Use get_max_fragment_size for medium_data tests

[sunshowers]

Currently, the medium_data tests all hang on illumos because (a) we first send a message and then receive it on the same thread, and (b) the tests fill up the pipe buffer before the send is complete. That's because illumos uses a smaller buffer size than other platforms like Linux.

The goal of these tests is to test situations where fragmentation doesn't happen, so use get_max_fragment_size which shouldn't fill up the pipe buffer under ordinary circumstances.

(There are other tests which check for fragmentation, so that code path is still covered.)

It would also be nice to move all of the receives to other threads in the future, but this appears to work quite well.

See #101.

[jdm]

This looks like a reasonable improvement!

[jdm]

Oh, lol—for the macOS implementation the max fragment size is usize::MAX, so that's why we're seeing capacity overflow panics in CI.

[sunshowers]

Oh, lol—for the macOS implementation the max fragment size is usize::MAX, so that's why we're seeing capacity overflow panics in CI.

Ah I guess that's because the macOS impl uses Mach ports. I'll set a cap on the fragment size used, thanks.

[sunshowers]

Updated! Capped it at the previously-used 64KiB value.

[sagudev]

Are we sure we need to change these values? I think you need to make sure that fragmentation works on illumos:

ipc-channel/src/platform/test.rs

Lines 224 to 229 in 4e51f95

	// These tests only apply to platforms that need fragmentation.
	#[cfg(all(
	not(feature = "force-inprocess"),
	any(target_os = "linux", target_os = "freebsd", target_os = "windows")
	))]
	mod fragment_tests {

[sunshowers]

Are we sure we need to change these values? I think you need to make sure that fragmentation works on illumos:

The huge_data tests do exercise fragmentation, but good point about those specific tests -- will enable that. Note however that ipc-channel doesn't yet compile on illumos, there's another PR I need to do which depends on this one.

[sunshowers]

I've updated the PR summary to indicate what's happening.

[sunshowers]

Also enabled the fragment tests on illumos.

[sunshowers]

Hi — is there any way I can help get this landed? Thanks!

[mrobinson]

Apologies for the wait and thanks for the fix. This looks good to me!