1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
/* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
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; version 2 of the License.
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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
#include "mysys_priv.h"
#include "mysys_err.h"
#include <errno.h>
#undef MY_HOW_OFTEN_TO_ALARM
#define MY_HOW_OFTEN_TO_ALARM ((int) my_time_to_wait_for_lock)
#ifdef NO_ALARM_LOOP
#undef NO_ALARM_LOOP
#endif
#include <my_alarm.h>
#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);
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
RETURN VALUE
0 Success
-1 An error has occurred and 'my_errno' is set
to indicate the actual error code.
*/
int my_lock(File fd, int locktype, my_off_t start, my_off_t length,
myf MyFlags)
{
#ifdef HAVE_FCNTL
int value;
ALARM_VARIABLES;
#endif
DBUG_ENTER("my_lock");
DBUG_PRINT("my",("fd: %d Op: %d start: %ld Length: %ld MyFlags: %lu",
fd,locktype,(long) start,(long) length,MyFlags));
if (my_disable_locking && ! (MyFlags & MY_FORCE_LOCK))
DBUG_RETURN(0);
#if defined(_WIN32)
{
int timeout_sec;
if (MyFlags & MY_NO_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)
{
struct flock lock;
lock.l_type= (short) locktype;
lock.l_whence= SEEK_SET;
lock.l_start= (off_t) start;
lock.l_len= (off_t) length;
if (MyFlags & (MY_NO_WAIT | MY_SHORT_WAIT))
{
if (fcntl(fd,F_SETLK,&lock) != -1) /* Check if we can lock */
DBUG_RETURN(0); /* Ok, file locked */
if (MyFlags & MY_NO_WAIT)
{
my_errno= (errno == EACCES) ? EAGAIN : errno ? errno : -1;
DBUG_RETURN(-1);
}
DBUG_PRINT("info",("Was locked, trying with alarm"));
ALARM_INIT;
while ((value=fcntl(fd,F_SETLKW,&lock)) && ! ALARM_TEST &&
errno == EINTR)
{ /* Setup again so we don`t miss it */
ALARM_REINIT;
}
ALARM_END;
if (value != -1)
DBUG_RETURN(0);
if (errno == EINTR)
errno=EAGAIN;
}
else if (fcntl(fd,F_SETLKW,&lock) != -1) /* Wait until a lock */
DBUG_RETURN(0);
}
#else
if (MyFlags & MY_SEEK_NOT_DONE)
{
if (my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE))
== MY_FILEPOS_ERROR)
{
/*
If an error has occurred in my_seek then we will already
have an error code in my_errno; Just return error code.
*/
DBUG_RETURN(-1);
}
}
if (lockf(fd,locktype,length) != -1)
DBUG_RETURN(0);
#endif /* HAVE_FCNTL */
#endif /* _WIN32 */
/* We got an error. We don't want EACCES errors */
my_errno=(errno == EACCES) ? EAGAIN : errno ? errno : -1;
if (MyFlags & MY_WME)
{
if (locktype == F_UNLCK)
my_error(EE_CANTUNLOCK,MYF(ME_BELL+ME_WAITTANG),my_errno);
else
my_error(EE_CANTLOCK,MYF(ME_BELL+ME_WAITTANG),my_errno);
}
DBUG_PRINT("error",("my_errno: %d (%d)",my_errno,errno));
DBUG_RETURN(-1);
} /* my_lock */
|
