemetry failure to send push notification to Service Worker reasons.
+// Key not found in local database.
+const kDROP_NOTIFICATION_REASON_KEY_NOT_FOUND = 0;
+// User cleared history.
+const kDROP_NOTIFICATION_REASON_NO_HISTORY = 1;
+// Version of message received not newer than previous one.
+const kDROP_NOTIFICATION_REASON_NO_VERSION_INCREMENT = 2;
+// Subscription has expired.
+const kDROP_NOTIFICATION_REASON_EXPIRED = 3;
+
 /**
  * State is change only in couple of functions:
  *   init - change state to PUSH_SERVICE_INIT if state was PUSH_SERVICE_UNINIT
@@ -673,6 +683,7 @@ this.PushService = {
       scope: record.scope
     };
 
+    Services.telemetry.getHistogramById("PUSH_API_NOTIFY_REGISTRATION_LOST").add();
     this._notifyListeners('pushsubscriptionchange', data);
   },
 
@@ -724,6 +735,12 @@ this.PushService = {
       .then(record => this._notifySubscriptionChangeObservers(record));
   },
 
+  _recordDidNotNotify: function(reason) {
+    Services.telemetry.
+      getHistogramById("PUSH_API_NOTIFICATION_RECEIVED_BUT_DID_NOT_NOTIFY").
+      add(reason);
+  },
+
   /**
    * Dispatches an incoming message to a service worker, recalculating the
    * quota for the associated push registration. If the quota is exceeded,
@@ -740,10 +757,12 @@ this.PushService = {
    */
   receivedPushMessage: function(keyID, message, updateFunc) {
     debug("receivedPushMessage()");
+    Services.telemetry.getHistogramById("PUSH_API_NOTIFICATION_RECEIVED").add();
 
     let shouldNotify = false;
     return this.getByKeyID(keyID).then(record => {
       if (!record) {
+        this._recordDidNotNotify(kDROP_NOTIFICATION_REASON_KEY_NOT_FOUND);
         throw new Error("No record for key ID " + keyID);
       }
       return record.getLastVisit();
@@ -751,15 +770,21 @@ this.PushService = {
       // As a special case, don't notify the service worker if the user
       // cleared their history.
       shouldNotify = isFinite(lastVisit);
+      if (!shouldNotify) {
+          this._recordDidNotNotify(kDROP_NOTIFICATION_REASON_NO_HISTORY);
+      }
       return this._db.update(keyID, record => {
         let newRecord = updateFunc(record);
         if (!newRecord) {
+          this._recordDidNotNotify(kDROP_NOTIFICATION_REASON_NO_VERSION_INCREMENT);
           return null;
         }
+        // FIXME(nsm): WHY IS expired checked here but then also checked in the next case?
         if (newRecord.isExpired()) {
           // Because `unregister` is advisory only, we can still receive messages
           // for stale registrations from the server.
           debug("receivedPushMessage: Ignoring update for expired key ID " + keyID);
+          this._recordDidNotNotify(kDROP_NOTIFICATION_REASON_EXPIRED);
           return null;
         }
         newRecord.receivedPush(lastVisit);
@@ -825,6 +850,7 @@ this.PushService = {
       scope: aPushRecord.scope
     };
 
+    Services.telemetry.getHistogramById("PUSH_API_NOTIFY").add();
     this._notifyListeners('push', data);
     return true;
   },

toolkit/components/telemetry/Histograms.json

@@ -9431,7 +9431,7 @@
     "high": "31622400",
     "n_buckets": 20,
     "description": "Time taken for a push subscription to expire its quota (seconds). The maximum is just over an year."
-  }
+  },
   "PUSH_API_QUOTA_RESET_TO": {
     "alert_emails": ["push@mozilla.com"],
     "expires_in_version": "55",
@@ -9440,6 +9440,31 @@
     "n_buckets": 10,
     "description": "The value a push record quota (a count) is reset to based on the user's browsing history."
   },
+  "PUSH_API_NOTIFICATION_RECEIVED": {
+    "alert_emails": ["push@mozilla.com"],
+    "expires_in_version": "55",
+    "kind": "count",
+    "description": "Push notification was received from server."
+  },
+  "PUSH_API_NOTIFICATION_RECEIVED_BUT_DID_NOT_NOTIFY": {
+    "alert_emails": ["push@mozilla.com"],
+    "expires_in_version": "55",
+    "kind": "enumerated",
+    "n_values": 15,
+    "description": "Push notification was received from server, but not delivered to ServiceWorker. Enumeration values are defined in dom/push/PushService.jsm as kDROP_NOTIFICATION_REASON_*."
+  },
+  "PUSH_API_NOTIFY": {
+    "alert_emails": ["push@mozilla.com"],
+    "expires_in_version": "55",
+    "kind": "count",
+    "description": "Attempt to notify ServiceWorker of push notification."
+  },
+  "PUSH_API_NOTIFY_REGISTRATION_LOST": {
+    "alert_emails": ["push@mozilla.com"],
+    "expires_in_version": "55",
+    "kind": "count",
+    "description": "Attempt to notify ServiceWorker of push notification resubscription."
+  },
   "FXA_CONFIGURED": {
     "alert_emails": ["fx-team@mozilla.com"],
     "expires_in_version": "45",