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[WIP] Fix: Improve Tello connection robustness (timeouts, error handling) #33

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[WIP] Fix: Improve Tello connection robustness (timeouts, error handling) #33

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68 changes: 47 additions & 21 deletions scratch-vm/src/extensions/scratch3_tello/telloProcessor.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ const dgram = require('dgram');
class TelloProcessor {
initialize () {
this.queue = []; // command queue
this.timer = null;

this.client = dgram.createSocket('udp4');
this.server = dgram.createSocket('udp4');
Expand All @@ -17,30 +18,28 @@ class TelloProcessor {
this.send('command');

this.client.on('message', (message, remote) => {
const readableMessage = message.toString();
const readableMessage = message.toString().trim();

// Previous command executed
if (readableMessage === 'ok') {
this.executing = false;
// Clear timeout since we got a response
if (this.timer) {
clearTimeout(this.timer);
this.timer = null;
}

// Mark as not executing so we can send the next command
this.executing = false;

// Update flying state based on successful commands
if (readableMessage === 'ok') {
if (this.executingCommand === 'takeoff') this.flying = true;
if (this.executingCommand === 'land') this.flying = false;
}
// Note: We do NOT set flying=false on error, because a failed 'flip'
// shouldn't prevent us from sending 'land' later.

// Dequeue
this.queue.shift();

// Send next element
this.inquire();
} else if (readableMessage.includes('error')) {
this.executing = false;
this.flying = false;

// Dequeue
this.queue.shift();

// Send next element
this.inquire();
}
// Dequeue and proceed
this.queue.shift();
this.inquire();
});

// Tello State
Expand Down Expand Up @@ -80,19 +79,46 @@ class TelloProcessor {
const msg = Buffer.from(cmd);
// While grounding, `command`, `mon`, `mdirection 2` and `takeoff` are only executable
if (!this.flying && cmd !== 'command' && cmd !== 'mon' && cmd !== 'mdirection 2' && cmd !== 'takeoff') {
// If we are on the ground and try to fly/flip, skip it silently or log warning
// But we must dequeue it to prevent blocking
this.queue.shift();
this.inquire();
return;
}

this.executing = true;
this.executingCommand = cmd;

// Set watchdog timer
this.timer = setTimeout(() => {
// console.warn(`[Tello] Timeout waiting for '${cmd}'. Skipping.`);
this.executing = false;
this.queue.shift();
this.inquire();
}, 3000);

this.client.send(msg, 0, msg.length, 8889, '192.168.10.1', (err, bytes) => {
if (err) throw err;
if (err) {
// console.error(`[Tello] Send error: ${err}`);
// Don't crash, just try to recover
clearTimeout(this.timer);
this.executing = false;
this.queue.shift();
this.inquire();
}
});
}

resetQueue () {
this.queue = [];
this.flying = false;
if (this.timer) {
clearTimeout(this.timer);
this.timer = null;
}
// We generally don't want to reset 'flying' state here blindly
// because the drone might still be in the air.
// But for safety/reset purposes as originally intended:
this.flying = false;
this.executing = false;
}
}
Expand Down