Merge branch 'tt/gc'

* tt/gc:
  Add --aggressive option to 'git gc'

Documentation/config.txt

@@ -384,6 +384,11 @@ format.suffix::
 	`.patch`. Use this variable to change that suffix (make sure to
 	include the dot if you want it).
 
+gc.aggressiveWindow::
+	The window size parameter used in the delta compression
+	algorithm used by 'git gc --aggressive'.  This defaults
+	to 10.
+
 gc.packrefs::
 	`git gc` does not run `git pack-refs` in a bare repository by
 	default so that older dumb-transport clients can still fetch

Documentation/git-gc.txt

@@ -8,7 +8,7 @@ git-gc - Cleanup unnecessary files and optimize the local repository
 
 SYNOPSIS
 --------
-'git-gc' [--prune]
+'git-gc' [--prune] [--aggressive]
 
 DESCRIPTION
 -----------
@@ -35,6 +35,13 @@ OPTIONS
 	repository at the same time (e.g. never use this option
 	in a cron script).
 
+--aggressive::
+	Usually 'git-gc' runs very quickly while providing good disk
+	space utilization and performance.   This option will cause
+	git-gc to more aggressive optimize the repository at the expense
+	of taking much more time.  The effects of this optimization are
+	persistent, so this option only needs to be sporadically; every
+	few hundred changesets or so.
 
 Configuration
 -------------
@@ -67,6 +74,13 @@ The optional configuration variable 'gc.packrefs' determines if
 is not run in bare repositories by default, to allow older dumb-transport
 clients fetch from the repository,  but this will change in the future.
 
+The optional configuration variable 'gc.aggressiveWindow' controls how
+much time is spent optimizing the delta compression of the objects in
+the repository when the --aggressive option is specified.  The larger
+the value, the more time is spent optimizing the delta compression.  See
+the documentation for the --window' option in gitlink:git-repack[1] for
+more details.  This defaults to 10.
+
 See Also
 --------
 gitlink:git-prune[1]

builtin-gc.c

@@ -15,13 +15,15 @@
 
 #define FAILED_RUN "failed to run %s"
 
-static const char builtin_gc_usage[] = "git-gc [--prune]";
+static const char builtin_gc_usage[] = "git-gc [--prune] [--aggressive]";
 
 static int pack_refs = -1;
+static int aggressive_window = -1;
 
+#define MAX_ADD 10
 static const char *argv_pack_refs[] = {"pack-refs", "--prune", NULL};
 static const char *argv_reflog[] = {"reflog", "expire", "--all", NULL};
-static const char *argv_repack[] = {"repack", "-a", "-d", "-l", NULL};
+static const char *argv_repack[MAX_ADD] = {"repack", "-a", "-d", "-l", NULL};
 static const char *argv_prune[] = {"prune", NULL};
 static const char *argv_rerere[] = {"rerere", "gc", NULL};
 
@@ -34,13 +36,31 @@ static int gc_config(const char *var, const char *value)
 			pack_refs = git_config_bool(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "gc.aggressivewindow")) {
+		aggressive_window = git_config_int(var, value);
+		return 0;
+	}
 	return git_default_config(var, value);
 }
 
+static void append_option(const char **cmd, const char *opt, int max_length)
+{
+	int i;
+
+	for (i = 0; cmd[i]; i++)
+		;
+
+	if (i + 2 >= max_length)
+		die("Too many options specified");
+	cmd[i++] = opt;
+	cmd[i] = NULL;
+}
+
 int cmd_gc(int argc, const char **argv, const char *prefix)
 {
 	int i;
 	int prune = 0;
+	char buf[80];
 
 	git_config(gc_config);
 
@@ -53,6 +73,14 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 			prune = 1;
 			continue;
 		}
+		if (!strcmp(arg, "--aggressive")) {
+			append_option(argv_repack, "-f", MAX_ADD);
+			if (aggressive_window > 0) {
+				sprintf(buf, "--window=%d", aggressive_window);
+				append_option(argv_repack, buf, MAX_ADD);
+			}
+			continue;
+		}
 		/* perhaps other parameters later... */
 		break;
 	}