X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=libraries%2Flibldap_r%2Frdwr.c;h=47ed08f8242276e45144269d857ca839ff9a15b0;hb=e509d3ed9aa2fc3eeffa2db6d9831e1955d15e44;hp=34b2253cd6ef9be241dc981885632395d3a19a42;hpb=d9d11a315f9730ee3f6cad81da2508898ee3fc56;p=openldap

diff --git a/libraries/libldap_r/rdwr.c b/libraries/libldap_r/rdwr.c
index 34b2253cd6..47ed08f824 100644
--- a/libraries/libldap_r/rdwr.c
+++ b/libraries/libldap_r/rdwr.c
@@ -1,53 +1,121 @@
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 1998-2007 The OpenLDAP Foundation.
+ * 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 file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* This work was initially developed by Kurt D. Zeilenga for inclusion
+ * in OpenLDAP Software.  Additional significant contributors include:
+ *     Stuart Lynne
+ */
+
 /*
-** This is an improved implementation of Reader/Writer locks does
-** not protect writers from starvation.  That is, if a writer is
-** currently waiting on a reader, any new reader will get
-** the lock before the writer.
-**
-** Does not support cancellation nor does any status checking.
-*/
-
-/********************************************************
- * Adapted from:
+ * This is an improved implementation of Reader/Writer locks does
+ * not protect writers from starvation.  That is, if a writer is
+ * currently waiting on a reader, any new reader will get
+ * the lock before the writer.
+ *
+ * Does not support cancellation nor does any status checking.
+ */
+/* Adapted from publically available examples for:
  *	"Programming with Posix Threads"
- *		by David R Butenhof
- *		Addison-Wesley 
- ********************************************************
+ *		by David R Butenhof, Addison-Wesley 
+ *		http://cseng.aw.com/bookpage.taf?ISBN=0-201-63392-2
  */
 
 #include "portable.h"
 
-#include <stdlib.h>
+#include <ac/stdlib.h>
 
 #include <ac/errno.h>
 #include <ac/string.h>
+#include <ac/time.h>
 
-#include "ldap_pvt_thread.h"
+#include "ldap-int.h"
+#include "ldap_pvt_thread.h" /* Get the thread interface */
+#define LDAP_THREAD_RDWR_IMPLEMENTATION
+#include "ldap_thr_debug.h"  /* May rename the symbols defined below */
+
+/*
+ * implementations that provide their own compatible 
+ * reader/writer locks define LDAP_THREAD_HAVE_RDWR
+ * in ldap_pvt_thread.h
+ */
+#ifndef LDAP_THREAD_HAVE_RDWR
+
+struct ldap_int_thread_rdwr_s {
+	ldap_pvt_thread_mutex_t ltrw_mutex;
+	ldap_pvt_thread_cond_t ltrw_read;       /* wait for read */
+	ldap_pvt_thread_cond_t ltrw_write;      /* wait for write */
+	int ltrw_valid;
+#define LDAP_PVT_THREAD_RDWR_VALID 0x0bad
+	int ltrw_r_active;
+	int ltrw_w_active;
+	int ltrw_r_wait;
+	int ltrw_w_wait;
+#ifdef LDAP_RDWR_DEBUG
+	/* keep track of who has these locks */
+#define	MAX_READERS	32
+	int ltrw_more_readers; /* Set if ltrw_readers[] is incomplete */
+	ldap_pvt_thread_t ltrw_readers[MAX_READERS];
+	ldap_pvt_thread_t ltrw_writer;
+#endif
+};
 
 int 
-ldap_pvt_thread_rdwr_init( ldap_pvt_thread_rdwr_t *rw )
+ldap_pvt_thread_rdwr_init( ldap_pvt_thread_rdwr_t *rwlock )
 {
-	memset( rw, 0, sizeof(ldap_pvt_thread_rdwr_t) );
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+
+	rw = (struct ldap_int_thread_rdwr_s *) LDAP_CALLOC( 1,
+		sizeof( struct ldap_int_thread_rdwr_s ) );
+	if ( !rw )
+		return LDAP_NO_MEMORY;
 
 	/* we should check return results */
 	ldap_pvt_thread_mutex_init( &rw->ltrw_mutex );
 	ldap_pvt_thread_cond_init( &rw->ltrw_read );
 	ldap_pvt_thread_cond_init( &rw->ltrw_write );
 
-	rw->ltrw_valid = LDAP_PVT_THREAD_RDWR_VALUE;
+	rw->ltrw_valid = LDAP_PVT_THREAD_RDWR_VALID;
+
+	*rwlock = rw;
 	return 0;
 }
 
 int 
-ldap_pvt_thread_rdwr_destroy( ldap_pvt_thread_rdwr_t *rw )
+ldap_pvt_thread_rdwr_destroy( ldap_pvt_thread_rdwr_t *rwlock )
 {
-	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALUE )
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+
+	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALID )
 		return LDAP_PVT_THREAD_EINVAL;
 
 	ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
 	/* active threads? */
-	if( rw->ltrw_r_active > 0 || rw->ltrw_w_active > 1) {
+	if( rw->ltrw_r_active > 0 || rw->ltrw_w_active > 0) {
 		ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
 		return LDAP_PVT_THREAD_EBUSY;
 	}
@@ -60,24 +128,38 @@ ldap_pvt_thread_rdwr_destroy( ldap_pvt_thread_rdwr_t *rw )
 
 	rw->ltrw_valid = 0;
 
-#ifdef SLAP_CLEANUP
 	ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
-#endif
+
 	ldap_pvt_thread_mutex_destroy( &rw->ltrw_mutex );
 	ldap_pvt_thread_cond_destroy( &rw->ltrw_read );
 	ldap_pvt_thread_cond_destroy( &rw->ltrw_write );
 
+	LDAP_FREE(rw);
+	*rwlock = NULL;
 	return 0;
 }
 
-int ldap_pvt_thread_rdwr_rlock( ldap_pvt_thread_rdwr_t *rw )
+int ldap_pvt_thread_rdwr_rlock( ldap_pvt_thread_rdwr_t *rwlock )
 {
-	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALUE )
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+
+	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALID )
 		return LDAP_PVT_THREAD_EINVAL;
 
 	ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
-	if( rw->ltrw_w_active > 1 ) {
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
+	if( rw->ltrw_w_active > 0 ) {
 		/* writer is active */
 
 		rw->ltrw_r_wait++;
@@ -85,30 +167,57 @@ int ldap_pvt_thread_rdwr_rlock( ldap_pvt_thread_rdwr_t *rw )
 		do {
 			ldap_pvt_thread_cond_wait(
 				&rw->ltrw_read, &rw->ltrw_mutex );
-		} while( rw->ltrw_w_active > 1 );
+		} while( rw->ltrw_w_active > 0 );
 
 		rw->ltrw_r_wait--;
+		assert( rw->ltrw_r_wait >= 0 ); 
 	}
 
+#ifdef LDAP_RDWR_DEBUG
+	if( rw->ltrw_r_active < MAX_READERS )
+		rw->ltrw_readers[rw->ltrw_r_active] = ldap_pvt_thread_self();
+	else
+		rw->ltrw_more_readers = 1;
+#endif
 	rw->ltrw_r_active++;
 
+
 	ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
 
 	return 0;
 }
 
-int ldap_pvt_thread_rdwr_rtrylock( ldap_pvt_thread_rdwr_t *rw )
+int ldap_pvt_thread_rdwr_rtrylock( ldap_pvt_thread_rdwr_t *rwlock )
 {
-	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALUE )
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+
+	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALID )
 		return LDAP_PVT_THREAD_EINVAL;
 
 	ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
-	if( rw->ltrw_w_active > 1) {
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
+	if( rw->ltrw_w_active > 0) {
 		ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
 		return LDAP_PVT_THREAD_EBUSY;
 	}
 
+#ifdef LDAP_RDWR_DEBUG
+	if( rw->ltrw_r_active < MAX_READERS )
+		rw->ltrw_readers[rw->ltrw_r_active] = ldap_pvt_thread_self();
+	else
+		rw->ltrw_more_readers = 1;
+#endif
 	rw->ltrw_r_active++;
 
 	ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
@@ -116,14 +225,45 @@ int ldap_pvt_thread_rdwr_rtrylock( ldap_pvt_thread_rdwr_t *rw )
 	return 0;
 }
 
-int ldap_pvt_thread_rdwr_runlock( ldap_pvt_thread_rdwr_t *rw )
+int ldap_pvt_thread_rdwr_runlock( ldap_pvt_thread_rdwr_t *rwlock )
 {
-	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALUE )
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+
+	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALID )
 		return LDAP_PVT_THREAD_EINVAL;
 
 	ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
 	rw->ltrw_r_active--;
+#ifdef LDAP_RDWR_DEBUG
+	/* Remove us from the list of readers */
+	{
+		ldap_pvt_thread_t self = ldap_pvt_thread_self();
+		int i, j;
+		for( i = j = rw->ltrw_r_active; i >= 0; i--) {
+			if (rw->ltrw_readers[i] == self) {
+				rw->ltrw_readers[i] = rw->ltrw_readers[j];
+				rw->ltrw_readers[j] = 0;
+				break;
+			}
+		}
+		if( !rw->ltrw_more_readers )
+			assert( i >= 0 );
+		else if( j == 0 )
+			rw->ltrw_more_readers = 0;
+	}
+#endif
+
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
 
 	if (rw->ltrw_r_active == 0 && rw->ltrw_w_wait > 0 ) {
 		ldap_pvt_thread_cond_signal( &rw->ltrw_write );
@@ -134,13 +274,26 @@ int ldap_pvt_thread_rdwr_runlock( ldap_pvt_thread_rdwr_t *rw )
 	return 0;
 }
 
-int ldap_pvt_thread_rdwr_wlock( ldap_pvt_thread_rdwr_t *rw )
+int ldap_pvt_thread_rdwr_wlock( ldap_pvt_thread_rdwr_t *rwlock )
 {
-	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALUE )
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+
+	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALID )
 		return LDAP_PVT_THREAD_EINVAL;
 
 	ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
 	if ( rw->ltrw_w_active > 0 || rw->ltrw_r_active > 0 ) {
 		rw->ltrw_w_wait++;
 
@@ -150,8 +303,12 @@ int ldap_pvt_thread_rdwr_wlock( ldap_pvt_thread_rdwr_t *rw )
 		} while ( rw->ltrw_w_active > 0 || rw->ltrw_r_active > 0 );
 
 		rw->ltrw_w_wait--;
+		assert( rw->ltrw_w_wait >= 0 ); 
 	}
 
+#ifdef LDAP_RDWR_DEBUG
+	rw->ltrw_writer = ldap_pvt_thread_self();
+#endif
 	rw->ltrw_w_active++;
 
 	ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
@@ -159,18 +316,34 @@ int ldap_pvt_thread_rdwr_wlock( ldap_pvt_thread_rdwr_t *rw )
 	return 0;
 }
 
-int ldap_pvt_thread_rdwr_wtrylock( ldap_pvt_thread_rdwr_t *rw )
+int ldap_pvt_thread_rdwr_wtrylock( ldap_pvt_thread_rdwr_t *rwlock )
 {
-	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALUE )
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+
+	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALID )
 		return LDAP_PVT_THREAD_EINVAL;
 
 	ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
 	if ( rw->ltrw_w_active > 0 || rw->ltrw_r_active > 0 ) {
 		ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
 		return LDAP_PVT_THREAD_EBUSY;
 	}
 
+#ifdef LDAP_RDWR_DEBUG
+	rw->ltrw_writer = ldap_pvt_thread_self();
+#endif
 	rw->ltrw_w_active++;
 
 	ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
@@ -178,15 +351,28 @@ int ldap_pvt_thread_rdwr_wtrylock( ldap_pvt_thread_rdwr_t *rw )
 	return 0;
 }
 
-int ldap_pvt_thread_rdwr_wunlock( ldap_pvt_thread_rdwr_t *rw )
+int ldap_pvt_thread_rdwr_wunlock( ldap_pvt_thread_rdwr_t *rwlock )
 {
-	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALUE )
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+
+	if( rw->ltrw_valid != LDAP_PVT_THREAD_RDWR_VALID )
 		return LDAP_PVT_THREAD_EINVAL;
 
 	ldap_pvt_thread_mutex_lock( &rw->ltrw_mutex );
 
 	rw->ltrw_w_active--;
 
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
 	if (rw->ltrw_r_wait > 0) {
 		ldap_pvt_thread_cond_broadcast( &rw->ltrw_read );
 
@@ -194,12 +380,16 @@ int ldap_pvt_thread_rdwr_wunlock( ldap_pvt_thread_rdwr_t *rw )
 		ldap_pvt_thread_cond_signal( &rw->ltrw_write );
 	}
 
+#ifdef LDAP_RDWR_DEBUG
+	assert( rw->ltrw_writer == ldap_pvt_thread_self() );
+	rw->ltrw_writer = 0;
+#endif
 	ldap_pvt_thread_mutex_unlock( &rw->ltrw_mutex );
 
 	return 0;
 }
 
-#ifdef LDAP_DEBUG
+#ifdef LDAP_RDWR_DEBUG
 
 /* just for testing, 
  * return 0 if false, suitable for assert(ldap_pvt_thread_rdwr_Xchk(rdwr))
@@ -211,20 +401,58 @@ int ldap_pvt_thread_rdwr_wunlock( ldap_pvt_thread_rdwr_t *rw )
  * a lock are caught.
  */
 
-int ldap_pvt_thread_rdwr_readers(ldap_pvt_thread_rdwr_t *rw)
+int ldap_pvt_thread_rdwr_readers(ldap_pvt_thread_rdwr_t *rwlock)
 {
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
 	return( rw->ltrw_r_active );
 }
 
-int ldap_pvt_thread_rdwr_writers(ldap_pvt_thread_rdwr_t *rw)
+int ldap_pvt_thread_rdwr_writers(ldap_pvt_thread_rdwr_t *rwlock)
 {
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
 	return( rw->ltrw_w_active );
 }
 
-int ldap_pvt_thread_rdwr_active(ldap_pvt_thread_rdwr_t *rw)
+int ldap_pvt_thread_rdwr_active(ldap_pvt_thread_rdwr_t *rwlock)
 {
-	return(ldap_pvt_thread_rdwr_readers(rw) +
-	       ldap_pvt_thread_rdwr_writers(rw));
+	struct ldap_int_thread_rdwr_s *rw;
+
+	assert( rwlock != NULL );
+	rw = *rwlock;
+
+	assert( rw != NULL );
+	assert( rw->ltrw_valid == LDAP_PVT_THREAD_RDWR_VALID );
+	assert( rw->ltrw_w_active >= 0 ); 
+	assert( rw->ltrw_w_wait >= 0 ); 
+	assert( rw->ltrw_r_active >= 0 ); 
+	assert( rw->ltrw_r_wait >= 0 ); 
+
+	return(ldap_pvt_thread_rdwr_readers(rwlock) +
+	       ldap_pvt_thread_rdwr_writers(rwlock));
 }
 
-#endif /* LDAP_DEBUG */
+#endif /* LDAP_RDWR_DEBUG */
+
+#endif /* LDAP_THREAD_HAVE_RDWR */