pigpio-client Do you have automatic reconnection? about pigpio-client

[guymcswain]

Please explain the conditions under which automatic reconnection is useful. I don't think under an error condition it would be useful.

[bulentkusva]

yes in case of error or if you can not connect to the server you will need to try again

[guymcswain]

I suppose I could implement using the reconnector npm package. If so, what should be used for startTimeout endTimeout maxTimes ?

I just haven't had the need for this so I need some guidance on the use case. Thanks.

[guymcswain]

@bulentkusva
I have created a branch in this repo called 'autoreconnect'. It will solve 3 cases that I consider important or that I have recently run into:

1. After initial creation of pigpio-client object, if not successfully connected, automatically reconnect if any error occurs. Likely errors encountered are ECONNREFUSED or EHOSTUNREACH when the remote pigpiod process or host is not available. This case is currently covered and has been tested somewhat.

2. After pigpio-client is connected, if a socket receives an error or is forcibly closed, then destroy current connections, emit 'disconnected' event to application and wait for pigpio-client.connect() to reestablish connections. The code covers this case and I have successfully completed a preliminary test.

3. Detect a dead peer on notification socket using built-in pigpio keep alive packet. This covers the case when the remote host running pigpiod is unexpectedly reset - say due to a power loss - and comes back up without connections, yet pigpio-client still has open connections (ie no errors have occurred). The code for this case is not yet written. I'm currently working on it.

Cases 2 and 3, require a change to your application. You must monitor for 'disconnected' event and call connect() method after any housekeeping. You'll need to re-initialize pigpio as the state of pins, pwm, alerts, etc have all been reset. In my app, I just called my init() function after attaching a one time listener to the new 'connected' event. Like so:

  // on disconnect re-initialize pigpio
  pigpio.on('disconnected', (reason) => {
    console.log('rcencoder: received disconnect event')
    console.log('rcencoder: re-initializing pigpio')
    pigpio.connect()
    pigpio.once('connected', () => { init()})
  })

[guymcswain]

Case 3 (dead connection) is now covered and tested (one time) successfully. After I complete more testing I'll merge this branch into master. Release to NPM as v1.1.0?