fix: make the logs line buffered

[mahdifrmz]

fixes #9432
Not quite sure if that's what you want, but storing the log message in buffers eliminated the tiny write syscalls for me.
I just changed the Logger struct.

[lnicola]

Oh, I didn't even realize that was our logging sink. I'm surprised it behaves like this, since it's already using a BufWriter.

Anyway, #9274 will probably get rid or replace that code.

[lnicola]

Oh, it's stderr that's not buffered.

[mahdifrmz]

Yeah, I actually checked stderr, I think that's the main issue.

[matklad]

TIL: rust-lang/rust#64413

Let's just quickly fix this by formatting the string to memory with format, and then writing the whole thing to stderr in one go.

[lnicola]

Can we wrap stderr in a LineWriter or BufWriter and stick it in self?

[mahdifrmz]

Let's just quickly fix this by formatting the string to memory with format, and then writing the whole thing to stderr in one go.

I've done the same for the Logger in this PR. or you mean for the whole source code?

[lnicola]

Suggested change

	self.flush();
	w.lock().flush();

(or better, hoist that to a local).

Then flush is dead code.

[mahdifrmz]

Well we can't remove flush as it's part of Log trait.
Instead, I will put the actual flush inside of it.

[lnicola]

Ah, sorry, I missed that.

[lnicola]

Not to be too nit-picky, but this feels strange -- what if log calls flush internally?

I would have left flush unchanged, moved w.lock() to a variable, then called flush on that in this branch.

[mahdifrmz]

I guess what you're suggesting makes sense, that way we had to acquire the lock twice.

[lnicola]

Maybe

Suggested change

	writer.flush().unwrap();
	let _ = writer.flush();

But I'm not sure how I feel about it. This might cause some spurious panics when we're run by another program and it closes our stderr.

[mahdifrmz]

Yeah, I only put the unwrap() to get rid of the warning. thanks for mentioning.

[lnicola]

Yeah, then maybe let's ignore the errors here.

[lnicola]

bors r+

[bors]

Build succeeded:

• Rust (macos-latest)
• Rust (ubuntu-latest)
• Rust (windows-latest)
• TypeScript (ubuntu-latest)
• TypeScript (windows-latest)