wait for processes by their name

[s417-lama]

Implement #4848 and refactored the code in wait command.

We can now specify the process name and wait for jobs with its name, like:

$ for i in (seq); sleep 10 &; end
$ wait sleep

TODOs:

• Changes to fish usage are reflected in user documentation/manpages.
• Tests have been added for regressions fixed
• User-visible changes noted in CHANGELOG.md

[ridiculousfish]

Nice tests! Can you please update doc_src/wait.txt to reflect these changes?

[s417-lama]

I reflected the changes to doc_src/wait.txt :)

[s417-lama]

Although I committed the fix for the bug, I think I misunderstood the error in test.

I expect the behaviour like below:

$ for i in (seq 2 4); ls | sleep $i | cat > /dev/null &; end
$ sleep 3 | cat &
$ sleep 1 &
$ wait -n cat
$ jobs | wc -l
3

However, the failed test seems to behave

$ for i in (seq 2 4); ls | sleep $i | cat > /dev/null &; end
$ sleep 3 | cat &
$ sleep 1 &
$ wait -n cat
$ jobs | wc -l
2

Was one of the jobs finished immediately?
I tried many times, but I cannot reproduce the error in my local environment.

In the log file in failed test,

Job 4, 'sleep 1 &' has ended

is printed, but sleep 1 & should be Job 5, not Job 4... :(

[s417-lama]

This might be related to #4778 or #4540

[mqudsi]

If you run jobs after each line you can see what's what.

[s417-lama]

I cannot reproduce the bug although I tried the test many times :_(

After merging the current master branch I run the script below, but it never breaks in my environment.

set n 3
while [ $n = 3 ]
    for i in (seq 2 4); ls | sleep $i | cat > /dev/null &; end

    echo "jobs 1."
    jobs

    sleep 3 | cat &

    echo "jobs 2."
    jobs

    sleep 1 &

    echo "jobs 3."
    jobs

    wait -n cat
    set n (jobs | wc -l)

    echo "jobs 4."
    jobs

    wait

    echo "---"
end

How do we deal with this bug?

[faho]

Urgh... Sorry, I missed a change in the tests, which is why they are now failing!

Readding that line!

[mqudsi]

I think waiting for processes by name is messy and brittle and job ids should always be used.