int mail_transaction_log_lock_head(struct mail_transaction_log *log)
{
struct mail_transaction_log_file *file;
int ret = 0;
if (!log->log_2_unlink_checked) {
/* we need to check once in a while if .log.2 should be deleted
to avoid wasting space on such old files. but we also don't
want to waste time on checking it when the same mailbox
gets opened over and over again rapidly (e.g. pop3). so
do this only when there have actually been some changes
to mailbox (i.e. when it's being locked here) */
log->log_2_unlink_checked = TRUE;
mail_transaction_log_2_unlink_old(log);
}
/* we want to get the head file locked. this is a bit racy,
since by the time we have it locked a new log file may have been
created.
creating new log file requires locking the head file, so if we
can lock it and don't see another file, we can be sure no-one is
creating a new log at the moment */
for (;;) {
file = log->head;
if (mail_transaction_log_file_lock(file) < 0)
return -1;
file->refcount++;
ret = mail_transaction_log_refresh(log, TRUE);
if (--file->refcount == 0) {
mail_transaction_logs_clean(log);
file = NULL;
}
if (ret == 0 && log->head == file) {
/* success */
break;
}
if (file != NULL)
mail_transaction_log_file_unlock(file);
if (ret < 0)
break;
/* try again */
}
return ret;
}
int mail_transaction_log_lock_head(struct mail_transaction_log *log,
const char *lock_reason)
{
struct mail_transaction_log_file *file;
time_t lock_wait_started, lock_secs = 0;
const char *reason;
int ret = 0;
if (!log->log_2_unlink_checked) {
/* we need to check once in a while if .log.2 should be deleted
to avoid wasting space on such old files. but we also don't
want to waste time on checking it when the same mailbox
gets opened over and over again rapidly (e.g. pop3). so
do this only when there have actually been some changes
to mailbox (i.e. when it's being locked here) */
log->log_2_unlink_checked = TRUE;
mail_transaction_log_2_unlink_old(log);
}
/* we want to get the head file locked. this is a bit racy,
since by the time we have it locked a new log file may have been
created.
creating new log file requires locking the head file, so if we
can lock it and don't see another file, we can be sure no-one is
creating a new log at the moment */
lock_wait_started = time(NULL);
for (;;) {
file = log->head;
if (mail_transaction_log_file_lock(file) < 0)
return -1;
file->refcount++;
ret = mail_transaction_log_refresh(log, TRUE, &reason);
if (--file->refcount == 0) {
mail_transaction_log_file_unlock(file, t_strdup_printf(
"trying to lock head for %s", lock_reason));
mail_transaction_logs_clean(log);
file = NULL;
}
if (ret == 0 && log->head == file) {
/* success */
i_assert(file != NULL);
lock_secs = file->lock_created - lock_wait_started;
break;
}
if (file != NULL) {
mail_transaction_log_file_unlock(file, t_strdup_printf(
"trying to lock head for %s", lock_reason));
}
if (ret < 0)
break;
/* try again */
}
if (lock_secs > MAIL_TRANSACTION_LOG_LOCK_WARN_SECS) {
i_warning("Locking transaction log file %s took %ld seconds (%s)",
log->head->filepath, (long)lock_secs, lock_reason);
}
i_assert(ret < 0 || log->head != NULL);
return ret;
}
