[PATCH] t9300-fast-import: don't hang if background fast-import exits too early
- From
SZEDER Gábor <szeder.dev@gmail.com>
- Date
- Nov 30, 2019, 10:46 UTC
- Message-ID
- <20191130104644.17350-1-szeder.dev@gmail.com>
The five tests checking 'git fast-import's checkpoint handling in 't9300-fast-import.sh', all with the prefix "V:" in their test description, can hang indefinitely if 'git fast-import' unexpectedly dies early in any of these tests.
These five tests run 'git fast-import' in the background, while feeding instructions to its standard input through a fifo from a background subshell, and reading and verifying its standard output through another fifo in the test script's main shell process. This "reading and verifying" is basically a 'while read ...' shell loop iterating until 'git fast-import' outputs the expected line, ignoring any other output. This doesn't work very well when 'git fast-import' dies before printing that particular line, because the 'read' builtin doesn't get EOF after the death of 'git fast-import', as their input and output are not connected directly but through a fifo. Consequently, that 'read' hangs waiting for the next line from the already dead 'git fast-import', leaving the test script and in turn the whole test suite hanging.
Avoid this hang by checking whether the background 'git fast-import' process exited unexpectedly early, and interrupt the 'while read' loop if it did. We have to jump through some hoops to achive that, though:
- Start the background 'git fast-import' in another background
subshell, which then waits until that 'git fast-import' process
exits. If it does exit, then report its exit code, and write a
message to the fifo used for 'git fast-import's standard output,
thus un-block the 'read' builtin in the main shell process. - Modify that 'while read' loop to break the loop upon seeing that
message, and fail the test in the usual way. - Once the test is finished kill that background subshell as well,
and do so before killing the background 'git fast-import'.
Otherwise the background 'git fast-import' and subshell would die
racily, and if 'git fast-import' were to die sooner, then we might
get some undesired and potentially confusing messages in the
test's output.Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> --- t/t9300-fast-import.sh | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh index e707fb861e..dcfaa9cc36 100755 --- a/t/t9300-fast-import.sh +++ b/t/t9300-fast-import.sh @@ -3148,63 +3148,74 @@ test_expect_success 'U: validate root delete result' ' # The commands in input_file should not produce any output on the file # descriptor set with --cat-blob-fd (or stdout if unspecified). # # To make sure you're observing the side effects of checkpoint *before* # fast-import terminates (and thus writes out its state), check that the # fast-import process is still running using background_import_still_running # *after* evaluating the test conditions. background_import_then_checkpoint () { options=$1 input_file=$2 mkfifo V.input exec 8<>V.input rm V.input mkfifo V.output exec 9<>V.output rm V.output - git fast-import $options <&8 >&9 & - echo $! >V.pid + ( + git fast-import $options <&8 >&9 & + echo $! >V.fi.pid + wait $! + echo >&2 "background fast-import terminated too early with exit code $?" + # Un-block the read loop in the main shell process. + echo >&9 UNEXPECTED + ) & + echo $! >V.sh.pid # We don't mind if fast-import has already died by the time the test # ends. - test_when_finished " + test_when_finished ' exec 8>&-; exec 9>&-; - kill $(cat V.pid) && wait $(cat V.pid) - true" + kill $(cat V.sh.pid) && wait $(cat V.sh.pid) + kill $(cat V.fi.pid) && wait $(cat V.sh.pid) + true' # Start in the background to ensure we adhere strictly to (blocking) # pipes writing sequence. We want to assume that the write below could # block, e.g. if fast-import blocks writing its own output to &9 # because there is no reader on &9 yet. ( cat "$input_file" echo "checkpoint" echo "progress checkpoint" ) >&8 & error=1 ;# assume the worst while read output <&9 do if test "$output" = "progress checkpoint" then error=0 break + elif test "$output" = "UNEXPECTED" + then + break fi # otherwise ignore cruft echo >&2 "cruft: $output" done if test $error -eq 1 then false fi } background_import_still_running () { - if ! kill -0 "$(cat V.pid)" + if ! kill -0 "$(cat V.fi.pid)" then echo >&2 "background fast-import terminated too early" false fi }
-- 2.24.0.643.gac013444ca