Unable to use the Writer from a different thread.

[duggaraju]

I craeate a tokio pipe. in the thread where the pipe is created, I am reading from the read end till end of file. In another thread where I pass the writeer as a raw fd, I try to create a new PipeWrite (PipeWrite::from_raw_rd_checked(fd)). However that call fails because the creation of AsyncFd() seems to be failing since the file descriptor is already registerered?
Is there a way to safely separate the writing and reading across two different threads?

[duggaraju]

Note that I can't pass the created PipeWriter directly to the other thread (the only shared state is the file descriptor number)

[NobodyXu]

You need to either call <PipeWrite as IntoRawFd>::into_raw_fd, which will deregister the fd from tokio, or you need to dup the fd before recreating the PipeWrite.

[duggaraju]

Thanks. The only issue i see is into_raw_fd() does mem::forget(). Is there a way to close the fd after i read everything from the pipe? Just as a safety to avoid leaking since the methods in PipeFd are not public

[NobodyXu]

Thanks. The only issue i see is into_raw_fd() does mem::forget().

It forget the PipeFd, which closes the fd on drop.

Is there a way to close the fd after i read everything from the pipe?

If you created a PipeRead, then it will contains a PipeFd.

Just as a safety to avoid leaking since the methods in PipeFd are not public

If you are worried about leaking the fd when passing to a different thread, you can use std::os::unix::io::OwnedFd.

[yskszk63]

@duggaraju
(Sorry for the late response...)

In my environment, it seems to be possible to write across threads with PipeWrite::from_raw_rd_checked.
Here is the code I wrote to try it out.
https://github.com/yskszk63/tokio-pipe/blob/add-example/examples/inter-thread.rs

If there are any misunderstandings, I would appreciate it if you could point them out.