EZSP: Removed the queue for sending commands to devices

[kirovilya]

This allows to send multiple commands without waiting for a response from the device.
Useful when the signal from the device to the coordinator is bad.

[Koenkk]

Thanks!

[matt-oakes]

Hi @kirovilya @Koenkk,

I can see that other adapters such as Z-Stack have this queue on the sendZclFrameToEndpoint method too. Is there a reason why it can't be removed for those adapters as well as EZSP?

FYI, Thanks for the great library!

[Koenkk]

@matt-oakes for z-stack it is needed to not ddos the coordinator.

[matt-oakes]

Thanks for the reply! Is there not also a queue inside znp which should mean that only one message at a time is sent?

zigbee-herdsman/src/adapter/z-stack/znp/znp.ts

Line 302 in cb5dd54

return this.queue.execute<ZpiObject>(async (): Promise<ZpiObject> => {

Is there a need for two queues?

I beleive EZSP also has this queue when it comes to actually sending commands

zigbee-herdsman/src/adapter/ezsp/driver/ezsp.ts

Line 553 in cb5dd54

return this.queue.execute<EZSPFrameData>(async (): Promise<EZSPFrameData> => {

This makes sense to me as you want to serial port to be used serially, but I'm not not sure what the "outer" queue in z-stack is doing.

[kirovilya]

For ezsp, I removed the queue when sending a command to a device, so as not to wait for the successful completion of the previous command for the same device.
The need was that sometimes delivering a command to the device and confirming delivery can take a long time (up to 10 seconds or more) and in case of a bad signal, it will not even reach the device. And at this time the user’s device “freezes” and does not react at all, but after a timeout, all his sent commands will come out with a timeout error.
If you remove the waiting queue, then all commands will be sent (some of them will reach the device) and only those commands that did not receive a response due to a timeout will be returned with an error. This way we keep the device available in case of communication problems.

[matt-oakes]

Understood. Does this mean that Z-Stack would also benefit from having the same change made?