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cat: call pipe() once with multiple input #11699

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cat: call pipe() once with multiple input #11699

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4 changes: 3 additions & 1 deletion src/uu/cat/src/splice.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,8 @@ pub(super) fn write_fast_using_splice<R: FdReadable, S: AsRawFd + AsFd>(
handle: &InputHandle<R>,
write_fd: &S,
) -> CatResult<bool> {
use std::{fs::File, sync::OnceLock};
static BROKER: OnceLock<Option<(File, File)>> = OnceLock::new();
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@sylvestre sylvestre Apr 12, 2026

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can we find a better name for BROKER?

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@oech3 oech3 Apr 12, 2026

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pipes are used to avoid limitation for splice():
one of a in/output should be pipe. So BROKER is used.

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@oech3 oech3 Apr 12, 2026

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But PIPE_CACHE is OK for me.

if splice(&handle.reader, &write_fd, MAX_ROOTLESS_PIPE_SIZE).is_ok() {
// fcntl improves throughput
// todo: avoid fcntl overhead for small input, but don't fcntl inside of the loop
Expand All @@ -34,7 +36,7 @@ pub(super) fn write_fast_using_splice<R: FdReadable, S: AsRawFd + AsFd>(
Err(_) => return Ok(true),
}
}
} else if let Ok((pipe_rd, pipe_wr)) = pipe() {
} else if let Some((pipe_rd, pipe_wr)) = BROKER.get_or_init(|| pipe().ok()).as_ref() {
// both of in/output are not pipe. needs broker to use splice() with additional costs
loop {
match splice(&handle.reader, &pipe_wr, MAX_ROOTLESS_PIPE_SIZE) {
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