[PATCHv12 0/7] Expose submodule parallelism to the user

[PATCHv12 0/7] Expose submodule parallelism to the user

[Stefan Beller]

Thanks Junio for a review of v11!

I addressed the memory issue with the interdiff (in patch 1/7) as follows:
Interdiff to v11:

diff --git a/submodule.c b/submodule.c
index 263cb2a..45d0967 100644
--- a/submodule.c
+++ b/submodule.c
@@ -219,6 +219,9 @@ void gitmodules_config(void)
 int parse_submodule_update_strategy(const char *value,
                struct submodule_update_strategy *dst)
 {
+       const char *com;
+
+       free((void*)dst->command);
        dst->command = NULL;
        if (!strcmp(value, "none"))
                dst->type = SM_UPDATE_NONE;
@@ -228,9 +231,10 @@ int parse_submodule_update_strategy(const char *value,
                dst->type = SM_UPDATE_REBASE;
        else if (!strcmp(value, "merge"))
                dst->type = SM_UPDATE_MERGE;
-       else if (skip_prefix(value, "!", &dst->command))
+       else if (skip_prefix(value, "!", &com)) {
                dst->type = SM_UPDATE_COMMAND;
-       else
+               dst->command = xstrdup(com);
+       } else
                return -1;
        return 0;
 }

Stefan Beller (7):
  submodule-config: keep update strategy around
  submodule-config: drop check against NULL
  fetching submodules: respect `submodule.fetchJobs` config option
  submodule update: direct error message to stderr
  git submodule update: have a dedicated helper for cloning
  submodule update: expose parallelism to the user
  clone: allow an explicit argument for parallel submodule clones

 Documentation/config.txt        |   6 +
 Documentation/git-clone.txt     |   6 +-
 Documentation/git-submodule.txt |   7 +-
 builtin/clone.c                 |  19 +++-
 builtin/fetch.c                 |   2 +-
 builtin/submodule--helper.c     | 239 ++++++++++++++++++++++++++++++++++++++++
 git-submodule.sh                |  54 ++++-----
 submodule-config.c              |  18 ++-
 submodule-config.h              |   2 +
 submodule.c                     |  39 ++++++-
 submodule.h                     |  18 +++
 t/t5526-fetch-submodules.sh     |  14 +++
 t/t7400-submodule-basic.sh      |   4 +-
 t/t7406-submodule-update.sh     |  27 +++++
 14 files changed, 406 insertions(+), 49 deletions(-)

-- 
2.7.0.rc0.34.g65aed89

[PATCHv12 1/7] submodule-config: keep update strategy around

[Stefan Beller]

Currently submodule.<name>.update is only handled by git-submodule.sh.
C code will start to need to make use of that value as more of the
functionality of git-submodule.sh moves into library code in C.

Add the update field to 'struct submodule' and populate it so it can
be read as sm->update or from sm->update_command.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 submodule-config.c | 12 ++++++++++++
 submodule-config.h |  2 ++
 submodule.c        | 23 +++++++++++++++++++++++
 submodule.h        | 16 ++++++++++++++++
 4 files changed, 53 insertions(+)

diff --git a/submodule-config.c b/submodule-config.c
index afe0ea8..f8d1be9 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -194,6 +194,8 @@ static struct submodule *lookup_or_create_by_name(struct submodule_cache *cache,
 
 	submodule->path = NULL;
 	submodule->url = NULL;
+	submodule->update_strategy.type = SM_UPDATE_UNSPECIFIED;
+	submodule->update_strategy.command = NULL;
 	submodule->fetch_recurse = RECURSE_SUBMODULES_NONE;
 	submodule->ignore = NULL;
 
@@ -311,6 +313,16 @@ static int parse_config(const char *var, const char *value, void *data)
 			free((void *) submodule->url);
 			submodule->url = xstrdup(value);
 		}
+	} else if (!strcmp(item.buf, "update")) {
+		if (!value)
+			ret = config_error_nonbool(var);
+		else if (!me->overwrite &&
+			 submodule->update_strategy.type != SM_UPDATE_UNSPECIFIED)
+			warn_multiple_config(me->commit_sha1, submodule->name,
+					     "update");
+		else if (parse_submodule_update_strategy(value,
+			 &submodule->update_strategy) < 0)
+				die(_("invalid value for %s"), var);
 	}
 
 	strbuf_release(&name);
diff --git a/submodule-config.h b/submodule-config.h
index 9061e4e..092ebfc 100644
--- a/submodule-config.h
+++ b/submodule-config.h
@@ -2,6 +2,7 @@
 #define SUBMODULE_CONFIG_CACHE_H
 
 #include "hashmap.h"
+#include "submodule.h"
 #include "strbuf.h"
 
 /*
@@ -14,6 +15,7 @@ struct submodule {
 	const char *url;
 	int fetch_recurse;
 	const char *ignore;
+	struct submodule_update_strategy update_strategy;
 	/* the sha1 blob id of the responsible .gitmodules file */
 	unsigned char gitmodules_sha1[20];
 };
diff --git a/submodule.c b/submodule.c
index b83939c..1de465f 100644
--- a/submodule.c
+++ b/submodule.c
@@ -210,6 +210,29 @@ void gitmodules_config(void)
 	}
 }
 
+int parse_submodule_update_strategy(const char *value,
+		struct submodule_update_strategy *dst)
+{
+	const char *com;
+
+	free((void*)dst->command);
+	dst->command = NULL;
+	if (!strcmp(value, "none"))
+		dst->type = SM_UPDATE_NONE;
+	else if (!strcmp(value, "checkout"))
+		dst->type = SM_UPDATE_CHECKOUT;
+	else if (!strcmp(value, "rebase"))
+		dst->type = SM_UPDATE_REBASE;
+	else if (!strcmp(value, "merge"))
+		dst->type = SM_UPDATE_MERGE;
+	else if (skip_prefix(value, "!", &com)) {
+		dst->type = SM_UPDATE_COMMAND;
+		dst->command = xstrdup(com);
+	} else
+		return -1;
+	return 0;
+}
+
 void handle_ignore_submodules_arg(struct diff_options *diffopt,
 				  const char *arg)
 {
diff --git a/submodule.h b/submodule.h
index cbc0003..3464500 100644
--- a/submodule.h
+++ b/submodule.h
@@ -13,6 +13,20 @@ enum {
 	RECURSE_SUBMODULES_ON = 2
 };
 
+enum submodule_update_type {
+	SM_UPDATE_UNSPECIFIED = 0,
+	SM_UPDATE_CHECKOUT,
+	SM_UPDATE_REBASE,
+	SM_UPDATE_MERGE,
+	SM_UPDATE_NONE,
+	SM_UPDATE_COMMAND
+};
+
+struct submodule_update_strategy {
+	enum submodule_update_type type;
+	const char *command;
+};
+
 int is_staging_gitmodules_ok(void);
 int update_path_in_gitmodules(const char *oldpath, const char *newpath);
 int remove_path_from_gitmodules(const char *path);
@@ -21,6 +35,8 @@ void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
 		const char *path);
 int submodule_config(const char *var, const char *value, void *cb);
 void gitmodules_config(void);
+int parse_submodule_update_strategy(const char *value,
+		struct submodule_update_strategy *dst);
 void handle_ignore_submodules_arg(struct diff_options *diffopt, const char *);
 void show_submodule_summary(FILE *f, const char *path,
 		const char *line_prefix,
-- 
2.7.0.rc0.34.g65aed89

[PATCHv12 2/7] submodule-config: drop check against NULL

[Stefan Beller]

Adhere to the common coding style of Git and not check explicitly
for NULL throughout the file. There are still other occurrences in the
code base but that is usually inside of conditions with side effects.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 submodule-config.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/submodule-config.c b/submodule-config.c
index f8d1be9..02bcaa7 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -266,7 +266,7 @@ static int parse_config(const char *var, const char *value, void *data)
 	if (!strcmp(item.buf, "path")) {
 		if (!value)
 			ret = config_error_nonbool(var);
-		else if (!me->overwrite && submodule->path != NULL)
+		else if (!me->overwrite && submodule->path)
 			warn_multiple_config(me->commit_sha1, submodule->name,
 					"path");
 		else {
@@ -290,7 +290,7 @@ static int parse_config(const char *var, const char *value, void *data)
 	} else if (!strcmp(item.buf, "ignore")) {
 		if (!value)
 			ret = config_error_nonbool(var);
-		else if (!me->overwrite && submodule->ignore != NULL)
+		else if (!me->overwrite && submodule->ignore)
 			warn_multiple_config(me->commit_sha1, submodule->name,
 					"ignore");
 		else if (strcmp(value, "untracked") &&
@@ -306,7 +306,7 @@ static int parse_config(const char *var, const char *value, void *data)
 	} else if (!strcmp(item.buf, "url")) {
 		if (!value) {
 			ret = config_error_nonbool(var);
-		} else if (!me->overwrite && submodule->url != NULL) {
+		} else if (!me->overwrite && submodule->url) {
 			warn_multiple_config(me->commit_sha1, submodule->name,
 					"url");
 		} else {
-- 
2.7.0.rc0.34.g65aed89

[PATCHv12 3/7] fetching submodules: respect `submodule.fetchJobs` config option

[Stefan Beller]

This allows to configure fetching and updating in parallel
without having the command line option.

This moved the responsibility to determine how many parallel processes
to start from builtin/fetch to submodule.c as we need a way to communicate
"The user did not specify the number of parallel processes in the command
line options" in the builtin fetch. The submodule code takes care of
the precedence (CLI > config > default).

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/config.txt    |  6 ++++++
 builtin/fetch.c             |  2 +-
 submodule.c                 | 16 +++++++++++++++-
 submodule.h                 |  2 ++
 t/t5526-fetch-submodules.sh | 14 ++++++++++++++
 5 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 2d06b11..3b02732 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -2646,6 +2646,12 @@ submodule.<name>.ignore::
 	"--ignore-submodules" option. The 'git submodule' commands are not
 	affected by this setting.
 
+submodule.fetchJobs::
+	Specifies how many submodules are fetched/cloned at the same time.
+	A positive integer allows up to that number of submodules fetched
+	in parallel. A value of 0 will give some reasonable default.
+	If unset, it defaults to 1.
+
 tag.sort::
 	This variable controls the sort ordering of tags when displayed by
 	linkgit:git-tag[1]. Without the "--sort=<value>" option provided, the
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 586840d..5aa1c2d 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -37,7 +37,7 @@ static int prune = -1; /* unspecified */
 static int all, append, dry_run, force, keep, multiple, update_head_ok, verbosity;
 static int progress = -1, recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
 static int tags = TAGS_DEFAULT, unshallow, update_shallow;
-static int max_children = 1;
+static int max_children = -1;
 static const char *depth;
 static const char *upload_pack;
 static struct strbuf default_rla = STRBUF_INIT;
diff --git a/submodule.c b/submodule.c
index 1de465f..45d0967 100644
--- a/submodule.c
+++ b/submodule.c
@@ -15,6 +15,7 @@
 #include "thread-utils.h"
 
 static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
+static int parallel_jobs = 1;
 static struct string_list changed_submodule_paths;
 static int initialized_fetch_ref_tips;
 static struct sha1_array ref_tips_before_fetch;
@@ -169,7 +170,12 @@ void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
 
 int submodule_config(const char *var, const char *value, void *cb)
 {
-	if (starts_with(var, "submodule."))
+	if (!strcmp(var, "submodule.fetchjobs")) {
+		parallel_jobs = git_config_int(var, value);
+		if (parallel_jobs < 0)
+			die(_("negative values not allowed for submodule.fetchJobs"));
+		return 0;
+	} else if (starts_with(var, "submodule."))
 		return parse_submodule_config_option(var, value);
 	else if (!strcmp(var, "fetch.recursesubmodules")) {
 		config_fetch_recurse_submodules = parse_fetch_recurse_submodules_arg(var, value);
@@ -774,6 +780,9 @@ int fetch_populated_submodules(const struct argv_array *options,
 	argv_array_push(&spf.args, "--recurse-submodules-default");
 	/* default value, "--submodule-prefix" and its value are added later */
 
+	if (max_parallel_jobs < 0)
+		max_parallel_jobs = parallel_jobs;
+
 	calculate_changed_submodule_paths();
 	run_processes_parallel(max_parallel_jobs,
 			       get_next_submodule,
@@ -1120,3 +1129,8 @@ void connect_work_tree_and_git_dir(const char *work_tree, const char *git_dir)
 	strbuf_release(&rel_path);
 	free((void *)real_work_tree);
 }
+
+int parallel_submodules(void)
+{
+	return parallel_jobs;
+}
diff --git a/submodule.h b/submodule.h
index 3464500..3166608 100644
--- a/submodule.h
+++ b/submodule.h
@@ -26,6 +26,7 @@ struct submodule_update_strategy {
 	enum submodule_update_type type;
 	const char *command;
 };
+#define SUBMODULE_UPDATE_STRATEGY_INIT {SM_UPDATE_UNSPECIFIED, NULL}
 
 int is_staging_gitmodules_ok(void);
 int update_path_in_gitmodules(const char *oldpath, const char *newpath);
@@ -57,5 +58,6 @@ int find_unpushed_submodules(unsigned char new_sha1[20], const char *remotes_nam
 		struct string_list *needs_pushing);
 int push_unpushed_submodules(unsigned char new_sha1[20], const char *remotes_name);
 void connect_work_tree_and_git_dir(const char *work_tree, const char *git_dir);
+int parallel_submodules(void);
 
 #endif
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 1241146..954d0e4 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -471,4 +471,18 @@ test_expect_success "don't fetch submodule when newly recorded commits are alrea
 	test_i18ncmp expect.err actual.err
 '
 
+test_expect_success 'fetching submodules respects parallel settings' '
+	git config fetch.recurseSubmodules true &&
+	(
+		cd downstream &&
+		GIT_TRACE=$(pwd)/trace.out git fetch --jobs 7 &&
+		grep "7 tasks" trace.out &&
+		git config submodule.fetchJobs 8 &&
+		GIT_TRACE=$(pwd)/trace.out git fetch &&
+		grep "8 tasks" trace.out &&
+		GIT_TRACE=$(pwd)/trace.out git fetch --jobs 9 &&
+		grep "9 tasks" trace.out
+	)
+'
+
 test_done
-- 
2.7.0.rc0.34.g65aed89

[PATCHv12 4/7] submodule update: direct error message to stderr

[Stefan Beller]

Reroute the error message for specified but initialized submodules
to stderr instead of stdout.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 git-submodule.sh           | 4 ++--
 t/t7400-submodule-basic.sh | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/git-submodule.sh b/git-submodule.sh
index 9bc5c5f..9ee86d4 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -693,7 +693,7 @@ cmd_update()
 
 		if test "$update_module" = "none"
 		then
-			echo "Skipping submodule '$displaypath'"
+			echo >&2 "Skipping submodule '$displaypath'"
 			continue
 		fi
 
@@ -702,7 +702,7 @@ cmd_update()
 			# Only mention uninitialized submodules when its
 			# path have been specified
 			test "$#" != "0" &&
-			say "$(eval_gettext "Submodule path '\$displaypath' not initialized
+			say >&2 "$(eval_gettext "Submodule path '\$displaypath' not initialized
 Maybe you want to use 'update --init'?")"
 			continue
 		fi
diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index 540771c..5991e3c 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -462,7 +462,7 @@ test_expect_success 'update --init' '
 	git config --remove-section submodule.example &&
 	test_must_fail git config submodule.example.url &&
 
-	git submodule update init > update.out &&
+	git submodule update init 2> update.out &&
 	cat update.out &&
 	test_i18ngrep "not initialized" update.out &&
 	test_must_fail git rev-parse --resolve-git-dir init/.git &&
@@ -480,7 +480,7 @@ test_expect_success 'update --init from subdirectory' '
 	mkdir -p sub &&
 	(
 		cd sub &&
-		git submodule update ../init >update.out &&
+		git submodule update ../init 2>update.out &&
 		cat update.out &&
 		test_i18ngrep "not initialized" update.out &&
 		test_must_fail git rev-parse --resolve-git-dir ../init/.git &&
-- 
2.7.0.rc0.34.g65aed89

[PATCHv12 5/7] git submodule update: have a dedicated helper for cloning

[Stefan Beller]

This introduces a new helper function in git submodule--helper
which takes care of cloning all submodules, which we want to
parallelize eventually.

Some tests (such as empty URL, update_mode=none) are required in the
helper to make the decision for cloning. These checks have been
moved into the C function as well (no need to repeat them in the
shell script).

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/submodule--helper.c | 231 ++++++++++++++++++++++++++++++++++++++++++++
 git-submodule.sh            |  45 +++------
 2 files changed, 242 insertions(+), 34 deletions(-)

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index f4c3eff..7629a41 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -255,6 +255,236 @@ static int module_clone(int argc, const char **argv, const char *prefix)
 	return 0;
 }
 
+struct submodule_update_clone {
+	/* states */
+	int count;
+	int print_unmatched;
+	/* configuration */
+	int quiet;
+	const char *reference;
+	const char *depth;
+	const char *recursive_prefix;
+	const char *prefix;
+	struct module_list list;
+	struct string_list projectlines;
+	struct submodule_update_strategy update;
+	struct pathspec pathspec;
+};
+#define SUBMODULE_UPDATE_CLONE_INIT {0, 0, 0, NULL, NULL, NULL, NULL, MODULE_LIST_INIT, STRING_LIST_INIT_DUP, SUBMODULE_UPDATE_STRATEGY_INIT}
+
+static int update_clone_inspect_next_task(struct child_process *cp,
+					  struct strbuf *err,
+					  struct submodule_update_clone *pp,
+					  void **pp_task_cb,
+					  const struct cache_entry *ce)
+{
+	const struct submodule *sub = NULL;
+	struct strbuf displaypath_sb = STRBUF_INIT;
+	struct strbuf sb = STRBUF_INIT;
+	const char *displaypath = NULL;
+	char *url = NULL;
+	int needs_cloning = 0;
+
+	if (ce_stage(ce)) {
+		if (pp->recursive_prefix)
+			strbuf_addf(err, "Skipping unmerged submodule %s/%s\n",
+				    pp->recursive_prefix, ce->name);
+		else
+			strbuf_addf(err, "Skipping unmerged submodule %s\n",
+				    ce->name);
+		goto cleanup;
+	}
+
+	sub = submodule_from_path(null_sha1, ce->name);
+
+	if (pp->recursive_prefix)
+		displaypath = relative_path(pp->recursive_prefix,
+					    ce->name, &displaypath_sb);
+	else
+		displaypath = ce->name;
+
+	if (pp->update.type == SM_UPDATE_NONE ||
+	    (pp->update.type == SM_UPDATE_UNSPECIFIED &&
+	     sub->update_strategy.type == SM_UPDATE_NONE)) {
+		strbuf_addf(err, "Skipping submodule '%s'\n",
+			    displaypath);
+		goto cleanup;
+	}
+
+	/*
+	 * Looking up the url in .git/config.
+	 * We must not fall back to .gitmodules as we only want
+	 * to process configured submodules.
+	 */
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "submodule.%s.url", sub->name);
+	git_config_get_string(sb.buf, &url);
+	if (!url) {
+		/*
+		 * Only mention uninitialized submodules when its
+		 * path have been specified
+		 */
+		if (pp->pathspec.nr)
+			strbuf_addf(err, _("Submodule path '%s' not initialized\n"
+				    "Maybe you want to use 'update --init'?"),
+				    displaypath);
+		goto cleanup;
+	}
+
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "%s/.git", ce->name);
+	needs_cloning = !file_exists(sb.buf);
+
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "%06o %s %d %d\t%s\n", ce->ce_mode,
+			sha1_to_hex(ce->sha1), ce_stage(ce),
+			needs_cloning, ce->name);
+	string_list_append(&pp->projectlines, sb.buf);
+
+	if (needs_cloning) {
+		cp->git_cmd = 1;
+		cp->no_stdin = 1;
+		cp->stdout_to_stderr = 1;
+		cp->err = -1;
+		argv_array_push(&cp->args, "submodule--helper");
+		argv_array_push(&cp->args, "clone");
+		if (pp->quiet)
+			argv_array_push(&cp->args, "--quiet");
+
+		if (pp->prefix)
+			argv_array_pushl(&cp->args, "--prefix", pp->prefix, NULL);
+
+		argv_array_pushl(&cp->args, "--path", sub->path, NULL);
+		argv_array_pushl(&cp->args, "--name", sub->name, NULL);
+		argv_array_pushl(&cp->args, "--url", strdup(url), NULL);
+		if (pp->reference)
+			argv_array_push(&cp->args, pp->reference);
+		if (pp->depth)
+			argv_array_push(&cp->args, pp->depth);
+
+
+	}
+
+cleanup:
+	free(url);
+	strbuf_reset(&displaypath_sb);
+	strbuf_reset(&sb);
+
+	return needs_cloning;
+}
+
+static int update_clone_get_next_task(struct child_process *cp,
+				      struct strbuf *err,
+				      void *pp_cb,
+				      void **pp_task_cb)
+{
+	struct submodule_update_clone *pp = pp_cb;
+
+	for (; pp->count < pp->list.nr; pp->count++) {
+		const struct cache_entry *ce = pp->list.entries[pp->count];
+		if (update_clone_inspect_next_task(cp, err, pp,
+						   pp_task_cb, ce)) {
+			pp->count++;
+			return 1;
+		}
+	}
+	return 0;
+}
+
+static int update_clone_start_failure(struct child_process *cp,
+				      struct strbuf *err,
+				      void *pp_cb,
+				      void *pp_task_cb)
+{
+	struct submodule_update_clone *pp = pp_cb;
+
+	strbuf_addf(err, "error when starting a child process");
+	pp->print_unmatched = 1;
+
+	return 1;
+}
+
+static int update_clone_task_finished(int result,
+				      struct child_process *cp,
+				      struct strbuf *err,
+				      void *pp_cb,
+				      void *pp_task_cb)
+{
+	struct submodule_update_clone *pp = pp_cb;
+
+	if (!result) {
+		return 0;
+	} else {
+		strbuf_addf(err, "error in one child process");
+		pp->print_unmatched = 1;
+		return 1;
+	}
+}
+
+static int update_clone(int argc, const char **argv, const char *prefix)
+{
+	const char *update = NULL;
+	struct string_list_item *item;
+	struct submodule_update_clone pp = SUBMODULE_UPDATE_CLONE_INIT;
+
+	struct option module_list_options[] = {
+		OPT_STRING(0, "prefix", &prefix,
+			   N_("path"),
+			   N_("path into the working tree")),
+		OPT_STRING(0, "recursive_prefix", &pp.recursive_prefix,
+			   N_("path"),
+			   N_("path into the working tree, across nested "
+			      "submodule boundaries")),
+		OPT_STRING(0, "update", &update,
+			   N_("string"),
+			   N_("update command for submodules")),
+		OPT_STRING(0, "reference", &pp.reference, "<repository>",
+			   N_("Use the local reference repository "
+			      "instead of a full clone")),
+		OPT_STRING(0, "depth", &pp.depth, "<depth>",
+			   N_("Create a shallow clone truncated to the "
+			      "specified number of revisions")),
+		OPT__QUIET(&pp.quiet, N_("do't print cloning progress")),
+		OPT_END()
+	};
+
+	const char *const git_submodule_helper_usage[] = {
+		N_("git submodule--helper list [--prefix=<path>] [<path>...]"),
+		NULL
+	};
+	pp.prefix = prefix;
+
+	argc = parse_options(argc, argv, prefix, module_list_options,
+			     git_submodule_helper_usage, 0);
+
+	if (update)
+		if (parse_submodule_update_strategy(update, &pp.update) < 0)
+			die(_("bad value for update parameter"));
+
+	if (module_list_compute(argc, argv, prefix, &pp.pathspec, &pp.list) < 0) {
+		printf("#unmatched\n");
+		return 1;
+	}
+
+	gitmodules_config();
+	/* Overlay the parsed .gitmodules file with .git/config */
+	git_config(submodule_config, NULL);
+	run_processes_parallel(1, update_clone_get_next_task,
+				  update_clone_start_failure,
+				  update_clone_task_finished,
+				  &pp);
+
+	if (pp.print_unmatched) {
+		printf("#unmatched\n");
+		return 1;
+	}
+
+	for_each_string_list_item(item, &pp.projectlines)
+		utf8_fprintf(stdout, "%s", item->string);
+
+	return 0;
+}
+
 struct cmd_struct {
 	const char *cmd;
 	int (*fn)(int, const char **, const char *);
@@ -264,6 +494,7 @@ static struct cmd_struct commands[] = {
 	{"list", module_list},
 	{"name", module_name},
 	{"clone", module_clone},
+	{"update-clone", update_clone}
 };
 
 int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
diff --git a/git-submodule.sh b/git-submodule.sh
index 9ee86d4..9f554fb 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -664,17 +664,18 @@ cmd_update()
 		cmd_init "--" "$@" || return
 	fi
 
-	cloned_modules=
-	git submodule--helper list --prefix "$wt_prefix" "$@" | {
+	git submodule--helper update-clone ${GIT_QUIET:+--quiet} \
+		${wt_prefix:+--prefix "$wt_prefix"} \
+		${prefix:+--recursive_prefix "$prefix"} \
+		${update:+--update "$update"} \
+		${reference:+--reference "$reference"} \
+		${depth:+--depth "$depth"} \
+		"$@" | {
 	err=
-	while read mode sha1 stage sm_path
+	while read mode sha1 stage just_cloned sm_path
 	do
 		die_if_unmatched "$mode"
-		if test "$stage" = U
-		then
-			echo >&2 "Skipping unmerged submodule $prefix$sm_path"
-			continue
-		fi
+
 		name=$(git submodule--helper name "$sm_path") || exit
 		url=$(git config submodule."$name".url)
 		branch=$(get_submodule_config "$name" branch master)
@@ -691,27 +692,10 @@ cmd_update()
 
 		displaypath=$(relative_path "$prefix$sm_path")
 
-		if test "$update_module" = "none"
-		then
-			echo >&2 "Skipping submodule '$displaypath'"
-			continue
-		fi
-
-		if test -z "$url"
-		then
-			# Only mention uninitialized submodules when its
-			# path have been specified
-			test "$#" != "0" &&
-			say >&2 "$(eval_gettext "Submodule path '\$displaypath' not initialized
-Maybe you want to use 'update --init'?")"
-			continue
-		fi
-
-		if ! test -d "$sm_path"/.git && ! test -f "$sm_path"/.git
+		if test $just_cloned -eq 1
 		then
-			git submodule--helper clone ${GIT_QUIET:+--quiet} --prefix "$prefix" --path "$sm_path" --name "$name" --url "$url" "$reference" "$depth" || exit
-			cloned_modules="$cloned_modules;$name"
 			subsha1=
+			update_module=checkout
 		else
 			subsha1=$(clear_local_git_env; cd "$sm_path" &&
 				git rev-parse --verify HEAD) ||
@@ -751,13 +735,6 @@ Maybe you want to use 'update --init'?")"
 				die "$(eval_gettext "Unable to fetch in submodule path '\$displaypath'")"
 			fi
 
-			# Is this something we just cloned?
-			case ";$cloned_modules;" in
-			*";$name;"*)
-				# then there is no local change to integrate
-				update_module=checkout ;;
-			esac
-
 			must_die_on_failure=
 			case "$update_module" in
 			checkout)
-- 
2.7.0.rc0.34.g65aed89

[PATCHv12 6/7] submodule update: expose parallelism to the user

[Stefan Beller]

Expose possible parallelism either via the "--jobs" CLI parameter or
the "submodule.fetchJobs" setting.

By having the variable initialized to -1, we make sure 0 can be passed
into the parallel processing machine, which will then pick as many parallel
workers as there are CPUs.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-submodule.txt |  7 ++++++-
 builtin/submodule--helper.c     | 16 ++++++++++++----
 git-submodule.sh                |  9 +++++++++
 t/t7406-submodule-update.sh     | 12 ++++++++++++
 4 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-submodule.txt b/Documentation/git-submodule.txt
index 1572f05..13adebf 100644
--- a/Documentation/git-submodule.txt
+++ b/Documentation/git-submodule.txt
@@ -16,7 +16,7 @@ SYNOPSIS
 'git submodule' [--quiet] deinit [-f|--force] [--] <path>...
 'git submodule' [--quiet] update [--init] [--remote] [-N|--no-fetch]
 	      [-f|--force] [--rebase|--merge] [--reference <repository>]
-	      [--depth <depth>] [--recursive] [--] [<path>...]
+	      [--depth <depth>] [--recursive] [--jobs <n>] [--] [<path>...]
 'git submodule' [--quiet] summary [--cached|--files] [(-n|--summary-limit) <n>]
 	      [commit] [--] [<path>...]
 'git submodule' [--quiet] foreach [--recursive] <command>
@@ -377,6 +377,11 @@ for linkgit:git-clone[1]'s `--reference` and `--shared` options carefully.
 	clone with a history truncated to the specified number of revisions.
 	See linkgit:git-clone[1]
 
+-j <n>::
+--jobs <n>::
+	This option is only valid for the update command.
+	Clone new submodules in parallel with as many jobs.
+	Defaults to the `submodule.fetchJobs` option.
 
 <path>...::
 	Paths to submodule(s). When specified this will restrict the command
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 7629a41..65bdc14 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -424,6 +424,7 @@ static int update_clone_task_finished(int result,
 static int update_clone(int argc, const char **argv, const char *prefix)
 {
 	const char *update = NULL;
+	int max_jobs = -1;
 	struct string_list_item *item;
 	struct submodule_update_clone pp = SUBMODULE_UPDATE_CLONE_INIT;
 
@@ -444,6 +445,8 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 		OPT_STRING(0, "depth", &pp.depth, "<depth>",
 			   N_("Create a shallow clone truncated to the "
 			      "specified number of revisions")),
+		OPT_INTEGER('j', "jobs", &max_jobs,
+			    N_("parallel jobs")),
 		OPT__QUIET(&pp.quiet, N_("do't print cloning progress")),
 		OPT_END()
 	};
@@ -469,10 +472,15 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 	gitmodules_config();
 	/* Overlay the parsed .gitmodules file with .git/config */
 	git_config(submodule_config, NULL);
-	run_processes_parallel(1, update_clone_get_next_task,
-				  update_clone_start_failure,
-				  update_clone_task_finished,
-				  &pp);
+
+	if (max_jobs < 0)
+		max_jobs = parallel_submodules();
+
+	run_processes_parallel(max_jobs,
+			       update_clone_get_next_task,
+			       update_clone_start_failure,
+			       update_clone_task_finished,
+			       &pp);
 
 	if (pp.print_unmatched) {
 		printf("#unmatched\n");
diff --git a/git-submodule.sh b/git-submodule.sh
index 9f554fb..10c5af9 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -645,6 +645,14 @@ cmd_update()
 		--depth=*)
 			depth=$1
 			;;
+		-j|--jobs)
+			case "$2" in '') usage ;; esac
+			jobs="--jobs=$2"
+			shift
+			;;
+		--jobs=*)
+			jobs=$1
+			;;
 		--)
 			shift
 			break
@@ -670,6 +678,7 @@ cmd_update()
 		${update:+--update "$update"} \
 		${reference:+--reference "$reference"} \
 		${depth:+--depth "$depth"} \
+		${jobs:+$jobs} \
 		"$@" | {
 	err=
 	while read mode sha1 stage just_cloned sm_path
diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index dda3929..7fd5142 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -774,4 +774,16 @@ test_expect_success 'submodule update --recursive drops module name before recur
 	 test_i18ngrep "Submodule path .deeper/submodule/subsubmodule.: checked out" actual
 	)
 '
+
+test_expect_success 'submodule update can be run in parallel' '
+	(cd super2 &&
+	 GIT_TRACE=$(pwd)/trace.out git submodule update --jobs 7 &&
+	 grep "7 tasks" trace.out &&
+	 git config submodule.fetchJobs 8 &&
+	 GIT_TRACE=$(pwd)/trace.out git submodule update &&
+	 grep "8 tasks" trace.out &&
+	 GIT_TRACE=$(pwd)/trace.out git submodule update --jobs 9 &&
+	 grep "9 tasks" trace.out
+	)
+'
 test_done
-- 
2.7.0.rc0.34.g65aed89

[PATCHv12 7/7] clone: allow an explicit argument for parallel submodule clones

[Stefan Beller]

Just pass it along to "git submodule update", which may pick reasonable
defaults if you don't specify an explicit number.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-clone.txt |  6 +++++-
 builtin/clone.c             | 19 +++++++++++++------
 t/t7406-submodule-update.sh | 15 +++++++++++++++
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index 6bf000d..6db7b6d 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -14,7 +14,7 @@ SYNOPSIS
 	  [-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>]
 	  [--dissociate] [--separate-git-dir <git dir>]
 	  [--depth <depth>] [--[no-]single-branch]
-	  [--recursive | --recurse-submodules] [--] <repository>
+	  [--recursive | --recurse-submodules] [--jobs <n>] [--] <repository>
 	  [<directory>]
 
 DESCRIPTION
@@ -221,6 +221,10 @@ objects from the source repository into a pack in the cloned repository.
 	The result is Git repository can be separated from working
 	tree.
 
+-j <n>::
+--jobs <n>::
+	The number of submodules fetched at the same time.
+	Defaults to the `submodule.fetchJobs` option.
 
 <repository>::
 	The (possibly remote) repository to clone from.  See the
diff --git a/builtin/clone.c b/builtin/clone.c
index a0b3cd9..b004fb4 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -50,6 +50,7 @@ static int option_progress = -1;
 static struct string_list option_config;
 static struct string_list option_reference;
 static int option_dissociate;
+static int max_jobs = -1;
 
 static struct option builtin_clone_options[] = {
 	OPT__VERBOSITY(&option_verbosity),
@@ -72,6 +73,8 @@ static struct option builtin_clone_options[] = {
 		    N_("initialize submodules in the clone")),
 	OPT_BOOL(0, "recurse-submodules", &option_recursive,
 		    N_("initialize submodules in the clone")),
+	OPT_INTEGER('j', "jobs", &max_jobs,
+		    N_("number of submodules cloned in parallel")),
 	OPT_STRING(0, "template", &option_template, N_("template-directory"),
 		   N_("directory from which templates will be used")),
 	OPT_STRING_LIST(0, "reference", &option_reference, N_("repo"),
@@ -95,10 +98,6 @@ static struct option builtin_clone_options[] = {
 	OPT_END()
 };
 
-static const char *argv_submodule[] = {
-	"submodule", "update", "--init", "--recursive", NULL
-};
-
 static const char *get_repo_path_1(struct strbuf *path, int *is_bundle)
 {
 	static char *suffix[] = { "/.git", "", ".git/.git", ".git" };
@@ -724,8 +723,16 @@ static int checkout(void)
 	err |= run_hook_le(NULL, "post-checkout", sha1_to_hex(null_sha1),
 			   sha1_to_hex(sha1), "1", NULL);
 
-	if (!err && option_recursive)
-		err = run_command_v_opt(argv_submodule, RUN_GIT_CMD);
+	if (!err && option_recursive) {
+		struct argv_array args = ARGV_ARRAY_INIT;
+		argv_array_pushl(&args, "submodule", "update", "--init", "--recursive", NULL);
+
+		if (max_jobs != -1)
+			argv_array_pushf(&args, "--jobs=%d", max_jobs);
+
+		err = run_command_v_opt(args.argv, RUN_GIT_CMD);
+		argv_array_clear(&args);
+	}
 
 	return err;
 }
diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index 7fd5142..090891e 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -786,4 +786,19 @@ test_expect_success 'submodule update can be run in parallel' '
 	 grep "9 tasks" trace.out
 	)
 '
+
+test_expect_success 'git clone passes the parallel jobs config on to submodules' '
+	test_when_finished "rm -rf super4" &&
+	GIT_TRACE=$(pwd)/trace.out git clone --recurse-submodules --jobs 7 . super4 &&
+	grep "7 tasks" trace.out &&
+	rm -rf super4 &&
+	git config --global submodule.fetchJobs 8 &&
+	GIT_TRACE=$(pwd)/trace.out git clone --recurse-submodules . super4 &&
+	grep "8 tasks" trace.out &&
+	rm -rf super4 &&
+	GIT_TRACE=$(pwd)/trace.out git clone --recurse-submodules --jobs 9 . super4 &&
+	grep "9 tasks" trace.out &&
+	rm -rf super4
+'
+
 test_done
-- 
2.7.0.rc0.34.g65aed89

Re: [PATCHv12 0/7] Expose submodule parallelism to the user

[Junio C Hamano]

Stefan Beller <sbeller@google.com> writes:

> Thanks Junio for a review of v11!
>
> I addressed the memory issue with the interdiff (in patch 1/7) as follows:
> Interdiff to v11:
>
> diff --git a/submodule.c b/submodule.c
> index 263cb2a..45d0967 100644
> --- a/submodule.c
> +++ b/submodule.c
> @@ -219,6 +219,9 @@ void gitmodules_config(void)
>  int parse_submodule_update_strategy(const char *value,
>                 struct submodule_update_strategy *dst)
>  {
> +       const char *com;
> +
> +       free((void*)dst->command);
>         dst->command = NULL;
>         if (!strcmp(value, "none"))
>                 dst->type = SM_UPDATE_NONE;
> @@ -228,9 +231,10 @@ int parse_submodule_update_strategy(const char *value,
>                 dst->type = SM_UPDATE_REBASE;
>         else if (!strcmp(value, "merge"))
>                 dst->type = SM_UPDATE_MERGE;
> -       else if (skip_prefix(value, "!", &dst->command))
> +       else if (skip_prefix(value, "!", &com)) {
>                 dst->type = SM_UPDATE_COMMAND;
> -       else
> +               dst->command = xstrdup(com);
> +       } else
>                 return -1;
>         return 0;
>  }

Unless you count "I want to write differently from what was
suggested" is a desirable thing to do, I do not see a point in
favouring the above that uses an extra variable and skip_prefix()
over what I gave you as "how about" patch.  But whatever.

 - Is dst->command always initialized to a NULL (otherwise the
   unconditional upfront free() makes it unsafe)?

 - Is there a global free_something() or something_clear() function
   that are used to release the resource held by a structure that
   has submodule_update_strategy structure embedded in it?  If so
   dst->command needs to be freed there as well.

Thanks.

> Stefan Beller (7):
>   submodule-config: keep update strategy around
>   submodule-config: drop check against NULL
>   fetching submodules: respect `submodule.fetchJobs` config option
>   submodule update: direct error message to stderr
>   git submodule update: have a dedicated helper for cloning
>   submodule update: expose parallelism to the user
>   clone: allow an explicit argument for parallel submodule clones
>
>  Documentation/config.txt        |   6 +
>  Documentation/git-clone.txt     |   6 +-
>  Documentation/git-submodule.txt |   7 +-
>  builtin/clone.c                 |  19 +++-
>  builtin/fetch.c                 |   2 +-
>  builtin/submodule--helper.c     | 239 ++++++++++++++++++++++++++++++++++++++++
>  git-submodule.sh                |  54 ++++-----
>  submodule-config.c              |  18 ++-
>  submodule-config.h              |   2 +
>  submodule.c                     |  39 ++++++-
>  submodule.h                     |  18 +++
>  t/t5526-fetch-submodules.sh     |  14 +++
>  t/t7400-submodule-basic.sh      |   4 +-
>  t/t7406-submodule-update.sh     |  27 +++++
>  14 files changed, 406 insertions(+), 49 deletions(-)

Re: [PATCHv12 0/7] Expose submodule parallelism to the user

[Stefan Beller]

On Thu, Feb 18, 2016 at 2:55 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Stefan Beller <sbeller@google.com> writes:
>
>> Thanks Junio for a review of v11!
>>
>> I addressed the memory issue with the interdiff (in patch 1/7) as follows:
>> Interdiff to v11:
>>
>> diff --git a/submodule.c b/submodule.c
>> index 263cb2a..45d0967 100644
>> --- a/submodule.c
>> +++ b/submodule.c
>> @@ -219,6 +219,9 @@ void gitmodules_config(void)
>>  int parse_submodule_update_strategy(const char *value,
>>                 struct submodule_update_strategy *dst)
>>  {
>> +       const char *com;
>> +
>> +       free((void*)dst->command);
>>         dst->command = NULL;
>>         if (!strcmp(value, "none"))
>>                 dst->type = SM_UPDATE_NONE;
>> @@ -228,9 +231,10 @@ int parse_submodule_update_strategy(const char *value,
>>                 dst->type = SM_UPDATE_REBASE;
>>         else if (!strcmp(value, "merge"))
>>                 dst->type = SM_UPDATE_MERGE;
>> -       else if (skip_prefix(value, "!", &dst->command))
>> +       else if (skip_prefix(value, "!", &com)) {
>>                 dst->type = SM_UPDATE_COMMAND;
>> -       else
>> +               dst->command = xstrdup(com);
>> +       } else
>>                 return -1;
>>         return 0;
>>  }
>
> Unless you count "I want to write differently from what was
> suggested" is a desirable thing to do, I do not see a point in
> favouring the above that uses an extra variable and skip_prefix()
> over what I gave you as "how about" patch.  But whatever.

The skip_prefix was there before, so it stuck there.
Also it seems a bit more high level to me hence easier to read,
(though I am biased). I'll use your suggestion.

>
>  - Is dst->command always initialized to a NULL (otherwise the
>    unconditional upfront free() makes it unsafe)?

Yes, although just currently. It seems hard to maintain going forward as
the struct submodule_update_strategy is part of the struct submodule
(as defined in submodule.h) as well as the struct submodule_update_clone
(as defined in submodule--helper.c) and both places take care of initializing
it to null.

>
>  - Is there a global free_something() or something_clear() function
>    that are used to release the resource held by a structure that
>    has submodule_update_strategy structure embedded in it?  If so
>    dst->command needs to be freed there as well.

Sure, I'll just reroll the series now.

>
> Thanks.
>
>> Stefan Beller (7):
>>   submodule-config: keep update strategy around
>>   submodule-config: drop check against NULL
>>   fetching submodules: respect `submodule.fetchJobs` config option
>>   submodule update: direct error message to stderr
>>   git submodule update: have a dedicated helper for cloning
>>   submodule update: expose parallelism to the user
>>   clone: allow an explicit argument for parallel submodule clones
>>
>>  Documentation/config.txt        |   6 +
>>  Documentation/git-clone.txt     |   6 +-
>>  Documentation/git-submodule.txt |   7 +-
>>  builtin/clone.c                 |  19 +++-
>>  builtin/fetch.c                 |   2 +-
>>  builtin/submodule--helper.c     | 239 ++++++++++++++++++++++++++++++++++++++++
>>  git-submodule.sh                |  54 ++++-----
>>  submodule-config.c              |  18 ++-
>>  submodule-config.h              |   2 +
>>  submodule.c                     |  39 ++++++-
>>  submodule.h                     |  18 +++
>>  t/t5526-fetch-submodules.sh     |  14 +++
>>  t/t7400-submodule-basic.sh      |   4 +-
>>  t/t7406-submodule-update.sh     |  27 +++++
>>  14 files changed, 406 insertions(+), 49 deletions(-)

Re: [PATCHv12 0/7] Expose submodule parallelism to the user

[Stefan Beller]

On Thu, Feb 18, 2016 at 3:12 PM, Stefan Beller <sbeller@google.com> wrote:
>> Unless you count "I want to write differently from what was
>> suggested" is a desirable thing to do, I do not see a point in
>> favouring the above that uses an extra variable and skip_prefix()
>> over what I gave you as "how about" patch.  But whatever.
>
> The skip_prefix was there before, so it stuck there.
> Also it seems a bit more high level to me hence easier to read,
> (though I am biased). I'll use your suggestion.

and it doesn't crash when passing in value == NULL.
(We don't do that currently, just a side observation)

Re: [PATCHv12 0/7] Expose submodule parallelism to the user

[Junio C Hamano]

Stefan Beller <sbeller@google.com> writes:

> On Thu, Feb 18, 2016 at 3:12 PM, Stefan Beller <sbeller@google.com> wrote:
>>> Unless you count "I want to write differently from what was
>>> suggested" is a desirable thing to do, I do not see a point in
>>> favouring the above that uses an extra variable and skip_prefix()
>>> over what I gave you as "how about" patch.  But whatever.
>>
>> The skip_prefix was there before, so it stuck there.

Sorry, but I thought this "parsing update strategy" was all new
code.

>> Also it seems a bit more high level to me hence easier to read,
>> (though I am biased). I'll use your suggestion.
>
> and it doesn't crash when passing in value == NULL.
> (We don't do that currently, just a side observation)

Hmph.  If you pass str==NULL with prefix="!" to what we have below,
I would think the first iteration would try to read from *str and do
a bizarre thing.

static inline int skip_prefix(const char *str, const char *prefix,
			      const char **out)
{
	do {
		if (!*prefix) {
			*out = str;
			return 1;
		}
	} while (*str++ == *prefix++);
	return 0;
}

Puzzled.

Re: [PATCHv12 0/7] Expose submodule parallelism to the user

[Stefan Beller]

On Thu, Feb 18, 2016 at 3:20 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Stefan Beller <sbeller@google.com> writes:
>
>> On Thu, Feb 18, 2016 at 3:12 PM, Stefan Beller <sbeller@google.com> wrote:
>>>> Unless you count "I want to write differently from what was
>>>> suggested" is a desirable thing to do, I do not see a point in
>>>> favouring the above that uses an extra variable and skip_prefix()
>>>> over what I gave you as "how about" patch.  But whatever.
>>>
>>> The skip_prefix was there before, so it stuck there.
>
> Sorry, but I thought this "parsing update strategy" was all new
> code.

I meant previous patches or in my mind. That's why I was hesitant to
throw out the skip_prefix.

>
>>> Also it seems a bit more high level to me hence easier to read,
>>> (though I am biased). I'll use your suggestion.
>>
>> and it doesn't crash when passing in value == NULL.
>> (We don't do that currently, just a side observation)
>
> Hmph.  If you pass str==NULL with prefix="!" to what we have below,
> I would think the first iteration would try to read from *str and do
> a bizarre thing.
>
> static inline int skip_prefix(const char *str, const char *prefix,
>                               const char **out)
> {
>         do {
>                 if (!*prefix) {
>                         *out = str;
>                         return 1;
>                 }
>         } while (*str++ == *prefix++);
>         return 0;
> }
>
> Puzzled.

And there I was asserting properties about methods
without looking them up.

ok.

Re: [PATCHv12 0/7] Expose submodule parallelism to the user

[Junio C Hamano]

Stefan Beller <sbeller@google.com> writes:

> On Thu, Feb 18, 2016 at 3:20 PM, Junio C Hamano <gitster@pobox.com> wrote:
>> Stefan Beller <sbeller@google.com> writes:
>>
>>> On Thu, Feb 18, 2016 at 3:12 PM, Stefan Beller <sbeller@google.com> wrote:
>>>>> Unless you count "I want to write differently from what was
>>>>> suggested" is a desirable thing to do, I do not see a point in
>>>>> favouring the above that uses an extra variable and skip_prefix()
>>>>> over what I gave you as "how about" patch.  But whatever.
>>>>
>>>> The skip_prefix was there before, so it stuck there.
>>
>> Sorry, but I thought this "parsing update strategy" was all new
>> code.
>
> I meant previous patches or in my mind. That's why I was hesitant to
> throw out the skip_prefix.

I actually think the attached on top of your final version would be
the best.  It would not make too big a difference in this codepath
that skips just one byte, the pattern naturally would apply to
prefix of any length, and this would serve as the BCP, ready to be
copied-and-pasted by others when writing new code.

And of course it does not waste an otherwise unnecessary temporary
variable ;-)

diff --git a/submodule.c b/submodule.c
index 911fa3b..8e08159 100644
--- a/submodule.c
+++ b/submodule.c
@@ -223,9 +223,9 @@ int parse_submodule_update_strategy(const char *value,
 		dst->type = SM_UPDATE_REBASE;
 	else if (!strcmp(value, "merge"))
 		dst->type = SM_UPDATE_MERGE;
-	else if (value[0] == '!') {
+	else if (skip_prefix(value, "!", &value)) {
 		dst->type = SM_UPDATE_COMMAND;
-		dst->command = xstrdup(value + 1);
+		dst->command = xstrdup(value);
 	} else
 		return -1;
 	return 0;