From: Emily Shaffer <emilyshaffer@google.com>
To: Jonathan Tan <jonathantanmy@google.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH v7 12/17] hook: allow parallel hook execution
Date: Mon, 22 Feb 2021 13:46:51 -0800 [thread overview]
Message-ID: <YDQmS2qN/lrm547L@google.com> (raw)
In-Reply-To: <20210201060422.1313603-1-jonathantanmy@google.com>
On Sun, Jan 31, 2021 at 10:04:22PM -0800, Jonathan Tan wrote:
>
> > In many cases, there's no reason not to allow hooks to execute in
> > parallel. run_processes_parallel() is well-suited - it's a task queue
> > that runs its housekeeping in series, which means users don't
> > need to worry about thread safety on their callback data. True
> > multithreaded execution with the async_* functions isn't necessary here.
> > Synchronous hook execution can be achieved by only allowing 1 job to run
> > at a time.
> >
> > Teach run_hooks() to use that function for simple hooks which don't
> > require stdin or capture of stderr.
>
> Which hooks would be run in parallel, and which hooks in series? I don't
> see code that distinguishes between them.
It's up to the caller, who can set run_hooks_opt.jobs. In part II of
this series I made a guess at which ones should run in parallel or in
series and specified it in Documentation/githooks.txt.
>
> >
> > Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
> > ---
> >
> > Notes:
> > Per AEvar's request - parallel hook execution on day zero.
> >
> > In most ways run_processes_parallel() worked great for me - but it didn't
> > have great support for hooks where we pipe to and from. I had to add this
> > support later in the series.
> >
> > Since I modified an existing and in-use library I'd appreciate a keen look on
> > these patches.
>
> What is the existing and in-use library that you're modifying?
Hm, this note wasn't super specific. From this point onwards in the
series I make changes to the run-command.h:run_processes_parallel()
library, although not in this commit itself. I think I meant "from here
on out, help me look at run-command.h".
I'll try to make the note a little better next series, sorry for the
confusion :) :)
>
> > @@ -246,11 +255,96 @@ void run_hooks_opt_clear(struct run_hooks_opt *o)
> > strvec_clear(&o->args);
> > }
> >
> > +
> > +static int pick_next_hook(struct child_process *cp,
> > + struct strbuf *out,
> > + void *pp_cb,
> > + void **pp_task_cb)
> > +{
> > + struct hook_cb_data *hook_cb = pp_cb;
> > +
> > + struct hook *hook = list_entry(hook_cb->run_me, struct hook, list);
> > +
> > + if (hook_cb->head == hook_cb->run_me)
> > + return 0;
> > +
> > + cp->env = hook_cb->options->env.v;
> > + cp->stdout_to_stderr = 1;
> > + cp->trace2_hook_name = hook->command.buf;
> > +
> > + /* reopen the file for stdin; run_command closes it. */
> > + if (hook_cb->options->path_to_stdin) {
> > + cp->no_stdin = 0;
> > + cp->in = xopen(hook_cb->options->path_to_stdin, O_RDONLY);
> > + } else {
> > + cp->no_stdin = 1;
> > + }
> > +
> > + /*
> > + * Commands from the config could be oneliners, but we know
> > + * for certain that hookdir commands are not.
> > + */
> > + if (hook->from_hookdir)
> > + cp->use_shell = 0;
> > + else
> > + cp->use_shell = 1;
> > +
> > + /* add command */
> > + strvec_push(&cp->args, hook->command.buf);
> > +
> > + /*
> > + * add passed-in argv, without expanding - let the user get back
> > + * exactly what they put in
> > + */
> > + strvec_pushv(&cp->args, hook_cb->options->args.v);
>
> I just skimmed over this setup-process-for-hook part - it would have
> been much clearer if it was refactored into its own function before this
> patch (or better yet, written as its own function in the first place).
> As it is, there are some unnecessary rewritings - e.g. setting stdin
> after env, and the use_shell setup.
Yeah, that makes sense. Will see if I can change it for next round :)
>
> > diff --git a/hook.h b/hook.h
>
> [snip]
>
> > +/*
> > + * Callback provided to feed_pipe_fn and consume_sideband_fn.
> > + */
> > +struct hook_cb_data {
> > + int rc;
> > + struct list_head *head;
> > + struct list_head *run_me;
> > + struct run_hooks_opt *options;
> > +};
>
> Could this be in hook.c instead?
It ends up being needed publicly by
https://lore.kernel.org/git/20201222000435.1529768-17-emilyshaffer@google.com
(receive-pack: convert receive hooks to hook.h), which writes its own
stdin provider callback. (In a later commit, a "void* options" gets
added to this struct.)
At that point it's needed because the run-command callback structure can
provide one context pointer for the overall work queue, and one context
pointer for the individual task; this one is the "overall work queue"
pointer.
From hook.h's perspective, the entire hook_cb_data is needed for
pick_next_hook; but run-command.h:run_processes_parallel() doesn't have
a way to tease out a smaller amount of the context pointer for various
callbacks. If we wanted to obfuscate "hook_cb_data" we'd need to add
another indirection and call back to hook.h first, who could then tease
out the client-provided context and then call the client callback, but
to me it sounds unnecessarily complex.
>
> Also, I think it's clearer if run_me was a struct hook, and set to NULL
> when iteration reaches the end. If you disagree, I think it needs some
> documentation (e.g. "the embedded linked list part of the hook that must
> be run next; if equal to head, then iteration has ended" or something
> like that).
Yeah, I don't see a huge reason not to do that, sure.
>
> > +#define RUN_HOOKS_OPT_INIT_SYNC { \
> > .env = STRVEC_INIT, \
> > .args = STRVEC_INIT, \
> > .path_to_stdin = NULL, \
> > + .jobs = 1, \
> > .run_hookdir = configured_hookdir_opt() \
> > }
>
> This is not used anywhere.
It is used in part II by hooks which are not able to be parallelized.
- Emily
next prev parent reply other threads:[~2021-02-22 21:47 UTC|newest]
Thread overview: 170+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 18:54 [PATCH v2 0/4] propose config-based hooks Emily Shaffer
2020-05-21 18:54 ` [PATCH v2 1/4] doc: propose hooks managed by the config Emily Shaffer
2020-05-22 10:13 ` Phillip Wood
2020-06-09 20:26 ` Emily Shaffer
2020-05-21 18:54 ` [PATCH v2 2/4] hook: scaffolding for git-hook subcommand Emily Shaffer
2020-05-21 18:54 ` [PATCH v2 3/4] hook: add list command Emily Shaffer
2020-05-22 10:27 ` Phillip Wood
2020-06-09 21:49 ` Emily Shaffer
2020-08-17 13:36 ` Phillip Wood
2020-05-24 23:00 ` Johannes Schindelin
2020-05-27 23:37 ` Emily Shaffer
2020-05-21 18:54 ` [PATCH v2 4/4] hook: add --porcelain to " Emily Shaffer
2020-05-24 23:00 ` Johannes Schindelin
2020-05-25 0:29 ` Johannes Schindelin
2020-07-28 22:24 ` [PATCH v3 0/6] propose config-based hooks Emily Shaffer
2020-07-28 22:24 ` [PATCH v3 1/6] doc: propose hooks managed by the config Emily Shaffer
2020-07-28 22:24 ` [PATCH v3 2/6] hook: scaffolding for git-hook subcommand Emily Shaffer
2020-07-28 22:24 ` [PATCH v3 3/6] hook: add list command Emily Shaffer
2020-07-28 22:24 ` [PATCH v3 4/6] hook: add --porcelain to " Emily Shaffer
2020-07-28 22:24 ` [RFC PATCH v3 5/6] parse-options: parse into argv_array Emily Shaffer
2020-07-29 19:33 ` Junio C Hamano
2020-07-30 23:41 ` Junio C Hamano
2020-07-28 22:24 ` [RFC PATCH v3 6/6] hook: add 'run' subcommand Emily Shaffer
2020-09-09 0:49 ` [PATCH v4 0/9] propose config-based hooks Emily Shaffer
2020-09-09 0:49 ` [PATCH v4 1/9] doc: propose hooks managed by the config Emily Shaffer
2020-09-23 22:59 ` Jonathan Tan
2020-09-24 21:54 ` Emily Shaffer
2020-10-07 9:23 ` Ævar Arnfjörð Bjarmason
2020-10-22 0:58 ` Emily Shaffer
2020-10-23 19:10 ` Ævar Arnfjörð Bjarmason
2020-10-29 15:38 ` Emily Shaffer
2020-10-29 20:04 ` Ævar Arnfjörð Bjarmason
2020-09-09 0:49 ` [PATCH v4 2/9] hook: scaffolding for git-hook subcommand Emily Shaffer
2020-10-05 23:24 ` Jonathan Nieder
2020-10-06 19:06 ` Emily Shaffer
2020-09-09 0:49 ` [PATCH v4 3/9] hook: add list command Emily Shaffer
2020-09-11 13:27 ` Phillip Wood
2020-09-11 16:51 ` Emily Shaffer
2020-09-23 23:04 ` Jonathan Tan
2020-10-06 20:46 ` Emily Shaffer
2020-09-27 19:23 ` Martin Ågren
2020-10-06 20:20 ` Emily Shaffer
2020-10-05 23:27 ` Jonathan Nieder
2020-09-09 0:49 ` [PATCH v4 4/9] hook: add --porcelain to " Emily Shaffer
2020-09-28 19:29 ` Josh Steadmon
2020-09-09 0:49 ` [PATCH v4 5/9] parse-options: parse into strvec Emily Shaffer
2020-10-05 23:30 ` Jonathan Nieder
2020-10-06 4:49 ` Junio C Hamano
2020-09-09 0:49 ` [PATCH v4 6/9] hook: add 'run' subcommand Emily Shaffer
2020-09-11 13:30 ` Phillip Wood
2020-09-28 19:29 ` Josh Steadmon
2020-10-05 23:39 ` Jonathan Nieder
2020-10-06 22:57 ` Emily Shaffer
2020-09-09 0:49 ` [PATCH v4 7/9] hook: replace run-command.h:find_hook Emily Shaffer
2020-09-09 20:32 ` Junio C Hamano
2020-09-10 19:08 ` Emily Shaffer
2020-09-23 23:20 ` Jonathan Tan
2020-10-05 23:42 ` Jonathan Nieder
2020-09-09 0:49 ` [PATCH v4 8/9] commit: use config-based hooks Emily Shaffer
2020-09-10 13:50 ` Phillip Wood
2020-09-10 22:21 ` Junio C Hamano
2020-09-23 23:47 ` Jonathan Tan
2020-10-05 21:27 ` Emily Shaffer
2020-10-05 23:48 ` Jonathan Nieder
2020-10-06 19:08 ` Emily Shaffer
2020-09-09 0:49 ` [PATCH v4 9/9] run_commit_hook: take strvec instead of varargs Emily Shaffer
2020-09-10 14:16 ` Phillip Wood
2020-09-11 13:20 ` Phillip Wood
2020-09-09 21:04 ` [PATCH v4 0/9] propose config-based hooks Junio C Hamano
2020-10-14 23:24 ` [PATCH v5 0/8] propose config-based hooks (part I) Emily Shaffer
2020-10-14 23:24 ` [PATCH v5 1/8] doc: propose hooks managed by the config Emily Shaffer
2020-10-15 16:31 ` Ævar Arnfjörð Bjarmason
2020-10-16 17:29 ` Junio C Hamano
2020-10-21 23:37 ` Emily Shaffer
2020-10-14 23:24 ` [PATCH v5 2/8] hook: scaffolding for git-hook subcommand Emily Shaffer
2020-10-14 23:24 ` [PATCH v5 3/8] hook: add list command Emily Shaffer
2020-10-14 23:24 ` [PATCH v5 4/8] hook: include hookdir hook in list Emily Shaffer
2020-10-14 23:24 ` [PATCH v5 5/8] hook: implement hookcmd.<name>.skip Emily Shaffer
2020-10-14 23:24 ` [PATCH v5 6/8] parse-options: parse into strvec Emily Shaffer
2020-10-14 23:24 ` [PATCH v5 7/8] hook: add 'run' subcommand Emily Shaffer
2020-10-14 23:24 ` [PATCH v5 8/8] hook: replace find_hook() with hook_exists() Emily Shaffer
2020-12-05 1:45 ` [PATCH v6 00/17] propose config-based hooks (part I) Emily Shaffer
2020-12-05 1:45 ` [PATCH 01/17] doc: propose hooks managed by the config Emily Shaffer
2020-12-05 1:45 ` [PATCH 02/17] hook: scaffolding for git-hook subcommand Emily Shaffer
2020-12-05 1:45 ` [PATCH 03/17] hook: add list command Emily Shaffer
2020-12-05 1:45 ` [PATCH 04/17] hook: include hookdir hook in list Emily Shaffer
2020-12-05 1:45 ` [PATCH 05/17] hook: respect hook.runHookDir Emily Shaffer
2020-12-05 1:45 ` [PATCH 06/17] hook: implement hookcmd.<name>.skip Emily Shaffer
2020-12-05 1:45 ` [PATCH 07/17] parse-options: parse into strvec Emily Shaffer
2020-12-05 1:45 ` [PATCH 08/17] hook: add 'run' subcommand Emily Shaffer
2020-12-11 10:15 ` Phillip Wood
2020-12-15 21:41 ` Emily Shaffer
2020-12-05 1:45 ` [PATCH 09/17] hook: replace find_hook() with hook_exists() Emily Shaffer
2020-12-05 1:46 ` [PATCH 10/17] hook: support passing stdin to hooks Emily Shaffer
2020-12-05 1:46 ` [PATCH 11/17] run-command: allow stdin for run_processes_parallel Emily Shaffer
2020-12-05 1:46 ` [PATCH 12/17] hook: allow parallel hook execution Emily Shaffer
2020-12-05 1:46 ` [PATCH 13/17] hook: allow specifying working directory for hooks Emily Shaffer
2020-12-05 1:46 ` [PATCH 14/17] run-command: add stdin callback for parallelization Emily Shaffer
2020-12-05 1:46 ` [PATCH 15/17] hook: provide stdin by string_list or callback Emily Shaffer
2020-12-08 21:09 ` SZEDER Gábor
2020-12-08 22:11 ` Emily Shaffer
2020-12-05 1:46 ` [PATCH 16/17] run-command: allow capturing of collated output Emily Shaffer
2020-12-05 1:46 ` [PATCH 17/17] hooks: allow callers to capture output Emily Shaffer
2020-12-16 0:34 ` [PATCH v6 00/17] propose config-based hooks (part I) Josh Steadmon
2020-12-16 0:56 ` Junio C Hamano
2020-12-16 20:16 ` Emily Shaffer
2020-12-16 23:32 ` Junio C Hamano
2020-12-18 2:07 ` Emily Shaffer
2020-12-18 5:29 ` Junio C Hamano
2020-12-22 0:02 ` [PATCH v7 " Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 01/17] doc: propose hooks managed by the config Emily Shaffer
2021-01-23 15:38 ` Ævar Arnfjörð Bjarmason
2021-01-29 23:52 ` Emily Shaffer
2021-02-01 22:11 ` Junio C Hamano
2021-03-10 19:30 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 02/17] hook: scaffolding for git-hook subcommand Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 03/17] hook: add list command Emily Shaffer
2021-01-31 3:10 ` Jonathan Tan
2021-02-09 21:06 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 04/17] hook: include hookdir hook in list Emily Shaffer
2021-01-31 3:20 ` Jonathan Tan
2021-02-09 22:05 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 05/17] hook: respect hook.runHookDir Emily Shaffer
2021-01-31 3:35 ` Jonathan Tan
2021-02-09 22:31 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 06/17] hook: implement hookcmd.<name>.skip Emily Shaffer
2021-01-31 3:40 ` Jonathan Tan
2021-02-09 22:57 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 07/17] parse-options: parse into strvec Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 08/17] hook: add 'run' subcommand Emily Shaffer
2021-01-31 4:22 ` Jonathan Tan
2021-02-11 22:44 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 09/17] hook: replace find_hook() with hook_exists() Emily Shaffer
2021-01-31 4:39 ` Jonathan Tan
2021-02-12 22:15 ` Emily Shaffer
2021-02-18 22:23 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 10/17] hook: support passing stdin to hooks Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 11/17] run-command: allow stdin for run_processes_parallel Emily Shaffer
2021-02-01 5:38 ` Jonathan Tan
2021-02-19 20:23 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 12/17] hook: allow parallel hook execution Emily Shaffer
2021-02-01 6:04 ` Jonathan Tan
2021-02-22 21:46 ` Emily Shaffer [this message]
2020-12-22 0:02 ` [PATCH v7 13/17] hook: allow specifying working directory for hooks Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 14/17] run-command: add stdin callback for parallelization Emily Shaffer
2021-02-01 6:51 ` Jonathan Tan
2021-02-22 23:38 ` Emily Shaffer
2021-02-23 19:33 ` Jonathan Tan
2021-03-10 18:24 ` Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 15/17] hook: provide stdin by string_list or callback Emily Shaffer
2021-02-01 7:04 ` Jonathan Tan
2021-02-23 19:52 ` Emily Shaffer
2021-02-25 20:56 ` Jonathan Tan
2021-03-02 1:47 ` Emily Shaffer
2021-03-02 23:33 ` Jonathan Tan
2020-12-22 0:02 ` [PATCH v7 16/17] run-command: allow capturing of collated output Emily Shaffer
2020-12-22 0:02 ` [PATCH v7 17/17] hooks: allow callers to capture output Emily Shaffer
2020-12-22 2:11 ` [PATCH v7 00/17] propose config-based hooks (part I) Junio C Hamano
2020-12-28 18:34 ` Emily Shaffer
2020-12-28 22:50 ` Junio C Hamano
2020-12-28 22:37 ` [PATCH v3 18/17] doc: make git-hook.txt point of truth Emily Shaffer
2020-12-28 22:39 ` Emily Shaffer
2021-01-29 23:59 ` [PATCH v7 00/17] propose config-based hooks (part I) Emily Shaffer
2021-02-16 19:46 ` Josh Steadmon
2021-02-16 22:47 ` Junio C Hamano
2021-02-17 21:21 ` Josh Steadmon
2021-02-17 23:07 ` Junio C Hamano
2021-02-25 19:50 ` Junio C Hamano
2021-03-01 21:51 ` Emily Shaffer
2021-03-01 22:19 ` Junio C Hamano
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