kernel/git - git - PowerEL Git System

Author	SHA1	Message	Date
Stefan Beller	2a73b3dad0	run-command: do not pass child process data into callbacks The expected way to pass data into the callback is to pass them via the customizable callback pointer. The error reporting in default_{start_failure, task_finished} is not user friendly enough, that we want to encourage using the child data for such purposes. Furthermore the struct child data is cleaned by the run-command API, before we access them in the callbacks, leading to use-after-free situations. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Stefan Beller	c553c72eed	run-command: add an asynchronous parallel child processor This allows to run external commands in parallel with ordered output on stderr. If we run external commands in parallel we cannot pipe the output directly to the our stdout/err as it would mix up. So each process's output will flow through a pipe, which we buffer. One subprocess can be directly piped to out stdout/err for a low latency feedback to the user. Example: Let's assume we have 5 submodules A,B,C,D,E and each fetch takes a different amount of time as the different submodules vary in size, then the output of fetches in sequential order might look like this: time --> output: \|---A---\| \|-B-\| \|-------C-------\| \|-D-\| \|-E-\| When we schedule these submodules into maximal two parallel processes, a schedule and sample output over time may look like this: process 1: \|---A---\| \|-D-\| \|-E-\| process 2: \|-B-\| \|-------C-------\| output: \|---A---\|B\|---C-------\|DE So A will be perceived as it would run normally in the single child version. As B has finished by the time A is done, we can dump its whole progress buffer on stderr, such that it looks like it finished in no time. Once that is done, C is determined to be the visible child and its progress will be reported in real time. So this way of output is really good for human consumption, as it only changes the timing, not the actual output. For machine consumption the output needs to be prepared in the tasks, by either having a prefix per line or per block to indicate whose tasks output is displayed, because the output order may not follow the original sequential ordering: \|----A----\| \|--B--\| \|-C-\| will be scheduled to be all parallel: process 1: \|----A----\| process 2: \|--B--\| process 3: \|-C-\| output: \|----A----\|CB This happens because C finished before B did, so it will be queued for output before B. To detect when a child has finished executing, we check interleaved with other actions (such as checking the liveliness of children or starting new processes) whether the stderr pipe still exists. Once a child closed its stderr stream, we assume it is terminating very soon, and use `finish_command()` from the single external process execution interface to collect the exit status. By maintaining the strong assumption of stderr being open until the very end of a child process, we can avoid other hassle such as an implementation using `waitpid(-1)`, which is not implemented in Windows. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
René Scharfe	d318027932	run-command: introduce CHILD_PROCESS_INIT Most struct child_process variables are cleared using memset first after declaration. Provide a macro, CHILD_PROCESS_INIT, that can be used to initialize them statically instead. That's shorter, doesn't require a function call and is slightly more readable (especially given that we already have STRBUF_INIT, ARGV_ARRAY_INIT etc.). Helped-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Jonathan Nieder	c0f19bf3b9	tests: check error message from run_command In git versions starting at v1.7.5-rc0~29^2 until v1.7.5-rc3~2 (Revert "run-command: prettify -D_FORTIFY_SOURCE workaround", 2011-04-18) fixed it, the run_command facility would write a truncated error message when the command is present but cannot be executed for some other reason. For example, if I add a 'hello' command to git: $ echo 'echo hello' >git-hello $ chmod +x git-hello $ PATH=.:$PATH git hello hello and make it non-executable, this is what I normally get: $ chmod -x git-hello $ git hello fatal: cannot exec 'git-hello': Permission denied But with the problematic versions, we get disturbing output: $ PATH=.:$PATH git hello fatal: $ Add some tests to make sure it doesn't happen again. The hello-script used in these tests uses cat instead of echo because on Windows the bash spawned by git converts LF to CRLF in text written by echo while the bash running tests does not, causing the test to fail if "echo" is used. Thanks to Hannes for noticing. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Improved-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	14 years ago
Johannes Sixt	2b541bf8be	start_command: detect execvp failures early Previously, failures during execvp could be detected only by finish_command. However, in some situations it is beneficial for the parent process to know earlier that the child process will not run. The idea to use a pipe to signal failures to the parent process and the test case were lifted from patches by Ilari Liusvaara. Signed-off-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago