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draft-try for https://github.com/paradigmxyz/reth/issues/12841#issuecomment-2840600638

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This commit is contained in:
Леонид Юрьев (Leonid Yuriev)
2025-04-30 10:14:16 +03:00
parent 5c44dd201c
commit 0bfb4e06f2
1 changed files with 42 additions and 17 deletions
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59
src/lck-posix.c
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@@ -7,6 +7,17 @@
#include "internals.h"
static void yield(void) {
#if defined(_POSIX_PRIORITY_SCHEDULING) && _POSIX_PRIORITY_SCHEDULING > 0
sched_yield();
#elif _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _DEFAULT_SOURCE
usleep(42);
#else
const struct timespec ts = {.tv_nsec = 42, .tv_sec = 0};
nanosleep(&ts, nullptr);
#endif
}
#if MDBX_LOCKING == MDBX_LOCKING_SYSV
#include <sys/sem.h>
#endif /* MDBX_LOCKING == MDBX_LOCKING_SYSV */
@@ -283,21 +294,19 @@ __cold MDBX_INTERNAL int lck_seize(MDBX_env *env) {
if (env->lck_mmap.fd == INVALID_HANDLE_VALUE) {
/* LY: without-lck mode (e.g. exclusive or on read-only filesystem) */
rc = lck_op(env->lazy_fd, op_setlk, (env->flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, 0, OFF_T_MAX);
if (rc != MDBX_SUCCESS) {
if (unlikely(rc != MDBX_SUCCESS)) {
ERROR("%s, err %u", "without-lck", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
}
return MDBX_RESULT_TRUE /* Done: return with exclusive locking. */;
}
#if defined(_POSIX_PRIORITY_SCHEDULING) && _POSIX_PRIORITY_SCHEDULING > 0
sched_yield();
#endif
retry:
yield();
if (rc == MDBX_RESULT_TRUE) {
rc = lck_op(env->lck_mmap.fd, op_setlk, F_UNLCK, 0, 1);
if (rc != MDBX_SUCCESS) {
if (unlikely(rc != MDBX_SUCCESS)) {
ERROR("%s, err %u", "unlock-before-retry", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
@@ -306,29 +315,29 @@ retry:
/* Firstly try to get exclusive locking. */
rc = lck_op(env->lck_mmap.fd, op_setlk, F_WRLCK, 0, 1);
if (rc == MDBX_SUCCESS) {
if (likely(rc == MDBX_SUCCESS)) {
rc = check_fstat(env);
if (MDBX_IS_ERROR(rc))
return rc;
continue_dxb_exclusive:
rc = lck_op(env->lazy_fd, op_setlk, (env->flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, 0, OFF_T_MAX);
if (rc == MDBX_SUCCESS)
if (likely(rc == MDBX_SUCCESS))
return MDBX_RESULT_TRUE /* Done: return with exclusive locking. */;
int err = check_fstat(env);
if (MDBX_IS_ERROR(err))
if (unlikely(MDBX_IS_ERROR(err)))
return err;
/* the cause may be a collision with POSIX's file-lock recovery. */
if (!(rc == EAGAIN || rc == EACCES || rc == EBUSY || rc == EWOULDBLOCK || rc == EDEADLK)) {
if (unlikely(!(rc == EAGAIN || rc == EACCES || rc == EBUSY || rc == EWOULDBLOCK || rc == EDEADLK))) {
ERROR("%s, err %u", "dxb-exclusive", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
}
/* Fallback to lck-shared */
} else if (!(rc == EAGAIN || rc == EACCES || rc == EBUSY || rc == EWOULDBLOCK || rc == EDEADLK)) {
} else if (unlikely(!(rc == EAGAIN || rc == EACCES || rc == EBUSY || rc == EWOULDBLOCK || rc == EDEADLK))) {
ERROR("%s, err %u", "try-exclusive", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
@@ -345,26 +354,26 @@ retry:
/* Here may be await during transient processes, for instance until another
* competing process doesn't call lck_downgrade(). */
rc = lck_op(env->lck_mmap.fd, op_setlkw, F_RDLCK, 0, 1);
if (rc != MDBX_SUCCESS) {
if (unlikely(rc != MDBX_SUCCESS)) {
ERROR("%s, err %u", "try-shared", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
}
rc = check_fstat(env);
if (rc == MDBX_RESULT_TRUE)
if (unlikely(rc == MDBX_RESULT_TRUE))
goto retry;
if (rc != MDBX_SUCCESS) {
if (unlikely(rc != MDBX_SUCCESS)) {
ERROR("%s, err %u", "lck_fstat", rc);
return rc;
}
/* got shared, retry exclusive */
rc = lck_op(env->lck_mmap.fd, op_setlk, F_WRLCK, 0, 1);
if (rc == MDBX_SUCCESS)
if (likely(rc == MDBX_SUCCESS))
goto continue_dxb_exclusive;
if (!(rc == EAGAIN || rc == EACCES || rc == EBUSY || rc == EWOULDBLOCK || rc == EDEADLK)) {
if (unlikely(!(rc == EAGAIN || rc == EACCES || rc == EBUSY || rc == EWOULDBLOCK || rc == EDEADLK))) {
ERROR("%s, err %u", "try-exclusive", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
@@ -372,10 +381,26 @@ retry:
/* Lock against another process operating in without-lck or exclusive mode. */
rc = lck_op(env->lazy_fd, op_setlk, (env->flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, env->pid, 1);
if (rc != MDBX_SUCCESS) {
if (unlikely(rc == EAGAIN)) {
yield();
rc = lck_op(env->lazy_fd, op_setlk, (env->flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, env->pid, 1);
if (unlikely(rc == EAGAIN)) {
yield();
rc = lck_op(env->lazy_fd, op_setlk, (env->flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, env->pid, 1);
if (unlikely(rc == EAGAIN)) {
yield();
rc = lck_op(env->lazy_fd, op_setlk, (env->flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, env->pid, 1);
if (unlikely(rc == EAGAIN)) {
yield();
rc = lck_op(env->lazy_fd, op_setlk, (env->flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, env->pid, 1);
}
}
}
}
if (unlikely(rc != MDBX_SUCCESS)) {
ERROR("%s, err %u", "lock-against-without-lck", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
return (rc == EAGAIN) ? MDBX_BUSY : rc;
}
/* Done: return with shared locking. */