1 files changed, 446 insertions, 0 deletions
diff --git a/servers/slapd/back-monitor/cache.c b/servers/slapd/back-monitor/cache.c
new file mode 100644
index 0000000..97bf39f
--- /dev/null
+++ b/servers/slapd/back-monitor/cache.c
@@ -0,0 +1,446 @@
+/* cache.c - routines to maintain an in-core cache of entries */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * 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>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include "ac/string.h"
+
+#include "slap.h"
+
+#include "back-monitor.h"
+
+/*
+ * The cache maps DNs to Entries.
+ * Each entry, on turn, holds the list of its children in the e_private field.
+ * This is used by search operation to perform onelevel and subtree candidate
+ * selection.
+ */
+typedef struct monitor_cache_t {
+	struct berval		mc_ndn;
+	Entry   		*mc_e;
+} monitor_cache_t;
+
+/*
+ * compares entries based on the dn
+ */
+int
+monitor_cache_cmp(
+	const void	*c1,
+	const void	*c2 )
+{
+	monitor_cache_t 	*cc1 = ( monitor_cache_t * )c1;
+	monitor_cache_t 	*cc2 = ( monitor_cache_t * )c2;
+
+	/*
+	 * case sensitive, because the dn MUST be normalized
+	 */
+	return ber_bvcmp( &cc1->mc_ndn, &cc2->mc_ndn );
+}
+
+/*
+ * checks for duplicate entries
+ */
+int
+monitor_cache_dup(
+	void		*c1,
+	void		*c2 )
+{
+	monitor_cache_t *cc1 = ( monitor_cache_t * )c1;
+	monitor_cache_t *cc2 = ( monitor_cache_t * )c2;
+
+	/*
+	 * case sensitive, because the dn MUST be normalized
+	 */
+	return ber_bvcmp( &cc1->mc_ndn, &cc2->mc_ndn ) == 0 ? -1 : 0;
+}
+
+/*
+ * adds an entry to the cache and inits the mutex
+ */
+int
+monitor_cache_add(
+	monitor_info_t	*mi,
+	Entry		*e )
+{
+	monitor_cache_t	*mc;
+	int		rc;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+
+	mc = ( monitor_cache_t * )ch_malloc( sizeof( monitor_cache_t ) );
+	mc->mc_ndn = e->e_nname;
+	mc->mc_e = e;
+	ldap_pvt_thread_mutex_lock( &mi->mi_cache_mutex );
+	rc = ldap_avl_insert( &mi->mi_cache, ( caddr_t )mc,
+			monitor_cache_cmp, monitor_cache_dup );
+	ldap_pvt_thread_mutex_unlock( &mi->mi_cache_mutex );
+
+	return rc;
+}
+
+/*
+ * locks the entry (no r/w)
+ */
+int
+monitor_cache_lock(
+	Entry		*e )
+{
+	monitor_entry_t *mp;
+
+	assert( e != NULL );
+	assert( e->e_private != NULL );
+
+	mp = ( monitor_entry_t * )e->e_private;
+	ldap_pvt_thread_mutex_lock( &mp->mp_mutex );
+
+	return( 0 );
+}
+
+/*
+ * tries to lock the entry (no r/w)
+ */
+int
+monitor_cache_trylock(
+	Entry		*e )
+{
+	monitor_entry_t *mp;
+
+	assert( e != NULL );
+	assert( e->e_private != NULL );
+
+	mp = ( monitor_entry_t * )e->e_private;
+	return ldap_pvt_thread_mutex_trylock( &mp->mp_mutex );
+}
+
+/*
+ * gets an entry from the cache based on the normalized dn 
+ * with mutex locked
+ */
+int
+monitor_cache_get(
+	monitor_info_t	*mi,
+	struct berval	*ndn,
+	Entry		**ep )
+{
+	monitor_cache_t tmp_mc, *mc;
+
+	assert( mi != NULL );
+	assert( ndn != NULL );
+	assert( ep != NULL );
+
+	*ep = NULL;
+
+	tmp_mc.mc_ndn = *ndn;
+retry:;
+	ldap_pvt_thread_mutex_lock( &mi->mi_cache_mutex );
+	mc = ( monitor_cache_t * )ldap_avl_find( mi->mi_cache,
+			( caddr_t )&tmp_mc, monitor_cache_cmp );
+
+	if ( mc != NULL ) {
+		/* entry is returned with mutex locked */
+		if ( monitor_cache_trylock( mc->mc_e ) ) {
+			ldap_pvt_thread_mutex_unlock( &mi->mi_cache_mutex );
+			ldap_pvt_thread_yield();
+			goto retry;
+		}
+		*ep = mc->mc_e;
+	}
+
+	ldap_pvt_thread_mutex_unlock( &mi->mi_cache_mutex );
+
+	return ( *ep == NULL ? -1 : 0 );
+}
+
+/*
+ * gets an entry from the cache based on the normalized dn 
+ * with mutex locked
+ */
+int
+monitor_cache_remove(
+	monitor_info_t	*mi,
+	struct berval	*ndn,
+	Entry		**ep )
+{
+	monitor_cache_t tmp_mc, *mc;
+	struct berval	pndn;
+
+	assert( mi != NULL );
+	assert( ndn != NULL );
+	assert( ep != NULL );
+
+	*ep = NULL;
+
+	dnParent( ndn, &pndn );
+
+retry:;
+	ldap_pvt_thread_mutex_lock( &mi->mi_cache_mutex );
+
+	tmp_mc.mc_ndn = *ndn;
+	mc = ( monitor_cache_t * )ldap_avl_find( mi->mi_cache,
+			( caddr_t )&tmp_mc, monitor_cache_cmp );
+
+	if ( mc != NULL ) {
+		monitor_cache_t *pmc;
+
+		if ( monitor_cache_trylock( mc->mc_e ) ) {
+			ldap_pvt_thread_mutex_unlock( &mi->mi_cache_mutex );
+			goto retry;
+		}
+
+		tmp_mc.mc_ndn = pndn;
+		pmc = ( monitor_cache_t * )ldap_avl_find( mi->mi_cache,
+			( caddr_t )&tmp_mc, monitor_cache_cmp );
+		if ( pmc != NULL ) {
+			monitor_entry_t	*mp = (monitor_entry_t *)mc->mc_e->e_private,
+					*pmp = (monitor_entry_t *)pmc->mc_e->e_private;
+			Entry		**entryp;
+
+			if ( monitor_cache_trylock( pmc->mc_e ) ) {
+				monitor_cache_release( mi, mc->mc_e );
+				ldap_pvt_thread_mutex_unlock( &mi->mi_cache_mutex );
+				goto retry;
+			}
+
+			for ( entryp = &pmp->mp_children; *entryp != NULL;  ) {
+				monitor_entry_t	*next = (monitor_entry_t *)(*entryp)->e_private;
+				if ( next == mp ) {
+					*entryp = next->mp_next;
+					entryp = NULL;
+					break;
+				}
+
+				entryp = &next->mp_next;
+			}
+
+			if ( entryp != NULL ) {
+				Debug( LDAP_DEBUG_ANY,
+					"monitor_cache_remove(\"%s\"): "
+					"not in parent's list\n",
+					ndn->bv_val );
+			}
+
+			/* either succeeded, and the entry is no longer
+			 * in its parent's list, or failed, and the
+			 * entry is neither mucked with nor returned */
+			monitor_cache_release( mi, pmc->mc_e );
+
+			if ( entryp == NULL ) {
+				monitor_cache_t *tmpmc;
+
+				tmp_mc.mc_ndn = *ndn;
+				tmpmc = ldap_avl_delete( &mi->mi_cache,
+					( caddr_t )&tmp_mc, monitor_cache_cmp );
+				assert( tmpmc == mc );
+
+				*ep = mc->mc_e;
+				ch_free( mc );
+				mc = NULL;
+
+				/* NOTE: we destroy the mutex, but otherwise
+				 * leave the private data around; specifically,
+				 * callbacks need be freed by someone else */
+
+				ldap_pvt_thread_mutex_destroy( &mp->mp_mutex );
+				mp->mp_next = NULL;
+				mp->mp_children = NULL;
+			}
+
+		}
+
+		if ( mc ) {
+			monitor_cache_release( mi, mc->mc_e );
+		}
+	}
+
+	ldap_pvt_thread_mutex_unlock( &mi->mi_cache_mutex );
+
+	return ( *ep == NULL ? -1 : 0 );
+}
+
+/*
+ * If the entry exists in cache, it is returned in locked status;
+ * otherwise, if the parent exists, if it may generate volatile 
+ * descendants an attempt to generate the required entry is
+ * performed and, if successful, the entry is returned
+ */
+int
+monitor_cache_dn2entry(
+	Operation		*op,
+	SlapReply		*rs,
+	struct berval		*ndn,
+	Entry			**ep,
+	Entry			**matched )
+{
+	monitor_info_t *mi = (monitor_info_t *)op->o_bd->be_private;
+	int 			rc;
+	struct berval		p_ndn = BER_BVNULL;
+	Entry 			*e_parent;
+	monitor_entry_t 	*mp;
+		
+	assert( mi != NULL );
+	assert( ndn != NULL );
+	assert( ep != NULL );
+	assert( matched != NULL );
+
+	*matched = NULL;
+
+	if ( !dnIsSuffix( ndn, &op->o_bd->be_nsuffix[ 0 ] ) ) {
+		return( -1 );
+	}
+
+	rc = monitor_cache_get( mi, ndn, ep );
+       	if ( !rc && *ep != NULL ) {
+		return( 0 );
+	}
+
+	/* try with parent/ancestors */
+	if ( BER_BVISNULL( ndn ) ) {
+		BER_BVSTR( &p_ndn, "" );
+
+	} else {
+		dnParent( ndn, &p_ndn );
+	}
+
+	rc = monitor_cache_dn2entry( op, rs, &p_ndn, &e_parent, matched );
+	if ( rc || e_parent == NULL ) {
+		return( -1 );
+	}
+
+	mp = ( monitor_entry_t * )e_parent->e_private;
+	rc = -1;
+	if ( mp->mp_flags & MONITOR_F_VOLATILE_CH ) {
+		/* parent entry generates volatile children */
+		rc = monitor_entry_create( op, rs, ndn, e_parent, ep );
+	}
+
+	if ( !rc ) {
+		monitor_cache_lock( *ep );
+		monitor_cache_release( mi, e_parent );
+
+	} else {
+		*matched = e_parent;
+	}
+	
+	return( rc );
+}
+
+/*
+ * releases the lock of the entry; if it is marked as volatile, it is
+ * destroyed.
+ */
+int
+monitor_cache_release(
+	monitor_info_t	*mi,
+	Entry		*e )
+{
+	monitor_entry_t *mp;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+	assert( e->e_private != NULL );
+	
+	mp = ( monitor_entry_t * )e->e_private;
+
+	if ( mp->mp_flags & MONITOR_F_VOLATILE ) {
+		monitor_cache_t	*mc, tmp_mc;
+
+		/* volatile entries do not return to cache */
+		ldap_pvt_thread_mutex_lock( &mi->mi_cache_mutex );
+		tmp_mc.mc_ndn = e->e_nname;
+		mc = ldap_avl_delete( &mi->mi_cache,
+				( caddr_t )&tmp_mc, monitor_cache_cmp );
+		ldap_pvt_thread_mutex_unlock( &mi->mi_cache_mutex );
+		if ( mc != NULL ) {
+			ch_free( mc );
+		}
+		
+		ldap_pvt_thread_mutex_unlock( &mp->mp_mutex );
+		ldap_pvt_thread_mutex_destroy( &mp->mp_mutex );
+		ch_free( mp );
+		e->e_private = NULL;
+		entry_free( e );
+
+		return( 0 );
+	}
+	
+	ldap_pvt_thread_mutex_unlock( &mp->mp_mutex );
+
+	return( 0 );
+}
+
+static void
+monitor_entry_destroy( void *v_mc )
+{
+	monitor_cache_t		*mc = (monitor_cache_t *)v_mc;
+
+	if ( mc->mc_e != NULL ) {
+		monitor_entry_t *mp;
+
+		assert( mc->mc_e->e_private != NULL );
+	
+		mp = ( monitor_entry_t * )mc->mc_e->e_private;
+
+		if ( mp->mp_cb ) {
+			monitor_callback_t	*cb;
+
+			for ( cb = mp->mp_cb; cb != NULL; ) {
+				monitor_callback_t	*next = cb->mc_next;
+
+				if ( cb->mc_free ) {
+					(void)cb->mc_free( mc->mc_e, &cb->mc_private );
+				}
+				ch_free( mp->mp_cb );
+
+				cb = next;
+			}
+		}
+
+		ldap_pvt_thread_mutex_destroy( &mp->mp_mutex );
+
+		ch_free( mp );
+		mc->mc_e->e_private = NULL;
+		entry_free( mc->mc_e );
+	}
+
+	ch_free( mc );
+}
+
+int
+monitor_cache_destroy(
+	monitor_info_t	*mi )
+{
+	if ( mi->mi_cache ) {
+		ldap_avl_free( mi->mi_cache, monitor_entry_destroy );
+	}
+
+	return 0;
+}
+
+int monitor_back_release(
+	Operation *op,
+	Entry *e,
+	int rw )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	return monitor_cache_release( mi, e );
+}