X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=servers%2Fslapd%2Foverlays%2Fsyncprov.c;h=a284d2ae0a619d3df6801445ce98f03ec0ea928f;hb=c68bb6a0e1e760b2a03f9745a44fbadb98b22061;hp=3309eba85a85310f41f78684052032c260bbca88;hpb=04391a9ec6b2f9c2e395dfab468bcde9e5ab8213;p=openldap

diff --git a/servers/slapd/overlays/syncprov.c b/servers/slapd/overlays/syncprov.c
index 3309eba85a..a284d2ae0a 100644
--- a/servers/slapd/overlays/syncprov.c
+++ b/servers/slapd/overlays/syncprov.c
@@ -2,7 +2,7 @@
 /* syncprov.c - syncrepl provider */
 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
  *
- * Copyright 2004-2005 The OpenLDAP Foundation.
+ * Copyright 2004-2008 The OpenLDAP Foundation.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -25,6 +25,8 @@
 #include <ac/string.h>
 #include "lutil.h"
 #include "slap.h"
+#include "config.h"
+#include "ldap_rq.h"
 
 /* A modify request on a particular entry */
 typedef struct modinst {
@@ -59,9 +61,17 @@ typedef struct syncops {
 	int		s_rid;
 	struct berval s_filterstr;
 	int		s_flags;	/* search status */
+#define	PS_IS_REFRESHING	0x01
+#define	PS_IS_DETACHED		0x02
+#define	PS_WROTE_BASE		0x04
+#define	PS_FIND_BASE		0x08
+#define	PS_FIX_FILTER		0x10
+
 	int		s_inuse;	/* reference count */
 	struct syncres *s_res;
 	struct syncres *s_restail;
+	struct re_s	*s_qtask;	/* task for playing psearch responses */
+#define	RUNQ_INTERVAL	36000	/* a long time */
 	ldap_pvt_thread_mutex_t	s_mutex;
 } syncops;
 
@@ -82,9 +92,6 @@ typedef struct sync_control {
 #define SLAP_SYNC_PERSIST				(LDAP_SYNC_RESERVED<<SLAP_CONTROL_SHIFT)
 #define SLAP_SYNC_REFRESH_AND_PERSIST	(LDAP_SYNC_REFRESH_AND_PERSIST<<SLAP_CONTROL_SHIFT)
 
-#define	PS_IS_REFRESHING	0x01
-#define	PS_IS_DETACHED		0x02
-
 /* Record of which searches matched at premodify step */
 typedef struct syncmatches {
 	struct syncmatches *sm_next;
@@ -115,10 +122,12 @@ typedef struct syncprov_info_t {
 	int		si_chkops;	/* checkpointing info */
 	int		si_chktime;
 	int		si_numops;	/* number of ops since last checkpoint */
+	int		si_nopres;	/* Skip present phase */
+	int		si_usehint;	/* use reload hint */
 	time_t	si_chklast;	/* time of last checkpoint */
 	Avlnode	*si_mods;	/* entries being modified */
 	sessionlog	*si_logs;
-	ldap_pvt_thread_mutex_t	si_csn_mutex;
+	ldap_pvt_thread_rdwr_t	si_csn_rwlock;
 	ldap_pvt_thread_mutex_t	si_ops_mutex;
 	ldap_pvt_thread_mutex_t	si_mods_mutex;
 	char		si_ctxcsnbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
@@ -141,7 +150,7 @@ typedef struct fbase_cookie {
 	int fscope;	/* if TRUE then fdn is within the psearch scope */
 } fbase_cookie;
 
-static AttributeName csn_anlist[2];
+static AttributeName csn_anlist[3];
 static AttributeName uuid_anlist[2];
 
 /* Build a LDAPsync intermediate state control */
@@ -158,8 +167,6 @@ syncprov_state_ctrl(
 {
 	Attribute* a;
 	int ret;
-	int res;
-	const char *text = NULL;
 
 	BerElementBuffer berbuf;
 	BerElement *ber = (BerElement *)&berbuf;
@@ -179,6 +186,8 @@ syncprov_state_ctrl(
 		}
 	}
 
+	/* FIXME: what if entryuuid is NULL or empty ? */
+
 	if ( send_cookie && cookie ) {
 		ber_printf( ber, "{eOON}",
 			entry_sync_state, &entryuuid_bv, cookie );
@@ -358,36 +367,15 @@ findbase_cb( Operation *op, SlapReply *rs )
 		 * Just store whatever we got.
 		 */
 		if ( fc->fss->s_eid == NOID ) {
-			fc->fbase = 1;
+			fc->fbase = 2;
 			fc->fss->s_eid = rs->sr_entry->e_id;
 			ber_dupbv( &fc->fss->s_base, &rs->sr_entry->e_nname );
 
 		} else if ( rs->sr_entry->e_id == fc->fss->s_eid &&
 			dn_match( &rs->sr_entry->e_nname, &fc->fss->s_base )) {
 
-		/* OK, the DN is the same and the entryID is the same. Now
-		 * see if the fdn resides in the scope.
-		 */
+		/* OK, the DN is the same and the entryID is the same. */
 			fc->fbase = 1;
-			switch ( fc->fss->s_op->ors_scope ) {
-			case LDAP_SCOPE_BASE:
-				fc->fscope = dn_match( fc->fdn, &rs->sr_entry->e_nname );
-				break;
-			case LDAP_SCOPE_ONELEVEL: {
-				struct berval pdn;
-				dnParent( fc->fdn, &pdn );
-				fc->fscope = dn_match( &pdn, &rs->sr_entry->e_nname );
-				break; }
-			case LDAP_SCOPE_SUBTREE:
-				fc->fscope = dnIsSuffix( fc->fdn, &rs->sr_entry->e_nname );
-				break;
-#ifdef LDAP_SCOPE_SUBORDINATE
-			case LDAP_SCOPE_SUBORDINATE:
-				fc->fscope = dnIsSuffix( fc->fdn, &rs->sr_entry->e_nname ) &&
-					!dn_match( fc->fdn, &rs->sr_entry->e_nname );
-				break;
-#endif
-			}
 		}
 	}
 	if ( rs->sr_err != LDAP_SUCCESS ) {
@@ -396,44 +384,83 @@ findbase_cb( Operation *op, SlapReply *rs )
 	return LDAP_SUCCESS;
 }
 
+static Filter generic_filter = { LDAP_FILTER_PRESENT, { 0 }, NULL };
+static struct berval generic_filterstr = BER_BVC("(objectclass=*)");
+
 static int
 syncprov_findbase( Operation *op, fbase_cookie *fc )
 {
 	opcookie *opc = op->o_callback->sc_private;
 	slap_overinst *on = opc->son;
-	syncprov_info_t		*si = on->on_bi.bi_private;
 
-	slap_callback cb = {0};
-	Operation fop;
-	SlapReply frs = { REP_RESULT };
-	int rc;
+	/* Use basic parameters from syncrepl search, but use
+	 * current op's threadctx / tmpmemctx
+	 */
+	ldap_pvt_thread_mutex_lock( &fc->fss->s_mutex );
+	if ( fc->fss->s_flags & PS_FIND_BASE ) {
+		slap_callback cb = {0};
+		Operation fop;
+		SlapReply frs = { REP_RESULT };
+		BackendInfo *bi;
+		int rc;
 
-	fop = *op;
+		fc->fss->s_flags ^= PS_FIND_BASE;
+		ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );
 
-	cb.sc_response = findbase_cb;
-	cb.sc_private = fc;
+		fop = *fc->fss->s_op;
 
-	fop.o_sync_mode &= SLAP_CONTROL_MASK;	/* turn off sync mode */
-	fop.o_managedsait = SLAP_CONTROL_CRITICAL;
-	fop.o_callback = &cb;
-	fop.o_tag = LDAP_REQ_SEARCH;
-	fop.ors_scope = LDAP_SCOPE_BASE;
-	fop.ors_deref = fc->fss->s_op->ors_deref;
-	fop.ors_limit = NULL;
-	fop.ors_slimit = 1;
-	fop.ors_tlimit = SLAP_NO_LIMIT;
-	fop.ors_attrs = slap_anlist_no_attrs;
-	fop.ors_attrsonly = 1;
-	fop.ors_filter = fc->fss->s_op->ors_filter;
-	fop.ors_filterstr = fc->fss->s_op->ors_filterstr;
+		fop.o_hdr = op->o_hdr;
+		fop.o_bd = op->o_bd;
+		fop.o_time = op->o_time;
+		fop.o_tincr = op->o_tincr;
+		bi = op->o_bd->bd_info;
 
-	fop.o_req_ndn = fc->fss->s_op->o_req_ndn;
+		cb.sc_response = findbase_cb;
+		cb.sc_private = fc;
 
-	fop.o_bd->bd_info = on->on_info->oi_orig;
-	rc = fop.o_bd->be_search( &fop, &frs );
-	fop.o_bd->bd_info = (BackendInfo *)on;
+		fop.o_sync_mode = 0;	/* turn off sync mode */
+		fop.o_managedsait = SLAP_CONTROL_CRITICAL;
+		fop.o_callback = &cb;
+		fop.o_tag = LDAP_REQ_SEARCH;
+		fop.ors_scope = LDAP_SCOPE_BASE;
+		fop.ors_limit = NULL;
+		fop.ors_slimit = 1;
+		fop.ors_tlimit = SLAP_NO_LIMIT;
+		fop.ors_attrs = slap_anlist_no_attrs;
+		fop.ors_attrsonly = 1;
+		fop.ors_filter = &generic_filter;
+		fop.ors_filterstr = generic_filterstr;
 
-	if ( fc->fbase ) return LDAP_SUCCESS;
+		rc = overlay_op_walk( &fop, &frs, op_search, on->on_info, on );
+		op->o_bd->bd_info = bi;
+	} else {
+		ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );
+		fc->fbase = 1;
+	}
+
+	/* After the first call, see if the fdn resides in the scope */
+	if ( fc->fbase == 1 ) {
+		switch ( fc->fss->s_op->ors_scope ) {
+		case LDAP_SCOPE_BASE:
+			fc->fscope = dn_match( fc->fdn, &fc->fss->s_base );
+			break;
+		case LDAP_SCOPE_ONELEVEL: {
+			struct berval pdn;
+			dnParent( fc->fdn, &pdn );
+			fc->fscope = dn_match( &pdn, &fc->fss->s_base );
+			break; }
+		case LDAP_SCOPE_SUBTREE:
+			fc->fscope = dnIsSuffix( fc->fdn, &fc->fss->s_base );
+			break;
+		case LDAP_SCOPE_SUBORDINATE:
+			fc->fscope = dnIsSuffix( fc->fdn, &fc->fss->s_base ) &&
+				!dn_match( fc->fdn, &fc->fss->s_base );
+			break;
+		}
+	}
+
+	if ( fc->fbase )
+		return LDAP_SUCCESS;
 
 	/* If entryID has changed, then the base of this search has
 	 * changed. Invalidate the psearch.
@@ -449,16 +476,18 @@ syncprov_findbase( Operation *op, fbase_cookie *fc )
  * was not checkpointed at the previous shutdown.
  *
  * 2: when the current contextCSN is known and we have a sync cookie, we search
- * for one entry with CSN <= the cookie CSN. (Used to search for =.) If an
- * entry is found, the cookie CSN is valid, otherwise it is stale.
+ * for one entry with CSN = the cookie CSN. If not found, try <= cookie CSN.
+ * If an entry is found, the cookie CSN is valid, otherwise it is stale.
  *
  * 3: during a refresh phase, we search for all entries with CSN <= the cookie
  * CSN, and generate Present records for them. We always collect this result
  * in SyncID sets, even if there's only one match.
  */
-#define	FIND_MAXCSN	1
-#define	FIND_CSN	2
-#define	FIND_PRESENT	3
+typedef enum find_csn_t {
+	FIND_MAXCSN	= 1,
+	FIND_CSN	= 2,
+	FIND_PRESENT	= 3
+} find_csn_t;
 
 static int
 findmax_cb( Operation *op, SlapReply *rs )
@@ -481,7 +510,11 @@ findcsn_cb( Operation *op, SlapReply *rs )
 {
 	slap_callback *sc = op->o_callback;
 
-	if ( rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS ) {
+	/* We just want to know that at least one exists, so it's OK if
+	 * we exceed the unchecked limit.
+	 */
+	if ( rs->sr_err == LDAP_ADMINLIMIT_EXCEEDED ||
+		(rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS )) {
 		sc->sc_private = (void *)1;
 	}
 	return LDAP_SUCCESS;
@@ -537,7 +570,7 @@ findpres_cb( Operation *op, SlapReply *rs )
 }
 
 static int
-syncprov_findcsn( Operation *op, int mode )
+syncprov_findcsn( Operation *op, find_csn_t mode )
 {
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	syncprov_info_t		*si = on->on_bi.bi_private;
@@ -547,16 +580,17 @@ syncprov_findcsn( Operation *op, int mode )
 	SlapReply frs = { REP_RESULT };
 	char buf[LDAP_LUTIL_CSNSTR_BUFSIZE + STRLENOF("(entryCSN<=)")];
 	char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
-	struct berval fbuf, maxcsn;
-	Filter cf, af;
+	struct berval maxcsn;
+	Filter cf;
 #ifdef LDAP_COMP_MATCH
 	AttributeAssertion eq = { NULL, BER_BVNULL, NULL };
 #else
 	AttributeAssertion eq = { NULL, BER_BVNULL };
 #endif
-	int i, rc = LDAP_SUCCESS;
 	fpres_cookie pcookie;
 	sync_control *srs = NULL;
+	struct slap_limits_set fc_limits;
+	int i, rc = LDAP_SUCCESS, findcsn_retry = 1;
 
 	if ( mode != FIND_MAXCSN ) {
 		srs = op->o_controls[slap_cids.sc_LDAPsync];
@@ -571,7 +605,6 @@ syncprov_findcsn( Operation *op, int mode )
 	/* We want pure entries, not referrals */
 	fop.o_managedsait = SLAP_CONTROL_CRITICAL;
 
-	fbuf.bv_val = buf;
 	cf.f_ava = &eq;
 	cf.f_av_desc = slap_schema.si_ad_entryCSN;
 	cf.f_next = NULL;
@@ -580,13 +613,14 @@ syncprov_findcsn( Operation *op, int mode )
 	fop.ors_limit = NULL;
 	fop.ors_tlimit = SLAP_NO_LIMIT;
 	fop.ors_filter = &cf;
-	fop.ors_filterstr = fbuf;
+	fop.ors_filterstr.bv_val = buf;
 
+again:
 	switch( mode ) {
 	case FIND_MAXCSN:
 		cf.f_choice = LDAP_FILTER_GE;
 		cf.f_av_value = si->si_ctxcsn;
-		fbuf.bv_len = sprintf( buf, "(entryCSN>=%s)",
+		fop.ors_filterstr.bv_len = sprintf( buf, "(entryCSN>=%s)",
 			cf.f_av_value.bv_val );
 		fop.ors_attrsonly = 0;
 		fop.ors_attrs = csn_anlist;
@@ -598,10 +632,21 @@ syncprov_findcsn( Operation *op, int mode )
 		maxcsn.bv_len = si->si_ctxcsn.bv_len;
 		break;
 	case FIND_CSN:
-		cf.f_choice = LDAP_FILTER_LE;
 		cf.f_av_value = srs->sr_state.ctxcsn;
-		fbuf.bv_len = sprintf( buf, "(entryCSN<=%s)",
-			cf.f_av_value.bv_val );
+		/* Look for exact match the first time */
+		if ( findcsn_retry ) {
+			cf.f_choice = LDAP_FILTER_EQUALITY;
+			fop.ors_filterstr.bv_len = sprintf( buf, "(entryCSN=%s)",
+				cf.f_av_value.bv_val );
+		/* On retry, look for <= */
+		} else {
+			cf.f_choice = LDAP_FILTER_LE;
+			fop.ors_limit = &fc_limits;
+			memset( &fc_limits, 0, sizeof( fc_limits ));
+			fc_limits.lms_s_unchecked = 1;
+			fop.ors_filterstr.bv_len = sprintf( buf, "(entryCSN<=%s)",
+				cf.f_av_value.bv_val );
+		}
 		fop.ors_attrsonly = 1;
 		fop.ors_attrs = slap_anlist_no_attrs;
 		fop.ors_slimit = 1;
@@ -609,14 +654,8 @@ syncprov_findcsn( Operation *op, int mode )
 		cb.sc_response = findcsn_cb;
 		break;
 	case FIND_PRESENT:
-		af.f_choice = LDAP_FILTER_AND;
-		af.f_next = NULL;
-		af.f_and = &cf;
-		cf.f_choice = LDAP_FILTER_LE;
-		cf.f_av_value = srs->sr_state.ctxcsn;
-		cf.f_next = op->ors_filter;
-		fop.ors_filter = &af;
-		filter2bv_x( &fop, fop.ors_filter, &fop.ors_filterstr );
+		fop.ors_filter = op->ors_filter;
+		fop.ors_filterstr = op->ors_filterstr;
 		fop.ors_attrsonly = 0;
 		fop.ors_attrs = uuid_anlist;
 		fop.ors_slimit = SLAP_NO_LIMIT;
@@ -649,160 +688,77 @@ syncprov_findcsn( Operation *op, int mode )
 		break;
 	case FIND_CSN:
 		/* If matching CSN was not found, invalidate the context. */
-		if ( !cb.sc_private ) rc = LDAP_NO_SUCH_OBJECT;
+		if ( !cb.sc_private ) {
+			/* If we didn't find an exact match, then try for <= */
+			if ( findcsn_retry ) {
+				findcsn_retry = 0;
+				goto again;
+			}
+			rc = LDAP_NO_SUCH_OBJECT;
+		}
 		break;
 	case FIND_PRESENT:
 		op->o_tmpfree( pcookie.uuids, op->o_tmpmemctx );
-		op->o_tmpfree( fop.ors_filterstr.bv_val, op->o_tmpmemctx );
 		break;
 	}
 
 	return rc;
 }
 
-/* Queue a persistent search response */
-static int
-syncprov_qresp( opcookie *opc, syncops *so, int mode )
+static void
+syncprov_free_syncop( syncops *so )
 {
-	syncres *sr;
-
-	sr = ch_malloc(sizeof(syncres) + opc->suuid.bv_len + 1 +
-		opc->sdn.bv_len + 1 + opc->sndn.bv_len + 1 + opc->sctxcsn.bv_len + 1 );
-	sr->s_next = NULL;
-	sr->s_dn.bv_val = (char *)(sr + 1);
-	sr->s_dn.bv_len = opc->sdn.bv_len;
-	sr->s_mode = mode;
-	sr->s_isreference = opc->sreference;
-	sr->s_ndn.bv_val = lutil_strcopy( sr->s_dn.bv_val, opc->sdn.bv_val );
-	sr->s_ndn.bv_len = opc->sndn.bv_len;
-	*(sr->s_ndn.bv_val++) = '\0';
-	sr->s_uuid.bv_val = lutil_strcopy( sr->s_ndn.bv_val, opc->sndn.bv_val );
-	sr->s_uuid.bv_len = opc->suuid.bv_len;
-	*(sr->s_uuid.bv_val++) = '\0';
-	sr->s_csn.bv_val = lutil_strcopy( sr->s_uuid.bv_val, opc->suuid.bv_val );
-	sr->s_csn.bv_len = opc->sctxcsn.bv_len;
-	strcpy( sr->s_csn.bv_val, opc->sctxcsn.bv_val );
+	syncres *sr, *srnext;
+	GroupAssertion *ga, *gnext;
 
-	if ( !so->s_res ) {
-		so->s_res = sr;
-	} else {
-		so->s_restail->s_next = sr;
+	ldap_pvt_thread_mutex_lock( &so->s_mutex );
+	if ( --so->s_inuse > 0 ) {
+		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
+		return;
 	}
-	so->s_restail = sr;
 	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-	return LDAP_SUCCESS;
-}
-
-/* Play back queued responses */
-static int
-syncprov_sendresp( Operation *op, opcookie *opc, syncops *so, Entry **e, int mode, int queue );
-
-static int
-syncprov_qplay( Operation *op, slap_overinst *on, syncops *so )
-{
-	syncres *sr, *srnext;
-	Entry *e;
-	opcookie opc;
-	int rc;
-
-	opc.son = on;
-	op->o_bd->bd_info = (BackendInfo *)on->on_info;
-	for (sr = so->s_res; sr; sr=srnext) {
-		srnext = sr->s_next;
-		opc.sdn = sr->s_dn;
-		opc.sndn = sr->s_ndn;
-		opc.suuid = sr->s_uuid;
-		opc.sctxcsn = sr->s_csn;
-		opc.sreference = sr->s_isreference;
-		e = NULL;
-
-		if ( sr->s_mode != LDAP_SYNC_DELETE ) {
-			rc = be_entry_get_rw( op, &opc.sndn, NULL, NULL, 0, &e );
-			if ( rc ) {
-				ch_free( sr );
-				so->s_res = srnext;
-				continue;
-			}
-		}
-		rc = syncprov_sendresp( op, &opc, so, &e, sr->s_mode, 0 );
-
-		if ( e ) {
-			be_entry_release_rw( op, e, 0 );
+	if ( so->s_flags & PS_IS_DETACHED ) {
+		filter_free( so->s_op->ors_filter );
+		for ( ga = so->s_op->o_groups; ga; ga=gnext ) {
+			gnext = ga->ga_next;
+			ch_free( ga );
 		}
-		if ( rc )
-			break;
-
+		ch_free( so->s_op );
+	}
+	ch_free( so->s_base.bv_val );
+	for ( sr=so->s_res; sr; sr=srnext ) {
+		srnext = sr->s_next;
 		ch_free( sr );
-		so->s_res = srnext;
 	}
-	op->o_bd->bd_info = (BackendInfo *)on;
-	if ( !so->s_res )
-		so->s_restail = NULL;
-	return rc;
+	ldap_pvt_thread_mutex_destroy( &so->s_mutex );
+	ch_free( so );
 }
 
 /* Send a persistent search response */
 static int
-syncprov_sendresp( Operation *op, opcookie *opc, syncops *so, Entry **e, int mode, int queue )
+syncprov_sendresp( Operation *op, opcookie *opc, syncops *so,
+	Entry **e, int mode )
 {
 	slap_overinst *on = opc->son;
-	syncprov_info_t *si = on->on_bi.bi_private;
 
 	SlapReply rs = { REP_SEARCH };
 	LDAPControl *ctrls[2];
 	struct berval cookie;
 	Entry e_uuid = {0};
 	Attribute a_uuid = {0};
-	Operation sop = *so->s_op;
-	Opheader ohdr;
 
 	if ( so->s_op->o_abandon )
 		return SLAPD_ABANDON;
 
-	ohdr = *sop.o_hdr;
-	sop.o_hdr = &ohdr;
-	sop.o_tmpmemctx = op->o_tmpmemctx;
-	sop.o_bd = op->o_bd;
-	sop.o_controls = op->o_controls;
-	sop.o_private = op->o_private;
-
-	/* If queueing is allowed */
-	if ( queue ) {
-		ldap_pvt_thread_mutex_lock( &so->s_mutex );
-		/* If we're still in refresh mode, must queue */
-		if (so->s_flags & PS_IS_REFRESHING) {
-			return syncprov_qresp( opc, so, mode );
-		}
-		/* If connection is free but queue is non-empty,
-		 * try to flush the queue.
-		 */
-		if ( so->s_res ) {
-			rs.sr_err = syncprov_qplay( &sop, on, so );
-		}
-		/* If the connection is busy, must queue */
-		if ( sop.o_conn->c_writewaiter || rs.sr_err == LDAP_BUSY ) {
-			return syncprov_qresp( opc, so, mode );
-		}
-		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-
-		/* If syncprov_qplay returned any other error, bail out. */
-		if ( rs.sr_err ) {
-			return rs.sr_err;
-		}
-	} else {
-		/* Queueing not allowed and conn is busy, give up */
-		if ( sop.o_conn->c_writewaiter )
-			return LDAP_BUSY;
-	}
-
 	ctrls[1] = NULL;
 	slap_compose_sync_cookie( op, &cookie, &opc->sctxcsn, so->s_rid );
 
 	e_uuid.e_attrs = &a_uuid;
 	a_uuid.a_desc = slap_schema.si_ad_entryUUID;
 	a_uuid.a_nvals = &opc->suuid;
-	rs.sr_err = syncprov_state_ctrl( &sop, &rs, &e_uuid,
+	rs.sr_err = syncprov_state_ctrl( op, &rs, &e_uuid,
 		mode, ctrls, 0, 1, &cookie );
+	op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 
 	rs.sr_ctrls = ctrls;
 	op->o_bd->bd_info = (BackendInfo *)on->on_info;
@@ -812,8 +768,8 @@ syncprov_sendresp( Operation *op, opcookie *opc, syncops *so, Entry **e, int mod
 		if ( rs.sr_entry->e_private )
 			rs.sr_flags = REP_ENTRY_MUSTRELEASE;
 		if ( opc->sreference ) {
-			rs.sr_ref = get_entry_referrals( &sop, rs.sr_entry );
-			send_search_reference( &sop, &rs );
+			rs.sr_ref = get_entry_referrals( op, rs.sr_entry );
+			rs.sr_err = send_search_reference( op, &rs );
 			ber_bvarray_free( rs.sr_ref );
 			if ( !rs.sr_entry )
 				*e = NULL;
@@ -824,8 +780,8 @@ syncprov_sendresp( Operation *op, opcookie *opc, syncops *so, Entry **e, int mod
 		rs.sr_entry = *e;
 		if ( rs.sr_entry->e_private )
 			rs.sr_flags = REP_ENTRY_MUSTRELEASE;
-		rs.sr_attrs = sop.ors_attrs;
-		send_search_entry( &sop, &rs );
+		rs.sr_attrs = op->ors_attrs;
+		rs.sr_err = send_search_entry( op, &rs );
 		if ( !rs.sr_entry )
 			*e = NULL;
 		break;
@@ -837,60 +793,196 @@ syncprov_sendresp( Operation *op, opcookie *opc, syncops *so, Entry **e, int mod
 		if ( opc->sreference ) {
 			struct berval bv = BER_BVNULL;
 			rs.sr_ref = &bv;
-			send_search_reference( &sop, &rs );
+			rs.sr_err = send_search_reference( op, &rs );
 		} else {
-			send_search_entry( &sop, &rs );
+			rs.sr_err = send_search_entry( op, &rs );
 		}
 		break;
 	default:
 		assert(0);
 	}
-	op->o_tmpfree( rs.sr_ctrls[0], op->o_tmpmemctx );
-	op->o_private = sop.o_private;
-	rs.sr_ctrls = NULL;
-	/* Check queue again here; if we were hanging in a send and eventually
-	 * recovered, there may be more to send now. But don't check if the
-	 * original psearch has been abandoned.
-	 */
-	if ( so->s_op->o_abandon )
-		return SLAPD_ABANDON;
+	/* In case someone else freed it already? */
+	if ( rs.sr_ctrls ) {
+		op->o_tmpfree( rs.sr_ctrls[0], op->o_tmpmemctx );
+		rs.sr_ctrls = NULL;
+	}
+
+	return rs.sr_err;
+}
 
-	if ( rs.sr_err == LDAP_SUCCESS && queue && so->s_res ) {
+/* Play back queued responses */
+static int
+syncprov_qplay( Operation *op, slap_overinst *on, syncops *so )
+{
+	syncres *sr;
+	Entry *e;
+	opcookie opc;
+	int rc = 0;
+
+	opc.son = on;
+
+	for (;;) {
 		ldap_pvt_thread_mutex_lock( &so->s_mutex );
-		rs.sr_err = syncprov_qplay( &sop, on, so );
+		sr = so->s_res;
+		if ( sr )
+			so->s_res = sr->s_next;
+		if ( !so->s_res )
+			so->s_restail = NULL;
 		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
+
+		if ( !sr || so->s_op->o_abandon )
+			break;
+
+		opc.sdn = sr->s_dn;
+		opc.sndn = sr->s_ndn;
+		opc.suuid = sr->s_uuid;
+		opc.sctxcsn = sr->s_csn;
+		opc.sreference = sr->s_isreference;
+		e = NULL;
+
+		if ( sr->s_mode != LDAP_SYNC_DELETE ) {
+			rc = overlay_entry_get_ov( op, &opc.sndn, NULL, NULL, 0, &e, on );
+			if ( rc ) {
+				Debug( LDAP_DEBUG_SYNC, "syncprov_qplay: failed to get %s, "
+					"error (%d), ignoring...\n", opc.sndn.bv_val, rc, 0 );
+				ch_free( sr );
+				rc = 0;
+				continue;
+			}
+		}
+		rc = syncprov_sendresp( op, &opc, so, &e, sr->s_mode );
+
+		if ( e ) {
+			overlay_entry_release_ov( op, e, 0, on );
+		}
+
+		ch_free( sr );
+
+		if ( rc )
+			break;
 	}
-	return rs.sr_err;
+	return rc;
+}
+
+/* runqueue task for playing back queued responses */
+static void *
+syncprov_qtask( void *ctx, void *arg )
+{
+	struct re_s *rtask = arg;
+	syncops *so = rtask->arg;
+	slap_overinst *on = so->s_op->o_private;
+	OperationBuffer opbuf;
+	Operation *op;
+	BackendDB be;
+	int rc;
+
+	op = (Operation *) &opbuf;
+	*op = *so->s_op;
+	op->o_hdr = (Opheader *)(op+1);
+	op->o_controls = (void **)(op->o_hdr+1);
+	memset( op->o_controls, 0, SLAP_MAX_CIDS * sizeof(void *));
+
+	*op->o_hdr = *so->s_op->o_hdr;
+
+	op->o_tmpmemctx = slap_sl_mem_create(SLAP_SLAB_SIZE, SLAP_SLAB_STACK, ctx);
+	op->o_tmpmfuncs = &slap_sl_mfuncs;
+	op->o_threadctx = ctx;
+
+	/* syncprov_qplay expects a fake db */
+	be = *so->s_op->o_bd;
+	be.be_flags |= SLAP_DBFLAG_OVERLAY;
+	op->o_bd = &be;
+	op->o_private = NULL;
+	op->o_callback = NULL;
+
+	rc = syncprov_qplay( op, on, so );
+
+	/* decrement use count... */
+	syncprov_free_syncop( so );
+
+	/* wait until we get explicitly scheduled again */
+	ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
+	ldap_pvt_runqueue_stoptask( &slapd_rq, rtask );
+	if ( rc == 0 ) {
+		ldap_pvt_runqueue_resched( &slapd_rq, rtask, 1 );
+	} else {
+		/* bail out on any error */
+		ldap_pvt_runqueue_remove( &slapd_rq, rtask );
+	}
+	ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
+
+	return NULL;
 }
 
+/* Start the task to play back queued psearch responses */
 static void
-syncprov_free_syncop( syncops *so )
+syncprov_qstart( syncops *so )
 {
-	syncres *sr, *srnext;
-	GroupAssertion *ga, *gnext;
+	int wake=0;
+	ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
+	if ( !so->s_qtask ) {
+		so->s_qtask = ldap_pvt_runqueue_insert( &slapd_rq, RUNQ_INTERVAL,
+			syncprov_qtask, so, "syncprov_qtask",
+			so->s_op->o_conn->c_peer_name.bv_val );
+		++so->s_inuse;
+		wake = 1;
+	} else {
+		if (!ldap_pvt_runqueue_isrunning( &slapd_rq, so->s_qtask ) &&
+			!so->s_qtask->next_sched.tv_sec ) {
+			so->s_qtask->interval.tv_sec = 0;
+			ldap_pvt_runqueue_resched( &slapd_rq, so->s_qtask, 0 );
+			so->s_qtask->interval.tv_sec = RUNQ_INTERVAL;
+			++so->s_inuse;
+			wake = 1;
+		}
+	}
+	ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
+	if ( wake )
+		slap_wake_listener();
+}
+
+/* Queue a persistent search response */
+static int
+syncprov_qresp( opcookie *opc, syncops *so, int mode )
+{
+	syncres *sr;
+
+	sr = ch_malloc(sizeof(syncres) + opc->suuid.bv_len + 1 +
+		opc->sdn.bv_len + 1 + opc->sndn.bv_len + 1 + opc->sctxcsn.bv_len + 1 );
+	sr->s_next = NULL;
+	sr->s_dn.bv_val = (char *)(sr + 1);
+	sr->s_dn.bv_len = opc->sdn.bv_len;
+	sr->s_mode = mode;
+	sr->s_isreference = opc->sreference;
+	sr->s_ndn.bv_val = lutil_strcopy( sr->s_dn.bv_val,
+		 opc->sdn.bv_val ) + 1;
+	sr->s_ndn.bv_len = opc->sndn.bv_len;
+	sr->s_uuid.bv_val = lutil_strcopy( sr->s_ndn.bv_val,
+		 opc->sndn.bv_val ) + 1;
+	sr->s_uuid.bv_len = opc->suuid.bv_len;
+	AC_MEMCPY( sr->s_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
+	sr->s_csn.bv_val = sr->s_uuid.bv_val + sr->s_uuid.bv_len + 1;
+	sr->s_csn.bv_len = opc->sctxcsn.bv_len;
+	strcpy( sr->s_csn.bv_val, opc->sctxcsn.bv_val );
 
 	ldap_pvt_thread_mutex_lock( &so->s_mutex );
-	so->s_inuse--;
-	if ( so->s_inuse > 0 ) {
-		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-		return;
+	if ( !so->s_res ) {
+		so->s_res = sr;
+	} else {
+		so->s_restail->s_next = sr;
 	}
-	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-	if ( so->s_flags & PS_IS_DETACHED ) {
-		filter_free( so->s_op->ors_filter );
-		for ( ga = so->s_op->o_groups; ga; ga=gnext ) {
-			gnext = ga->ga_next;
-			ch_free( ga );
-		}
-		ch_free( so->s_op );
+	so->s_restail = sr;
+
+	/* If the base of the psearch was modified, check it next time round */
+	if ( so->s_flags & PS_WROTE_BASE ) {
+		so->s_flags ^= PS_WROTE_BASE;
+		so->s_flags |= PS_FIND_BASE;
 	}
-	ch_free( so->s_base.bv_val );
-	for ( sr=so->s_res; sr; sr=srnext ) {
-		srnext = sr->s_next;
-		ch_free( sr );
+	if ( so->s_flags & PS_IS_DETACHED ) {
+		syncprov_qstart( so );
 	}
-	ldap_pvt_thread_mutex_destroy( &so->s_mutex );
-	ch_free( so );
+	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
+	return LDAP_SUCCESS;
 }
 
 static int
@@ -968,11 +1060,12 @@ syncprov_matchops( Operation *op, opcookie *opc, int saveit )
 
 	fbase_cookie fc;
 	syncops *ss, *sprev, *snext;
-	Entry *e;
+	Entry *e = NULL;
 	Attribute *a;
 	int rc;
 	struct berval newdn;
 	int freefdn = 0;
+	BackendDB *b0 = op->o_bd, db;
 
 	fc.fdn = &op->o_req_ndn;
 	/* compute new DN */
@@ -985,29 +1078,37 @@ syncprov_matchops( Operation *op, opcookie *opc, int saveit )
 		freefdn = 1;
 	}
 	if ( op->o_tag != LDAP_REQ_ADD ) {
-		op->o_bd->bd_info = (BackendInfo *)on->on_info;
-		rc = be_entry_get_rw( op, fc.fdn, NULL, NULL, 0, &e );
+		if ( !SLAP_ISOVERLAY( op->o_bd )) {
+			db = *op->o_bd;
+			op->o_bd = &db;
+		}
+		rc = overlay_entry_get_ov( op, fc.fdn, NULL, NULL, 0, &e, on );
 		/* If we're sending responses now, make a copy and unlock the DB */
 		if ( e && !saveit ) {
 			Entry *e2 = entry_dup( e );
-			be_entry_release_rw( op, e, 0 );
+			overlay_entry_release_ov( op, e, 0, on );
 			e = e2;
 		}
-		op->o_bd->bd_info = (BackendInfo *)on;
-		if ( rc ) return;
+		if ( rc ) {
+			op->o_bd = b0;
+			return;
+		}
 	} else {
 		e = op->ora_e;
 	}
 
-	if ( saveit ) {
+	if ( saveit || op->o_tag == LDAP_REQ_ADD ) {
 		ber_dupbv_x( &opc->sdn, &e->e_name, op->o_tmpmemctx );
 		ber_dupbv_x( &opc->sndn, &e->e_nname, op->o_tmpmemctx );
 		opc->sreference = is_entry_referral( e );
-	}
-	if ( saveit || op->o_tag == LDAP_REQ_ADD ) {
 		a = attr_find( e->e_attrs, slap_schema.si_ad_entryUUID );
 		if ( a )
 			ber_dupbv_x( &opc->suuid, &a->a_nvals[0], op->o_tmpmemctx );
+	} else if ( op->o_tag == LDAP_REQ_MODRDN && !saveit ) {
+		op->o_tmpfree( opc->sndn.bv_val, op->o_tmpmemctx );
+		op->o_tmpfree( opc->sdn.bv_val, op->o_tmpmemctx );
+		ber_dupbv_x( &opc->sdn, &e->e_name, op->o_tmpmemctx );
+		ber_dupbv_x( &opc->sndn, &e->e_nname, op->o_tmpmemctx );
 	}
 
 	ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
@@ -1031,12 +1132,22 @@ syncprov_matchops( Operation *op, opcookie *opc, int saveit )
 				"search base has changed" );
 			sprev->s_next = snext;
 			syncprov_drop_psearch( ss, 1 );
+			ss = sprev;
 			continue;
 		}
 
+
 		/* If we're sending results now, look for this op in old matches */
 		if ( !saveit ) {
 			syncmatches *old;
+
+			/* Did we modify the search base? */
+			if ( dn_match( &op->o_req_ndn, &ss->s_base )) {
+				ldap_pvt_thread_mutex_lock( &ss->s_mutex );
+				ss->s_flags |= PS_WROTE_BASE;
+				ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
+			}
+
 			for ( sm=opc->smatches, old=(syncmatches *)&opc->smatches; sm;
 				old=sm, sm=sm->sm_next ) {
 				if ( sm->sm_op == ss ) {
@@ -1055,26 +1166,22 @@ syncprov_matchops( Operation *op, opcookie *opc, int saveit )
 				sm = op->o_tmpalloc( sizeof(syncmatches), op->o_tmpmemctx );
 				sm->sm_next = opc->smatches;
 				sm->sm_op = ss;
-				ss->s_inuse++;
+				ldap_pvt_thread_mutex_lock( &ss->s_mutex );
+				++ss->s_inuse;
+				ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
 				opc->smatches = sm;
 			} else {
 				/* if found send UPDATE else send ADD */
-				ss->s_inuse++;
-				ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
-				syncprov_sendresp( op, opc, ss, &e,
-					found ? LDAP_SYNC_MODIFY : LDAP_SYNC_ADD, 1 );
-				ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
-				ss->s_inuse--;
+				syncprov_qresp( opc, ss,
+					found ? LDAP_SYNC_MODIFY : LDAP_SYNC_ADD );
 			}
 		} else if ( !saveit && found ) {
 			/* send DELETE */
-			ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
-			syncprov_sendresp( op, opc, ss, NULL, LDAP_SYNC_DELETE, 1 );
-			ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
+			syncprov_qresp( opc, ss, LDAP_SYNC_DELETE );
 		}
 	}
 	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
-done:
+
 	if ( op->o_tag != LDAP_REQ_ADD && e ) {
 		op->o_bd->bd_info = (BackendInfo *)on->on_info;
 		be_entry_release_rw( op, e, 0 );
@@ -1083,6 +1190,7 @@ done:
 	if ( freefdn ) {
 		op->o_tmpfree( fc.fdn->bv_val, op->o_tmpmemctx );
 	}
+	op->o_bd = b0;
 }
 
 static int
@@ -1140,16 +1248,22 @@ syncprov_checkpoint( Operation *op, SlapReply *rs, slap_overinst *on )
 	syncprov_info_t		*si = on->on_bi.bi_private;
 	Modifications mod;
 	Operation opm;
+	SlapReply rsm = { 0 };
 	struct berval bv[2];
 	slap_callback cb = {0};
-	int manage = get_manageDSAit(op);
 
-	mod.sml_values = bv;
-	bv[1].bv_val = NULL;
-	bv[0] = si->si_ctxcsn;
+	/* If ctxcsn is empty, delete it */
+	if ( BER_BVISEMPTY( &si->si_ctxcsn )) {
+		mod.sml_values = NULL;
+	} else {
+		mod.sml_values = bv;
+		bv[1].bv_val = NULL;
+		bv[0] = si->si_ctxcsn;
+	}
 	mod.sml_nvalues = NULL;
 	mod.sml_desc = slap_schema.si_ad_contextCSN;
 	mod.sml_op = LDAP_MOD_REPLACE;
+	mod.sml_flags = 0;
 	mod.sml_next = NULL;
 
 	cb.sc_response = slap_null_cb;
@@ -1161,12 +1275,16 @@ syncprov_checkpoint( Operation *op, SlapReply *rs, slap_overinst *on )
 	opm.o_req_ndn = op->o_bd->be_nsuffix[0];
 	opm.o_bd->bd_info = on->on_info->oi_orig;
 	opm.o_managedsait = SLAP_CONTROL_NONCRITICAL;
-	opm.o_bd->be_modify( &opm, rs );
-	opm.o_managedsait = manage;
+	SLAP_DBFLAGS( opm.o_bd ) |= SLAP_DBFLAG_NOLASTMOD;
+	opm.o_bd->be_modify( &opm, &rsm );
+	SLAP_DBFLAGS( opm.o_bd ) ^= SLAP_DBFLAG_NOLASTMOD;
+	if ( mod.sml_next != NULL ) {
+		slap_mods_free( mod.sml_next, 1 );
+	}
 }
 
 static void
-syncprov_add_slog( Operation *op, struct berval *csn )
+syncprov_add_slog( Operation *op )
 {
 	opcookie *opc = op->o_callback->sc_private;
 	slap_overinst *on = opc->son;
@@ -1178,18 +1296,18 @@ syncprov_add_slog( Operation *op, struct berval *csn )
 	{
 		/* Allocate a record. UUIDs are not NUL-terminated. */
 		se = ch_malloc( sizeof( slog_entry ) + opc->suuid.bv_len + 
-			csn->bv_len + 1 );
+			op->o_csn.bv_len + 1 );
 		se->se_next = NULL;
 		se->se_tag = op->o_tag;
 
-		se->se_uuid.bv_val = (char *)(se+1);
-		se->se_csn.bv_val = se->se_uuid.bv_val + opc->suuid.bv_len + 1;
+		se->se_uuid.bv_val = (char *)(&se[1]);
 		AC_MEMCPY( se->se_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
 		se->se_uuid.bv_len = opc->suuid.bv_len;
 
-		AC_MEMCPY( se->se_csn.bv_val, csn->bv_val, csn->bv_len );
-		se->se_csn.bv_val[csn->bv_len] = '\0';
-		se->se_csn.bv_len = csn->bv_len;
+		se->se_csn.bv_val = se->se_uuid.bv_val + opc->suuid.bv_len;
+		AC_MEMCPY( se->se_csn.bv_val, op->o_csn.bv_val, op->o_csn.bv_len );
+		se->se_csn.bv_val[op->o_csn.bv_len] = '\0';
+		se->se_csn.bv_len = op->o_csn.bv_len;
 
 		ldap_pvt_thread_mutex_lock( &sl->sl_mutex );
 		if ( sl->sl_head ) {
@@ -1206,9 +1324,6 @@ syncprov_add_slog( Operation *op, struct berval *csn )
 			sl->sl_mincsn.bv_len = se->se_csn.bv_len;
 			ch_free( se );
 			sl->sl_num--;
-			if ( !sl->sl_head ) {
-				sl->sl_tail = NULL;
-			}
 		}
 		ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
 	}
@@ -1227,13 +1342,14 @@ playlog_cb( Operation *op, SlapReply *rs )
 /* enter with sl->sl_mutex locked, release before returning */
 static void
 syncprov_playlog( Operation *op, SlapReply *rs, sessionlog *sl,
-	struct berval *oldcsn, struct berval *ctxcsn )
+	sync_control *srs, struct berval *ctxcsn )
 {
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
-	syncprov_info_t		*si = on->on_bi.bi_private;
 	slog_entry *se;
 	int i, j, ndel, num, nmods, mmods;
+	char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
 	BerVarray uuids;
+	struct berval delcsn;
 
 	if ( !sl->sl_num ) {
 		ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
@@ -1246,19 +1362,34 @@ syncprov_playlog( Operation *op, SlapReply *rs, sessionlog *sl,
 
 	uuids = op->o_tmpalloc( (num+1) * sizeof( struct berval ) +
 		num * UUID_LEN, op->o_tmpmemctx );
-
 	uuids[0].bv_val = (char *)(uuids + num + 1);
 
+	delcsn.bv_len = 0;
+	delcsn.bv_val = cbuf;
+
 	/* Make a copy of the relevant UUIDs. Put the Deletes up front
 	 * and everything else at the end. Do this first so we can
 	 * unlock the list mutex.
 	 */
+	Debug( LDAP_DEBUG_SYNC, "srs csn %s\n", srs->sr_state.ctxcsn.bv_val, 0, 0 );
 	for ( se=sl->sl_head; se; se=se->se_next ) {
-		if ( ber_bvcmp( &se->se_csn, oldcsn ) < 0 ) continue;
-		if ( ber_bvcmp( &se->se_csn, ctxcsn ) > 0 ) break;
+		Debug( LDAP_DEBUG_SYNC, "log csn %s\n", se->se_csn.bv_val, 0, 0 );
+		ndel = ber_bvcmp( &se->se_csn, &srs->sr_state.ctxcsn );
+		if ( ndel <= 0 ) {
+			Debug( LDAP_DEBUG_SYNC, "cmp %d, too old\n", ndel, 0, 0 );
+			continue;
+		}
+		ndel = ber_bvcmp( &se->se_csn, ctxcsn );
+		if ( ndel > 0 ) {
+			Debug( LDAP_DEBUG_SYNC, "cmp %d, too new\n", ndel, 0, 0 );
+			break;
+		}
 		if ( se->se_tag == LDAP_REQ_DELETE ) {
 			j = i;
 			i++;
+			AC_MEMCPY( cbuf, se->se_csn.bv_val, se->se_csn.bv_len );
+			delcsn.bv_len = se->se_csn.bv_len;
+			delcsn.bv_val[delcsn.bv_len] = '\0';
 		} else {
 			nmods++;
 			j = num - nmods;
@@ -1339,6 +1470,7 @@ syncprov_playlog( Operation *op, SlapReply *rs, sessionlog *sl,
 			mf.f_av_value = uuids[i];
 			cb.sc_private = NULL;
 			fop.ors_slimit = 1;
+			frs.sr_nentries = 0;
 			rc = fop.o_bd->be_search( &fop, &frs );
 
 			/* If entry was not found, add to delete list */
@@ -1349,9 +1481,14 @@ syncprov_playlog( Operation *op, SlapReply *rs, sessionlog *sl,
 		fop.o_bd->bd_info = (BackendInfo *)on;
 	}
 	if ( ndel ) {
+		struct berval cookie;
+
+		slap_compose_sync_cookie( op, &cookie, &delcsn, srs->sr_state.rid );
 		uuids[ndel].bv_val = NULL;
-		syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET, NULL, 0, uuids, 1 );
+		syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET, &cookie, 0, uuids, 1 );
+		op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 	}
+	op->o_tmpfree( uuids, op->o_tmpmemctx );
 }
 
 static int
@@ -1364,13 +1501,14 @@ syncprov_op_response( Operation *op, SlapReply *rs )
 
 	if ( rs->sr_err == LDAP_SUCCESS )
 	{
-		struct berval maxcsn = BER_BVNULL, curcsn = BER_BVNULL;
+		struct berval maxcsn = BER_BVNULL;
 		char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
+		int do_check = 0, have_psearches;
 
 		/* Update our context CSN */
 		cbuf[0] = '\0';
-		ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
-		slap_get_commit_csn( op, &maxcsn, &curcsn );
+		ldap_pvt_thread_rdwr_wlock( &si->si_csn_rwlock );
+		slap_get_commit_csn( op, &maxcsn );
 		if ( !BER_BVISNULL( &maxcsn ) ) {
 			strcpy( cbuf, maxcsn.bv_val );
 			if ( ber_bvcmp( &maxcsn, &si->si_ctxcsn ) > 0 ) {
@@ -1382,13 +1520,12 @@ syncprov_op_response( Operation *op, SlapReply *rs )
 		/* Don't do any processing for consumer contextCSN updates */
 		if ( SLAP_SYNC_SHADOW( op->o_bd ) && 
 			op->o_msgid == SLAP_SYNC_UPDATE_MSGID ) {
-			ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+			ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
 			return SLAP_CB_CONTINUE;
 		}
 
 		si->si_numops++;
 		if ( si->si_chkops || si->si_chktime ) {
-			int do_check=0;
 			if ( si->si_chkops && si->si_numops >= si->si_chkops ) {
 				do_check = 1;
 				si->si_numops = 0;
@@ -1398,17 +1535,23 @@ syncprov_op_response( Operation *op, SlapReply *rs )
 				do_check = 1;
 				si->si_chklast = op->o_time;
 			}
-			if ( do_check ) {
-				syncprov_checkpoint( op, rs, on );
-			}
 		}
-		ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
+
+		if ( do_check ) {
+			ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
+			syncprov_checkpoint( op, rs, on );
+			ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
+		}
 
 		opc->sctxcsn.bv_len = maxcsn.bv_len;
 		opc->sctxcsn.bv_val = cbuf;
 
 		/* Handle any persistent searches */
-		if ( si->si_ops ) {
+		ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
+		have_psearches = ( si->si_ops != NULL );
+		ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
+		if ( have_psearches ) {
 			switch(op->o_tag) {
 			case LDAP_REQ_ADD:
 			case LDAP_REQ_MODIFY:
@@ -1423,8 +1566,7 @@ syncprov_op_response( Operation *op, SlapReply *rs )
 				for ( sm = opc->smatches; sm; sm=sm->sm_next ) {
 					if ( sm->sm_op->s_op->o_abandon )
 						continue;
-					syncprov_sendresp( op, opc, sm->sm_op, NULL,
-						LDAP_SYNC_DELETE, 1 );
+					syncprov_qresp( opc, sm->sm_op, LDAP_SYNC_DELETE );
 				}
 				break;
 			}
@@ -1432,7 +1574,7 @@ syncprov_op_response( Operation *op, SlapReply *rs )
 
 		/* Add any log records */
 		if ( si->si_logs && op->o_tag != LDAP_REQ_ADD ) {
-			syncprov_add_slog( op, &curcsn );
+			syncprov_add_slog( op );
 		}
 
 	}
@@ -1467,7 +1609,7 @@ syncprov_op_compare( Operation *op, SlapReply *rs )
 		a.a_vals = bv;
 		a.a_nvals = a.a_vals;
 
-		ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
 
 		rs->sr_err = access_allowed( op, &e, op->oq_compare.rs_ava->aa_desc,
 			&op->oq_compare.rs_ava->aa_value, ACL_COMPARE, NULL );
@@ -1496,7 +1638,7 @@ syncprov_op_compare( Operation *op, SlapReply *rs )
 
 return_results:;
 
-		ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 
 		send_ldap_result( op, rs );
 
@@ -1514,12 +1656,19 @@ syncprov_op_mod( Operation *op, SlapReply *rs )
 {
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	syncprov_info_t		*si = on->on_bi.bi_private;
+	slap_callback *cb;
+	opcookie *opc;
+	int have_psearches, cbsize;
+
+	ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
+	have_psearches = ( si->si_ops != NULL );
+	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
 
-	slap_callback *cb = op->o_tmpcalloc(1, sizeof(slap_callback)+
-		sizeof(opcookie) +
-		(si->si_ops ? sizeof(modinst) : 0 ),
-		op->o_tmpmemctx);
-	opcookie *opc = (opcookie *)(cb+1);
+	cbsize = sizeof(slap_callback) + sizeof(opcookie) +
+		(have_psearches ? sizeof(modinst) : 0 );
+
+	cb = op->o_tmpcalloc(1, cbsize, op->o_tmpmemctx);
+	opc = (opcookie *)(cb+1);
 	opc->son = on;
 	cb->sc_response = syncprov_op_response;
 	cb->sc_cleanup = syncprov_op_cleanup;
@@ -1530,7 +1679,7 @@ syncprov_op_mod( Operation *op, SlapReply *rs )
 	/* If there are active persistent searches, lock this operation.
 	 * See seqmod.c for the locking logic on its own.
 	 */
-	if ( si->si_ops ) {
+	if ( have_psearches ) {
 		modtarget *mt, mtdummy;
 		modinst *mi;
 
@@ -1577,7 +1726,7 @@ syncprov_op_mod( Operation *op, SlapReply *rs )
 		}
 	}
 
-	if (( si->si_ops || si->si_logs ) && op->o_tag != LDAP_REQ_ADD )
+	if (( have_psearches || si->si_logs ) && op->o_tag != LDAP_REQ_ADD )
 		syncprov_matchops( op, opc, 1 );
 
 	return SLAP_CB_CONTINUE;
@@ -1596,6 +1745,8 @@ typedef struct searchstate {
 	slap_overinst *ss_on;
 	syncops *ss_so;
 	int ss_present;
+	struct berval ss_ctxcsn;
+	char ss_csnbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
 } searchstate;
 
 static int
@@ -1610,7 +1761,7 @@ syncprov_search_cleanup( Operation *op, SlapReply *rs )
 }
 
 static void
-syncprov_detach_op( Operation *op, syncops *so )
+syncprov_detach_op( Operation *op, syncops *so, slap_overinst *on )
 {
 	Operation *op2;
 	int i, alen = 0;
@@ -1636,8 +1787,9 @@ syncprov_detach_op( Operation *op, syncops *so )
 	*op2->o_hdr = *op->o_hdr;
 	op2->o_tag = op->o_tag;
 	op2->o_time = op->o_time;
-	op2->o_bd = op->o_bd;
+	op2->o_bd = on->on_info->oi_origdb;
 	op2->o_request = op->o_request;
+	op2->o_private = on;
 
 	if ( i ) {
 		op2->ors_attrs = (AttributeName *)(op2->o_hdr + 1);
@@ -1664,7 +1816,15 @@ syncprov_detach_op( Operation *op, syncops *so )
 	op2->ors_filterstr.bv_val = ptr;
 	strcpy( ptr, so->s_filterstr.bv_val );
 	op2->ors_filterstr.bv_len = so->s_filterstr.bv_len;
-	op2->ors_filter = str2filter( ptr );
+
+	/* Skip the AND/GE clause that we stuck on in front */
+	if ( so->s_flags & PS_FIX_FILTER ) {
+		op2->ors_filter = op->ors_filter->f_and->f_next;
+		so->s_flags ^= PS_FIX_FILTER;
+	} else {
+		op2->ors_filter = op->ors_filter;
+	}
+	op2->ors_filter = filter_dup( op2->ors_filter, NULL );
 	so->s_op = op2;
 
 	/* Copy any cached group ACLs individually */
@@ -1676,14 +1836,17 @@ syncprov_detach_op( Operation *op, syncops *so )
 		g2->ga_next = op2->o_groups;
 		op2->o_groups = g2;
 	}
+	/* Don't allow any further group caching */
+	op2->o_do_not_cache = 1;
 
 	/* Add op2 to conn so abandon will find us */
-	ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
 	op->o_conn->c_n_ops_executing++;
 	op->o_conn->c_n_ops_completed--;
 	LDAP_STAILQ_INSERT_TAIL( &op->o_conn->c_ops, op2, o_next );
 	so->s_flags |= PS_IS_DETACHED;
-	ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
+
+	/* Prevent anyone else from trying to send a result for this op */
+	op->o_abandon = 1;
 }
 
 static int
@@ -1691,39 +1854,63 @@ syncprov_search_response( Operation *op, SlapReply *rs )
 {
 	searchstate *ss = op->o_callback->sc_private;
 	slap_overinst *on = ss->ss_on;
-	syncprov_info_t		*si = on->on_bi.bi_private;
+	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
 	sync_control *srs = op->o_controls[slap_cids.sc_LDAPsync];
 
 	if ( rs->sr_type == REP_SEARCH || rs->sr_type == REP_SEARCHREF ) {
-		int i;
+		Attribute *a;
 		/* If we got a referral without a referral object, there's
 		 * something missing that we cannot replicate. Just ignore it.
 		 * The consumer will abort because we didn't send the expected
 		 * control.
 		 */
 		if ( !rs->sr_entry ) {
-			assert( rs->sr_entry );
+			assert( rs->sr_entry != NULL );
 			Debug( LDAP_DEBUG_ANY, "bogus referral in context\n",0,0,0 );
 			return SLAP_CB_CONTINUE;
 		}
-		if ( !BER_BVISNULL( &srs->sr_state.ctxcsn )) {
-			Attribute *a = attr_find( rs->sr_entry->e_attrs,
-				slap_schema.si_ad_entryCSN );
-			
+		a = attr_find( rs->sr_entry->e_attrs, slap_schema.si_ad_entryCSN );
+		if ( a == NULL && rs->sr_operational_attrs != NULL ) {
+			a = attr_find( rs->sr_operational_attrs, slap_schema.si_ad_entryCSN );
+		}
+		if ( a ) {
+			/* If not a persistent search */
+			/* Make sure entry is less than the snapshot'd contextCSN */
+			if ( !ss->ss_so && ber_bvcmp( &a->a_nvals[0], &ss->ss_ctxcsn ) > 0 ) {
+				Debug( LDAP_DEBUG_SYNC, "Entry %s CSN %s greater than snapshot %s\n",
+					rs->sr_entry->e_name.bv_val,
+					a->a_nvals[0].bv_val,
+					ss->ss_ctxcsn.bv_val );
+				return LDAP_SUCCESS;
+			}
+
 			/* Don't send the ctx entry twice */
-			if ( a && bvmatch( &a->a_nvals[0], &srs->sr_state.ctxcsn ) )
+			if ( !BER_BVISNULL( &srs->sr_state.ctxcsn ) &&
+				bvmatch( &a->a_nvals[0], &srs->sr_state.ctxcsn ) ) {
+				Debug( LDAP_DEBUG_SYNC, "Entry %s CSN %s matches ctx %s\n",
+					rs->sr_entry->e_name.bv_val,
+					a->a_nvals[0].bv_val,
+					srs->sr_state.ctxcsn.bv_val );
 				return LDAP_SUCCESS;
+			}
 		}
 		rs->sr_ctrls = op->o_tmpalloc( sizeof(LDAPControl *)*2,
 			op->o_tmpmemctx );
 		rs->sr_ctrls[1] = NULL;
-		rs->sr_err = syncprov_state_ctrl( op, rs, rs->sr_entry,
-			LDAP_SYNC_ADD, rs->sr_ctrls, 0, 0, NULL );
+		/* If we're in delta-sync mode, always send a cookie */
+		if ( si->si_nopres && si->si_usehint && a ) {
+			struct berval cookie;
+			slap_compose_sync_cookie( op, &cookie, a->a_nvals, srs->sr_state.rid );
+			rs->sr_err = syncprov_state_ctrl( op, rs, rs->sr_entry,
+				LDAP_SYNC_ADD, rs->sr_ctrls, 0, 1, &cookie );
+		} else {
+			rs->sr_err = syncprov_state_ctrl( op, rs, rs->sr_entry,
+				LDAP_SYNC_ADD, rs->sr_ctrls, 0, 0, NULL );
+		}
 	} else if ( rs->sr_type == REP_RESULT && rs->sr_err == LDAP_SUCCESS ) {
 		struct berval cookie;
 
-		slap_compose_sync_cookie( op, &cookie,
-			&op->ors_filter->f_and->f_ava->aa_value,
+		slap_compose_sync_cookie( op, &cookie, &ss->ss_ctxcsn,
 			srs->sr_state.rid );
 
 		/* Is this a regular refresh? */
@@ -1734,26 +1921,38 @@ syncprov_search_response( Operation *op, SlapReply *rs )
 			rs->sr_err = syncprov_done_ctrl( op, rs, rs->sr_ctrls,
 				0, 1, &cookie, ss->ss_present ?  LDAP_SYNC_REFRESH_PRESENTS :
 					LDAP_SYNC_REFRESH_DELETES );
+			op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 		} else {
-			int locked = 0;
 		/* It's RefreshAndPersist, transition to Persist phase */
-			syncprov_sendinfo( op, rs, ( ss->ss_present && rs->sr_nentries ) ?
+			syncprov_sendinfo( op, rs, ss->ss_present ?
 	 			LDAP_TAG_SYNC_REFRESH_PRESENT : LDAP_TAG_SYNC_REFRESH_DELETE,
 				&cookie, 1, NULL, 0 );
-			/* Flush any queued persist messages */
-			if ( ss->ss_so->s_res ) {
-				ldap_pvt_thread_mutex_lock( &ss->ss_so->s_mutex );
-				locked = 1;
-				syncprov_qplay( op, on, ss->ss_so );
-			}
+			op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 
-			/* Turn off the refreshing flag */
-			ss->ss_so->s_flags ^= PS_IS_REFRESHING;
-			if ( locked )
+			/* Detach this Op from frontend control */
+			ldap_pvt_thread_mutex_lock( &ss->ss_so->s_mutex );
+			ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
+
+			/* But not if this connection was closed along the way */
+			if ( op->o_abandon ) {
+				ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
 				ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );
+				/* syncprov_ab_cleanup will free this syncop */
+				return SLAPD_ABANDON;
 
-			/* Detach this Op from frontend control */
-			syncprov_detach_op( op, ss->ss_so );
+			} else {
+				/* Turn off the refreshing flag */
+				ss->ss_so->s_flags ^= PS_IS_REFRESHING;
+
+				syncprov_detach_op( op, ss->ss_so, on );
+
+				ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
+
+				/* If there are queued responses, fire them off */
+				if ( ss->ss_so->s_res )
+					syncprov_qstart( ss->ss_so );
+			}
+			ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );
 
 			return LDAP_SUCCESS;
 		}
@@ -1768,8 +1967,7 @@ syncprov_op_search( Operation *op, SlapReply *rs )
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	syncprov_info_t		*si = (syncprov_info_t *)on->on_bi.bi_private;
 	slap_callback	*cb;
-	int gotstate = 0, nochange = 0, do_present = 1;
-	Filter *fand, *fava;
+	int gotstate = 0, nochange = 0, do_present;
 	syncops *sop = NULL;
 	searchstate *ss;
 	sync_control *srs;
@@ -1783,6 +1981,8 @@ syncprov_op_search( Operation *op, SlapReply *rs )
 		return rs->sr_err;
 	}
 
+	do_present = si->si_nopres ? 0 : 1;
+
 	srs = op->o_controls[slap_cids.sc_LDAPsync];
 	op->o_managedsait = SLAP_CONTROL_NONCRITICAL;
 
@@ -1797,14 +1997,16 @@ syncprov_op_search( Operation *op, SlapReply *rs )
 		fc.fbase = 0;
 		so.s_eid = NOID;
 		so.s_op = op;
-		so.s_flags = PS_IS_REFRESHING;
+		so.s_flags = PS_IS_REFRESHING | PS_FIND_BASE;
 		/* syncprov_findbase expects to be called as a callback... */
 		sc.sc_private = &opc;
 		opc.son = on;
+		ldap_pvt_thread_mutex_init( &so.s_mutex );
 		cb = op->o_callback;
 		op->o_callback = &sc;
 		rs->sr_err = syncprov_findbase( op, &fc );
 		op->o_callback = cb;
+		ldap_pvt_thread_mutex_destroy( &so.s_mutex );
 
 		if ( rs->sr_err != LDAP_SUCCESS ) {
 			send_ldap_result( op, rs );
@@ -1823,10 +2025,10 @@ syncprov_op_search( Operation *op, SlapReply *rs )
 	}
 
 	/* snapshot the ctxcsn */
-	ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
+	ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
 	strcpy( csnbuf, si->si_ctxcsnbuf );
 	ctxcsn.bv_len = si->si_ctxcsn.bv_len;
-	ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+	ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 	ctxcsn.bv_val = csnbuf;
 	
 	/* If we have a cookie, handle the PRESENT lookups */
@@ -1857,10 +2059,13 @@ syncprov_op_search( Operation *op, SlapReply *rs )
 		sl=si->si_logs;
 		if ( sl ) {
 			ldap_pvt_thread_mutex_lock( &sl->sl_mutex );
-			if ( ber_bvcmp( &srs->sr_state.ctxcsn, &sl->sl_mincsn ) >= 0 ) {
+			/* Are there any log entries, and is the consumer state
+			 * present in the session log?
+			 */
+			if ( sl->sl_num > 0 && ber_bvcmp( &srs->sr_state.ctxcsn, &sl->sl_mincsn ) >= 0 ) {
 				do_present = 0;
 				/* mutex is unlocked in playlog */
-				syncprov_playlog( op, rs, sl, &srs->sr_state.ctxcsn, &ctxcsn );
+				syncprov_playlog( op, rs, sl, srs, &ctxcsn );
 			} else {
 				ldap_pvt_thread_mutex_unlock( &sl->sl_mutex );
 			}
@@ -1868,12 +2073,11 @@ syncprov_op_search( Operation *op, SlapReply *rs )
 		/* Is the CSN still present in the database? */
 		if ( syncprov_findcsn( op, FIND_CSN ) != LDAP_SUCCESS ) {
 			/* No, so a reload is required */
-#if 0		/* the consumer doesn't seem to send this hint */
-			if ( op->o_sync_rhint == 0 ) {
+			/* the 2.2 consumer doesn't send this hint */
+			if ( si->si_usehint && srs->sr_rhint == 0 ) {
 				send_ldap_error( op, rs, LDAP_SYNC_REFRESH_REQUIRED, "sync cookie is stale" );
 				return rs->sr_err;
 			}
-#endif
 		} else {
 			gotstate = 1;
 			/* If changed and doing Present lookup, send Present UUIDs */
@@ -1893,21 +2097,15 @@ shortcut:
 		sop->s_filterstr= op->ors_filterstr;
 	}
 
-	fand = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
-	fand->f_choice = LDAP_FILTER_AND;
-	fand->f_next = NULL;
-	fava = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
-	fava->f_choice = LDAP_FILTER_LE;
-	fava->f_ava = op->o_tmpalloc( sizeof(AttributeAssertion), op->o_tmpmemctx );
-	fava->f_ava->aa_desc = slap_schema.si_ad_entryCSN;
-#ifdef LDAP_COMP_MATCH
-	fava->f_ava->aa_cf = NULL;
-#endif
-	ber_dupbv_x( &fava->f_ava->aa_value, &ctxcsn, op->o_tmpmemctx );
-	fand->f_and = fava;
-	if ( gotstate ) {
-		fava->f_next = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
-		fava = fava->f_next;
+	/* If something changed, find the changes */
+	if ( gotstate && !nochange ) {
+		Filter *fand, *fava;
+
+		fand = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
+		fand->f_choice = LDAP_FILTER_AND;
+		fand->f_next = NULL;
+		fava = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
+		fand->f_and = fava;
 		fava->f_choice = LDAP_FILTER_GE;
 		fava->f_ava = op->o_tmpalloc( sizeof(AttributeAssertion), op->o_tmpmemctx );
 		fava->f_ava->aa_desc = slap_schema.si_ad_entryCSN;
@@ -1915,10 +2113,12 @@ shortcut:
 		fava->f_ava->aa_cf = NULL;
 #endif
 		ber_dupbv_x( &fava->f_ava->aa_value, &srs->sr_state.ctxcsn, op->o_tmpmemctx );
+		fava->f_next = op->ors_filter;
+		op->ors_filter = fand;
+		filter2bv_x( op, op->ors_filter, &op->ors_filterstr );
+		if ( sop )
+			sop->s_flags |= PS_FIX_FILTER;
 	}
-	fava->f_next = op->ors_filter;
-	op->ors_filter = fand;
-	filter2bv_x( op, op->ors_filter, &op->ors_filterstr );
 
 	/* Let our callback add needed info to returned entries */
 	cb = op->o_tmpcalloc(1, sizeof(slap_callback)+sizeof(searchstate), op->o_tmpmemctx);
@@ -1926,6 +2126,9 @@ shortcut:
 	ss->ss_on = on;
 	ss->ss_so = sop;
 	ss->ss_present = do_present;
+	ss->ss_ctxcsn.bv_len = ctxcsn.bv_len;
+	ss->ss_ctxcsn.bv_val = ss->ss_csnbuf;
+	strcpy( ss->ss_ctxcsn.bv_val, ctxcsn.bv_val );
 	cb->sc_response = syncprov_search_response;
 	cb->sc_cleanup = syncprov_search_cleanup;
 	cb->sc_private = ss;
@@ -1982,54 +2185,169 @@ syncprov_operational(
 				*ap = a;
 			}
 
-			ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
+			ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
 			if ( !ap ) {
 				strcpy( a->a_vals[0].bv_val, si->si_ctxcsnbuf );
 			} else {
 				ber_dupbv( &a->a_vals[0], &si->si_ctxcsn );
 			}
-			ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+			ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 		}
 	}
 	return SLAP_CB_CONTINUE;
 }
 
+enum {
+	SP_CHKPT = 1,
+	SP_SESSL,
+	SP_NOPRES,
+	SP_USEHINT
+};
+
+static ConfigDriver sp_cf_gen;
+
+static ConfigTable spcfg[] = {
+	{ "syncprov-checkpoint", "ops> <minutes", 3, 3, 0, ARG_MAGIC|SP_CHKPT,
+		sp_cf_gen, "( OLcfgOvAt:1.1 NAME 'olcSpCheckpoint' "
+			"DESC 'ContextCSN checkpoint interval in ops and minutes' "
+			"SYNTAX OMsDirectoryString SINGLE-VALUE )", NULL, NULL },
+	{ "syncprov-sessionlog", "ops", 2, 2, 0, ARG_INT|ARG_MAGIC|SP_SESSL,
+		sp_cf_gen, "( OLcfgOvAt:1.2 NAME 'olcSpSessionlog' "
+			"DESC 'Session log size in ops' "
+			"SYNTAX OMsInteger SINGLE-VALUE )", NULL, NULL },
+	{ "syncprov-nopresent", NULL, 2, 2, 0, ARG_ON_OFF|ARG_MAGIC|SP_NOPRES,
+		sp_cf_gen, "( OLcfgOvAt:1.3 NAME 'olcSpNoPresent' "
+			"DESC 'Omit Present phase processing' "
+			"SYNTAX OMsBoolean SINGLE-VALUE )", NULL, NULL },
+	{ "syncprov-reloadhint", NULL, 2, 2, 0, ARG_ON_OFF|ARG_MAGIC|SP_USEHINT,
+		sp_cf_gen, "( OLcfgOvAt:1.4 NAME 'olcSpReloadHint' "
+			"DESC 'Observe Reload Hint in Request control' "
+			"SYNTAX OMsBoolean SINGLE-VALUE )", NULL, NULL },
+	{ NULL, NULL, 0, 0, 0, ARG_IGNORED }
+};
+
+static ConfigOCs spocs[] = {
+	{ "( OLcfgOvOc:1.1 "
+		"NAME 'olcSyncProvConfig' "
+		"DESC 'SyncRepl Provider configuration' "
+		"SUP olcOverlayConfig "
+		"MAY ( olcSpCheckpoint $ olcSpSessionlog $ olcSpNoPresent ) )",
+			Cft_Overlay, spcfg },
+	{ NULL, 0, NULL }
+};
+
 static int
-syncprov_db_config(
-	BackendDB	*be,
-	const char	*fname,
-	int		lineno,
-	int		argc,
-	char	**argv
-)
+sp_cf_gen(ConfigArgs *c)
 {
-	slap_overinst		*on = (slap_overinst *)be->bd_info;
+	slap_overinst		*on = (slap_overinst *)c->bi;
 	syncprov_info_t		*si = (syncprov_info_t *)on->on_bi.bi_private;
-
-	if ( strcasecmp( argv[ 0 ], "syncprov-checkpoint" ) == 0 ) {
-		if ( argc != 3 ) {
-			fprintf( stderr, "%s: line %d: wrong number of arguments in "
-				"\"syncprov-checkpoint <ops> <minutes>\"\n", fname, lineno );
-			return -1;
+	int rc = 0;
+
+	if ( c->op == SLAP_CONFIG_EMIT ) {
+		switch ( c->type ) {
+		case SP_CHKPT:
+			if ( si->si_chkops || si->si_chktime ) {
+				struct berval bv;
+				bv.bv_len = sprintf( c->msg, "%d %d",
+					si->si_chkops, si->si_chktime );
+				bv.bv_val = c->msg;
+				value_add_one( &c->rvalue_vals, &bv );
+			} else {
+				rc = 1;
+			}
+			break;
+		case SP_SESSL:
+			if ( si->si_logs ) {
+				c->value_int = si->si_logs->sl_size;
+			} else {
+				rc = 1;
+			}
+			break;
+		case SP_NOPRES:
+			if ( si->si_nopres ) {
+				c->value_int = 1;
+			} else {
+				rc = 1;
+			}
+			break;
+		case SP_USEHINT:
+			if ( si->si_usehint ) {
+				c->value_int = 1;
+			} else {
+				rc = 1;
+			}
+			break;
 		}
-		si->si_chkops = atoi( argv[1] );
-		si->si_chktime = atoi( argv[2] ) * 60;
-		return 0;
-
-	} else if ( strcasecmp( argv[0], "syncprov-sessionlog" ) == 0 ) {
-		sessionlog *sl;
-		int size;
-		if ( argc != 2 ) {
-			fprintf( stderr, "%s: line %d: wrong number of arguments in "
-				"\"syncprov-sessionlog <size>\"\n", fname, lineno );
-			return -1;
+		return rc;
+	} else if ( c->op == LDAP_MOD_DELETE ) {
+		switch ( c->type ) {
+		case SP_CHKPT:
+			si->si_chkops = 0;
+			si->si_chktime = 0;
+			break;
+		case SP_SESSL:
+			if ( si->si_logs )
+				si->si_logs->sl_size = 0;
+			else
+				rc = LDAP_NO_SUCH_ATTRIBUTE;
+			break;
+		case SP_NOPRES:
+			if ( si->si_nopres )
+				si->si_nopres = 0;
+			else
+				rc = LDAP_NO_SUCH_ATTRIBUTE;
+			break;
+		case SP_USEHINT:
+			if ( si->si_usehint )
+				si->si_usehint = 0;
+			else
+				rc = LDAP_NO_SUCH_ATTRIBUTE;
+			break;
+		}
+		return rc;
+	}
+	switch ( c->type ) {
+	case SP_CHKPT:
+		if ( lutil_atoi( &si->si_chkops, c->argv[1] ) != 0 ) {
+			snprintf( c->msg, sizeof( c->msg ), "%s unable to parse checkpoint ops # \"%s\"",
+				c->argv[0], c->argv[1] );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->msg, 0 );
+			return ARG_BAD_CONF;
+		}
+		if ( si->si_chkops <= 0 ) {
+			snprintf( c->msg, sizeof( c->msg ), "%s invalid checkpoint ops # \"%d\"",
+				c->argv[0], si->si_chkops );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->msg, 0 );
+			return ARG_BAD_CONF;
 		}
-		size = atoi( argv[1] );
+		if ( lutil_atoi( &si->si_chktime, c->argv[2] ) != 0 ) {
+			snprintf( c->msg, sizeof( c->msg ), "%s unable to parse checkpoint time \"%s\"",
+				c->argv[0], c->argv[1] );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->msg, 0 );
+			return ARG_BAD_CONF;
+		}
+		if ( si->si_chktime <= 0 ) {
+			snprintf( c->msg, sizeof( c->msg ), "%s invalid checkpoint time \"%d\"",
+				c->argv[0], si->si_chkops );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->msg, 0 );
+			return ARG_BAD_CONF;
+		}
+		si->si_chktime *= 60;
+		break;
+	case SP_SESSL: {
+		sessionlog *sl;
+		int size = c->value_int;
+
 		if ( size < 0 ) {
-			fprintf( stderr,
-				"%s: line %d: session log size %d is negative\n",
-				fname, lineno, size );
-			return -1;
+			snprintf( c->msg, sizeof( c->msg ), "%s size %d is negative",
+				c->argv[0], size );
+			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
+				"%s: %s\n", c->log, c->msg, 0 );
+			return ARG_BAD_CONF;
 		}
 		sl = si->si_logs;
 		if ( !sl ) {
@@ -2042,24 +2360,29 @@ syncprov_db_config(
 			si->si_logs = sl;
 		}
 		sl->sl_size = size;
-		return 0;
+		}
+		break;
+	case SP_NOPRES:
+		si->si_nopres = c->value_int;
+		break;
+	case SP_USEHINT:
+		si->si_usehint = c->value_int;
+		break;
 	}
-
-	return SLAP_CONF_UNKNOWN;
+	return rc;
 }
 
-/* Cheating - we have no thread pool context for these functions,
- * so make one.
+/* ITS#3456 we cannot run this search on the main thread, must use a
+ * child thread in order to insure we have a big enough stack.
  */
-typedef struct thread_keys {
-	void *key;
-	void *data;
-	ldap_pvt_thread_pool_keyfree_t *xfree;
-} thread_keys;
-
-#define MAXKEYS	32
-/* A fake thread context */
-static thread_keys thrctx[MAXKEYS];
+static void *
+syncprov_db_otask(
+	void *ptr
+)
+{
+	syncprov_findcsn( ptr, FIND_MAXCSN );
+	return NULL;
+}
 
 /* Read any existing contextCSN from the underlying db.
  * Then search for any entries newer than that. If no value exists,
@@ -2073,13 +2396,20 @@ syncprov_db_open(
 	slap_overinst   *on = (slap_overinst *) be->bd_info;
 	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
 
-	Connection conn;
-	char opbuf[OPERATION_BUFFER_SIZE];
+	Connection conn = { 0 };
+	OperationBuffer opbuf = { 0 };
 	char ctxcsnbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
-	Operation *op = (Operation *)opbuf;
-	Entry *e;
+	Operation *op = (Operation *) &opbuf;
+	Entry *e = NULL;
 	Attribute *a;
 	int rc;
+	void *thrctx = NULL;
+
+	if ( !SLAP_LASTMOD( be )) {
+		Debug( LDAP_DEBUG_ANY,
+			"syncprov_db_open: invalid config, lastmod must be enabled\n", 0, 0, 0 );
+		return -1;
+	}
 
 	if ( slapMode & SLAP_TOOL_MODE ) {
 		return 0;
@@ -2090,6 +2420,7 @@ syncprov_db_open(
 		return rc;
 	}
 
+	thrctx = ldap_pvt_thread_pool_context();
 	connection_fake_init( &conn, op, thrctx );
 	op->o_bd = be;
 	op->o_dn = be->be_rootdn;
@@ -2097,11 +2428,12 @@ syncprov_db_open(
 
 	ctxcsnbuf[0] = '\0';
 
-	op->o_bd->bd_info = on->on_info->oi_orig;
-	rc = be_entry_get_rw( op, be->be_nsuffix, NULL,
-		slap_schema.si_ad_contextCSN, 0, &e );
+	rc = overlay_entry_get_ov( op, be->be_nsuffix, NULL,
+		slap_schema.si_ad_contextCSN, 0, &e, on );
 
 	if ( e ) {
+		ldap_pvt_thread_t tid;
+
 		a = attr_find( e->e_attrs, slap_schema.si_ad_contextCSN );
 		if ( a ) {
 			si->si_ctxcsn.bv_len = a->a_nvals[0].bv_len;
@@ -2112,31 +2444,33 @@ syncprov_db_open(
 			si->si_ctxcsnbuf[si->si_ctxcsn.bv_len] = '\0';
 			strcpy( ctxcsnbuf, si->si_ctxcsnbuf );
 		}
-		be_entry_release_rw( op, e, 0 );
-		op->o_bd->bd_info = (BackendInfo *)on;
-		op->o_req_dn = be->be_suffix[0];
-		op->o_req_ndn = be->be_nsuffix[0];
-		op->ors_scope = LDAP_SCOPE_SUBTREE;
-		syncprov_findcsn( op, FIND_MAXCSN );
-	} else if ( SLAP_SYNC_SHADOW( op->o_bd )) {
-		/* If we're also a consumer, and we didn't find the context entry,
-		 * then don't generate anything, wait for our provider to send it
-		 * to us.
-		 */
-		goto out;
+		overlay_entry_release_ov( op, e, 0, on );
+		if ( !BER_BVISEMPTY( &si->si_ctxcsn ) ) {
+			op->o_req_dn = be->be_suffix[0];
+			op->o_req_ndn = be->be_nsuffix[0];
+			op->ors_scope = LDAP_SCOPE_SUBTREE;
+			ldap_pvt_thread_create( &tid, 0, syncprov_db_otask, op );
+			ldap_pvt_thread_join( tid, NULL );
+		}
 	}
 
 	if ( BER_BVISEMPTY( &si->si_ctxcsn ) ) {
-		slap_get_csn( op, si->si_ctxcsnbuf, sizeof(si->si_ctxcsnbuf),
-				&si->si_ctxcsn, 0 );
+		if ( SLAP_SYNC_SHADOW( op->o_bd )) {
+		/* If we're also a consumer, and we didn't get a contextCSN,
+		 * then don't generate anything, wait for our provider to send it
+		 * to us.
+		 */
+			goto out;
+		}
+		si->si_ctxcsn.bv_len = sizeof( si->si_ctxcsnbuf );
+		slap_get_csn( op, &si->si_ctxcsn, 0 );
 	}
 
 	/* If our ctxcsn is different from what was read from the root
-	 * entry, write the new value out.
+	 * entry, make sure we do a checkpoint on close
 	 */
 	if ( strcmp( si->si_ctxcsnbuf, ctxcsnbuf )) {
-		SlapReply rs = {REP_RESULT};
-		syncprov_checkpoint( op, &rs, on );
+		si->si_numops++;
 	}
 
 out:
@@ -2153,28 +2487,24 @@ syncprov_db_close(
 {
     slap_overinst   *on = (slap_overinst *) be->bd_info;
     syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
-	int i;
 
 	if ( slapMode & SLAP_TOOL_MODE ) {
 		return 0;
 	}
 	if ( si->si_numops ) {
-		Connection conn;
-		char opbuf[OPERATION_BUFFER_SIZE];
-		Operation *op = (Operation *)opbuf;
+		Connection conn = {0};
+		OperationBuffer opbuf;
+		Operation *op = (Operation *) &opbuf;
 		SlapReply rs = {REP_RESULT};
+		void *thrctx;
 
+		thrctx = ldap_pvt_thread_pool_context();
 		connection_fake_init( &conn, op, thrctx );
 		op->o_bd = be;
 		op->o_dn = be->be_rootdn;
 		op->o_ndn = be->be_rootndn;
 		syncprov_checkpoint( op, &rs, on );
 	}
-	for ( i=0; thrctx[i].key; i++) {
-		if ( thrctx[i].xfree )
-			thrctx[i].xfree( thrctx[i].key, thrctx[i].data );
-		thrctx[i].key = NULL;
-	}
 
     return 0;
 }
@@ -2187,15 +2517,24 @@ syncprov_db_init(
 	slap_overinst	*on = (slap_overinst *)be->bd_info;
 	syncprov_info_t	*si;
 
+	if ( SLAP_ISGLOBALOVERLAY( be ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"syncprov must be instantiated within a database.\n",
+			0, 0, 0 );
+		return 1;
+	}
+
 	si = ch_calloc(1, sizeof(syncprov_info_t));
 	on->on_bi.bi_private = si;
-	ldap_pvt_thread_mutex_init( &si->si_csn_mutex );
+	ldap_pvt_thread_rdwr_init( &si->si_csn_rwlock );
 	ldap_pvt_thread_mutex_init( &si->si_ops_mutex );
 	ldap_pvt_thread_mutex_init( &si->si_mods_mutex );
 	si->si_ctxcsn.bv_val = si->si_ctxcsnbuf;
 
 	csn_anlist[0].an_desc = slap_schema.si_ad_entryCSN;
 	csn_anlist[0].an_name = slap_schema.si_ad_entryCSN->ad_cname;
+	csn_anlist[1].an_desc = slap_schema.si_ad_entryUUID;
+	csn_anlist[1].an_name = slap_schema.si_ad_entryUUID->ad_cname;
 
 	uuid_anlist[0].an_desc = slap_schema.si_ad_entryUUID;
 	uuid_anlist[0].an_name = slap_schema.si_ad_entryUUID->ad_cname;
@@ -2212,9 +2551,20 @@ syncprov_db_destroy(
 	syncprov_info_t	*si = (syncprov_info_t *)on->on_bi.bi_private;
 
 	if ( si ) {
+		if ( si->si_logs ) {
+			slog_entry *se = si->si_logs->sl_head;
+
+			while ( se ) {
+				slog_entry *se_next = se->se_next;
+				ch_free( se );
+				se = se_next;
+			}
+				
+			ch_free( si->si_logs );
+		}
 		ldap_pvt_thread_mutex_destroy( &si->si_mods_mutex );
 		ldap_pvt_thread_mutex_destroy( &si->si_ops_mutex );
-		ldap_pvt_thread_mutex_destroy( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_destroy( &si->si_csn_rwlock );
 		ch_free( si );
 	}
 
@@ -2227,7 +2577,8 @@ static int syncprov_parseCtrl (
 	LDAPControl *ctrl )
 {
 	ber_tag_t tag;
-	BerElement *ber;
+	BerElementBuffer berbuf;
+	BerElement *ber = (BerElement *)&berbuf;
 	ber_int_t mode;
 	ber_len_t len;
 	struct berval cookie = BER_BVNULL;
@@ -2261,11 +2612,7 @@ static int syncprov_parseCtrl (
 	 *      }
 	 */
 
-	ber = ber_init( &ctrl->ldctl_value );
-	if( ber == NULL ) {
-		rs->sr_text = "internal error";
-		return LDAP_OTHER;
-	}
+	ber_init2( ber, &ctrl->ldctl_value, 0 );
 
 	if ( (tag = ber_scanf( ber, "{i" /*}*/, &mode )) == LBER_ERROR ) {
 		rs->sr_text = "Sync control : mode decoding error";
@@ -2287,10 +2634,11 @@ static int syncprov_parseCtrl (
 	tag = ber_peek_tag( ber, &len );
 
 	if ( tag == LDAP_TAG_SYNC_COOKIE ) {
-		if (( ber_scanf( ber, /*{*/ "o", &cookie )) == LBER_ERROR ) {
+		if (( ber_scanf( ber, /*{*/ "m", &cookie )) == LBER_ERROR ) {
 			rs->sr_text = "Sync control : cookie decoding error";
 			return LDAP_PROTOCOL_ERROR;
 		}
+		tag = ber_peek_tag( ber, &len );
 	}
 	if ( tag == LDAP_TAG_RELOAD_HINT ) {
 		if (( ber_scanf( ber, /*{*/ "b", &rhint )) == LBER_ERROR ) {
@@ -2305,14 +2653,16 @@ static int syncprov_parseCtrl (
 	sr = op->o_tmpcalloc( 1, sizeof(struct sync_control), op->o_tmpmemctx );
 	sr->sr_rhint = rhint;
 	if (!BER_BVISNULL(&cookie)) {
-		ber_dupbv( &sr->sr_state.octet_str, &cookie );
-		slap_parse_sync_cookie( &sr->sr_state );
+		ber_dupbv_x( &sr->sr_state.octet_str, &cookie, op->o_tmpmemctx );
+		if ( slap_parse_sync_cookie( &sr->sr_state, op->o_tmpmemctx ) ||
+			sr->sr_state.rid == -1 ) {
+			rs->sr_text = "Sync control : cookie parsing error";
+			return LDAP_PROTOCOL_ERROR;
+		}
 	}
 
 	op->o_controls[slap_cids.sc_LDAPsync] = sr;
 
-	(void) ber_free( ber, 1 );
-
 	op->o_sync = ctrl->ldctl_iscritical
 		? SLAP_CONTROL_CRITICAL
 		: SLAP_CONTROL_NONCRITICAL;
@@ -2330,21 +2680,21 @@ static int syncprov_parseCtrl (
 static slap_overinst 		syncprov;
 
 int
-syncprov_init()
+syncprov_initialize()
 {
 	int rc;
 
 	rc = register_supported_control( LDAP_CONTROL_SYNC,
-		SLAP_CTRL_HIDE|SLAP_CTRL_SEARCH, NULL,
+		SLAP_CTRL_SEARCH, NULL,
 		syncprov_parseCtrl, &slap_cids.sc_LDAPsync );
 	if ( rc != LDAP_SUCCESS ) {
-		fprintf( stderr, "Failed to register control %d\n", rc );
+		Debug( LDAP_DEBUG_ANY,
+			"syncprov_init: Failed to register control %d\n", rc, 0, 0 );
 		return rc;
 	}
 
 	syncprov.on_bi.bi_type = "syncprov";
 	syncprov.on_bi.bi_db_init = syncprov_db_init;
-	syncprov.on_bi.bi_db_config = syncprov_db_config;
 	syncprov.on_bi.bi_db_destroy = syncprov_db_destroy;
 	syncprov.on_bi.bi_db_open = syncprov_db_open;
 	syncprov.on_bi.bi_db_close = syncprov_db_close;
@@ -2361,6 +2711,13 @@ syncprov_init()
 	syncprov.on_bi.bi_extended = syncprov_op_extended;
 	syncprov.on_bi.bi_operational = syncprov_operational;
 
+	syncprov.on_bi.bi_cf_ocs = spocs;
+
+	generic_filter.f_desc = slap_schema.si_ad_objectClass;
+
+	rc = config_register_schema( spcfg, spocs );
+	if ( rc ) return rc;
+
 	return overlay_register( &syncprov );
 }
 
@@ -2368,7 +2725,7 @@ syncprov_init()
 int
 init_module( int argc, char *argv[] )
 {
-	return syncprov_init();
+	return syncprov_initialize();
 }
 #endif /* SLAPD_OVER_SYNCPROV == SLAPD_MOD_DYNAMIC */