events: Add rate limiting based on event name when reporting to mixpanel

Change-type: patch
Signed-off-by: Cameron Diver <cameron@resin.io>

package.json

@@ -32,6 +32,7 @@
     "@types/express": "^4.11.1",
     "@types/knex": "^0.14.14",
     "@types/lodash": "^4.14.109",
+    "@types/memoizee": "^0.4.2",
     "@types/mz": "0.0.32",
     "@types/node": "^10.3.1",
     "@types/rwlock": "^5.0.2",

src/event-tracker.ts

@@ -1,6 +1,7 @@
 import * as Bluebird from 'bluebird';
 import mask = require('json-mask');
 import * as _ from 'lodash';
+import * as memoizee from 'memoizee';
 
 import Mixpanel = require('mixpanel');
 
@@ -13,6 +14,10 @@ interface InitArgs {
 	mixpanelToken: string;
 }
 
+// The minimum amount of time to wait between sending
+// events of the same type
+const eventDebounceTime = 60000;
+
 const mixpanelMask = [
 	'appId',
 	'delay',
@@ -78,9 +83,16 @@ export class EventTracker {
 		}
 
 		properties = this.assignDefaultProperties(properties);
-		this.client.track(event, properties);
+		this.debouncedLogger(event)(properties);
 	}
 
+	private debouncedLogger = memoizee((event: string) => {
+		// Call this function at maximum once every minute
+		return _.debounce((properties) => {
+			this.client.track(event, properties);
+		}, eventDebounceTime, { leading: true });
+	}, { primitive: true });
+
 	private logEvent(...args: string[]) {
 		console.log(...args);
 	}

test/09-event-tracker.spec.coffee

@@ -77,3 +77,39 @@ describe 'EventTracker', ->
 			uuid: 'barbaz'
 			distinct_id: 'barbaz'
 		})
+
+	describe 'Rate limiting', ->
+
+		it 'should rate limit events of the same type', ->
+			@eventTracker.client.track.reset()
+
+			@eventTracker.track('test', { });
+			@eventTracker.track('test', { });
+			@eventTracker.track('test', { });
+			@eventTracker.track('test', { });
+			@eventTracker.track('test', { });
+
+			expect(@eventTracker.client.track).to.have.callCount(1)
+
+		it 'should rate limit events of the same type with different arguments', ->
+			@eventTracker.client.track.reset()
+
+			@eventTracker.track('test2', { a: 1 });
+			@eventTracker.track('test2', { b: 2 });
+			@eventTracker.track('test2', { c: 3 });
+			@eventTracker.track('test2', { d: 4 });
+			@eventTracker.track('test2', { e: 5 });
+
+			expect(@eventTracker.client.track).to.have.callCount(1)
+
+		it 'should not rate limit events of different types', ->
+			@eventTracker.client.track.reset()
+
+			@eventTracker.track('test3', { a: 1 });
+			@eventTracker.track('test4', { b: 2 });
+			@eventTracker.track('test5', { c: 3 });
+			@eventTracker.track('test6', { d: 4 });
+			@eventTracker.track('test7', { e: 5 });
+
+			expect(@eventTracker.client.track).to.have.callCount(5)
+