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mdbx: use OFD (open file) locks on Linux.

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Change-Id: Id9718da28d4e367b0ff10976d2afaaf3d18122fb
This commit is contained in:
Leonid Yuriev 2019-08-10 12:53:16 +03:00
parent a008b0b16f
commit ce64c5aa37
1 changed files with 29 additions and 25 deletions
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54
src/lck-linux.c
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@ -38,6 +38,7 @@
#endif /* MDBX_USE_ROBUST */
uint32_t linux_kernel_version;
static int cmd_setlk = F_SETLK, cmd_setlkw = F_SETLKW, cmd_getlk = F_GETLK;
/*----------------------------------------------------------------------------*/
/* rthc */
@ -62,6 +63,15 @@ static __cold __attribute__((constructor)) void mdbx_global_constructor(void) {
}
}
#if defined(F_OFD_SETLK) && defined(F_OFD_SETLKW) && defined(F_OFD_GETLK)
if (linux_kernel_version >
0x030f0000 /* OFD locks are available since 3.15, but engages here only
for 3.16 and larer kernels (LTS) for reliability reasons */) {
cmd_setlk = F_OFD_SETLK;
cmd_setlkw = F_OFD_SETLKW;
cmd_getlk = F_OFD_GETLK;
}
#endif /* OFD locks */
mdbx_rthc_global_init();
}
@ -116,20 +126,25 @@ static __cold __attribute__((destructor)) void mdbx_global_destructor(void) {
static int mdbx_lck_op(mdbx_filehandle_t fd, int op, short lck, off_t offset,
off_t len) {
for (;;) {
int rc;
struct flock lock_op;
memset(&lock_op, 0, sizeof(lock_op));
lock_op.l_type = lck;
lock_op.l_whence = SEEK_SET;
lock_op.l_start = offset;
lock_op.l_len = len;
if ((rc = fcntl(fd, op, &lock_op)) == 0) {
if (op == F_GETLK && lock_op.l_type != F_UNLCK)
rc = -lock_op.l_pid;
} else if ((rc = errno) == EINTR) {
continue;
if (fcntl(fd, op, &lock_op) == 0) {
if (op == cmd_getlk) {
/* Checks reader by pid. Returns:
* MDBX_RESULT_TRUE - if pid is live (unable to acquire lock)
* MDBX_RESULT_FALSE - if pid is dead (lock acquired). */
return (lock_op.l_type == F_UNLCK) ? MDBX_RESULT_FALSE
: MDBX_RESULT_TRUE;
}
return 0;
}
return rc;
int rc = errno;
if (rc != EINTR)
return rc;
}
}
@ -137,7 +152,7 @@ static __inline int mdbx_lck_exclusive(int lfd, bool fallback2shared) {
assert(lfd != INVALID_HANDLE_VALUE);
if (flock(lfd, LOCK_EX | LOCK_NB))
return errno;
int rc = mdbx_lck_op(lfd, F_SETLK, F_WRLCK, 0, 1);
int rc = mdbx_lck_op(lfd, cmd_setlk, F_WRLCK, 0, 1);
if (rc != 0 && fallback2shared) {
while (flock(lfd, LOCK_SH)) {
int rc = errno;
@ -155,7 +170,7 @@ static __inline int mdbx_lck_shared(int lfd) {
if (rc != EINTR)
return rc;
}
return mdbx_lck_op(lfd, F_SETLKW, F_RDLCK, 0, 1);
return mdbx_lck_op(lfd, cmd_setlkw, F_RDLCK, 0, 1);
}
int mdbx_lck_downgrade(MDBX_env *env, bool complete) {
@ -165,28 +180,17 @@ int mdbx_lck_downgrade(MDBX_env *env, bool complete) {
int mdbx_rpid_set(MDBX_env *env) {
assert(env->me_lfd != INVALID_HANDLE_VALUE);
return mdbx_lck_op(env->me_lfd, F_SETLK, F_WRLCK, env->me_pid, 1);
return mdbx_lck_op(env->me_lfd, cmd_setlk, F_WRLCK, env->me_pid, 1);
}
int mdbx_rpid_clear(MDBX_env *env) {
assert(env->me_lfd != INVALID_HANDLE_VALUE);
return mdbx_lck_op(env->me_lfd, F_SETLKW, F_UNLCK, env->me_pid, 1);
return mdbx_lck_op(env->me_lfd, cmd_setlkw, F_UNLCK, env->me_pid, 1);
}
/* Checks reader by pid.
*
* Returns:
* MDBX_RESULT_TRUE, if pid is live (unable to acquire lock)
* MDBX_RESULT_FALSE, if pid is dead (lock acquired)
* or otherwise the errcode. */
int mdbx_rpid_check(MDBX_env *env, mdbx_pid_t pid) {
assert(env->me_lfd != INVALID_HANDLE_VALUE);
int rc = mdbx_lck_op(env->me_lfd, F_GETLK, F_WRLCK, pid, 1);
if (rc == 0)
return MDBX_RESULT_FALSE;
if (rc < 0 && -rc == pid)
return MDBX_RESULT_TRUE;
return rc;
return mdbx_lck_op(env->me_lfd, cmd_getlk, F_WRLCK, pid, 1);
}
/*---------------------------------------------------------------------------*/
@ -336,7 +340,7 @@ int __cold mdbx_lck_seize(MDBX_env *env) {
if (env->me_lfd == INVALID_HANDLE_VALUE) {
/* LY: without-lck mode (e.g. exclusive or on read-only filesystem) */
int rc = mdbx_lck_op(env->me_fd, F_SETLK,
int rc = mdbx_lck_op(env->me_fd, cmd_setlk,
(env->me_flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, 0,
LCK_WHOLE);
if (rc != 0) {
@ -348,7 +352,7 @@ int __cold mdbx_lck_seize(MDBX_env *env) {
if ((env->me_flags & MDBX_RDONLY) == 0) {
/* Check that another process don't operates in without-lck mode. */
int rc = mdbx_lck_op(env->me_fd, F_SETLK, F_WRLCK, env->me_pid, 1);
int rc = mdbx_lck_op(env->me_fd, cmd_setlk, F_WRLCK, env->me_pid, 1);
if (rc != 0) {
mdbx_error("%s(%s) failed: errcode %u", mdbx_func_,
"lock-against-without-lck", rc);