Long files confuse `hwatch`

[Ilya Grigoriev]

To reproduce: with hwatch 0.3.9 on Linux:

1. Download qq.tar.gz and unpack it. Update: I reuploaded the file, the previous one had an insane path inside the tar file

2. Run hwatch cat qq or HWATCH= hwatch cat qq

On my machine, this causes hwatch freeze and no part of the file is ever printed. The file has color sequences in it; hwatch --color cat qq also freezes. less -R qq and watch --color cat qq work with no problems.

For illustration, here's the end of the file in less -R:

The file is obtained with jj log which is equivalent to git log. I usually use hwatch with jj log with no problems, but for this particular state of the repo something went wrong.

I may or may not try to investigate this myself in the near future.

[Ilya Grigoriev]

I think I figured out the cause. The file is simply too long.

$ hwatch "head -n 500 qq"   # Works
$ hwatch "head -n 700 qq"   # Does not work

I think this should still be tracked as a bug. hwatch should handle large file, at least by failing gracefully or cutting them off when a file is too long.

[blacknon]

Thanks!

I think this should still be tracked as a bug. hwatch should handle large file, at least by failing gracefully or cutting them off when a file is too long.

That's certainly true.
I'll try to figure out how to fix it.

[blacknon]

It certainly doesn't move...
In version 0.3.11, I tried to cat the output of git log --color=always and git log (3000 lines), but it doesn't seem to be working.

It stopped outputting after about 2487 lines, so there may be a problem with writing to memory.
I'm suspecting the size of Buffer.

[blacknon]

I think this process is probably the cause.

hwatch/src/exec.rs

Lines 99 to 115 in 6695b35

 let (stdout_bytes, stderr_bytes) = match (stdout.fill_buf(), stderr.fill_buf()) 
 { 
     (Ok(stdout), Ok(stderr)) => { 
         // merge stdout/stderr 
         vec_output.write_all(stdout).expect(""); 
         vec_output.write_all(stderr).expect(""); 
  
         // stdout 
         vec_stdout.write_all(stdout).expect(""); 
  
         // stderr 
         vec_stderr.write_all(stderr).expect(""); 
  
         (stdout.len(), stderr.len()) 
     } 
     other => panic!("Some better error handling here, {other:?}"), 
 }; 

[blacknon]

Closed because it was applied in version 0.3.12.
Thank you for issue!

[Ilya Grigoriev]

It works beautifully now. No more need to add | head -n 300 to every command. Thank you!