Merge 'forced-updates-after-branch-list'

Move the warning about `--[no-]show-forced-updates` to the end of the
branch update list. Also, show a different message when a lot of time is
spent walking the commits. (Note, this time will not include the loose
object downloads for the tip commits, but may include some loose object
downloads for the reachable commits.)

Documentation/fetch-options.txt

@@ -173,6 +173,19 @@ endif::git-pull[]
 	is specified. This flag forces progress status even if the
 	standard error stream is not directed to a terminal.
 
+--show-forced-updates::
+	By default, git checks if a branch is force-updated during
+	fetch. This can be disabled through fetch.showForcedUpdates, but
+	the --show-forced-updates option guarantees this check occurs.
+	See linkgit:git-config[1].
+
+--no-show-forced-updates::
+	By default, git checks if a branch is force-updated during
+	fetch. Pass --no-show-forced-updates or set fetch.showForcedUpdates
+	to false to skip this check for performance reasons. If used during
+	'git-pull' the --ff-only option will still check for forced updates
+	before attempting a fast-forward update. See linkgit:git-config[1].
+
 -4::
 --ipv4::
 	Use IPv4 addresses only, ignoring IPv6 addresses.

builtin/fetch.c

@@ -20,6 +20,8 @@
 #include "utf8.h"
 #include "packfile.h"
 
+#define FORCED_UPDATES_DELAY_WARNING_IN_MS (10 * 1000)
+
 static const char * const builtin_fetch_usage[] = {
 	N_("git fetch [<options>] [<repository> [<refspec>...]]"),
 	N_("git fetch [<options>] <group>"),
@@ -37,6 +39,7 @@ enum {
 static int fetch_prune_config = -1; /* unspecified */
 static int fetch_show_forced_updates = 1;
 static int fetch_show_forced_updates_warning = 0;
+static uint64_t forced_updates_ms = 0;
 static int prune = -1; /* unspecified */
 #define PRUNE_BY_DEFAULT 0 /* do we prune by default? */
 
@@ -631,6 +634,7 @@ static int update_local_ref(struct ref *ref,
 	enum object_type type;
 	struct branch *current_branch = branch_get(NULL);
 	const char *pretty_ref = prettify_refname(ref->name);
+	int fast_forward = 0;
 
 	type = sha1_object_info(ref->new_oid.hash, NULL);
 	if (type < 0)
@@ -700,18 +704,19 @@ static int update_local_ref(struct ref *ref,
 		return r;
 	}
 
-	if (!fetch_show_forced_updates || in_merge_bases(current, updated)) {
+	if (fetch_show_forced_updates) {
+		uint64_t t_before = getnanotime();
+		fast_forward = in_merge_bases(current, updated);
+		forced_updates_ms += (getnanotime() - t_before) / 1000000;
+	} else {
+		fetch_show_forced_updates_warning = 1;
+		fast_forward = 1;
+	}
+
+	if (fast_forward) {
 		struct strbuf quickref = STRBUF_INIT;
 		int r;
 
-		if (!fetch_show_forced_updates && !fetch_show_forced_updates_warning) {
-			fetch_show_forced_updates_warning = 1;
-			warning(_("Fetch normally indicates which branches had a forced update, but that check has been disabled."));
-			warning(_("To re-enable, use '--show-forced-updates' flag or run 'git config fetch.showForcedUpdates true'."));
-			warning(_("OR if you just want to check if a branch with name <branch> was force-updated after fetching, run:"));
-			warning(_("    git rev-list --left-right --count <branch>...<branch>@{1}"));
-		}
-
 		strbuf_add_unique_abbrev(&quickref, current->object.oid.hash, DEFAULT_ABBREV);
 		strbuf_addstr(&quickref, "..");
 		strbuf_add_unique_abbrev(&quickref, ref->new_oid.hash, DEFAULT_ABBREV);
@@ -908,6 +913,17 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 		      " 'git remote prune %s' to remove any old, conflicting "
 		      "branches"), remote_name);
 
+	if (!fetch_show_forced_updates && fetch_show_forced_updates_warning) {
+		warning(_("Fetch normally indicates which branches had a forced update, but that check has been disabled."));
+		warning(_("To re-enable, use '--show-forced-updates' flag or run 'git config fetch.showForcedUpdates true'."));
+	}
+	if (fetch_show_forced_updates &&
+	    forced_updates_ms > FORCED_UPDATES_DELAY_WARNING_IN_MS) {
+		warning(_("It took %.2f seconds to check forced updates. You can use '--no-show-forced-updates'\n"),
+			forced_updates_ms / 1000.0);
+		warning(_("or run 'git config fetch.showForcedUpdates false' to avoid this check.\n"));
+	}
+
  abort:
 	strbuf_release(&note);
 	free(url);

builtin/pull.c

@@ -115,6 +115,7 @@ static char *opt_update_shallow;
 static char *opt_refmap;
 static char *opt_ipv4;
 static char *opt_ipv6;
+static int opt_show_forced_updates = 1;
 
 static struct option pull_options[] = {
 	/* Shared options */
@@ -226,6 +227,8 @@ static struct option pull_options[] = {
 	OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 		N_("use IPv6 addresses only"),
 		PARSE_OPT_NOARG),
+	OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
+		 N_("check for forced-updates on all updated branches")),
 
 	OPT_END()
 };
@@ -534,6 +537,10 @@ static int run_fetch(const char *repo, const char **refspecs)
 		argv_array_push(&args, opt_ipv4);
 	if (opt_ipv6)
 		argv_array_push(&args, opt_ipv6);
+	if (opt_show_forced_updates)
+		argv_array_push(&args, "--show-forced-updates");
+	else
+		argv_array_push(&args, "--no-show-forced-updates");
 
 	if (repo) {
 		argv_array_push(&args, repo);