Deno stopps at file.read()
I am currently working on a way to communicate with a COM device. I can successfully open and read from the COM port. The only problem is, is there is no data on the COM port Deno pauses at that point in the code because the Promise gets neither resolved or rejected.
Here is the link to the Stackoverflow problem.
https://stackoverflow.com/questions/75400521/abort-promise-after-delay-in-deno
Stack Overflow
Abort Promise after delay in Deno
I am currently trying to open a COM port with Deno. This works so far and I can read the data with
file.read(buffer).
The only problem now is that if there is no more data in the COM port and I try...
16 Replies
Hope someone can help 👍🏻
setTimeout and call close on your COM instance to close the read.I tried that and it does not work…
You can also do a
await Promise.race([file.read(), new Promise(res => setTimeout(res, TIMEOUT_MS))]) in the read method to internally include a timeout.
I can't remember if the read API supports it but if it does then AbortSignal is a "native" way to cancel an ongoing promise.Yes ChatGPT also suggested that 😅 only problem is that the program does not close because there are this one pending promise
The AbortSignal only works on readTextFile() method
file.read(buffer) has no abortSignal
Hmm, does it not close even if you call the
close() on it afterwards?
I guess the readable stream API might offer what you need, though I don't know how much you need the "read n chars" API you have for COM right now. Note though that file.read(buffer) does not guarantee that the buffer is "filled". It returns the number of bytes actually read.A readable stream does not work because the COM ports are some how different
There is also some internal API at least for unref'ing a Promise, ie. telling Deno that you do not care about a given Promise resolving or not anymore...
Okay
Possibly
Deno[Deno.internal].unrefPromiseI hope that they add a serial API in the future…
Okay
Unknown User•2y ago
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Nope 😅
I have written with djDev (creator of deno_seial) library and he fixed some parts. But set main branch still does not work. The library he created is awesome, but you need to use a sub branch that is not listed. The branch is als unstable.
https://raw.githubusercontent.com/DjDeveloperr/deno_serial/bddff5b/mod.ts
I am just @ˋMqxxˋ on GitHub
What sort of fixes did you make?
Unknown User•2y ago
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I did no fixes