Addition of option to allow events to expire after a certain time

lib/cube/event.js

@@ -6,7 +6,8 @@ var mongodb = require("mongodb"),
     tiers = require("./tiers"),
     types = require("./types"),
     bisect = require("./bisect"),
-    ObjectID = mongodb.ObjectID;
+    ObjectID = mongodb.ObjectID,
+    collector_config = require("../../bin/collector-config");
 
 var type_re = /^[a-z][a-zA-Z0-9_]+$/,
     invalidate = {$set: {i: true}},
@@ -22,6 +23,9 @@ var streamDelayDefault = 5000,
 // How frequently to invalidate metrics after receiving events.
 var invalidateInterval = 5000;
 
+// Set the Time To Live interval in seconds from the collector config
+var expireEventsAfterSeconds = collector_config.event_ttl_seconds;
+
 exports.putter = function(db) {
   var collection = types(db),
       knownByType = {},
@@ -63,7 +67,13 @@ exports.putter = function(db) {
       if (names.length) return saveEvents();
 
       // Events are indexed by time.
-      events.ensureIndex({"t": 1}, handle);
+      if (expireEventsAfterSeconds) {
+        // Events are indexed by time and expired after a supplied period (expireEventsAfterSeconds).
+        events.ensureIndex({"t": 1},  { expireAfterSeconds: expireEventsAfterSeconds }, handle);
+      }
+      else {
+        events.ensureIndex({"t": 1}, handle);
+      }
 
       // Create a capped collection for metrics. Three indexes are required: one
       // for finding metrics, one (_id) for updating, and one for invalidation.