libmdbx/src/lck-posix.c

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/*
* Copyright 2015-2022 Leonid Yuriev <leo@yuriev.ru>
* and other libmdbx authors: please see AUTHORS file.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted only as authorized by the OpenLDAP
* Public License.
*
* A copy of this license is available in the file LICENSE in the
* top-level directory of the distribution or, alternatively, at
* <http://www.OpenLDAP.org/license.html>.
*/
#if !(defined(_WIN32) || defined(_WIN64)) /* !Windows LCK-implementation */
#include "internals.h"
#if MDBX_LOCKING == MDBX_LOCKING_SYSV
#include <sys/sem.h>
#endif /* MDBX_LOCKING == MDBX_LOCKING_SYSV */
/*----------------------------------------------------------------------------*/
/* global constructor/destructor */
#if defined(__linux__) || defined(__gnu_linux__)
#include <sys/utsname.h>
#ifndef xMDBX_ALLOY
uint32_t linux_kernel_version;
bool mdbx_RunningOnWSL1;
#endif /* xMDBX_ALLOY */
MDBX_EXCLUDE_FOR_GPROF
__cold static uint8_t probe_for_WSL(const char *tag) {
const char *const WSL = strstr(tag, "WSL");
if (WSL && WSL[3] >= '2' && WSL[3] <= '9')
return WSL[3] - '0';
const char *const wsl = strstr(tag, "wsl");
if (wsl && wsl[3] >= '2' && wsl[3] <= '9')
return wsl[3] - '0';
if (WSL || wsl || strcasestr(tag, "Microsoft"))
/* Expecting no new kernel within WSL1, either it will explicitly
* marked by an appropriate WSL-version hint. */
return (linux_kernel_version < /* 4.19.x */ 0x04130000) ? 1 : 2;
return 0;
}
#endif /* Linux */
#ifdef ENABLE_GPROF
extern void _mcleanup(void);
extern void monstartup(unsigned long, unsigned long);
extern void _init(void);
extern void _fini(void);
extern void __gmon_start__(void) __attribute__((__weak__));
#endif /* ENABLE_GPROF */
MDBX_EXCLUDE_FOR_GPROF
__cold static __attribute__((__constructor__)) void
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mdbx_global_constructor(void) {
#ifdef ENABLE_GPROF
if (!&__gmon_start__)
monstartup((uintptr_t)&_init, (uintptr_t)&_fini);
#endif /* ENABLE_GPROF */
#if defined(__linux__) || defined(__gnu_linux__)
struct utsname buffer;
if (uname(&buffer) == 0) {
int i = 0;
char *p = buffer.release;
while (*p && i < 4) {
if (*p >= '0' && *p <= '9') {
long number = strtol(p, &p, 10);
if (number > 0) {
if (number > 255)
number = 255;
linux_kernel_version += number << (24 - i * 8);
}
++i;
} else {
++p;
}
}
/* "Official" way of detecting WSL1 but not WSL2
* https://github.com/Microsoft/WSL/issues/423#issuecomment-221627364
*
* WARNING: False negative detection of WSL1 will result in DATA LOSS!
* So, the REQUIREMENTS for this code:
* 1. MUST detect WSL1 without false-negatives.
* 2. DESIRABLE detect WSL2 but without the risk of violating the first. */
mdbx_RunningOnWSL1 = probe_for_WSL(buffer.version) == 1 ||
probe_for_WSL(buffer.sysname) == 1 ||
probe_for_WSL(buffer.release) == 1;
}
#endif /* Linux */
global_ctor();
}
MDBX_EXCLUDE_FOR_GPROF
__cold static __attribute__((__destructor__)) void
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mdbx_global_destructor(void) {
global_dtor();
#ifdef ENABLE_GPROF
if (!&__gmon_start__)
_mcleanup();
#endif /* ENABLE_GPROF */
}
/*----------------------------------------------------------------------------*/
/* lck */
/* Описание реализации блокировок для POSIX & Linux:
*
* lck-файл отображается в память, в нём организуется таблица читателей и
* размещаются совместно используемые posix-мьютексы (futex). Посредством
* этих мьютексов (см struct MDBX_lockinfo) реализуются:
* - Блокировка таблицы читателей для регистрации,
* т.е. функции osal_rdt_lock() и osal_rdt_unlock().
* - Блокировка БД для пишущих транзакций,
* т.е. функции mdbx_txn_lock() и mdbx_txn_unlock().
*
* Остальной функционал реализуется отдельно посредством файловых блокировок:
* - Первоначальный захват БД в режиме exclusive/shared и последующий перевод
* в операционный режим, функции osal_lck_seize() и osal_lck_downgrade().
* - Проверка присутствие процессов-читателей,
* т.е. функции osal_rpid_set(), osal_rpid_clear() и osal_rpid_check().
*
* Для блокировки файлов используется fcntl(F_SETLK), так как:
* - lockf() оперирует только эксклюзивной блокировкой и требует
* открытия файла в RW-режиме.
* - flock() не гарантирует атомарности при смене блокировок
* и оперирует только всем файлом целиком.
* - Для контроля процессов-читателей используются однобайтовые
* range-блокировки lck-файла посредством fcntl(F_SETLK). При этом
* в качестве позиции используется pid процесса-читателя.
* - Для первоначального захвата и shared/exclusive выполняется блокировка
* основного файла БД и при успехе lck-файла.
*
* ----------------------------------------------------------------------------
* УДЕРЖИВАЕМЫЕ БЛОКИРОВКИ В ЗАВИСИМОСТИ ОТ РЕЖИМА И СОСТОЯНИЯ
*
* Эксклюзивный режим без lck-файла:
* = заблокирован весь dxb-файл посредством F_RDLCK или F_WRLCK,
* в зависимости от MDBX_RDONLY.
*
* Не-операционный режим на время пере-инициализации и разрушении lck-файла:
* = F_WRLCK блокировка первого байта lck-файла, другие процессы ждут её
* снятия при получении F_RDLCK через F_SETLKW.
* - блокировки dxb-файла могут меняться до снятие эксклюзивной блокировки
* lck-файла:
* + для НЕ-эксклюзивного режима блокировка pid-байта в dxb-файле
* посредством F_RDLCK или F_WRLCK, в зависимости от MDBX_RDONLY.
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* + для ЭКСКЛЮЗИВНОГО режима блокировка всего dxb-файла
* посредством F_RDLCK или F_WRLCK, в зависимости от MDBX_RDONLY.
*
* ОПЕРАЦИОННЫЙ режим с lck-файлом:
* = F_RDLCK блокировка первого байта lck-файла, другие процессы не могут
* получить F_WRLCK и таким образом видят что БД используется.
* + F_WRLCK блокировка pid-байта в clk-файле после первой транзакции чтения.
* + для НЕ-эксклюзивного режима блокировка pid-байта в dxb-файле
* посредством F_RDLCK или F_WRLCK, в зависимости от MDBX_RDONLY.
* + для ЭКСКЛЮЗИВНОГО режима блокировка pid-байта всего dxb-файла
* посредством F_RDLCK или F_WRLCK, в зависимости от MDBX_RDONLY.
*/
#if MDBX_USE_OFDLOCKS
static int op_setlk, op_setlkw, op_getlk;
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__cold static void choice_fcntl(void) {
assert(!op_setlk && !op_setlkw && !op_getlk);
if ((runtime_flags & MDBX_DBG_LEGACY_MULTIOPEN) == 0
#if defined(__linux__) || defined(__gnu_linux__)
&& linux_kernel_version >
0x030f0000 /* OFD locks are available since 3.15, but engages here
only for 3.16 and later kernels (i.e. LTS) because
of reliability reasons */
#endif /* linux */
) {
op_setlk = F_OFD_SETLK;
op_setlkw = F_OFD_SETLKW;
op_getlk = F_OFD_GETLK;
return;
}
op_setlk = F_SETLK;
op_setlkw = F_SETLKW;
op_getlk = F_GETLK;
}
#else
#define op_setlk F_SETLK
#define op_setlkw F_SETLKW
#define op_getlk F_GETLK
#endif /* MDBX_USE_OFDLOCKS */
#ifndef OFF_T_MAX
#define OFF_T_MAX \
(((sizeof(off_t) > 4) ? INT64_MAX : INT32_MAX) & ~(size_t)0xffff)
#endif
static int lck_op(const mdbx_filehandle_t fd, int cmd, const int lck,
const off_t offset, off_t len) {
STATIC_ASSERT(sizeof(off_t) >= sizeof(void *) &&
sizeof(off_t) >= sizeof(size_t));
#ifdef __ANDROID_API__
STATIC_ASSERT_MSG((sizeof(off_t) * 8 == MDBX_WORDBITS),
"The bitness of system `off_t` type is mismatch. Please "
"fix build and/or NDK configuration.");
#endif /* Android */
jitter4testing(true);
assert(offset >= 0 && len > 0);
assert((uint64_t)offset < (uint64_t)INT64_MAX &&
(uint64_t)len < (uint64_t)INT64_MAX &&
(uint64_t)(offset + len) > (uint64_t)offset);
assert((uint64_t)offset < (uint64_t)OFF_T_MAX &&
(uint64_t)len <= (uint64_t)OFF_T_MAX &&
(uint64_t)(offset + len) <= (uint64_t)OFF_T_MAX);
assert((uint64_t)((off_t)((uint64_t)offset + (uint64_t)len)) ==
((uint64_t)offset + (uint64_t)len));
for (;;) {
struct flock lock_op;
STATIC_ASSERT_MSG(sizeof(off_t) <= sizeof(lock_op.l_start) &&
sizeof(off_t) <= sizeof(lock_op.l_len) &&
OFF_T_MAX == (off_t)OFF_T_MAX,
"Support for large/64-bit-sized files is misconfigured "
"for the target system and/or toolchain. "
"Please fix it or at least disable it completely.");
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;
int rc = fcntl(fd, cmd, &lock_op);
jitter4testing(true);
if (rc != -1) {
if (cmd == op_getlk) {
/* Checks reader by pid. Returns:
* MDBX_RESULT_TRUE - if pid is live (reader holds a lock).
* MDBX_RESULT_FALSE - if pid is dead (a lock could be placed). */
return (lock_op.l_type == F_UNLCK) ? MDBX_RESULT_FALSE
: MDBX_RESULT_TRUE;
}
return MDBX_SUCCESS;
}
rc = errno;
#if MDBX_USE_OFDLOCKS
if (rc == EINVAL &&
(cmd == F_OFD_SETLK || cmd == F_OFD_SETLKW || cmd == F_OFD_GETLK)) {
/* fallback to non-OFD locks */
if (cmd == F_OFD_SETLK)
cmd = F_SETLK;
else if (cmd == F_OFD_SETLKW)
cmd = F_SETLKW;
else
cmd = F_GETLK;
op_setlk = F_SETLK;
op_setlkw = F_SETLKW;
op_getlk = F_GETLK;
continue;
}
#endif /* MDBX_USE_OFDLOCKS */
if (rc != EINTR || cmd == op_setlkw) {
assert(MDBX_IS_ERROR(rc));
return rc;
}
}
}
MDBX_INTERNAL_FUNC int osal_lockfile(mdbx_filehandle_t fd, bool wait) {
#if MDBX_USE_OFDLOCKS
if (unlikely(op_setlk == 0))
choice_fcntl();
#endif /* MDBX_USE_OFDLOCKS */
return lck_op(fd, wait ? op_setlkw : op_setlk, F_WRLCK, 0, OFF_T_MAX);
}
MDBX_INTERNAL_FUNC int osal_rpid_set(MDBX_env *env) {
assert(env->me_lfd != INVALID_HANDLE_VALUE);
assert(env->me_pid > 0);
if (unlikely(osal_getpid() != env->me_pid))
return MDBX_PANIC;
return lck_op(env->me_lfd, op_setlk, F_WRLCK, env->me_pid, 1);
}
MDBX_INTERNAL_FUNC int osal_rpid_clear(MDBX_env *env) {
assert(env->me_lfd != INVALID_HANDLE_VALUE);
assert(env->me_pid > 0);
return lck_op(env->me_lfd, op_setlk, F_UNLCK, env->me_pid, 1);
}
MDBX_INTERNAL_FUNC int osal_rpid_check(MDBX_env *env, uint32_t pid) {
assert(env->me_lfd != INVALID_HANDLE_VALUE);
assert(pid > 0);
return lck_op(env->me_lfd, op_getlk, F_WRLCK, pid, 1);
}
/*---------------------------------------------------------------------------*/
#if MDBX_LOCKING > MDBX_LOCKING_SYSV
MDBX_INTERNAL_FUNC int osal_ipclock_stub(osal_ipclock_t *ipc) {
#if MDBX_LOCKING == MDBX_LOCKING_POSIX1988
return sem_init(ipc, false, 1) ? errno : 0;
#elif MDBX_LOCKING == MDBX_LOCKING_POSIX2001 || \
MDBX_LOCKING == MDBX_LOCKING_POSIX2008
return pthread_mutex_init(ipc, nullptr);
#else
#error "FIXME"
#endif
}
MDBX_INTERNAL_FUNC int osal_ipclock_destroy(osal_ipclock_t *ipc) {
#if MDBX_LOCKING == MDBX_LOCKING_POSIX1988
return sem_destroy(ipc) ? errno : 0;
#elif MDBX_LOCKING == MDBX_LOCKING_POSIX2001 || \
MDBX_LOCKING == MDBX_LOCKING_POSIX2008
return pthread_mutex_destroy(ipc);
#else
#error "FIXME"
#endif
}
#endif /* MDBX_LOCKING > MDBX_LOCKING_SYSV */
static int check_fstat(MDBX_env *env) {
struct stat st;
int rc = MDBX_SUCCESS;
if (fstat(env->me_lazy_fd, &st)) {
rc = errno;
ERROR("fstat(%s), err %d", "DXB", rc);
return rc;
}
if (!S_ISREG(st.st_mode) || st.st_nlink < 1) {
#ifdef EBADFD
rc = EBADFD;
#else
rc = EPERM;
#endif
ERROR("%s %s, err %d", "DXB",
(st.st_nlink < 1) ? "file was removed" : "not a regular file", rc);
return rc;
}
if (st.st_size < (off_t)(MDBX_MIN_PAGESIZE * NUM_METAS)) {
VERBOSE("dxb-file is too short (%u), exclusive-lock needed",
(unsigned)st.st_size);
rc = MDBX_RESULT_TRUE;
}
//----------------------------------------------------------------------------
if (fstat(env->me_lfd, &st)) {
rc = errno;
ERROR("fstat(%s), err %d", "LCK", rc);
return rc;
}
if (!S_ISREG(st.st_mode) || st.st_nlink < 1) {
#ifdef EBADFD
rc = EBADFD;
#else
rc = EPERM;
#endif
ERROR("%s %s, err %d", "LCK",
(st.st_nlink < 1) ? "file was removed" : "not a regular file", rc);
return rc;
}
/* Checking file size for detect the situation when we got the shared lock
* immediately after osal_lck_destroy(). */
if (st.st_size < (off_t)(sizeof(MDBX_lockinfo) + sizeof(MDBX_reader))) {
VERBOSE("lck-file is too short (%u), exclusive-lock needed",
(unsigned)st.st_size);
rc = MDBX_RESULT_TRUE;
}
return rc;
}
__cold MDBX_INTERNAL_FUNC int osal_lck_seize(MDBX_env *env) {
assert(env->me_lazy_fd != INVALID_HANDLE_VALUE);
if (unlikely(osal_getpid() != env->me_pid))
return MDBX_PANIC;
#if MDBX_USE_OFDLOCKS
if (unlikely(op_setlk == 0))
choice_fcntl();
#endif /* MDBX_USE_OFDLOCKS */
int rc = MDBX_SUCCESS;
#if defined(__linux__) || defined(__gnu_linux__)
if (unlikely(mdbx_RunningOnWSL1)) {
rc = ENOLCK /* No record locks available */;
ERROR("%s, err %u",
"WSL1 (Windows Subsystem for Linux) is mad and trouble-full, "
"injecting failure to avoid data loss",
rc);
return rc;
}
#endif /* Linux */
if (env->me_lfd == INVALID_HANDLE_VALUE) {
/* LY: without-lck mode (e.g. exclusive or on read-only filesystem) */
rc =
lck_op(env->me_lazy_fd, op_setlk,
(env->me_flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, 0, OFF_T_MAX);
if (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:
if (rc == MDBX_RESULT_TRUE) {
rc = lck_op(env->me_lfd, op_setlk, F_UNLCK, 0, 1);
if (rc != MDBX_SUCCESS) {
ERROR("%s, err %u", "unlock-before-retry", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
}
}
/* Firstly try to get exclusive locking. */
rc = lck_op(env->me_lfd, op_setlk, F_WRLCK, 0, 1);
if (rc == MDBX_SUCCESS) {
rc = check_fstat(env);
if (MDBX_IS_ERROR(rc))
return rc;
continue_dxb_exclusive:
rc =
lck_op(env->me_lazy_fd, op_setlk,
(env->me_flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, 0, OFF_T_MAX);
if (rc == MDBX_SUCCESS)
return MDBX_RESULT_TRUE /* Done: return with exclusive locking. */;
int err = check_fstat(env);
if (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)) {
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)) {
ERROR("%s, err %u", "try-exclusive", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
}
/* Here could be one of two:
* - osal_lck_destroy() from the another process was hold the lock
* during a destruction.
* - either osal_lck_seize() from the another process was got the exclusive
* lock and doing initialization.
* For distinguish these cases will use size of the lck-file later. */
/* Wait for lck-shared now. */
/* Here may be await during transient processes, for instance until another
* competing process doesn't call lck_downgrade(). */
rc = lck_op(env->me_lfd, op_setlkw, F_RDLCK, 0, 1);
if (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)
goto retry;
if (rc != MDBX_SUCCESS) {
ERROR("%s, err %u", "lck_fstat", rc);
return rc;
}
/* got shared, retry exclusive */
rc = lck_op(env->me_lfd, op_setlk, F_WRLCK, 0, 1);
if (rc == MDBX_SUCCESS)
goto continue_dxb_exclusive;
if (!(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;
}
/* Lock against another process operating in without-lck or exclusive mode. */
rc =
lck_op(env->me_lazy_fd, op_setlk,
(env->me_flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, env->me_pid, 1);
if (rc != MDBX_SUCCESS) {
ERROR("%s, err %u", "lock-against-without-lck", rc);
eASSERT(env, MDBX_IS_ERROR(rc));
return rc;
}
/* Done: return with shared locking. */
return MDBX_RESULT_FALSE;
}
MDBX_INTERNAL_FUNC int osal_lck_downgrade(MDBX_env *env) {
assert(env->me_lfd != INVALID_HANDLE_VALUE);
if (unlikely(osal_getpid() != env->me_pid))
return MDBX_PANIC;
int rc = MDBX_SUCCESS;
if ((env->me_flags & MDBX_EXCLUSIVE) == 0) {
rc = lck_op(env->me_lazy_fd, op_setlk, F_UNLCK, 0, env->me_pid);
if (rc == MDBX_SUCCESS)
rc = lck_op(env->me_lazy_fd, op_setlk, F_UNLCK, env->me_pid + 1,
OFF_T_MAX - env->me_pid - 1);
}
if (rc == MDBX_SUCCESS)
rc = lck_op(env->me_lfd, op_setlk, F_RDLCK, 0, 1);
if (unlikely(rc != 0)) {
ERROR("%s, err %u", "lck", rc);
assert(MDBX_IS_ERROR(rc));
}
return rc;
}
__cold MDBX_INTERNAL_FUNC int osal_lck_destroy(MDBX_env *env,
MDBX_env *inprocess_neighbor) {
if (unlikely(osal_getpid() != env->me_pid))
return MDBX_PANIC;
int rc = MDBX_SUCCESS;
struct stat lck_info;
MDBX_lockinfo *lck = env->me_lck_mmap.lck;
if (env->me_lfd != INVALID_HANDLE_VALUE && !inprocess_neighbor && lck &&
/* try get exclusive access */
lck_op(env->me_lfd, op_setlk, F_WRLCK, 0, OFF_T_MAX) == 0 &&
/* if LCK was not removed */
fstat(env->me_lfd, &lck_info) == 0 && lck_info.st_nlink > 0 &&
lck_op(env->me_lazy_fd, op_setlk,
(env->me_flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK, 0,
OFF_T_MAX) == 0) {
VERBOSE("%p got exclusive, drown locks", (void *)env);
#if MDBX_LOCKING == MDBX_LOCKING_SYSV
if (env->me_sysv_ipc.semid != -1)
rc = semctl(env->me_sysv_ipc.semid, 2, IPC_RMID) ? errno : 0;
#else
rc = osal_ipclock_destroy(&lck->mti_rlock);
if (rc == 0)
rc = osal_ipclock_destroy(&lck->mti_wlock);
#endif /* MDBX_LOCKING */
eASSERT(env, rc == 0);
if (rc == 0) {
const bool synced = lck->mti_unsynced_pages.weak == 0;
osal_munmap(&env->me_lck_mmap);
if (synced)
rc = ftruncate(env->me_lfd, 0) ? errno : 0;
}
jitter4testing(false);
}
/* 1) POSIX's fcntl() locks (i.e. when op_setlk == F_SETLK) should be restored
* after file was closed.
*
* 2) File locks would be released (by kernel) while the file-descriptors will
* be closed. But to avoid false-positive EACCESS and EDEADLK from the kernel,
* locks should be released here explicitly with properly order. */
/* close dxb and restore lock */
if (env->me_dsync_fd != INVALID_HANDLE_VALUE) {
if (unlikely(close(env->me_dsync_fd) != 0) && rc == MDBX_SUCCESS)
rc = errno;
env->me_dsync_fd = INVALID_HANDLE_VALUE;
}
if (env->me_lazy_fd != INVALID_HANDLE_VALUE) {
if (unlikely(close(env->me_lazy_fd) != 0) && rc == MDBX_SUCCESS)
rc = errno;
env->me_lazy_fd = INVALID_HANDLE_VALUE;
if (op_setlk == F_SETLK && inprocess_neighbor && rc == MDBX_SUCCESS) {
/* restore file-lock */
rc = lck_op(
inprocess_neighbor->me_lazy_fd, F_SETLKW,
(inprocess_neighbor->me_flags & MDBX_RDONLY) ? F_RDLCK : F_WRLCK,
(inprocess_neighbor->me_flags & MDBX_EXCLUSIVE)
? 0
: inprocess_neighbor->me_pid,
(inprocess_neighbor->me_flags & MDBX_EXCLUSIVE) ? OFF_T_MAX : 1);
}
}
/* close clk and restore locks */
if (env->me_lfd != INVALID_HANDLE_VALUE) {
if (unlikely(close(env->me_lfd) != 0) && rc == MDBX_SUCCESS)
rc = errno;
env->me_lfd = INVALID_HANDLE_VALUE;
if (op_setlk == F_SETLK && inprocess_neighbor && rc == MDBX_SUCCESS) {
/* restore file-locks */
rc = lck_op(inprocess_neighbor->me_lfd, F_SETLKW, F_RDLCK, 0, 1);
if (rc == MDBX_SUCCESS && inprocess_neighbor->me_live_reader)
rc = osal_rpid_set(inprocess_neighbor);
}
}
if (inprocess_neighbor && rc != MDBX_SUCCESS)
inprocess_neighbor->me_flags |= MDBX_FATAL_ERROR;
return rc;
}
/*---------------------------------------------------------------------------*/
__cold MDBX_INTERNAL_FUNC int osal_lck_init(MDBX_env *env,
MDBX_env *inprocess_neighbor,
int global_uniqueness_flag) {
#if MDBX_LOCKING == MDBX_LOCKING_SYSV
int semid = -1;
/* don't initialize semaphores twice */
(void)inprocess_neighbor;
if (global_uniqueness_flag == MDBX_RESULT_TRUE) {
struct stat st;
if (fstat(env->me_lazy_fd, &st))
return errno;
sysv_retry_create:
semid = semget(env->me_sysv_ipc.key, 2,
IPC_CREAT | IPC_EXCL |
(st.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO)));
if (unlikely(semid == -1)) {
int err = errno;
if (err != EEXIST)
return err;
/* remove and re-create semaphore set */
semid = semget(env->me_sysv_ipc.key, 2, 0);
if (semid == -1) {
err = errno;
if (err != ENOENT)
return err;
goto sysv_retry_create;
}
if (semctl(semid, 2, IPC_RMID)) {
err = errno;
if (err != EIDRM)
return err;
}
goto sysv_retry_create;
}
unsigned short val_array[2] = {1, 1};
if (semctl(semid, 2, SETALL, val_array))
return errno;
} else {
semid = semget(env->me_sysv_ipc.key, 2, 0);
if (semid == -1)
return errno;
/* check read & write access */
struct semid_ds data[2];
if (semctl(semid, 2, IPC_STAT, data) || semctl(semid, 2, IPC_SET, data))
return errno;
}
env->me_sysv_ipc.semid = semid;
return MDBX_SUCCESS;
#elif MDBX_LOCKING == MDBX_LOCKING_FUTEX
(void)inprocess_neighbor;
if (global_uniqueness_flag != MDBX_RESULT_TRUE)
return MDBX_SUCCESS;
#error "FIXME: Not implemented"
#elif MDBX_LOCKING == MDBX_LOCKING_POSIX1988
/* don't initialize semaphores twice */
(void)inprocess_neighbor;
if (global_uniqueness_flag == MDBX_RESULT_TRUE) {
if (sem_init(&env->me_lck_mmap.lck->mti_rlock, true, 1))
return errno;
if (sem_init(&env->me_lck_mmap.lck->mti_wlock, true, 1))
return errno;
}
return MDBX_SUCCESS;
#elif MDBX_LOCKING == MDBX_LOCKING_POSIX2001 || \
MDBX_LOCKING == MDBX_LOCKING_POSIX2008
if (inprocess_neighbor)
return MDBX_SUCCESS /* don't need any initialization for mutexes
if LCK already opened/used inside current process */
;
/* FIXME: Unfortunately, there is no other reliable way but to long testing
* on each platform. On the other hand, behavior like FreeBSD is incorrect
* and we can expect it to be rare. Moreover, even on FreeBSD without
* additional in-process initialization, the probability of an problem
* occurring is vanishingly small, and the symptom is a return of EINVAL
* while locking a mutex. In other words, in the worst case, the problem
* results in an EINVAL error at the start of the transaction, but NOT data
* loss, nor database corruption, nor other fatal troubles. Thus, the code
* below I am inclined to think the workaround for erroneous platforms (like
* FreeBSD), rather than a defect of libmdbx. */
#if defined(__FreeBSD__)
/* seems that shared mutexes on FreeBSD required in-process initialization */
(void)global_uniqueness_flag;
#else
/* shared mutexes on many other platforms (including Darwin and Linux's
* futexes) doesn't need any addition in-process initialization */
if (global_uniqueness_flag != MDBX_RESULT_TRUE)
return MDBX_SUCCESS;
#endif
pthread_mutexattr_t ma;
int rc = pthread_mutexattr_init(&ma);
if (rc)
return rc;
rc = pthread_mutexattr_setpshared(&ma, PTHREAD_PROCESS_SHARED);
if (rc)
goto bailout;
#if MDBX_LOCKING == MDBX_LOCKING_POSIX2008
#if defined(PTHREAD_MUTEX_ROBUST) || defined(pthread_mutexattr_setrobust)
rc = pthread_mutexattr_setrobust(&ma, PTHREAD_MUTEX_ROBUST);
#elif defined(PTHREAD_MUTEX_ROBUST_NP) || \
defined(pthread_mutexattr_setrobust_np)
rc = pthread_mutexattr_setrobust_np(&ma, PTHREAD_MUTEX_ROBUST_NP);
#elif _POSIX_THREAD_PROCESS_SHARED < 200809L
rc = pthread_mutexattr_setrobust_np(&ma, PTHREAD_MUTEX_ROBUST_NP);
#else
rc = pthread_mutexattr_setrobust(&ma, PTHREAD_MUTEX_ROBUST);
#endif
if (rc)
goto bailout;
#endif /* MDBX_LOCKING == MDBX_LOCKING_POSIX2008 */
#if defined(_POSIX_THREAD_PRIO_INHERIT) && _POSIX_THREAD_PRIO_INHERIT >= 0 && \
!defined(MDBX_SAFE4QEMU)
rc = pthread_mutexattr_setprotocol(&ma, PTHREAD_PRIO_INHERIT);
if (rc == ENOTSUP)
rc = pthread_mutexattr_setprotocol(&ma, PTHREAD_PRIO_NONE);
if (rc && rc != ENOTSUP)
goto bailout;
#endif /* PTHREAD_PRIO_INHERIT */
rc = pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_ERRORCHECK);
if (rc && rc != ENOTSUP)
goto bailout;
rc = pthread_mutex_init(&env->me_lck_mmap.lck->mti_rlock, &ma);
if (rc)
goto bailout;
rc = pthread_mutex_init(&env->me_lck_mmap.lck->mti_wlock, &ma);
bailout:
pthread_mutexattr_destroy(&ma);
return rc;
#else
#error "FIXME"
#endif /* MDBX_LOCKING > 0 */
}
__cold static int mdbx_ipclock_failed(MDBX_env *env, osal_ipclock_t *ipc,
const int err) {
int rc = err;
#if MDBX_LOCKING == MDBX_LOCKING_POSIX2008 || MDBX_LOCKING == MDBX_LOCKING_SYSV
if (err == EOWNERDEAD) {
/* We own the mutex. Clean up after dead previous owner. */
const bool rlocked = ipc == &env->me_lck->mti_rlock;
rc = MDBX_SUCCESS;
if (!rlocked) {
if (unlikely(env->me_txn)) {
/* env is hosed if the dead thread was ours */
env->me_flags |= MDBX_FATAL_ERROR;
env->me_txn = NULL;
rc = MDBX_PANIC;
}
}
WARNING("%clock owner died, %s", (rlocked ? 'r' : 'w'),
(rc ? "this process' env is hosed" : "recovering"));
int check_rc = cleanup_dead_readers(env, rlocked, NULL);
check_rc = (check_rc == MDBX_SUCCESS) ? MDBX_RESULT_TRUE : check_rc;
#if MDBX_LOCKING == MDBX_LOCKING_SYSV
rc = (rc == MDBX_SUCCESS) ? check_rc : rc;
#else
#if defined(PTHREAD_MUTEX_ROBUST) || defined(pthread_mutex_consistent)
int mreco_rc = pthread_mutex_consistent(ipc);
#elif defined(PTHREAD_MUTEX_ROBUST_NP) || defined(pthread_mutex_consistent_np)
int mreco_rc = pthread_mutex_consistent_np(ipc);
#elif _POSIX_THREAD_PROCESS_SHARED < 200809L
int mreco_rc = pthread_mutex_consistent_np(ipc);
#else
int mreco_rc = pthread_mutex_consistent(ipc);
#endif
check_rc = (mreco_rc == 0) ? check_rc : mreco_rc;
if (unlikely(mreco_rc))
ERROR("lock recovery failed, %s", mdbx_strerror(mreco_rc));
rc = (rc == MDBX_SUCCESS) ? check_rc : rc;
if (MDBX_IS_ERROR(rc))
pthread_mutex_unlock(ipc);
#endif /* MDBX_LOCKING == MDBX_LOCKING_POSIX2008 */
return rc;
}
#elif MDBX_LOCKING == MDBX_LOCKING_POSIX2001
(void)ipc;
#elif MDBX_LOCKING == MDBX_LOCKING_POSIX1988
(void)ipc;
#elif MDBX_LOCKING == MDBX_LOCKING_FUTEX
2020-09-15 20:03:42 +03:00
#ifdef _MSC_VER
#pragma message("warning: TODO")
#else
#warning "TODO"
2020-09-15 20:03:42 +03:00
#endif
(void)ipc;
#else
#error "FIXME"
#endif /* MDBX_LOCKING */
ERROR("mutex (un)lock failed, %s", mdbx_strerror(err));
if (rc != EDEADLK)
env->me_flags |= MDBX_FATAL_ERROR;
return rc;
}
#if defined(__ANDROID_API__) || defined(ANDROID) || defined(BIONIC)
MDBX_INTERNAL_FUNC int osal_check_tid4bionic(void) {
/* avoid 32-bit Bionic bug/hang with 32-pit TID */
if (sizeof(pthread_mutex_t) < sizeof(pid_t) + sizeof(unsigned)) {
pid_t tid = gettid();
if (unlikely(tid > 0xffff)) {
FATAL("Raise the ENOSYS(%d) error to avoid hang due "
"the 32-bit Bionic/Android bug with tid/thread_id 0x%08x(%i) "
"that dont fit in 16 bits, see "
"https://android.googlesource.com/platform/bionic/+/master/"
"docs/32-bit-abi.md#is-too-small-for-large-pids",
ENOSYS, tid, tid);
return ENOSYS;
}
}
return 0;
}
#endif /* __ANDROID_API__ || ANDROID) || BIONIC */
static int mdbx_ipclock_lock(MDBX_env *env, osal_ipclock_t *ipc,
const bool dont_wait) {
#if MDBX_LOCKING == MDBX_LOCKING_POSIX2001 || \
MDBX_LOCKING == MDBX_LOCKING_POSIX2008
int rc = osal_check_tid4bionic();
if (likely(rc == 0))
rc = dont_wait ? pthread_mutex_trylock(ipc) : pthread_mutex_lock(ipc);
rc = (rc == EBUSY && dont_wait) ? MDBX_BUSY : rc;
#elif MDBX_LOCKING == MDBX_LOCKING_POSIX1988
int rc = MDBX_SUCCESS;
if (dont_wait) {
if (sem_trywait(ipc)) {
rc = errno;
if (rc == EAGAIN)
rc = MDBX_BUSY;
}
} else if (sem_wait(ipc))
rc = errno;
#elif MDBX_LOCKING == MDBX_LOCKING_SYSV
struct sembuf op = {.sem_num = (ipc != &env->me_lck->mti_wlock),
.sem_op = -1,
.sem_flg = dont_wait ? IPC_NOWAIT | SEM_UNDO : SEM_UNDO};
int rc;
if (semop(env->me_sysv_ipc.semid, &op, 1)) {
rc = errno;
if (dont_wait && rc == EAGAIN)
rc = MDBX_BUSY;
} else {
rc = *ipc ? EOWNERDEAD : MDBX_SUCCESS;
*ipc = env->me_pid;
}
#else
#error "FIXME"
#endif /* MDBX_LOCKING */
if (unlikely(rc != MDBX_SUCCESS && rc != MDBX_BUSY))
rc = mdbx_ipclock_failed(env, ipc, rc);
return rc;
}
static int mdbx_ipclock_unlock(MDBX_env *env, osal_ipclock_t *ipc) {
#if MDBX_LOCKING == MDBX_LOCKING_POSIX2001 || \
MDBX_LOCKING == MDBX_LOCKING_POSIX2008
int rc = pthread_mutex_unlock(ipc);
(void)env;
#elif MDBX_LOCKING == MDBX_LOCKING_POSIX1988
int rc = sem_post(ipc) ? errno : MDBX_SUCCESS;
(void)env;
#elif MDBX_LOCKING == MDBX_LOCKING_SYSV
if (unlikely(*ipc != (pid_t)env->me_pid))
return EPERM;
*ipc = 0;
struct sembuf op = {.sem_num = (ipc != &env->me_lck->mti_wlock),
.sem_op = 1,
.sem_flg = SEM_UNDO};
int rc = semop(env->me_sysv_ipc.semid, &op, 1) ? errno : MDBX_SUCCESS;
#else
#error "FIXME"
#endif /* MDBX_LOCKING */
return rc;
}
MDBX_INTERNAL_FUNC int osal_rdt_lock(MDBX_env *env) {
TRACE("%s", ">>");
jitter4testing(true);
int rc = mdbx_ipclock_lock(env, &env->me_lck->mti_rlock, false);
TRACE("<< rc %d", rc);
return rc;
}
MDBX_INTERNAL_FUNC void osal_rdt_unlock(MDBX_env *env) {
TRACE("%s", ">>");
int rc = mdbx_ipclock_unlock(env, &env->me_lck->mti_rlock);
TRACE("<< rc %d", rc);
if (unlikely(rc != MDBX_SUCCESS))
mdbx_panic("%s() failed: err %d\n", __func__, rc);
jitter4testing(true);
}
int mdbx_txn_lock(MDBX_env *env, bool dont_wait) {
TRACE("%swait %s", dont_wait ? "dont-" : "", ">>");
jitter4testing(true);
int rc = mdbx_ipclock_lock(env, &env->me_lck->mti_wlock, dont_wait);
TRACE("<< rc %d", rc);
return MDBX_IS_ERROR(rc) ? rc : MDBX_SUCCESS;
}
void mdbx_txn_unlock(MDBX_env *env) {
TRACE("%s", ">>");
int rc = mdbx_ipclock_unlock(env, &env->me_lck->mti_wlock);
TRACE("<< rc %d", rc);
if (unlikely(rc != MDBX_SUCCESS))
mdbx_panic("%s() failed: err %d\n", __func__, rc);
jitter4testing(true);
}
#else
#ifdef _MSC_VER
#pragma warning(disable : 4206) /* nonstandard extension used: translation \
unit is empty */
#endif /* _MSC_VER (warnings) */
#endif /* !Windows LCK-implementation */