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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
#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 a write lock after a failed write_trylock() */
void write_lock();
/** 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(); }
void rd_lock() { uint32_t l; if (!read_trylock(l)) read_lock(l); }
void wr_lock() { if (!write_trylock()) write_lock(); }
void rd_unlock();
void wr_unlock();
};
#ifndef UNIV_PFS_RWLOCK
# define SRW_LOCK_INIT(key) init()
typedef srw_lock_low srw_lock;
#else
# define SRW_LOCK_INIT(key) init(key)
/** Slim reader-writer lock with PERFORMANCE_SCHEMA instrumentation */
class srw_lock
{
srw_lock_low lock;
PSI_rwlock *pfs_psi;
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();
}
void rd_lock()
{
uint32_t l;
if (lock.read_trylock(l))
return;
if (pfs_psi)
{
PSI_rwlock_locker_state state;
PSI_rwlock_locker *locker= PSI_RWLOCK_CALL(start_rwlock_rdwait)
(&state, pfs_psi, PSI_RWLOCK_READLOCK, __FILE__, __LINE__);
lock.read_lock(l);
if (locker)
PSI_RWLOCK_CALL(end_rwlock_rdwait)(locker, 0);
return;
}
lock.read_lock(l);
}
void rd_unlock()
{
if (pfs_psi)
PSI_RWLOCK_CALL(unlock_rwlock)(pfs_psi);
lock.rd_unlock();
}
void wr_lock()
{
if (lock.write_trylock())
return;
if (pfs_psi)
{
PSI_rwlock_locker_state state;
PSI_rwlock_locker *locker= PSI_RWLOCK_CALL(start_rwlock_wrwait)
(&state, pfs_psi, PSI_RWLOCK_WRITELOCK, __FILE__, __LINE__);
lock.write_lock();
if (locker)
PSI_RWLOCK_CALL(end_rwlock_rdwait)(locker, 0);
return;
}
lock.write_lock();
}
void wr_unlock()
{
if (pfs_psi)
PSI_RWLOCK_CALL(unlock_rwlock)(pfs_psi);
lock.wr_unlock();
}
bool rd_lock_try() { return lock.rd_lock_try(); }
bool wr_lock_try() { return lock.wr_lock_try(); }
};
#endif
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