Merge branch 'master' into db/fetch-pack

There's a number of tricky conflicts between master and
this topic right now due to the rewrite of builtin-push.
Junio must have handled these via rerere; I'd rather not
deal with them again so I'm pre-merging master into the
topic.  Besides this topic somehow started to depend on
the strbuf series that was in next, but is now in master.
It no longer compiles on its own without the strbuf API.

* master: (184 commits)
  Whip post 1.5.3.4 maintenance series into shape.
  Minor usage update in setgitperms.perl
  manual: use 'URL' instead of 'url'.
  manual: add some markup.
  manual: Fix example finding commits referencing given content.
  Fix wording in push definition.
  Fix some typos, punctuation, missing words, minor markup.
  manual: Fix or remove em dashes.
  Add a --dry-run option to git-push.
  Add a --dry-run option to git-send-pack.
  Fix in-place editing functions in convert.c
  instaweb: support for Ruby's WEBrick server
  instaweb: allow for use of auto-generated scripts
  Add 'git-p4 commit' as an alias for 'git-p4 submit'
  hg-to-git speedup through selectable repack intervals
  git-svn: respect Subversion's [auth] section configuration values
  gtksourceview2 support for gitview
  fix contrib/hooks/post-receive-email hooks.recipients error message
  Support cvs via git-shell
  rebase -i: use diff plumbing instead of porcelain
  ...

Conflicts:

	Makefile
	builtin-push.c
	rsh.c

1 files changed, 135 insertions, 2 deletions

diff --git a/builtin-gc.c b/builtin-gc.c
index 9397482610..956c32d1af 100644
--- a/builtin-gc.c
+++ b/builtin-gc.c
@@ -20,11 +20,13 @@ static const char builtin_gc_usage[] = "git-gc [--prune] [--aggressive]";
 
 static int pack_refs = 1;
 static int aggressive_window = -1;
+static int gc_auto_threshold = 6700;
+static int gc_auto_pack_limit = 20;
 
 #define MAX_ADD 10
 static const char *argv_pack_refs[] = {"pack-refs", "--all", "--prune", NULL};
 static const char *argv_reflog[] = {"reflog", "expire", "--all", NULL};
-static const char *argv_repack[MAX_ADD] = {"repack", "-a", "-d", "-l", NULL};
+static const char *argv_repack[MAX_ADD] = {"repack", "-d", "-l", NULL};
 static const char *argv_prune[] = {"prune", NULL};
 static const char *argv_rerere[] = {"rerere", "gc", NULL};
 
@@ -41,6 +43,14 @@ static int gc_config(const char *var, const char *value)
 		aggressive_window = git_config_int(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "gc.auto")) {
+		gc_auto_threshold = git_config_int(var, value);
+		return 0;
+	}
+	if (!strcmp(var, "gc.autopacklimit")) {
+		gc_auto_pack_limit = git_config_int(var, value);
+		return 0;
+	}
 	return git_default_config(var, value);
 }
 
@@ -57,10 +67,107 @@ static void append_option(const char **cmd, const char *opt, int max_length)
 	cmd[i] = NULL;
 }
 
+static int too_many_loose_objects(void)
+{
+	/*
+	 * Quickly check if a "gc" is needed, by estimating how
+	 * many loose objects there are.  Because SHA-1 is evenly
+	 * distributed, we can check only one and get a reasonable
+	 * estimate.
+	 */
+	char path[PATH_MAX];
+	const char *objdir = get_object_directory();
+	DIR *dir;
+	struct dirent *ent;
+	int auto_threshold;
+	int num_loose = 0;
+	int needed = 0;
+
+	if (gc_auto_threshold <= 0)
+		return 0;
+
+	if (sizeof(path) <= snprintf(path, sizeof(path), "%s/17", objdir)) {
+		warning("insanely long object directory %.*s", 50, objdir);
+		return 0;
+	}
+	dir = opendir(path);
+	if (!dir)
+		return 0;
+
+	auto_threshold = (gc_auto_threshold + 255) / 256;
+	while ((ent = readdir(dir)) != NULL) {
+		if (strspn(ent->d_name, "0123456789abcdef") != 38 ||
+		    ent->d_name[38] != '\0')
+			continue;
+		if (++num_loose > auto_threshold) {
+			needed = 1;
+			break;
+		}
+	}
+	closedir(dir);
+	return needed;
+}
+
+static int too_many_packs(void)
+{
+	struct packed_git *p;
+	int cnt;
+
+	if (gc_auto_pack_limit <= 0)
+		return 0;
+
+	prepare_packed_git();
+	for (cnt = 0, p = packed_git; p; p = p->next) {
+		char path[PATH_MAX];
+		size_t len;
+		int keep;
+
+		if (!p->pack_local)
+			continue;
+		len = strlen(p->pack_name);
+		if (PATH_MAX <= len + 1)
+			continue; /* oops, give up */
+		memcpy(path, p->pack_name, len-5);
+		memcpy(path + len - 5, ".keep", 6);
+		keep = access(p->pack_name, F_OK) && (errno == ENOENT);
+		if (keep)
+			continue;
+		/*
+		 * Perhaps check the size of the pack and count only
+		 * very small ones here?
+		 */
+		cnt++;
+	}
+	return gc_auto_pack_limit <= cnt;
+}
+
+static int need_to_gc(void)
+{
+	/*
+	 * Setting gc.auto and gc.autopacklimit to 0 or negative can
+	 * disable the automatic gc.
+	 */
+	if (gc_auto_threshold <= 0 && gc_auto_pack_limit <= 0)
+		return 0;
+
+	/*
+	 * If there are too many loose objects, but not too many
+	 * packs, we run "repack -d -l".  If there are too many packs,
+	 * we run "repack -A -d -l".  Otherwise we tell the caller
+	 * there is no need.
+	 */
+	if (too_many_packs())
+		append_option(argv_repack, "-A", MAX_ADD);
+	else if (!too_many_loose_objects())
+		return 0;
+	return 1;
+}
+
 int cmd_gc(int argc, const char **argv, const char *prefix)
 {
 	int i;
 	int prune = 0;
+	int auto_gc = 0;
 	char buf[80];
 
 	git_config(gc_config);
@@ -82,12 +189,34 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 			}
 			continue;
 		}
-		/* perhaps other parameters later... */
+		if (!strcmp(arg, "--auto")) {
+			auto_gc = 1;
+			continue;
+		}
 		break;
 	}
 	if (i != argc)
 		usage(builtin_gc_usage);
 
+	if (auto_gc) {
+		/*
+		 * Auto-gc should be least intrusive as possible.
+		 */
+		prune = 0;
+		if (!need_to_gc())
+			return 0;
+	} else {
+		/*
+		 * Use safer (for shared repos) "-A" option to
+		 * repack when not pruning. Auto-gc makes its
+		 * own decision.
+		 */
+		if (prune)
+			append_option(argv_repack, "-a", MAX_ADD);
+		else
+			append_option(argv_repack, "-A", MAX_ADD);
+	}
+
 	if (pack_refs && run_command_v_opt(argv_pack_refs, RUN_GIT_CMD))
 		return error(FAILED_RUN, argv_pack_refs[0]);
 
@@ -103,5 +232,9 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	if (run_command_v_opt(argv_rerere, RUN_GIT_CMD))
 		return error(FAILED_RUN, argv_rerere[0]);
 
+	if (auto_gc && too_many_loose_objects())
+		warning("There are too many unreachable loose objects; "
+			"run 'git prune' to remove them.");
+
 	return 0;
 }