Add --log-size to git log to print message size

With this option git-log prints log message size
just before the corresponding message.

Porcelain tools could use this to speedup parsing
of git-log output.

Note that size refers to log message only. If also
patch content is shown its size is not included.

In case it is not possible to know the size upfront
size value is set to zero.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-log.txt

@@ -64,6 +64,13 @@ include::pretty-options.txt[]
 --follow::
 	Continue listing the history of a file beyond renames.
 
+--log-size::
+	Before the log message print out its size in bytes. Intended
+	mainly for porcelain tools consumption. If git is unable to
+	produce a valid value size is set to zero.
+	Note that only message is considered, if also a diff is shown
+	its size is not included.
+
 <paths>...::
 	Show only commits that affect the specified paths.
 

log-tree.c

@@ -295,6 +295,9 @@ void show_log(struct rev_info *opt, const char *sep)
 	if (opt->add_signoff)
 		len = append_signoff(&msgbuf, &msgbuf_len, len,
 				     opt->add_signoff);
+	if (opt->show_log_size)
+		printf("log size %i\n", len);
+
 	printf("%s%s%s", msgbuf, extra, sep);
 	free(msgbuf);
 }

revision.c

@@ -1150,6 +1150,10 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 					die("unknown date format %s", arg);
 				continue;
 			}
+			if (!strcmp(arg, "--log-size")) {
+				revs->show_log_size = 1;
+				continue;
+			}
 
 			/*
 			 * Grepping the commit log

revision.h

@@ -81,6 +81,7 @@ struct rev_info {
 	const char	*log_reencode;
 	const char	*subject_prefix;
 	int		no_inline;
+	int		show_log_size;
 
 	/* Filter by commit log message */
 	struct grep_opt	*grep_filter;