Minor tweak.

lib/cube/server/event.js

@@ -57,8 +57,8 @@ exports.putter = function(db) {
       // Events are indexed by time.
       events.ensureIndex({"t": 1}, handle);
 
-      // Create a capped collection for metrics. Two indexes are required:
-      // one for computing, and the other for invalidating.
+      // Create a capped collection for metrics. Three indexes are required: one
+      // for finding metrics, one (_id) for updating, and one for invalidation.
       db.createCollection(type + "_metrics", metric_options, function(error, metrics) {
         handle(error);
         metrics.ensureIndex({"i": 1, "_id.e": 1, "_id.l": 1, "_id.t": 1}, handle);

lib/cube/server/metric.js

@@ -102,10 +102,10 @@ exports.getter = function(db) {
       // Immediately report back whatever we have. If any values are missing,
       // merge them into contiguous intervals and asynchronously compute them.
       function foundMetrics(error, cursor) {
-        if (error) throw error;
+        handle(error);
         var time = start;
         cursor.each(function(error, row) {
-          if (error) throw error;
+          handle(error);
           if (row) {
             info.stat("metrics_cached", name, step).add(1);
             callback(row._id.t, row.v);
@@ -136,10 +136,10 @@ exports.getter = function(db) {
         filter.t.$gte = start;
         filter.t.$lt = stop;
         type.events.find(filter, fields, event_options, function(error, cursor) {
-          if (error) throw error;
+          handle(error);
           var time = start, values = [];
           cursor.each(function(error, row) {
-            if (error) throw error;
+            handle(error);
             if (row) {
               var then = tier.floor(row.t);
               if (time < then) {
@@ -168,7 +168,7 @@ exports.getter = function(db) {
             },
             i: false,
             v: new Double(value)
-          }, function(error) { if (error) throw error; });
+          }, handle);
           info.stat("metrics_computed", name, step).add(1);
         } else {
           info.stat("metrics_zeroed", name, step).add(1);
@@ -230,3 +230,7 @@ exports.getter = function(db) {
         : function(time, value) { callback({time: time, value: value}); });
   };
 };
+
+function handle(error) {
+  if (error) throw error;
+}