Blame SOURCES/0034-Ticket-48954-replication-fails-because-anchorcsn-can.patch

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From 1cd2d9b06b8bc006078ed26bb0d3cbe808681a86 Mon Sep 17 00:00:00 2001
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From: Ludwig Krispenz <lkrispen@redhat.com>
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Date: Fri, 12 Aug 2016 14:06:21 +0200
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Subject: [PATCH 34/35] Ticket 48954 - replication fails because anchorcsn
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 cannot be found
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Bug Description: the anchorcsn is calculated based on supploier and consumer
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                 ruv. If this csn is not found in the changelog
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                 replication stops.
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Fix Description: Fix consists of two parts
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                 1. log start-iteration csn record for all replicas
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                    after initialization
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                 2. If the csn still cannot be found
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                    - log an error
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                    - use the closest csn available by calling
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                      cursor->c_get with DB_SET_RANGE instead of DB_SET
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https://fedorahosted.org/389/ticket/48954
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Reviewed by: Noriko, Thierry. thanks
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(cherry picked from commit 0721856d5a203689c15ea66ffe6c94ce4d785bd7)
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---
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 ldap/servers/plugins/replication/cl5_clcache.c   | 32 +++++++++++--
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 ldap/servers/plugins/replication/repl5_replica.c | 58 ++++++++++++++++--------
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 2 files changed, 67 insertions(+), 23 deletions(-)
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diff --git a/ldap/servers/plugins/replication/cl5_clcache.c b/ldap/servers/plugins/replication/cl5_clcache.c
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index 2d3bb28..74f0fec 100644
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--- a/ldap/servers/plugins/replication/cl5_clcache.c
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+++ b/ldap/servers/plugins/replication/cl5_clcache.c
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@@ -376,6 +376,7 @@ clcache_load_buffer_bulk ( CLC_Buffer *buf, int flag )
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 	DBC *cursor = NULL;
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 	int rc = 0;
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 	int tries = 0;
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+	int use_flag = flag;
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 #if 0 /* txn control seems not improving anything so turn it off */
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 	if ( *(_pool->pl_dbenv) ) {
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@@ -400,20 +401,44 @@ clcache_load_buffer_bulk ( CLC_Buffer *buf, int flag )
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 retry:
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 	if ( 0 == ( rc = clcache_open_cursor ( txn, buf, &cursor )) ) {
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-		if ( flag == DB_NEXT ) {
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+		if ( use_flag == DB_NEXT ) {
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 			/* For bulk read, position the cursor before read the next block */
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 			rc = cursor->c_get ( cursor,
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 								 & buf->buf_key,
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 								 & buf->buf_data,
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 								 DB_SET );
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+			if (rc == DB_NOTFOUND) {
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+				/* the start position in the changelog is not found
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+				 * 1. log an error
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+				 * 2. try to find another starting position as close
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+				 *    as possible
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+				 */
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+				slapi_log_error ( SLAPI_LOG_FATAL, "clcache_load_buffer_bulk",
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+							"changelog record with csn (%s) not found for DB_NEXT\n",
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+							(char *)buf->buf_key.data );
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+				rc = cursor->c_get ( cursor, & buf->buf_key, & buf->buf_data,
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+							 DB_SET_RANGE );
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+				/* this moves the cursor ahead of the tageted csn,
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+				 * so we achieved what was intended with DB_SET/DB_NEXT
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+				 * continute at this csn.
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+				 */
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+				use_flag = DB_CURRENT;
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+			}
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 		}
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 		/*
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 		 * Continue if the error is no-mem since we don't need to
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 		 * load in the key record anyway with DB_SET.
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 		 */
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-		if ( 0 == rc || DB_BUFFER_SMALL == rc )
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-			rc = clcache_cursor_get ( cursor, buf, flag );
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+		if ( 0 == rc || DB_BUFFER_SMALL == rc ) {
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+			rc = clcache_cursor_get ( cursor, buf, use_flag );
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+			if ( rc == DB_NOTFOUND && use_flag == DB_SET) {
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+				slapi_log_error ( SLAPI_LOG_FATAL, "clcache_load_buffer_bulk",
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+							"changelog record with csn (%s) not found for DB_SET\n",
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+							(char *)buf->buf_key.data );
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+				rc = clcache_cursor_get ( cursor, buf, DB_SET_RANGE );
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+			}
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+		}
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 	}
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@@ -434,6 +459,7 @@ retry:
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 		/* back off */
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 		interval = PR_MillisecondsToInterval(slapi_rand() % 100);
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 		DS_Sleep(interval);
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+		use_flag = flag;
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 		goto retry;
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 	}
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 	if ((rc == DB_LOCK_DEADLOCK) && (tries >= MAX_TRIALS)) {
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diff --git a/ldap/servers/plugins/replication/repl5_replica.c b/ldap/servers/plugins/replication/repl5_replica.c
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index b5d65ef..7360d97 100644
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--- a/ldap/servers/plugins/replication/repl5_replica.c
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+++ b/ldap/servers/plugins/replication/repl5_replica.c
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@@ -3794,41 +3794,59 @@ replica_remove_legacy_attr (const Slapi_DN *repl_root_sdn, const char *attr)
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     slapi_mods_done (&smods);
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     slapi_pblock_destroy (pb);
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 }
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+typedef struct replinfo {
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+    char *repl_gen;
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+    char *repl_name;
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+} replinfo;
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+
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+static int
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+replica_log_start_iteration(const ruv_enum_data *rid_data, void *data)
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+{
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+    int rc = 0;
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+    replinfo *r_info = (replinfo *)data;
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+    slapi_operation_parameters op_params;
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+
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+    if (rid_data->csn == NULL) return 0;
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+
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+    memset (&op_params, 0, sizeof (op_params));
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+    op_params.operation_type = SLAPI_OPERATION_DELETE;
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+    op_params.target_address.sdn = slapi_sdn_new_ndn_byval(START_ITERATION_ENTRY_DN);
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+    op_params.target_address.uniqueid = START_ITERATION_ENTRY_UNIQUEID;
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+    op_params.csn = csn_dup(rid_data->csn);
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+    rc = cl5WriteOperation(r_info->repl_name, r_info->repl_gen, &op_params, PR_FALSE);
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+    if (rc == CL5_SUCCESS)
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+        rc = 0;
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+    else
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+        rc = -1;
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+
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+    slapi_sdn_free(&op_params.target_address.sdn);
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+    csn_free (&op_params.csn);
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+
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+    return rc;
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+}
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 static int 
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 replica_log_ruv_elements_nolock (const Replica *r)
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 {
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     int rc = 0;
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-    slapi_operation_parameters op_params;
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     RUV *ruv;
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     char *repl_gen; 
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-    CSN *csn = NULL;
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+    replinfo r_info;
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     ruv = (RUV*) object_get_data (r->repl_ruv);
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     PR_ASSERT (ruv);
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-    if ((ruv_get_min_csn(ruv, &csn) == RUV_SUCCESS) && csn)
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-    {
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         /* we log it as a delete operation to have the least number of fields
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            to set. the entry can be identified by a special target uniqueid and
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            special target dn */
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-        memset (&op_params, 0, sizeof (op_params));
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-        op_params.operation_type = SLAPI_OPERATION_DELETE;
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-        op_params.target_address.sdn = slapi_sdn_new_ndn_byval(START_ITERATION_ENTRY_DN);
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-        op_params.target_address.uniqueid = START_ITERATION_ENTRY_UNIQUEID;
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-        op_params.csn = csn;
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-        repl_gen = ruv_get_replica_generation (ruv);
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-
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-        rc = cl5WriteOperation(r->repl_name, repl_gen, &op_params, PR_FALSE); 
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-        if (rc == CL5_SUCCESS)
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-            rc = 0;
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-        else
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-            rc = -1;
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+    repl_gen = ruv_get_replica_generation (ruv);
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-        slapi_ch_free ((void**)&repl_gen);
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-        slapi_sdn_free(&op_params.target_address.sdn);
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-        csn_free (&csn);
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-    }
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+    r_info.repl_name = r->repl_name;
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+    r_info.repl_gen = repl_gen;
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+
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+    rc = ruv_enumerate_elements(ruv, replica_log_start_iteration, &r_info);
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+
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+    slapi_ch_free ((void**)&repl_gen);
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     return rc;
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 }
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-- 
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2.4.11
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