From 401132f74937854b8e7e65c2ba392bc156fadd27 Mon Sep 17 00:00:00 2001

From: Ludwig Krispenz <lkrispen@redhat.com>

Date: Fri, 12 Aug 2016 14:06:21 +0200

Subject: [PATCH 388/390] Ticket 48954 - replication fails because anchorcsn

 cannot be found

Bug Description: the anchorcsn is calculated based on supploier and consumer

                 ruv. If this csn is not found in the changelog

                 replication stops.

Fix Description: Fix consists of two parts

                 1. log start-iteration csn record for all replicas

                    after initialization

                 2. If the csn still cannot be found

                    - log an error

                    - use the closest csn available by calling

                      cursor->c_get with DB_SET_RANGE instead of DB_SET

https://fedorahosted.org/389/ticket/48954

Reviewed by: Noriko, Thierry. thanks

(cherry picked from commit 08b0ee8e45d8ce8c869c193ee31ee7f983c59819)

---

 ldap/servers/plugins/replication/cl5_clcache.c   | 32 +++++++++++--

 ldap/servers/plugins/replication/repl5_replica.c | 58 ++++++++++++++++--------

 2 files changed, 67 insertions(+), 23 deletions(-)

diff --git a/ldap/servers/plugins/replication/cl5_clcache.c b/ldap/servers/plugins/replication/cl5_clcache.c

index 9e1d3b7..0b8feee 100644

--- a/ldap/servers/plugins/replication/cl5_clcache.c

+++ b/ldap/servers/plugins/replication/cl5_clcache.c

@@ -406,6 +406,7 @@ clcache_load_buffer_bulk ( CLC_Buffer *buf, int flag )

 	DBC *cursor = NULL;

 	int rc = 0;

 	int tries = 0;

+	int use_flag = flag;

 #if 0 /* txn control seems not improving anything so turn it off */

 	if ( *(_pool->pl_dbenv) ) {

@@ -430,20 +431,44 @@ clcache_load_buffer_bulk ( CLC_Buffer *buf, int flag )

 retry:

 	if ( 0 == ( rc = clcache_open_cursor ( txn, buf, &cursor )) ) {

-		if ( flag == DB_NEXT ) {

+		if ( use_flag == DB_NEXT ) {

 			/* For bulk read, position the cursor before read the next block */

 			rc = cursor->c_get ( cursor,

 								 & buf->buf_key,

 								 & buf->buf_data,

 								 DB_SET );

+			if (rc == DB_NOTFOUND) {

+				/* the start position in the changelog is not found

+				 * 1. log an error

+				 * 2. try to find another starting position as close

+				 *    as possible

+				 */

+				slapi_log_error ( SLAPI_LOG_FATAL, "clcache_load_buffer_bulk",

+							"changelog record with csn (%s) not found for DB_NEXT\n",

+							(char *)buf->buf_key.data );

+				rc = cursor->c_get ( cursor, & buf->buf_key, & buf->buf_data,

+							 DB_SET_RANGE );

+				/* this moves the cursor ahead of the tageted csn,

+				 * so we achieved what was intended with DB_SET/DB_NEXT

+				 * continute at this csn.

+				 */

+				use_flag = DB_CURRENT;

+			}

 		}

 		/*

 		 * Continue if the error is no-mem since we don't need to

 		 * load in the key record anyway with DB_SET.

 		 */

-		if ( 0 == rc || DB_BUFFER_SMALL == rc )

-			rc = clcache_cursor_get ( cursor, buf, flag );

+		if ( 0 == rc || DB_BUFFER_SMALL == rc ) {

+			rc = clcache_cursor_get ( cursor, buf, use_flag );

+			if ( rc == DB_NOTFOUND && use_flag == DB_SET) {

+				slapi_log_error ( SLAPI_LOG_FATAL, "clcache_load_buffer_bulk",

+							"changelog record with csn (%s) not found for DB_SET\n",

+							(char *)buf->buf_key.data );

+				rc = clcache_cursor_get ( cursor, buf, DB_SET_RANGE );

+			}

+		}

 	}

@@ -464,6 +489,7 @@ retry:

 		/* back off */

 		interval = PR_MillisecondsToInterval(slapi_rand() % 100);

 		DS_Sleep(interval);

+		use_flag = flag;

 		goto retry;

 	}

 	if ((rc == DB_LOCK_DEADLOCK) && (tries >= MAX_TRIALS)) {

diff --git a/ldap/servers/plugins/replication/repl5_replica.c b/ldap/servers/plugins/replication/repl5_replica.c

index d25d00d..e7d58cf 100644

--- a/ldap/servers/plugins/replication/repl5_replica.c

+++ b/ldap/servers/plugins/replication/repl5_replica.c

@@ -3513,41 +3513,59 @@ replica_remove_legacy_attr (const Slapi_DN *repl_root_sdn, const char *attr)

     slapi_mods_done (&smods);

     slapi_pblock_destroy (pb);

 }

+typedef struct replinfo {

+    char *repl_gen;

+    char *repl_name;

+} replinfo;

+

+static int

+replica_log_start_iteration(const ruv_enum_data *rid_data, void *data)

+{

+    int rc = 0;

+    replinfo *r_info = (replinfo *)data;

+    slapi_operation_parameters op_params;

+

+    if (rid_data->csn == NULL) return 0;

+

+    memset (&op_params, 0, sizeof (op_params));

+    op_params.operation_type = SLAPI_OPERATION_DELETE;

+    op_params.target_address.sdn = slapi_sdn_new_ndn_byval(START_ITERATION_ENTRY_DN);

+    op_params.target_address.uniqueid = START_ITERATION_ENTRY_UNIQUEID;

+    op_params.csn = csn_dup(rid_data->csn);

+    rc = cl5WriteOperation(r_info->repl_name, r_info->repl_gen, &op_params, PR_FALSE);

+    if (rc == CL5_SUCCESS)

+        rc = 0;

+    else

+        rc = -1;

+

+    slapi_sdn_free(&op_params.target_address.sdn);

+    csn_free (&op_params.csn);

+

+    return rc;

+}

 static int 

 replica_log_ruv_elements_nolock (const Replica *r)

 {

     int rc = 0;

-    slapi_operation_parameters op_params;

     RUV *ruv;

     char *repl_gen; 

-    CSN *csn = NULL;

+    replinfo r_info;

     ruv = (RUV*) object_get_data (r->repl_ruv);

     PR_ASSERT (ruv);

-    if ((ruv_get_min_csn(ruv, &csn) == RUV_SUCCESS) && csn)

-    {

         /* we log it as a delete operation to have the least number of fields

            to set. the entry can be identified by a special target uniqueid and

            special target dn */

-        memset (&op_params, 0, sizeof (op_params));

-        op_params.operation_type = SLAPI_OPERATION_DELETE;

-        op_params.target_address.sdn = slapi_sdn_new_ndn_byval(START_ITERATION_ENTRY_DN);

-        op_params.target_address.uniqueid = START_ITERATION_ENTRY_UNIQUEID;

-        op_params.csn = csn;

-        repl_gen = ruv_get_replica_generation (ruv);

-

-        rc = cl5WriteOperation(r->repl_name, repl_gen, &op_params, PR_FALSE); 

-        if (rc == CL5_SUCCESS)

-            rc = 0;

-        else

-            rc = -1;

+    repl_gen = ruv_get_replica_generation (ruv);

-        slapi_ch_free ((void**)&repl_gen);

-        slapi_sdn_free(&op_params.target_address.sdn);

-        csn_free (&csn;;

-    }

+    r_info.repl_name = r->repl_name;

+    r_info.repl_gen = repl_gen;

+

+    rc = ruv_enumerate_elements(ruv, replica_log_start_iteration, &r_info);

+

+    slapi_ch_free ((void**)&repl_gen);

     return rc;

 }

-- 

2.4.11