mktree --batch: build more than one tree object

This option works in a similar way to the '--batch' option of 'git cat-file'.
It enables creation of many tree objects with a single process.

The change was motivated by performance considerations in applications that
need to create many tree objects. A non-rigorous test showed tree creation
times improved from (roughly) 200ms to 50ms.

Signed-off-by: Josh Micich <josh.micich@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-mktree.txt b/Documentation/git-mktree.txt
index 7336f48bd1e90dabf8e735dc27023b65309e1aef..81e3326772d94464708cc2037715e1e62eae5f11 100644 (file)
--- a/Documentation/git-mktree.txt
+++ b/Documentation/git-mktree.txt
@@ -8,7 +8,7 @@ git-mktree - Build a tree-object from ls-tree formatted text
 
 SYNOPSIS
 --------
-'git mktree' [-z] [--missing]
+'git mktree' [-z] [--missing] [--batch]
 
 DESCRIPTION
 -----------
@@ -28,6 +28,12 @@ OPTIONS
        object.  This option has no effect on the treatment of gitlink entries
        (aka "submodules") which are always allowed to be missing.
 
+--batch::
+       Allow building of more than one tree object before exiting.  Each
+       tree is separated by as single blank line. The final new-line is
+       optional.  Note - if the '-z' option is used, lines are terminated
+       with NUL.
+
 Author
 ------
 Written by Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-mktree.c b/builtin-mktree.c
index 5ff04753b756a72c521d6a95321417812e90e865..73b0abbd8d9bb6d3b312c382b72f8a6e9d124cfa 100644 (file)
--- a/builtin-mktree.c
+++ b/builtin-mktree.c
@@ -63,7 +63,7 @@ static void write_tree(unsigned char *sha1)
 }
 
 static const char *mktree_usage[] = {
-       "git mktree [-z] [--missing]",
+       "git mktree [-z] [--missing] [--batch]",
        NULL
 };
 
@@ -122,20 +122,46 @@ int cmd_mktree(int ac, const char **av, const char *prefix)
        unsigned char sha1[20];
        int line_termination = '\n';
        int allow_missing = 0;
+       int is_batch_mode = 0;
+       int got_eof = 0;
+
        const struct option option[] = {
                OPT_SET_INT('z', NULL, &line_termination, "input is NUL terminated", '\0'),
                OPT_SET_INT( 0 , "missing", &allow_missing, "allow missing objects", 1),
+               OPT_SET_INT( 0 , "batch", &is_batch_mode, "allow creation of more than one tree", 1),
                OPT_END()
        };
 
        ac = parse_options(ac, av, option, mktree_usage, 0);
 
-       while (strbuf_getline(&sb, stdin, line_termination) != EOF)
-               mktree_line(sb.buf, sb.len, line_termination, allow_missing);
-
+       while (!got_eof) {
+               while (1) {
+                       if (strbuf_getline(&sb, stdin, line_termination) == EOF) {
+                               got_eof = 1;
+                               break;
+                       }
+                       if (sb.buf[0] == '\0') {
+                               /* empty lines denote tree boundaries in batch mode */
+                               if (is_batch_mode)
+                                       break;
+                               die("input format error: (blank line only valid in batch mode)");
+                       }
+                       mktree_line(sb.buf, sb.len, line_termination, allow_missing);
+               }
+               if (is_batch_mode && got_eof && used < 1) {
+                       /*
+                        * Execution gets here if the last tree entry is terminated with a
+                        * new-line.  The final new-line has been made optional to be
+                        * consistent with the original non-batch behaviour of mktree.
+                        */
+                       ; /* skip creating an empty tree */
+               } else {
+                       write_tree(sha1);
+                       puts(sha1_to_hex(sha1));
+                       fflush(stdout);
+               }
+               used=0; /* reset tree entry buffer for re-use in batch mode */
+       }
        strbuf_release(&sb);
-
-       write_tree(sha1);
-       puts(sha1_to_hex(sha1));
        exit(0);
 }