Add the ability to send configured percentile values using the standa…

…rd statsd config.percentThreshold. Default to false since it wasn't in previous versions and we want to keep back compat.

lib/stackdriver.js

@@ -49,6 +49,17 @@ function StackdriverBackend(startupTime, config, emitter) {
 	this.sendTimerMaxes = ('sendTimerMaxes' in config.stackdriver) ? config.stackdriver.sendTimerMaxes : true;
 	this.sendTimerSums = ('sendTimerSums' in config.stackdriver) ? config.stackdriver.sendTimerSums : true;
 	this.sendTimerAvgs = ('sendTimerAvgs' in config.stackdriver) ? config.stackdriver.sendTimerAvgs : true;
+
+	// Timer percentiles are set to false by default since we didn't have those in earlier revs
+	this.sendTimerPercentiles = ('sendTimerPercentiles' in config.stackdriver) ? config.stackdriver.sendTimerPercentiles : false;
+
+	// Use the default 90th percentile as supplied in statsd if none are configured
+	this.percentileValues = ('percentThreshold' in config) ? config.percentThreshold : ['90'];
+
+	if (this.debug) {
+		util.log('Stackdriver Backend set to report timer percentiles ' + this.percentileValues);
+	}
+
 	this.sendSets = ('sendSets' in config.stackdriver) ? config.stackdriver.sendSets : true;
 
 	this.stackdriverHost = 'custom-gateway.stackdriver.com';
@@ -304,6 +315,16 @@ StackdriverBackend.prototype.flush = function(timestamp, metrics) {
 					collected_at: timestamp
 				});
 			}
+			if (this.sendTimerPercentiles) {
+				// send a point for each configured percentile, defaults to just 90th per statsd default
+				for (var i=0; i < this.percentileValues.length; i++) {
+					this.add_point_to_message(stackdriverMessage, {
+						name : timer_key + "." + this.percentileValues[i] + "_pct",
+						value : metrics.timer_data[timer_key]["upper_" + this.percentileValues[i]],
+						collected_at: timestamp
+					});
+				}
+			}
 		}
 	}