diff options
Diffstat (limited to 'mysys/my_lock.c')
| -rw-r--r-- | mysys/my_lock.c | 140 |
1 files changed, 114 insertions, 26 deletions
diff --git a/mysys/my_lock.c b/mysys/my_lock.c index c0522ee849d..62f39bd3b71 100644 --- a/mysys/my_lock.c +++ b/mysys/my_lock.c @@ -22,13 +22,113 @@ #undef NO_ALARM_LOOP #endif #include <my_alarm.h> -#ifdef __WIN__ -#include <sys/locking.h> -#endif #ifdef __NETWARE__ #include <nks/fsio.h> #endif +#ifdef _WIN32 +#define WIN_LOCK_INFINITE -1 +#define WIN_LOCK_SLEEP_MILLIS 100 + +static int win_lock(File fd, int locktype, my_off_t start, my_off_t length, + int timeout_sec) +{ + LARGE_INTEGER liOffset,liLength; + DWORD dwFlags; + OVERLAPPED ov= {0}; + HANDLE hFile= (HANDLE)my_get_osfhandle(fd); + DWORD lastError= 0; + int i; + int timeout_millis= timeout_sec * 1000; + + DBUG_ENTER("win_lock"); + + liOffset.QuadPart= start; + liLength.QuadPart= length; + + ov.Offset= liOffset.LowPart; + ov.OffsetHigh= liOffset.HighPart; + + if (locktype == F_UNLCK) + { + if (UnlockFileEx(hFile, 0, liLength.LowPart, liLength.HighPart, &ov)) + DBUG_RETURN(0); + /* + For compatibility with fcntl implementation, ignore error, + if region was not locked + */ + if (GetLastError() == ERROR_NOT_LOCKED) + { + SetLastError(0); + DBUG_RETURN(0); + } + goto error; + } + else if (locktype == F_RDLCK) + /* read lock is mapped to a shared lock. */ + dwFlags= 0; + else + /* write lock is mapped to an exclusive lock. */ + dwFlags= LOCKFILE_EXCLUSIVE_LOCK; + + /* + Drop old lock first to avoid double locking. + During analyze of Bug#38133 (Myisamlog test fails on Windows) + I met the situation that the program myisamlog locked the file + exclusively, then additionally shared, then did one unlock, and + then blocked on an attempt to lock it exclusively again. + Unlocking before every lock fixed the problem. + Note that this introduces a race condition. When the application + wants to convert an exclusive lock into a shared one, it will now + first unlock the file and then lock it shared. A waiting exclusive + lock could step in here. For reasons described in Bug#38133 and + Bug#41124 (Server hangs on Windows with --external-locking after + INSERT...SELECT) and in the review thread at + http://lists.mysql.com/commits/60721 it seems to be the better + option than not to unlock here. + If one day someone notices a way how to do file lock type changes + on Windows without unlocking before taking the new lock, please + change this code accordingly to fix the race condition. + */ + if (!UnlockFileEx(hFile, 0, liLength.LowPart, liLength.HighPart, &ov) && + (GetLastError() != ERROR_NOT_LOCKED)) + goto error; + + if (timeout_sec == WIN_LOCK_INFINITE) + { + if (LockFileEx(hFile, dwFlags, 0, liLength.LowPart, liLength.HighPart, &ov)) + DBUG_RETURN(0); + goto error; + } + + dwFlags|= LOCKFILE_FAIL_IMMEDIATELY; + timeout_millis= timeout_sec * 1000; + /* Try lock in a loop, until the lock is acquired or timeout happens */ + for(i= 0; ;i+= WIN_LOCK_SLEEP_MILLIS) + { + if (LockFileEx(hFile, dwFlags, 0, liLength.LowPart, liLength.HighPart, &ov)) + DBUG_RETURN(0); + + if (GetLastError() != ERROR_LOCK_VIOLATION) + goto error; + + if (i >= timeout_millis) + break; + Sleep(WIN_LOCK_SLEEP_MILLIS); + } + + /* timeout */ + errno= EAGAIN; + DBUG_RETURN(-1); + +error: + my_osmaperr(GetLastError()); + DBUG_RETURN(-1); +} +#endif + + + /* Lock a part of a file @@ -48,8 +148,9 @@ int my_lock(File fd, int locktype, my_off_t start, my_off_t length, #ifdef __NETWARE__ int nxErrno; #endif + DBUG_ENTER("my_lock"); - DBUG_PRINT("my",("Fd: %d Op: %d start: %ld Length: %ld MyFlags: %d", + DBUG_PRINT("my",("fd: %d Op: %d start: %ld Length: %ld MyFlags: %d", fd,locktype,(long) start,(long) length,MyFlags)); #ifdef VMS DBUG_RETURN(0); @@ -97,29 +198,16 @@ int my_lock(File fd, int locktype, my_off_t start, my_off_t length, DBUG_RETURN(0); } } -#elif defined(HAVE_LOCKING) - /* Windows */ +#elif defined(_WIN32) { - my_bool error= FALSE; - pthread_mutex_lock(&my_file_info[fd].mutex); - if (MyFlags & MY_SEEK_NOT_DONE) - { - if( my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE)) - == MY_FILEPOS_ERROR ) - { - /* - If my_seek fails my_errno will already contain an error code; - just unlock and return error code. - */ - DBUG_PRINT("error",("my_errno: %d (%d)",my_errno,errno)); - pthread_mutex_unlock(&my_file_info[fd].mutex); - DBUG_RETURN(-1); - } - } - error= locking(fd,locktype,(ulong) length) && errno != EINVAL; - pthread_mutex_unlock(&my_file_info[fd].mutex); - if (!error) - DBUG_RETURN(0); + int timeout_sec; + if (MyFlags & MY_DONT_WAIT) + timeout_sec= 0; + else + timeout_sec= WIN_LOCK_INFINITE; + + if(win_lock(fd, locktype, start, length, timeout_sec) == 0) + DBUG_RETURN(0); } #else #if defined(HAVE_FCNTL) |