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-%s.pid.
uname() and kill(..,0) are added to MinGW compatibility layer so that
it'll work on Windows. Actually uname() is stub so it won't prevent
multiple gc running on a shared repo. But that's for Windows
contributors to step in.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
- new code is taken out in a separate function for clarity
- file locking
- implementing kill(pid, 0) on windows (but not tested)
Documentation/git-gc.txt | 6 ++++-
builtin/gc.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++
compat/mingw.c | 6 +++++
compat/mingw.h | 6 +++++
git-compat-util.h | 1 +
5 files changed, 80 insertions(+), 1 deletion(-)
diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt
index 2402ed6..e158a3b 100644
--- a/Documentation/git-gc.txt
+++ b/Documentation/git-gc.txt
@@ -9,7 +9,7 @@ git-gc - Cleanup unnecessary files and optimize the local repository
SYNOPSIS
--------
[verse]
-'git gc' [--aggressive] [--auto] [--quiet] [--prune=<date> | --no-prune]
+'git gc' [--aggressive] [--auto] [--quiet] [--prune=<date> | --no-prune] [--force]
DESCRIPTION
-----------
@@ -72,6 +72,10 @@ automatic consolidation of packs.
--quiet::
Suppress all progress reports.
+--force::
+ Force `git gc` to run even if there may be another `git gc`
+ instance running on this repository.
+
Configuration
-------------
diff --git a/builtin/gc.c b/builtin/gc.c
index 6be6c8d..1f33908 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -167,11 +167,66 @@ static int need_to_gc(void)
return 1;
}
+static int gc_running(int force)
+{
+ static struct lock_file lock;
+ struct utsname utsname;
+ struct stat st;
+ uintmax_t pid;
+ FILE *fp;
+ int fd, should_exit;
+
+ if (uname(&utsname))
+ strcpy(utsname.nodename, "unknown");
+
+ fd = hold_lock_file_for_update(&lock,
+ git_path("gc-%s.pid", utsname.nodename), 0);
+ if (!force) {
+ if (fd < 0)
+ return 1;
+
+ fp = fopen(git_path("gc-%s.pid", utsname.nodename), "r");
+ 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, &pid) == 1 &&
+ !kill(pid, 0);
+ if (fp != NULL)
+ fclose(fp);
+ if (should_exit) {
+ if (fd >= 0)
+ rollback_lock_file(&lock);
+ return 1;
+ }
+ }
+
+ if (fd >= 0) {
+ struct strbuf sb = STRBUF_INIT;
+ strbuf_addf(&sb, "%"PRIuMAX"\n", (uintmax_t) getpid());
+ write_in_full(fd, sb.buf, sb.len);
+ strbuf_release(&sb);
+ commit_lock_file(&lock);
+ }
+
+ return 0;
+}
+
int cmd_gc(int argc, const char **argv, const char *prefix)
{
int aggressive = 0;
int auto_gc = 0;
int quiet = 0;
+ int force = 0;
struct option builtin_gc_options[] = {
OPT__QUIET(&quiet, N_("suppress progress reporting")),
@@ -180,6 +235,7 @@ 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 +281,12 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
} else
add_repack_all_option();
+ if (gc_running(force)) {
+ if (auto_gc)
+ return 0; /* be quiet on --auto */
+ die(_("gc is already running (use --force if not)"));
+ }
+
if (pack_refs && run_command_v_opt(pack_refs_cmd.argv, RUN_GIT_CMD))
return error(FAILED_RUN, pack_refs_cmd.argv[0]);
diff --git a/compat/mingw.c b/compat/mingw.c
index bb92c43..22ee9ef 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1086,6 +1086,12 @@ int mingw_kill(pid_t pid, int sig)
errno = err_win_to_posix(GetLastError());
CloseHandle(h);
return -1;
+ } else if (pid > 0 && sig == 0) {
+ HANDLE h = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid);
+ if (h) {
+ CloseHandle(h);
+ return 0;
+ }
}
errno = EINVAL;
diff --git a/compat/mingw.h b/compat/mingw.h
index bd0a88b..2c25d2d 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -68,6 +68,10 @@ struct itimerval {
};
#define ITIMER_REAL 0
+struct utsname {
+ char nodename[128];
+};
+
/*
* sanitize preprocessor namespace polluted by Windows headers defining
* macros which collide with git local versions
@@ -86,6 +90,8 @@ static inline int fchmod(int fildes, mode_t mode)
{ errno = ENOSYS; return -1; }
static inline pid_t fork(void)
{ errno = ENOSYS; return -1; }
+static inline int uname(struct utsname *buf)
+{ errno = ENOSYS; return -1; }
static inline unsigned int alarm(unsigned int seconds)
{ return 0; }
static inline int fsync(int fd)
diff --git a/git-compat-util.h b/git-compat-util.h
index 115cb1d..c6a53cb 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -139,6 +139,7 @@
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
+#include <sys/utsname.h>
#include <termios.h>
#ifndef NO_SYS_SELECT_H
#include <sys/select.h>
--
1.8.2.83.gc99314b
--
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