On Tue, Dec 17, 2013 at 6:54 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
> Samuel Bronson <naesten@xxxxxxxxx> writes:
>
>> On Mon, Dec 16, 2013 at 4:32 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
>>> Samuel Bronson <naesten@xxxxxxxxx> writes:
>>>
>>>> for i in 1 2
>>>> do
>>>> test_expect_success "orderfile using option ($i)" '
>>>> git diff -Oorder_file_$i --name-only HEAD^..HEAD >actual &&
>>>> test_cmp expect_$i actual
>>>> '
>>>
>>> This funny indentation in the previous step needs to be fixed, and
>>> the added block below should match.
>>
>> Even though this results in oddly-indented --verbose output?
>>
>>>> + rm -f order_fifo &&
>>>> + mkfifo order_fifo &&
>>>> + cat order_file_$i >order_fifo &
>>>> + git diff -O order_fifo --name-only HEAD^..HEAD >actual &&
>>>
>>> I think this part can be racy depending on which between cat and
>>> "git diff" are scheduled first, no? Try running this test under
>>> load and I think you will see it deadlocked.
>>>
>>> Besides, the above breaks && chain; even if mkfifo breaks (hence not
>>> allowing cat to run), "git diff" will go ahead and run, no?
>>
>> Hmm. Well, what I really wanted to put here was a "process substitution":
>>
>> git diff -O <(cat order_file_$i) --name-only HEAD^..HEAD >actual &&
>>
>> but I did not see this feature listed in the dash(1) manpage, so I
>> assumed it wasn't allowed by POSIX. And, having looked, I indeed
>> don't see it mentioned in POSIX either.
>>
>> I'm not terribly surprised that I screwed up the translation to FIFOs;
>> how would I really want to do it?
>
> How about not doing a fifo?
That would certainly defeat the purpose of the test, which is to test
against a fifo :-)
I'm not sure about the deadlock though. Both read and write will wait
for each other to start operating on the fifo.
You can probably fix the &&-chain by doing something like:
mkfifo order_fifo && {
cat order_file_$i >order_fifo &
git diff -O order_fifo --name-only HEAD^..HEAD >actual
} && ...
Also, "rm -f order_fifo" should probably be done in test_when_finished
rather than at the beginning of the test.
Antoine,
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