Re: [PATCH 5/6] submodule: improve submodule_has_commits
From: Stefan Beller <hidden>
Date: 2017-04-29 00:28:23
On Fri, Apr 28, 2017 at 4:54 PM, Brandon Williams [off-list ref] wrote:
Teach 'submodule_has_commits()' to ensure that if a commit exists in a submodule, that it is also reachable from a ref. This is a prepritory step prior to merging the logic which checkes for
s/prepritory/preparatory/ s/checkes/checks/ This is the first commit in the series that changes user observable behavior, I guess there will be tests in a later patch? Can you elaborate in this commit message more about why it is useful (or at least harmless for performing this check in the case of fetch/push)?
quoted hunk ↗ jump to hunk
diff --git a/submodule.c b/submodule.c index 3bcf44521..100d31d39 100644 --- a/submodule.c +++ b/submodule.c@@ -648,6 +648,30 @@ static int submodule_has_commits(const char *path, struct oid_array *commits) return 0; oid_array_for_each_unique(commits, check_has_commit, &has_commit); + + if (has_commit) { + /* + * Even if the submodule is checked out and the commit is + * present, make sure it is reachable from a ref. + */ + struct child_process cp = CHILD_PROCESS_INIT; + struct strbuf out = STRBUF_INIT; + + argv_array_pushl(&cp.args, "rev-list", "-n", "1", NULL); + oid_array_for_each_unique(commits, append_oid_to_argv, &cp.args); + argv_array_pushl(&cp.args, "--not", "--all", NULL); + + prepare_submodule_repo_env(&cp.env_array); + cp.git_cmd = 1; + cp.no_stdin = 1; + cp.dir = path; + + if (capture_command(&cp, &out, 1024) || out.len) + has_commit = 0;
So if we fail to launch capture_command, we assume we do not have the commits? capture_command can fail for reasons that are hard to track down or even spurious (OOM due to excessive output, disk failure, corrupt repo, error in executing the process, getting a signal and so on), some of them are ok to ignore, others should never be ignored. So I'd rather die on capture_command, and inspect out.len only in case of successful capturing. In addition to that we're only interested if there is any output, such that we can optimize further: c.f. http://public-inbox.org/git/20170324223848.GH31294@aiede.mtv.corp.google.com/ if (start_command(&cp)) die("cannot start git-rev-list in submodule'%s', sub->path); /* read only one character, if any */ if (xread(cp.out, &tmp, 1); has_commit = 0; /* * close cp.out, such that the child may get SIGPIPE, upon which * it dies (silently, maybe we need to suppress cp.err ?) */ close(cp.out); /* * Though we need to be nitpicky about finish_command IIUC by now: * TODO(sbeller): if this turns out to be true, fixup is_submodule_modified */ int code = finish_command(&cp); if (!code && code != 128 + SIGPIPE) die("git rev-list failed in submodule'%s'", sub->path); Upon rereading the patch, I notice the '-n 1', which would make the optimized code above useless, so just consider it food for thought. Thanks, Stefan