implement purging old positions after configured duration

src/mqtt.js

@@ -78,6 +78,11 @@ const optionsList = [
         type: Number,
         description: "Nodes that haven't been heard from in this many seconds will be purged from the database.",
     },
+    {
+        name: "purge-positions-after-seconds",
+        type: Number,
+        description: "Positions older than this many seconds will be purged from the database.",
+    },
 ];
 
 // parse command line args
@@ -114,6 +119,7 @@ const decryptionKeys = options["decryption-keys"] ?? [
 ];
 const purgeIntervalSeconds = options["purge-interval-seconds"] ?? 10;
 const purgeNodesUnheardForSeconds = options["purge-nodes-unheard-for-seconds"] ?? null;
+const purgePositionsAfterSeconds = options["purge-positions-after-seconds"] ?? null;
 
 // create mqtt client
 const client = mqtt.connect(mqttBrokerUrl, {
@@ -139,6 +145,7 @@ const Waypoint = root.lookupType("Waypoint");
 if(purgeIntervalSeconds){
     setInterval(async () => {
         await purgeUnheardNodes();
+        await purgeOldPositions();
     }, purgeIntervalSeconds * 1000);
 }
 
@@ -168,6 +175,32 @@ async function purgeUnheardNodes() {
 
 }
 
+/**
+ * Purges all positions from the database that are older than the configured timeframe.
+ */
+async function purgeOldPositions() {
+
+    // make sure seconds provided
+    if(!purgePositionsAfterSeconds){
+        return;
+    }
+
+    // delete all positions that are older than the configured purge time
+    try {
+        await prisma.position.deleteMany({
+            where: {
+                created_at: {
+                    // last updated before x seconds ago
+                    lt: new Date(Date.now() - purgePositionsAfterSeconds * 1000),
+                },
+            }
+        });
+    } catch(e) {
+        // do nothing
+    }
+
+}
+
 function createNonce(packetId, fromNode) {
 
     // Expand packetId to 64 bits