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authorNguyễn Thái Ngọc Duy <pclouds@gmail.com>2013-08-08 11:05:38 (GMT)
committerJunio C Hamano <gitster@pobox.com>2013-08-09 16:10:05 (GMT)
commit64a99eb4760de2ce2f0c04e146c0a55c34f50f20 (patch)
treef09135da1c7fab5195cceef09e865599b37b4ffe /builtin/gc.c
parentf59bebb78edb26e4f66c2754bc4d168c5d4ebb4a (diff)
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gc: reject if another gc is running, unless --force is given
This may happen when `git gc --auto` is run automatically, then the user, to avoid wait time, switches to a new terminal, keeps working and `git gc --auto` is started again because the first gc instance has not clean up the repository. This patch tries to avoid multiple gc running, especially in --auto mode. In the worst case, gc may be delayed 12 hours if a daemon reuses the pid stored in gc.pid. kill(pid, 0) support is added to MinGW port so it should work on Windows too. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin/gc.c')
-rw-r--r--builtin/gc.c67
1 files changed, 67 insertions, 0 deletions
diff --git a/builtin/gc.c b/builtin/gc.c
index 6be6c8d..6e0d81a 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -167,11 +167,69 @@ static int need_to_gc(void)
return 1;
}
+/* return NULL on success, else hostname running the gc */
+static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
+{
+ static struct lock_file lock;
+ static char locking_host[128];
+ char my_host[128];
+ struct strbuf sb = STRBUF_INIT;
+ struct stat st;
+ uintmax_t pid;
+ FILE *fp;
+ int fd, should_exit;
+
+ if (gethostname(my_host, sizeof(my_host)))
+ strcpy(my_host, "unknown");
+
+ fd = hold_lock_file_for_update(&lock, git_path("gc.pid"),
+ LOCK_DIE_ON_ERROR);
+ if (!force) {
+ fp = fopen(git_path("gc.pid"), "r");
+ memset(locking_host, 0, sizeof(locking_host));
+ should_exit =
+ fp != NULL &&
+ !fstat(fileno(fp), &st) &&
+ /*
+ * 12 hour limit is very generous as gc should
+ * never take that long. On the other hand we
+ * don't really need a strict limit here,
+ * running gc --auto one day late is not a big
+ * problem. --force can be used in manual gc
+ * after the user verifies that no gc is
+ * running.
+ */
+ time(NULL) - st.st_mtime <= 12 * 3600 &&
+ fscanf(fp, "%"PRIuMAX" %127c", &pid, locking_host) == 2 &&
+ /* be gentle to concurrent "gc" on remote hosts */
+ (strcmp(locking_host, my_host) || !kill(pid, 0));
+ if (fp != NULL)
+ fclose(fp);
+ if (should_exit) {
+ if (fd >= 0)
+ rollback_lock_file(&lock);
+ *ret_pid = pid;
+ return locking_host;
+ }
+ }
+
+ strbuf_addf(&sb, "%"PRIuMAX" %s",
+ (uintmax_t) getpid(), my_host);
+ write_in_full(fd, sb.buf, sb.len);
+ strbuf_release(&sb);
+ commit_lock_file(&lock);
+
+ return NULL;
+}
+
int cmd_gc(int argc, const char **argv, const char *prefix)
{
int aggressive = 0;
int auto_gc = 0;
int quiet = 0;
+ int force = 0;
+ const char *name;
+ pid_t pid;
struct option builtin_gc_options[] = {
OPT__QUIET(&quiet, N_("suppress progress reporting")),
@@ -180,6 +238,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
PARSE_OPT_OPTARG, NULL, (intptr_t)prune_expire },
OPT_BOOLEAN(0, "aggressive", &aggressive, N_("be more thorough (increased runtime)")),
OPT_BOOLEAN(0, "auto", &auto_gc, N_("enable auto-gc mode")),
+ OPT_BOOL(0, "force", &force, N_("force running gc even if there may be another gc running")),
OPT_END()
};
@@ -225,6 +284,14 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
} else
add_repack_all_option();
+ name = lock_repo_for_gc(force, &pid);
+ if (name) {
+ if (auto_gc)
+ return 0; /* be quiet on --auto */
+ die(_("gc is already running on machine '%s' pid %"PRIuMAX" (use --force if not)"),
+ name, (uintmax_t)pid);
+ }
+
if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
return error(FAILED_RUN, pack_refs_cmd.argv[0]);