From 044b6a9efecf9941073b99ced4cb2881b18aee62 Mon Sep 17 00:00:00 2001 From: Michael Haggerty Date: Mon, 11 May 2015 12:35:25 +0200 Subject: lockfile: allow file locking to be retried with a timeout Currently, there is only one attempt to lock a file. If it fails, the whole operation fails. But it might sometimes be advantageous to try acquiring a file lock a few times before giving up. So add a new function, hold_lock_file_for_update_timeout(), that allows a timeout to be specified. Make hold_lock_file_for_update() a thin wrapper around the new function. If timeout_ms is positive, then retry for at least that many milliseconds to acquire the lock. On each failed attempt, use select() to wait for a backoff time that increases quadratically (capped at 1 second) and has a random component to prevent two processes from getting synchronized. If timeout_ms is negative, retry indefinitely. In a moment we will switch to using the new function when locking packed-refs. Signed-off-by: Michael Haggerty Signed-off-by: Junio C Hamano --- lockfile.h | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'lockfile.h') diff --git a/lockfile.h b/lockfile.h index cd2ec95d30..b4abc61c00 100644 --- a/lockfile.h +++ b/lockfile.h @@ -74,8 +74,20 @@ struct lock_file { extern void unable_to_lock_message(const char *path, int err, struct strbuf *buf); extern NORETURN void unable_to_lock_die(const char *path, int err); -extern int hold_lock_file_for_update(struct lock_file *, const char *path, int); -extern int hold_lock_file_for_append(struct lock_file *, const char *path, int); +extern int hold_lock_file_for_update_timeout( + struct lock_file *lk, const char *path, + int flags, long timeout_ms); + +static inline int hold_lock_file_for_update( + struct lock_file *lk, const char *path, + int flags) +{ + return hold_lock_file_for_update_timeout(lk, path, flags, 0); +} + +extern int hold_lock_file_for_append(struct lock_file *lk, const char *path, + int flags); + extern FILE *fdopen_lock_file(struct lock_file *, const char *mode); extern char *get_locked_file_path(struct lock_file *); extern int commit_lock_file_to(struct lock_file *, const char *path); -- cgit v1.2.3