add polling lock, and reduce inner handler timeout

packages/doorman-api/src/common/DoormanHandler.ts

@@ -64,7 +64,7 @@ const FALLBACK_CALLBACK: CallbackResult = [null, REJECT_RESPONSE];
 
 const MINIMUM_MS_TO_SEND_RESPONSE: number = 250;
 const FUNCTION_MAXIMUM_DURATION_MS: number = 10_000;
-const INNER_HANDLER_MAXIMUM_DURATION_MS: number = 9_000;
+const INNER_HANDLER_MAXIMUM_DURATION_MS: number = 8_750;
 
 /**
  * A decorator for twilio handlers. It provides a metrics registry and 

packages/doorman-client/src/functions/buzzer-activated.ts

@@ -78,6 +78,8 @@ export const handler: ServerlessFunctionSignature<TwilioContext, BuzzerDialEvent
   let intervals: Timer[] = [];
   let timeouts: Timer[] = [];
 
+  let pollLock = false;
+
   const unlockPromise = new Promise<VoiceResponse>((resolve, reject) => {
     intervals.push(setInterval(() => {
       getMetricFromRegistry<Counter>(metricsRegistry, BuzzerActivatedMetrics.POLL_ATTEMPTS)
@@ -86,12 +88,20 @@ export const handler: ServerlessFunctionSignature<TwilioContext, BuzzerDialEvent
       const recordPollLatency = getMetricFromRegistry<Summary>(metricsRegistry, BuzzerActivatedMetrics.POLL_LATENCY)
         .startTimer({ door: config.door });
 
+
+      // prevent multiple polling at once
+      if (pollLock) {
+        return;
+      }
+
+      pollLock = true;
       fetch(context.DOORMAN_URL + `/api/door/status?door=${config.door}`)
         .then(res => res.json())
         .then(async (rawBody) => {
           let body = rawBody as StatusResponse;
           recordPollLatency();
           if (body?.status === DoorStatus.OPEN) {
+            pollLock = false;
             clearInterval(intervals[0]);
             const twiml = doorOpenTwiml(config);
 
@@ -112,7 +122,7 @@ export const handler: ServerlessFunctionSignature<TwilioContext, BuzzerDialEvent
             }
           }
         }).catch(err => console.log(invokeId + err));
-    }, 1250));
+    }, 400));
   });
 
   const gracefulFallbackPromise = new Promise<VoiceResponse>((resolve, reject) => {