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/*****************************************************************************
Copyright (c) 2020, MariaDB Corporation.
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 Street, Fifth Floor, Boston, MA 02110-1335 USA
*****************************************************************************/
#pragma once
#include "univ.i"
#if !(defined __linux__ || defined _WIN32 || defined __OpenBSD__)
# define SRW_LOCK_DUMMY
#elif 0 // defined SAFE_MUTEX
# define SRW_LOCK_DUMMY /* Use dummy implementation for debugging purposes */
#endif
#ifdef SRW_LOCK_DUMMY
/** An exclusive-only variant of srw_lock */
class srw_mutex
{
pthread_mutex_t lock;
public:
void init() { pthread_mutex_init(&lock, nullptr); }
void destroy() { pthread_mutex_destroy(&lock); }
void wr_lock() { pthread_mutex_lock(&lock); }
void wr_unlock() { pthread_mutex_unlock(&lock); }
bool wr_lock_try() { return !pthread_mutex_trylock(&lock); }
};
#else
# define srw_mutex srw_lock_low
#endif
#include "rw_lock.h"
/** Slim reader-writer lock with no recursion */
class srw_lock_low final : private rw_lock
{
#ifdef UNIV_PFS_RWLOCK
friend class srw_lock;
#endif
#ifdef SRW_LOCK_DUMMY
pthread_mutex_t mutex;
pthread_cond_t cond_shared;
pthread_cond_t cond_exclusive;
#endif
/** @return pointer to the lock word */
rw_lock *word() { return static_cast<rw_lock*>(this); }
/** Wait for a read lock.
@param l lock word from a failed read_trylock() */
void read_lock(uint32_t l);
/** Wait for an update lock.
@param l lock word from a failed update_trylock() */
void update_lock(uint32_t l);
/** Wait for a write lock after a failed write_trylock() or upgrade_trylock()
@param holding_u whether we already hold u_lock() */
void write_lock(bool holding_u);
/** Wait for signal
@param l lock word from a failed acquisition */
inline void writer_wait(uint32_t l);
/** Wait for signal
@param l lock word from a failed acquisition */
inline void readers_wait(uint32_t l);
/** Send signal to one waiter */
inline void writer_wake();
/** Send signal to all waiters */
inline void readers_wake();
public:
#ifdef SRW_LOCK_DUMMY
void init();
void destroy();
#else
void init() { DBUG_ASSERT(!is_locked_or_waiting()); }
void destroy() { DBUG_ASSERT(!is_locked_or_waiting()); }
#endif
bool rd_lock_try() { uint32_t l; return read_trylock(l); }
bool wr_lock_try() { return write_trylock(); }
template<bool support_u_lock= false>
void rd_lock() { uint32_t l; if (!read_trylock(l)) read_lock(l); }
void u_lock() { uint32_t l; if (!update_trylock(l)) update_lock(l); }
bool u_lock_try() { uint32_t l; return update_trylock(l); }
void u_wr_upgrade() { if (!upgrade_trylock()) write_lock(true); }
template<bool support_u_lock= false>
void wr_lock() { if (!write_trylock()) write_lock(false); }
void rd_unlock();
void u_unlock();
void wr_unlock();
};
#ifndef UNIV_PFS_RWLOCK
# define SRW_LOCK_INIT(key) init()
# define SRW_LOCK_ARGS(file, line) /* nothing */
# define SRW_LOCK_CALL /* nothing */
typedef srw_lock_low srw_lock;
#else
# define SRW_LOCK_INIT(key) init(key)
# define SRW_LOCK_ARGS(file, line) file, line
# define SRW_LOCK_CALL __FILE__, __LINE__
/** Slim reader-writer lock with PERFORMANCE_SCHEMA instrumentation */
class srw_lock
{
srw_lock_low lock;
PSI_rwlock *pfs_psi;
template<bool support_u_lock>
ATTRIBUTE_NOINLINE void psi_rd_lock(const char *file, unsigned line);
template<bool support_u_lock>
ATTRIBUTE_NOINLINE void psi_wr_lock(const char *file, unsigned line);
ATTRIBUTE_NOINLINE void psi_u_lock(const char *file, unsigned line);
ATTRIBUTE_NOINLINE void psi_u_wr_upgrade(const char *file, unsigned line);
public:
void init(mysql_pfs_key_t key)
{
lock.init();
pfs_psi= PSI_RWLOCK_CALL(init_rwlock)(key, this);
}
void destroy()
{
if (pfs_psi)
{
PSI_RWLOCK_CALL(destroy_rwlock)(pfs_psi);
pfs_psi= nullptr;
}
lock.destroy();
}
template<bool support_u_lock= false>
void rd_lock(const char *file, unsigned line)
{
if (psi_likely(pfs_psi != nullptr))
psi_rd_lock<support_u_lock>(file, line);
else
lock.rd_lock();
}
void rd_unlock()
{
if (pfs_psi)
PSI_RWLOCK_CALL(unlock_rwlock)(pfs_psi);
lock.rd_unlock();
}
void u_lock(const char *file, unsigned line)
{
if (psi_likely(pfs_psi != nullptr))
psi_u_lock(file, line);
else
lock.u_lock();
}
void u_unlock()
{
if (pfs_psi)
PSI_RWLOCK_CALL(unlock_rwlock)(pfs_psi);
lock.u_unlock();
}
template<bool support_u_lock= false>
void wr_lock(const char *file, unsigned line)
{
if (psi_likely(pfs_psi != nullptr))
psi_wr_lock<support_u_lock>(file, line);
else
lock.wr_lock();
}
void wr_unlock()
{
if (pfs_psi)
PSI_RWLOCK_CALL(unlock_rwlock)(pfs_psi);
lock.wr_unlock();
}
void u_wr_upgrade(const char *file, unsigned line)
{
if (psi_likely(pfs_psi != nullptr))
psi_u_wr_upgrade(file, line);
else
lock.u_wr_upgrade();
}
bool rd_lock_try() { return lock.rd_lock_try(); }
bool u_lock_try() { return lock.u_lock_try(); }
bool wr_lock_try() { return lock.wr_lock_try(); }
};
#endif
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