cache.c

ldap服务器源码

/* cache.c - routines to maintain an in-core cache of entries */
/* $OpenLDAP: pkg/ldap/servers/slapd/back-bdb/cache.c,v 1.88.2.21 2007/01/25 12:42:38 hyc Exp $ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
 *
 * Copyright 2000-2007 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 the file LICENSE in the
 * top-level directory of the distribution or, alternatively, at
 * <http://www.OpenLDAP.org/license.html>.
 */

#include "portable.h"

#include <stdio.h>

#include <ac/errno.h>
#include <ac/string.h>
#include <ac/socket.h>

#include "slap.h"

#include "back-bdb.h"

#include "ldap_rq.h"

#ifdef BDB_HIER
#define bdb_cache_lru_add	hdb_cache_lru_add
#endif
static void bdb_cache_lru_add( struct bdb_info *bdb, EntryInfo *ei );

static int	bdb_cache_delete_internal(Cache *cache, EntryInfo *e, int decr);
#ifdef LDAP_DEBUG
#ifdef SLAPD_UNUSED
static void	bdb_lru_print(Cache *cache);
#endif
#endif

static EntryInfo *
bdb_cache_entryinfo_new( Cache *cache )
{
	EntryInfo *ei = NULL;

	if ( cache->c_eifree ) {
		ldap_pvt_thread_rdwr_wlock( &cache->c_rwlock );
		if ( cache->c_eifree ) {
			ei = cache->c_eifree;
			cache->c_eifree = ei->bei_lrunext;
		}
		ldap_pvt_thread_rdwr_wunlock( &cache->c_rwlock );
	}
	if ( ei ) {
		ei->bei_lrunext = NULL;
		ei->bei_state = 0;
	} else {
		ei = ch_calloc(1, sizeof(struct bdb_entry_info));
		ldap_pvt_thread_mutex_init( &ei->bei_kids_mutex );
	}

	return ei;
}

/* Atomically release and reacquire a lock */
int
bdb_cache_entry_db_relock(
	DB_ENV *env,
	u_int32_t locker,
	EntryInfo *ei,
	int rw,
	int tryOnly,
	DB_LOCK *lock )
{
#ifdef NO_THREADS
	return 0;
#else
	int	rc;
	DBT	lockobj;
	DB_LOCKREQ list[2];

	if ( !lock ) return 0;

	lockobj.data = &ei->bei_id;
	lockobj.size = sizeof(ei->bei_id) + 1;

	list[0].op = DB_LOCK_PUT;
	list[0].lock = *lock;
	list[1].op = DB_LOCK_GET;
	list[1].lock = *lock;
	list[1].mode = rw ? DB_LOCK_WRITE : DB_LOCK_READ;
	list[1].obj = &lockobj;
	rc = env->lock_vec(env, locker, tryOnly ? DB_LOCK_NOWAIT : 0,
		list, 2, NULL );

	if (rc && !tryOnly) {
		Debug( LDAP_DEBUG_TRACE,
			"bdb_cache_entry_db_relock: entry %ld, rw %d, rc %d\n",
			ei->bei_id, rw, rc );
	} else {
		*lock = list[1].lock;
	}
	return rc;
#endif
}

static int
bdb_cache_entry_db_lock( DB_ENV *env, u_int32_t locker, EntryInfo *ei,
	int rw, int tryOnly, DB_LOCK *lock )
{
#ifdef NO_THREADS
	return 0;
#else
	int       rc;
	DBT       lockobj;
	int       db_rw;

	if ( !lock ) return 0;

	if (rw)
		db_rw = DB_LOCK_WRITE;
	else
		db_rw = DB_LOCK_READ;

	lockobj.data = &ei->bei_id;
	lockobj.size = sizeof(ei->bei_id) + 1;

	rc = LOCK_GET(env, locker, tryOnly ? DB_LOCK_NOWAIT : 0,
					&lockobj, db_rw, lock);
	if (rc && !tryOnly) {
		Debug( LDAP_DEBUG_TRACE,
			"bdb_cache_entry_db_lock: entry %ld, rw %d, rc %d\n",
			ei->bei_id, rw, rc );
	}
	return rc;
#endif /* NO_THREADS */
}

int
bdb_cache_entry_db_unlock ( DB_ENV *env, DB_LOCK *lock )
{
#ifdef NO_THREADS
	return 0;
#else
	int rc;

	if ( !lock || lock->mode == DB_LOCK_NG ) return 0;

	rc = LOCK_PUT ( env, lock );
	return rc;
#endif
}

static int
bdb_cache_entryinfo_destroy( EntryInfo *e )
{
	ldap_pvt_thread_mutex_destroy( &e->bei_kids_mutex );
	free( e->bei_nrdn.bv_val );
#ifdef BDB_HIER
	free( e->bei_rdn.bv_val );
#endif
	free( e );
	return 0;
}

#define LRU_DELETE( cache, ei ) do { \
	if ( (ei)->bei_lruprev != NULL ) { \
		(ei)->bei_lruprev->bei_lrunext = (ei)->bei_lrunext; \
	} else { \
		(cache)->c_lruhead = (ei)->bei_lrunext; \
	} \
	if ( (ei)->bei_lrunext != NULL ) { \
		(ei)->bei_lrunext->bei_lruprev = (ei)->bei_lruprev; \
	} else { \
		(cache)->c_lrutail = (ei)->bei_lruprev; \
	} \
	(ei)->bei_lrunext = (ei)->bei_lruprev = NULL; \
} while(0)

#define LRU_ADD( cache, ei ) do { \
	(ei)->bei_lrunext = (cache)->c_lruhead; \
	if ( (ei)->bei_lrunext != NULL ) { \
		(ei)->bei_lrunext->bei_lruprev = (ei); \
	} \
	(cache)->c_lruhead = (ei); \
	(ei)->bei_lruprev = NULL; \
	if ( !ldap_pvt_thread_mutex_trylock( &(cache)->lru_tail_mutex )) { \
		if ( (cache)->c_lrutail == NULL ) \
			(cache)->c_lrutail = (ei); \
		ldap_pvt_thread_mutex_unlock( &(cache)->lru_tail_mutex ); \
	} \
} while(0)

/* Do a length-ordered sort on normalized RDNs */
static int
bdb_rdn_cmp( const void *v_e1, const void *v_e2 )
{
	const EntryInfo *e1 = v_e1, *e2 = v_e2;
	int rc = e1->bei_nrdn.bv_len - e2->bei_nrdn.bv_len;
	if (rc == 0) {
		rc = strncmp( e1->bei_nrdn.bv_val, e2->bei_nrdn.bv_val,
			e1->bei_nrdn.bv_len );
	}
	return rc;
}

static int
bdb_id_cmp( const void *v_e1, const void *v_e2 )
{
	const EntryInfo *e1 = v_e1, *e2 = v_e2;
	return e1->bei_id - e2->bei_id;
}

/* Create an entryinfo in the cache. Caller must release the locks later.
 */
static int
bdb_entryinfo_add_internal(
	struct bdb_info *bdb,
	EntryInfo *ei,
	EntryInfo **res )
{
	EntryInfo *ei2 = NULL;

	*res = NULL;

	ei2 = bdb_cache_entryinfo_new( &bdb->bi_cache );

	ldap_pvt_thread_rdwr_wlock( &bdb->bi_cache.c_rwlock );
	bdb_cache_entryinfo_lock( ei->bei_parent );

	ei2->bei_id = ei->bei_id;
	ei2->bei_parent = ei->bei_parent;
#ifdef BDB_HIER
	ei2->bei_rdn = ei->bei_rdn;
#endif
#ifdef SLAP_ZONE_ALLOC
	ei2->bei_bdb = bdb;
#endif

	/* Add to cache ID tree */
	if (avl_insert( &bdb->bi_cache.c_idtree, ei2, bdb_id_cmp, avl_dup_error )) {
		EntryInfo *eix;
		eix = avl_find( bdb->bi_cache.c_idtree, ei2, bdb_id_cmp );
		bdb_cache_entryinfo_destroy( ei2 );
		ei2 = eix;
#ifdef BDB_HIER
		/* It got freed above because its value was
		 * assigned to ei2.
		 */
		ei->bei_rdn.bv_val = NULL;
#endif
	} else {
		bdb->bi_cache.c_eiused++;
		ber_dupbv( &ei2->bei_nrdn, &ei->bei_nrdn );

		/* This is a new leaf node. But if parent had no kids, then it was
		 * a leaf and we would be decrementing that. So, only increment if
		 * the parent already has kids.
		 */
		if ( ei->bei_parent->bei_kids || !ei->bei_parent->bei_id )
			bdb->bi_cache.c_leaves++;
		avl_insert( &ei->bei_parent->bei_kids, ei2, bdb_rdn_cmp,
			avl_dup_error );
#ifdef BDB_HIER
		ei->bei_parent->bei_ckids++;
#endif
	}

	*res = ei2;
	return 0;
}

/* Find the EntryInfo for the requested DN. If the DN cannot be found, return
 * the info for its closest ancestor. *res should be NULL to process a
 * complete DN starting from the tree root. Otherwise *res must be the
 * immediate parent of the requested DN, and only the RDN will be searched.
 * The EntryInfo is locked upon return and must be unlocked by the caller.
 */
int
bdb_cache_find_ndn(
	Operation	*op,
	DB_TXN		*txn,
	struct berval	*ndn,
	EntryInfo	**res )
{
	struct bdb_info *bdb = (struct bdb_info *) op->o_bd->be_private;
	EntryInfo	ei, *eip, *ei2;
	int rc = 0;
	char *ptr;

	/* this function is always called with normalized DN */
	if ( *res ) {
		/* we're doing a onelevel search for an RDN */
		ei.bei_nrdn.bv_val = ndn->bv_val;
		ei.bei_nrdn.bv_len = dn_rdnlen( op->o_bd, ndn );
		eip = *res;
	} else {
		/* we're searching a full DN from the root */
		ptr = ndn->bv_val + ndn->bv_len - op->o_bd->be_nsuffix[0].bv_len;
		ei.bei_nrdn.bv_val = ptr;
		ei.bei_nrdn.bv_len = op->o_bd->be_nsuffix[0].bv_len;
		/* Skip to next rdn if suffix is empty */
		if ( ei.bei_nrdn.bv_len == 0 ) {
			for (ptr = ei.bei_nrdn.bv_val - 2; ptr > ndn->bv_val
				&& !DN_SEPARATOR(*ptr); ptr--) /* empty */;
			if ( ptr >= ndn->bv_val ) {
				if (DN_SEPARATOR(*ptr)) ptr++;
				ei.bei_nrdn.bv_len = ei.bei_nrdn.bv_val - ptr;
				ei.bei_nrdn.bv_val = ptr;
			}
		}
		eip = &bdb->bi_cache.c_dntree;
	}
	
	for ( bdb_cache_entryinfo_lock( eip ); eip; ) {
		ei.bei_parent = eip;
		ei2 = (EntryInfo *)avl_find( eip->bei_kids, &ei, bdb_rdn_cmp );
		if ( !ei2 ) {
			int len = ei.bei_nrdn.bv_len;
				
			if ( BER_BVISEMPTY( ndn )) {
				*res = eip;
				return LDAP_SUCCESS;
			}

			ei.bei_nrdn.bv_len = ndn->bv_len -
				(ei.bei_nrdn.bv_val - ndn->bv_val);
			bdb_cache_entryinfo_unlock( eip );

			rc = bdb_dn2id( op, txn, &ei.bei_nrdn, &ei );
			if (rc) {
				bdb_cache_entryinfo_lock( eip );
				*res = eip;
				return rc;
			}

			/* DN exists but needs to be added to cache */
			ei.bei_nrdn.bv_len = len;
			rc = bdb_entryinfo_add_internal( bdb, &ei, &ei2 );
			/* add_internal left eip and c_rwlock locked */
			ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );
			if ( rc ) {
				*res = eip;
				return rc;
			}
		} else if ( ei2->bei_state & CACHE_ENTRY_DELETED ) {
			/* In the midst of deleting? Give it a chance to
			 * complete.
			 */
			bdb_cache_entryinfo_unlock( eip );
			ldap_pvt_thread_yield();
			bdb_cache_entryinfo_lock( eip );
			*res = eip;
			return DB_NOTFOUND;
		}
		bdb_cache_entryinfo_unlock( eip );
		bdb_cache_entryinfo_lock( ei2 );

		eip = ei2;

		/* Advance to next lower RDN */
		for (ptr = ei.bei_nrdn.bv_val - 2; ptr > ndn->bv_val
			&& !DN_SEPARATOR(*ptr); ptr--) /* empty */;
		if ( ptr >= ndn->bv_val ) {
			if (DN_SEPARATOR(*ptr)) ptr++;
			ei.bei_nrdn.bv_len = ei.bei_nrdn.bv_val - ptr - 1;
			ei.bei_nrdn.bv_val = ptr;
		}
		if ( ptr < ndn->bv_val ) {
			*res = eip;
			break;
		}
	}

	return rc;
}

#ifdef BDB_HIER
/* Walk up the tree from a child node, looking for an ID that's already
 * been linked into the cache.
 */
int
hdb_cache_find_parent(
	Operation *op,
	DB_TXN *txn,
	u_int32_t	locker,
	ID id,
	EntryInfo **res )
{
	struct bdb_info *bdb = (struct bdb_info *) op->o_bd->be_private;
	EntryInfo ei, eip, *ei2 = NULL, *ein = NULL, *eir = NULL;
	int rc;
	int addlru = 0;

	ei.bei_id = id;
	ei.bei_kids = NULL;
	ei.bei_ckids = 0;

	for (;;) {
		rc = hdb_dn2id_parent( op, txn, locker, &ei, &eip.bei_id );
		if ( rc ) break;

		/* Save the previous node, if any */
		ei2 = ein;

		/* Create a new node for the current ID */
		ein = bdb_cache_entryinfo_new( &bdb->bi_cache );
		ein->bei_id = ei.bei_id;
		ein->bei_kids = ei.bei_kids;
		ein->bei_nrdn = ei.bei_nrdn;
		ein->bei_rdn = ei.bei_rdn;
		ein->bei_ckids = ei.bei_ckids;
#ifdef SLAP_ZONE_ALLOC
		ein->bei_bdb = bdb;
#endif
		ei.bei_ckids = 0;
		
		/* This node is not fully connected yet */
		ein->bei_state = CACHE_ENTRY_NOT_LINKED;

		/* Insert this node into the ID tree */
		ldap_pvt_thread_rdwr_wlock( &bdb->bi_cache.c_rwlock );
		if ( avl_insert( &bdb->bi_cache.c_idtree, (caddr_t)ein,
			bdb_id_cmp, avl_dup_error ) ) {

			/* Someone else created this node just before us.
			 * Free our new copy and use the existing one.
			 */
			bdb_cache_entryinfo_destroy( ein );
			ein = (EntryInfo *)avl_find( bdb->bi_cache.c_idtree,
				(caddr_t) &ei, bdb_id_cmp );
			
			/* Link in any kids we've already processed */
			if ( ei2 ) {
				bdb_cache_entryinfo_lock( ein );
				avl_insert( &ein->bei_kids, (caddr_t)ei2,
					bdb_rdn_cmp, avl_dup_error );
				ein->bei_ckids++;
				bdb_cache_entryinfo_unlock( ein );
			}
			addlru = 0;

		}

		/* If this is the first time, save this node
		 * to be returned later.
		 */
		if ( eir == NULL ) eir = ein;

		/* If there was a previous node, link it to this one */
		if ( ei2 ) ei2->bei_parent = ein;

		/* Look for this node's parent */
		if ( eip.bei_id ) {
			ei2 = (EntryInfo *) avl_find( bdb->bi_cache.c_idtree,
					(caddr_t) &eip, bdb_id_cmp );
		} else {
			ei2 = &bdb->bi_cache.c_dntree;
		}