my_lock.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:2k
- /* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
- #if defined(__EMX__) || defined(__NETWARE__)
- #include "../mysys/my_lock.c"
- #else
- #undef MAP_TO_USE_RAID /* Avoid RAID mappings */
- #include <my_global.h>
- #include <my_sys.h>
- #include <mysys_err.h>
- #include <my_pthread.h>
- #include <thr_alarm.h>
- #include <errno.h>
- /* Lock a part of a file */
- int my_lock(File fd,int locktype,my_off_t start,my_off_t length,myf MyFlags)
- {
- thr_alarm_t alarmed;
- ALARM alarm_buff;
- uint wait_for_alarm;
- struct flock m_lock;
- DBUG_ENTER("my_lock");
- DBUG_PRINT("my",("Fd: %d Op: %d start: %ld Length: %ld MyFlags: %d",
- fd,locktype,(ulong) start,(ulong) length,MyFlags));
- if (my_disable_locking)
- DBUG_RETURN(0); /* purecov: inspected */
- m_lock.l_type=(short) locktype;
- m_lock.l_whence=0L;
- m_lock.l_start=(long) start;
- m_lock.l_len=(long) length;
- wait_for_alarm=(MyFlags & MY_DONT_WAIT ? MY_HOW_OFTEN_TO_ALARM :
- (uint) 12*60*60);
- if (fcntl(fd,F_SETLK,&m_lock) != -1) /* Check if we can lock */
- DBUG_RETURN(0); /* Ok, file locked */
- DBUG_PRINT("info",("Was locked, trying with alarm"));
- if (!thr_alarm(&alarmed,wait_for_alarm,&alarm_buff))
- {
- int value;
- while ((value=fcntl(fd,F_SETLKW,&m_lock)) && !thr_got_alarm(&alarmed) &&
- errno == EINTR) ;
- thr_end_alarm(&alarmed);
- if (value != -1)
- DBUG_RETURN(0);
- }
- else
- {
- errno=EINTR;
- }
- if (errno == EINTR || errno == EACCES)
- my_errno=EAGAIN; /* Easier to check for this */
- else
- my_errno=errno;
- if (MyFlags & MY_WME)
- {
- if (locktype == F_UNLCK)
- my_error(EE_CANTUNLOCK,MYF(ME_BELL+ME_WAITTANG),errno);
- else
- my_error(EE_CANTLOCK,MYF(ME_BELL+ME_WAITTANG),errno);
- }
- DBUG_PRINT("error",("errno: %d",errno));
- DBUG_RETURN(-1);
- }
- #endif