submodules: introduce check to see whether to touch a submodule

In later patches we introduce the --recurse-submodule flag for commands
that modify the working directory, e.g. git-checkout.

It is potentially expensive to check if a submodule needs an update,
because a common theme to interact with submodules is to spawn a child
process for each interaction.

So let's introduce a function that checks if a submodule needs
to be checked for an update before attempting the update.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/submodule.c b/submodule.c
index 591f4a694e5592e8b7d7c3a818854b3588f2479a..8b2c0212bed26fe35013cc6222782c546414b4de 100644 (file)
--- a/submodule.c
+++ b/submodule.c
@@ -548,6 +548,22 @@ void set_config_update_recurse_submodules(int value)
        config_update_recurse_submodules = value;
 }
 
+int should_update_submodules(void)
+{
+       return config_update_recurse_submodules == RECURSE_SUBMODULES_ON;
+}
+
+const struct submodule *submodule_from_ce(const struct cache_entry *ce)
+{
+       if (!S_ISGITLINK(ce->ce_mode))
+               return NULL;
+
+       if (!should_update_submodules())
+               return NULL;
+
+       return submodule_from_path(null_sha1, ce->name);
+}
+
 static int has_remote(const char *refname, const struct object_id *oid,
                      int flags, void *cb_data)
 {

diff --git a/submodule.h b/submodule.h
index b4e60c08d2757f21b20454a5da5b830f5c154f8b..6f3fe85c7c293fa7d0327354ec52054b118e1d42 100644 (file)
--- a/submodule.h
+++ b/submodule.h
@@ -65,6 +65,13 @@ extern void show_submodule_inline_diff(FILE *f, const char *path,
                const struct diff_options *opt);
 extern void set_config_fetch_recurse_submodules(int value);
 extern void set_config_update_recurse_submodules(int value);
+/* Check if we want to update any submodule.*/
+extern int should_update_submodules(void);
+/*
+ * Returns the submodule struct if the given ce entry is a submodule
+ * and it should be updated. Returns NULL otherwise.
+ */
+extern const struct submodule *submodule_from_ce(const struct cache_entry *ce);
 extern void check_for_new_submodule_commits(unsigned char new_sha1[20]);
 extern int fetch_populated_submodules(const struct argv_array *options,
                               const char *prefix, int command_line_option,