Adding upstream version 1:10.5.12.upstream/1%10.5.12upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 377 insertions, 0 deletions

diff --git a/mysys/thr_rwlock.c b/mysys/thr_rwlock.c
new file mode 100644
index 00000000..a8711d51
--- /dev/null
+++ b/mysys/thr_rwlock.c
@@ -0,0 +1,377 @@
+/* Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
+
+   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 St, Fifth Floor, Boston, MA 02110-1335  USA */
+
+/* Synchronization - readers / writer thread locks */
+
+#include "mysys_priv.h"
+#if defined(NEED_MY_RW_LOCK)
+#include <errno.h>
+
+#ifdef _WIN32
+
+int my_rw_init(my_rw_lock_t *rwp)
+{
+  InitializeSRWLock(&rwp->srwlock);
+  rwp->have_exclusive_srwlock = FALSE;
+  return 0;
+}
+
+
+int my_rw_rdlock(my_rw_lock_t *rwp)
+{
+  AcquireSRWLockShared(&rwp->srwlock);
+  return 0;
+}
+
+
+int my_rw_tryrdlock(my_rw_lock_t *rwp)
+{
+  if (!TryAcquireSRWLockShared(&rwp->srwlock))
+    return EBUSY;
+  return 0;
+}
+
+
+int my_rw_wrlock(my_rw_lock_t *rwp)
+{
+  AcquireSRWLockExclusive(&rwp->srwlock);
+  rwp->have_exclusive_srwlock= TRUE;
+  return 0;
+}
+
+int my_rw_trywrlock(my_rw_lock_t *rwp)
+{
+  if (!TryAcquireSRWLockExclusive(&rwp->srwlock))
+    return EBUSY;
+  rwp->have_exclusive_srwlock= TRUE;
+  return 0;
+}
+
+
+int  my_rw_unlock(my_rw_lock_t *rwp)
+{
+  if (rwp->have_exclusive_srwlock)
+  {
+    rwp->have_exclusive_srwlock= FALSE;
+    ReleaseSRWLockExclusive(&rwp->srwlock);
+  }
+  else
+  {
+    ReleaseSRWLockShared(&rwp->srwlock);
+  }
+  return 0;
+}
+
+int my_rw_destroy(my_rw_lock_t* rwp)
+{
+  DBUG_ASSERT(!rwp->have_exclusive_srwlock);
+  return 0;
+}
+
+#else
+
+/*
+  Source base from Sun Microsystems SPILT, simplified for MySQL use
+  -- Joshua Chamas
+  Some cleanup and additional code by Monty
+*/
+
+/*
+*  Multithreaded Demo Source
+*
+*  Copyright (C) 1995 by Sun Microsystems, Inc.
+* 
+*
+*  This file is a product of SunSoft, Inc. and is provided for
+*  unrestricted use provided that this legend is included on all
+*  media and as a part of the software program in whole or part.
+*  Users may copy, modify or distribute this file at will.
+*
+*  THIS FILE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
+*  THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
+*  PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
+*
+*  This file is provided with no support and without any obligation on the
+*  part of SunSoft, Inc. to assist in its use, correction, modification or
+*  enhancement.
+*
+*  SUNSOFT AND SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT
+*  TO THE INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS
+*  FILE OR ANY PART THEREOF.
+*
+*  IN NO EVENT WILL SUNSOFT OR SUN MICROSYSTEMS, INC. BE LIABLE FOR ANY
+*  LOST REVENUE OR PROFITS OR OTHER SPECIAL, INDIRECT AND CONSEQUENTIAL
+*  DAMAGES, EVEN IF THEY HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
+*  DAMAGES.
+*
+*  SunSoft, Inc.
+*  2550 Garcia Avenue
+*  Mountain View, California  94043
+*/
+
+int my_rw_init(my_rw_lock_t *rwp)
+{
+  pthread_condattr_t	cond_attr;
+
+  pthread_mutex_init( &rwp->lock, MY_MUTEX_INIT_FAST);
+  pthread_condattr_init( &cond_attr );
+  pthread_cond_init( &rwp->readers, &cond_attr );
+  pthread_cond_init( &rwp->writers, &cond_attr );
+  pthread_condattr_destroy(&cond_attr);
+
+  rwp->state	= 0;
+  rwp->waiters	= 0;
+#ifdef SAFE_MUTEX
+  rwp->write_thread   = 0;
+#endif
+
+  return(0);
+}
+
+
+int my_rw_destroy(my_rw_lock_t *rwp)
+{
+  DBUG_ASSERT(rwp->state == 0);
+  pthread_mutex_destroy( &rwp->lock );
+  pthread_cond_destroy( &rwp->readers );
+  pthread_cond_destroy( &rwp->writers );
+  return(0);
+}
+
+
+int my_rw_rdlock(my_rw_lock_t *rwp)
+{
+  pthread_mutex_lock(&rwp->lock);
+
+  /* active or queued writers */
+  while (( rwp->state < 0 ) || rwp->waiters)
+    pthread_cond_wait( &rwp->readers, &rwp->lock);
+
+  rwp->state++;
+  pthread_mutex_unlock(&rwp->lock);
+  return(0);
+}
+
+int my_rw_tryrdlock(my_rw_lock_t *rwp)
+{
+  int res;
+  pthread_mutex_lock(&rwp->lock);
+  if ((rwp->state < 0 ) || rwp->waiters)
+    res= EBUSY;					/* Can't get lock */
+  else
+  {
+    res=0;
+    rwp->state++;
+  }
+  pthread_mutex_unlock(&rwp->lock);
+  return(res);
+}
+
+
+int my_rw_wrlock(my_rw_lock_t *rwp)
+{
+  pthread_mutex_lock(&rwp->lock);
+  rwp->waiters++;				/* another writer queued */
+
+  my_rw_lock_assert_not_write_owner(rwp);
+
+  while (rwp->state)
+    pthread_cond_wait(&rwp->writers, &rwp->lock);
+  rwp->state	= -1;
+  rwp->waiters--;
+#ifdef SAFE_MUTEX
+  rwp->write_thread= pthread_self();
+#endif
+  pthread_mutex_unlock(&rwp->lock);
+  return(0);
+}
+
+
+int my_rw_trywrlock(my_rw_lock_t *rwp)
+{
+  int res;
+
+  pthread_mutex_lock(&rwp->lock);
+  if (rwp->state)
+    res= EBUSY;					/* Can't get lock */    
+  else
+  {
+    res=0;
+    rwp->state	= -1;
+#ifdef SAFE_MUTEX
+  rwp->write_thread= pthread_self();
+#endif
+  }
+  pthread_mutex_unlock(&rwp->lock);
+  return(res);
+}
+
+
+int my_rw_unlock(my_rw_lock_t *rwp)
+{
+  DBUG_PRINT("rw_unlock",
+	     ("state: %d waiters: %d", rwp->state, rwp->waiters));
+  pthread_mutex_lock(&rwp->lock);
+
+  DBUG_ASSERT(rwp->state != 0);
+
+  if (rwp->state == -1)		/* writer releasing */
+  {
+    my_rw_lock_assert_write_owner(rwp);
+    rwp->state= 0;		/* mark as available */
+#ifdef SAFE_MUTEX
+    rwp->write_thread= 0;
+#endif
+
+    if ( rwp->waiters )		/* writers queued */
+      pthread_cond_signal( &rwp->writers );
+    else
+      pthread_cond_broadcast( &rwp->readers );
+  }
+  else
+  {
+    if ( --rwp->state == 0 &&   /* no more readers */
+        rwp->waiters)
+      pthread_cond_signal( &rwp->writers );
+  }
+
+  pthread_mutex_unlock( &rwp->lock );
+  return(0);
+}
+
+#endif /* !defined _WIN32 */
+#endif /* NEED_MY_RW_LOCK*/
+
+
+int rw_pr_init(rw_pr_lock_t *rwlock)
+{
+  pthread_mutex_init(&rwlock->lock, NULL);
+  pthread_cond_init(&rwlock->no_active_readers, NULL);
+  rwlock->active_readers= 0;
+  rwlock->writers_waiting_readers= 0;
+  rwlock->active_writer= FALSE;
+#ifdef SAFE_MUTEX
+  rwlock->writer_thread= 0;
+#endif
+  return 0;
+}
+
+
+int rw_pr_destroy(rw_pr_lock_t *rwlock)
+{
+  pthread_cond_destroy(&rwlock->no_active_readers);
+  pthread_mutex_destroy(&rwlock->lock);
+  return 0;
+}
+
+
+int rw_pr_rdlock(rw_pr_lock_t *rwlock)
+{
+  pthread_mutex_lock(&rwlock->lock);
+  /*
+    The fact that we were able to acquire 'lock' mutex means
+    that there are no active writers and we can acquire rd-lock.
+    Increment active readers counter to prevent requests for
+    wr-lock from succeeding and unlock mutex.
+  */
+  rwlock->active_readers++;
+  pthread_mutex_unlock(&rwlock->lock);
+  return 0;
+}
+
+
+int rw_pr_wrlock(rw_pr_lock_t *rwlock)
+{
+  pthread_mutex_lock(&rwlock->lock);
+
+  if (rwlock->active_readers != 0)
+  {
+    /* There are active readers. We have to wait until they are gone. */
+    rwlock->writers_waiting_readers++;
+
+    while (rwlock->active_readers != 0)
+      pthread_cond_wait(&rwlock->no_active_readers, &rwlock->lock);
+
+    rwlock->writers_waiting_readers--;
+  }
+
+  /*
+    We own 'lock' mutex so there is no active writers.
+    Also there are no active readers.
+    This means that we can grant wr-lock.
+    Not releasing 'lock' mutex until unlock will block
+    both requests for rd and wr-locks.
+    Set 'active_writer' flag to simplify unlock.
+
+    Thanks to the fact wr-lock/unlock in the absence of
+    contention from readers is essentially mutex lock/unlock
+    with a few simple checks make this rwlock implementation
+    wr-lock optimized.
+  */
+  rwlock->active_writer= TRUE;
+#ifdef SAFE_MUTEX
+  rwlock->writer_thread= pthread_self();
+#endif
+  return 0;
+}
+
+
+int rw_pr_unlock(rw_pr_lock_t *rwlock)
+{
+  if (rwlock->active_writer)
+  {
+    /* We are unlocking wr-lock. */
+#ifdef SAFE_MUTEX
+    rwlock->writer_thread= 0;
+#endif
+    rwlock->active_writer= FALSE;
+    if (rwlock->writers_waiting_readers)
+    {
+      /*
+        Avoid expensive cond signal in case when there is no contention
+        or it is wr-only.
+
+        Note that from view point of performance it would be better to
+        signal on the condition variable after unlocking mutex (as it
+        reduces number of contex switches).
+
+        Unfortunately this would mean that such rwlock can't be safely
+        used by MDL subsystem, which relies on the fact that it is OK
+        to destroy rwlock once it is in unlocked state.
+      */
+      pthread_cond_signal(&rwlock->no_active_readers);
+    }
+    pthread_mutex_unlock(&rwlock->lock);
+  }
+  else
+  {
+    /* We are unlocking rd-lock. */
+    pthread_mutex_lock(&rwlock->lock);
+    rwlock->active_readers--;
+    if (rwlock->active_readers == 0 &&
+        rwlock->writers_waiting_readers)
+    {
+      /*
+        If we are last reader and there are waiting
+        writers wake them up.
+      */
+      pthread_cond_signal(&rwlock->no_active_readers);
+    }
+    pthread_mutex_unlock(&rwlock->lock);
+  }
+  return 0;
+}
+
+