builtin-merge: avoid run_command_v_opt() for recursive and subtree

The try_merge_strategy() function always ran the strategy in a separate
process, though this is not always necessary. The recursive and subtree
strategy can be called without a fork(). This patch adds a check, and
calls recursive in the same process without wasting resources.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-merge.c b/builtin-merge.c
index 9ad9791068c9330f28413ac67315246989c8d96d..b857cf6246978846e0c19895fd6f66266cf6a6f4 100644 (file)
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -23,6 +23,7 @@
 #include "color.h"
 #include "rerere.h"
 #include "help.h"
+#include "merge-recursive.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -545,28 +546,64 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
        struct commit_list *j;
        struct strbuf buf;
 
-       args = xmalloc((4 + commit_list_count(common) +
-                       commit_list_count(remoteheads)) * sizeof(char *));
-       strbuf_init(&buf, 0);
-       strbuf_addf(&buf, "merge-%s", strategy);
-       args[i++] = buf.buf;
-       for (j = common; j; j = j->next)
-               args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
-       args[i++] = "--";
-       args[i++] = head_arg;
-       for (j = remoteheads; j; j = j->next)
-               args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
-       args[i] = NULL;
-       ret = run_command_v_opt(args, RUN_GIT_CMD);
-       strbuf_release(&buf);
-       i = 1;
-       for (j = common; j; j = j->next)
-               free((void *)args[i++]);
-       i += 2;
-       for (j = remoteheads; j; j = j->next)
-               free((void *)args[i++]);
-       free(args);
-       return -ret;
+       if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
+               int clean;
+               struct commit *result;
+               struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
+               int index_fd;
+               struct commit_list *reversed = NULL;
+               struct merge_options o;
+
+               if (remoteheads->next) {
+                       error("Not handling anything other than two heads merge.");
+                       return 2;
+               }
+
+               init_merge_options(&o);
+               if (!strcmp(strategy, "subtree"))
+                       o.subtree_merge = 1;
+
+               o.branch1 = head_arg;
+               o.branch2 = remoteheads->item->util;
+
+               for (j = common; j; j = j->next)
+                       commit_list_insert(j->item, &reversed);
+
+               index_fd = hold_locked_index(lock, 1);
+               clean = merge_recursive(&o, lookup_commit(head),
+                               remoteheads->item, reversed, &result);
+               if (active_cache_changed &&
+                               (write_cache(index_fd, active_cache, active_nr) ||
+                                commit_locked_index(lock)))
+                       die ("unable to write %s", get_index_file());
+               return clean ? 0 : 1;
+       } else {
+               args = xmalloc((4 + commit_list_count(common) +
+                                       commit_list_count(remoteheads)) * sizeof(char *));
+               strbuf_init(&buf, 0);
+               strbuf_addf(&buf, "merge-%s", strategy);
+               args[i++] = buf.buf;
+               for (j = common; j; j = j->next)
+                       args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
+               args[i++] = "--";
+               args[i++] = head_arg;
+               for (j = remoteheads; j; j = j->next)
+                       args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
+               args[i] = NULL;
+               ret = run_command_v_opt(args, RUN_GIT_CMD);
+               strbuf_release(&buf);
+               i = 1;
+               for (j = common; j; j = j->next)
+                       free((void *)args[i++]);
+               i += 2;
+               for (j = remoteheads; j; j = j->next)
+                       free((void *)args[i++]);
+               free(args);
+               discard_cache();
+               if (read_cache() < 0)
+                       die("failed to read the cache");
+               return -ret;
+       }
 }
 
 static void count_diff_files(struct diff_queue_struct *q,
@@ -777,10 +814,6 @@ static int evaluate_result(void)
        int cnt = 0;
        struct rev_info rev;
 
-       discard_cache();
-       if (read_cache() < 0)
-               die("failed to read the cache");
-
        /* Check how many files differ. */
        init_revisions(&rev, "");
        setup_revisions(0, NULL, &rev, NULL);
@@ -914,12 +947,14 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 
        for (i = 0; i < argc; i++) {
                struct object *o;
+               struct commit *commit;
 
                o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
                if (!o)
                        die("%s - not something we can merge", argv[i]);
-               remotes = &commit_list_insert(lookup_commit(o->sha1),
-                       remotes)->next;
+               commit = lookup_commit(o->sha1);
+               commit->util = (void *)argv[i];
+               remotes = &commit_list_insert(commit, remotes)->next;
 
                strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
                setenv(buf.buf, argv[i], 1);
@@ -1113,7 +1148,6 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                }
 
                /* Automerge succeeded. */
-               discard_cache();
                write_tree_trivial(result_tree);
                automerge_was_ok = 1;
                break;