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mdbx: add fallback2shared for mdbx_lck_exclusive().

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This commit is contained in:
Leo Yuriev 2018-08-01 18:25:41 +03:00
parent 5a1f388db5
commit ac54a3959d
1 changed files with 13 additions and 5 deletions
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18
src/lck-posix.c
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@ -68,11 +68,19 @@ static int mdbx_lck_op(mdbx_filehandle_t fd, int op, int lck, off_t offset,
}
}
static __inline int mdbx_lck_exclusive(int lfd) {
static __inline int mdbx_lck_exclusive(int lfd, bool fallback2shared) {
assert(lfd != INVALID_HANDLE_VALUE);
if (flock(lfd, LOCK_EX | LOCK_NB))
return errno;
return mdbx_lck_op(lfd, F_SETLK, F_WRLCK, 0, 1);
int rc = mdbx_lck_op(lfd, F_SETLK, F_WRLCK, 0, 1);
if (rc != 0 && fallback2shared) {
while (flock(lfd, LOCK_SH)) {
int rc = errno;
if (rc != EINTR)
return rc;
}
}
return rc;
}
static __inline int mdbx_lck_shared(int lfd) {
@ -161,7 +169,7 @@ bailout:
void __cold mdbx_lck_destroy(MDBX_env *env) {
if (env->me_lfd != INVALID_HANDLE_VALUE) {
/* try get exclusive access */
if (env->me_lck && mdbx_lck_exclusive(env->me_lfd) == 0) {
if (env->me_lck && mdbx_lck_exclusive(env->me_lfd, false) == 0) {
mdbx_info("%s: got exclusive, drown mutexes", mdbx_func_);
int rc = pthread_mutex_destroy(&env->me_lck->mti_rmutex);
if (rc == 0)
@ -230,7 +238,7 @@ static int __cold internal_seize_lck(int lfd) {
assert(lfd != INVALID_HANDLE_VALUE);
/* try exclusive access */
int rc = mdbx_lck_exclusive(lfd);
int rc = mdbx_lck_exclusive(lfd, false);
if (rc == 0)
/* got exclusive */
return MDBX_RESULT_TRUE;
@ -239,7 +247,7 @@ static int __cold internal_seize_lck(int lfd) {
rc = mdbx_lck_shared(lfd);
if (rc == 0) {
/* got shared, try exclusive again */
rc = mdbx_lck_exclusive(lfd);
rc = mdbx_lck_exclusive(lfd, true);
if (rc == 0)
/* now got exclusive */
return MDBX_RESULT_TRUE;