Bug 838072 - Part 1: Refactor data collection internals into function; r=rnewman

services/metrics/collector.jsm

@@ -147,7 +147,7 @@ Collector.prototype = Object.freeze({
    * The resolved value to the promise is this `Collector` instance.
    */
   collectConstantData: function () {
-    let promises = [];
+    let entries = [];
 
     for (let [name, entry] of this._providers) {
       if (entry.constantsCollected) {
@@ -156,29 +156,52 @@ Collector.prototype = Object.freeze({
         continue;
       }
 
+      entries.push(entry);
+    }
+
+    let onCollect = function (entry, result) {
+      entry.constantsCollected = true;
+    };
+
+    return this._callCollectOnProviders(entries, "collectConstantData",
+                                        onCollect);
+  },
+
+  _callCollectOnProviders: function (entries, fnProperty, onCollect=null) {
+    let promises = [];
+
+    for (let entry of entries) {
+      let provider = entry.provider;
       let collectPromise;
       try {
-        collectPromise = entry.provider.collectConstantData();
+        collectPromise = provider[fnProperty].call(provider);
       } catch (ex) {
-        this._log.warn("Exception when calling " + name +
-                       ".collectConstantData: " +
-                       CommonUtils.exceptionStr(ex));
-        this.providerErrors.get(name).push(ex);
+        this._log.warn("Exception when calling " + provider.name + "." +
+                       fnProperty + ": " + CommonUtils.exceptionStr(ex));
+        this.providerErrors.get(provider.name).push(ex);
         continue;
       }
 
       if (!collectPromise) {
-        throw new Error("Provider does not return a promise from " +
-                        "collectConstantData():" + name);
+        this._log.warn("Provider does not return a promise from " +
+                       fnProperty + "(): " + provider.name);
+        continue;
       }
 
       let promise = collectPromise.then(function onCollected(result) {
-        entry.constantsCollected = true;
+        if (onCollect) {
+          try {
+            onCollect(entry, result);
+          } catch (ex) {
+            this._log.warn("onCollect callback threw: " +
+                           CommonUtils.exceptionStr(ex));
+          }
+        }
 
         return Promise.resolve(result);
       });
 
-      promises.push([name, promise]);
+      promises.push([provider.name, promise]);
     }
 
     return this._handleCollectionPromises(promises);