Synchronize push monitor heartbeats to api calls (fixes #1422)

package.json

@@ -79,7 +79,7 @@
         "chroma-js": "^2.1.2",
         "command-exists": "~1.2.9",
         "compare-versions": "~3.6.0",
-        "dayjs": "~1.10.8",
+        "dayjs": "^1.11.0",
         "express": "~4.17.3",
         "express-basic-auth": "~1.2.1",
         "favico.js": "^0.3.10",
@@ -102,7 +102,7 @@
         "prom-client": "~13.2.0",
         "prometheus-api-metrics": "~3.2.1",
         "qrcode": "~1.5.0",
-        "redbean-node": "0.1.3",
+        "redbean-node": "0.1.4",
         "socket.io": "~4.4.1",
         "socket.io-client": "~4.4.1",
         "socks-proxy-agent": "^6.1.1",

server/model/monitor.js

@@ -192,7 +192,7 @@ class Monitor extends BeanModel {
 
             let bean = R.dispense("heartbeat");
             bean.monitor_id = this.id;
-            bean.time = R.isoDateTime(dayjs.utc());
+            bean.time = R.isoDateTimeMillis(dayjs.utc());
             bean.status = DOWN;
 
             if (this.isUpsideDown()) {
@@ -367,22 +367,33 @@ class Monitor extends BeanModel {
                     bean.msg = dnsMessage;
                     bean.status = UP;
                 } else if (this.type === "push") {      // Type: Push
-                    const time = R.isoDateTime(dayjs.utc().subtract(this.interval, "second"));
+                    log.debug("monitor", `[${this.name}] Checking monitor at ${dayjs().format("YYYY-MM-DD HH:mm:ss.SSS")}`);
+                    const bufferTime = 1000; // 1s buffer to accommodate clock differences
 
-                    let heartbeatCount = await R.count("heartbeat", " monitor_id = ? AND time > ? ", [
-                        this.id,
-                        time
-                    ]);
+                    if (previousBeat) {
+                        const msSinceLastBeat = dayjs.utc().valueOf() - dayjs.utc(previousBeat.time).valueOf();
 
-                    log.debug("monitor", "heartbeatCount" + heartbeatCount + " " + time);
+                        log.debug("monitor", `[${this.name}] msSinceLastBeat = ${msSinceLastBeat}`);
 
-                    if (heartbeatCount <= 0) {
-                        throw new Error("No heartbeat in the time window");
+                        // If the previous beat was down or pending we use the regular
+                        // beatInterval/retryInterval in the setTimeout further below
+                        if (previousBeat.status !== UP || msSinceLastBeat > beatInterval * 1000 + bufferTime) {
+                            throw new Error("No heartbeat in the time window");
+                        } else {
+                            let timeout = beatInterval * 1000 - msSinceLastBeat;
+                            if (timeout < 0) {
+                                timeout = bufferTime;
+                            } else {
+                                timeout += bufferTime;
+                            }
+                            // No need to insert successful heartbeat for push type, so end here
+                            retries = 0;
+                            log.debug("monitor", `[${this.name}] timeout = ${timeout}`);
+                            this.heartbeatInterval = setTimeout(beat, timeout);
+                            return;
+                        }
                     } else {
-                        // No need to insert successful heartbeat for push type, so end here
-                        retries = 0;
-                        this.heartbeatInterval = setTimeout(beat, beatInterval * 1000);
-                        return;
+                        throw new Error("No heartbeat in the time window");
                     }
 
                 } else if (this.type === "steam") {

server/routers/api-router.js

@@ -59,14 +59,15 @@ router.get("/api/push/:pushToken", async (request, response) => {
         let duration = 0;
 
         let bean = R.dispense("heartbeat");
-        bean.time = R.isoDateTime(dayjs.utc());
+        bean.time = R.isoDateTimeMillis(dayjs.utc());
 
         if (previousHeartbeat) {
             isFirstBeat = false;
             previousStatus = previousHeartbeat.status;
             duration = dayjs(bean.time).diff(dayjs(previousHeartbeat.time), "second");
         }
 
+        log.debug("router", `/api/push/ called at ${dayjs().format("YYYY-MM-DD HH:mm:ss.SSS")}`);
         log.debug("router", "PreviousStatus: " + previousStatus);
         log.debug("router", "Current Status: " + status);