Flesh out txn support

Only in back-mdb; back-bdb needs work but it's deprecated;
not worth the effort. In particular txn, retry after deadlocks
makes the whole thing too messy.

servers/slapd/back-mdb/id2entry.c

@@ -526,6 +526,29 @@ ok:
 	return 0;
 }
 
+#ifdef LDAP_X_TXN
+int mdb_txn( Operation *op, int txnop, OpExtra **ptr )
+{
+	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
+	mdb_op_info **moip = (mdb_op_info **)ptr, *moi = *moip;
+	int rc;
+
+	switch( txnop ) {
+	case SLAP_TXN_BEGIN:
+		return mdb_opinfo_get( op, mdb, 0, moip );
+	case SLAP_TXN_COMMIT:
+		rc = mdb_txn_commit( moi->moi_txn );
+		op->o_tmpfree( op->o_tmpmemctx, moi );
+		return rc;
+	case SLAP_TXN_ABORT:
+		mdb_txn_abort( moi->moi_txn );
+		op->o_tmpfree( op->o_tmpmemctx, moi );
+		return 0;
+	}
+	return LDAP_OTHER;
+}
+#endif
+
 /* Count up the sizes of the components of an entry */
 static int mdb_entry_partsize(struct mdb_info *mdb, MDB_txn *txn, Entry *e,
 	Ecount *eh)

servers/slapd/back-mdb/init.c

@@ -456,6 +456,7 @@ mdb_back_initialize(
 	bi->bi_op_search = mdb_search;
 
 	bi->bi_op_unbind = 0;
+	bi->bi_op_txn = mdb_txn;
 
 	bi->bi_extended = mdb_extended;
 

servers/slapd/back-mdb/proto-mdb.h

@@ -196,6 +196,7 @@ int mdb_id2edata(
 int mdb_entry_return( Operation *op, Entry *e );
 BI_entry_release_rw mdb_entry_release;
 BI_entry_get_rw mdb_entry_get;
+BI_op_txn mdb_txn;
 
 int mdb_entry_decode( Operation *op, MDB_txn *txn, MDB_val *data, Entry **e );
 

servers/slapd/connection.c

@@ -1172,8 +1172,13 @@ operations_error:
 
 	ber_set_option( op->o_ber, LBER_OPT_BER_MEMCTX, &memctx_null );
 
-	LDAP_STAILQ_REMOVE( &conn->c_ops, op, Operation, o_next);
-	LDAP_STAILQ_NEXT(op, o_next) = NULL;
+#ifdef LDAP_X_TXN
+	if ( rc != LDAP_X_TXN_SPECIFY_OKAY )
+#endif
+	{
+		LDAP_STAILQ_REMOVE( &conn->c_ops, op, Operation, o_next);
+		LDAP_STAILQ_NEXT(op, o_next) = NULL;
+	}
 	conn->c_n_ops_executing--;
 	conn->c_n_ops_completed++;
 
@@ -1188,7 +1193,12 @@ operations_error:
 
 	connection_resched( conn );
 	ldap_pvt_thread_mutex_unlock( &conn->c_mutex );
-	slap_op_free( op, ctx );
+#ifdef LDAP_X_TXN
+	if ( rc != LDAP_X_TXN_SPECIFY_OKAY )
+#endif
+	{
+		slap_op_free( op, ctx );
+	}
 	return NULL;
 }
 

servers/slapd/slap.h

@@ -2183,6 +2183,13 @@ typedef int (BI_acl_group) LDAP_P(( Operation *op, Entry *target,
 typedef int (BI_acl_attribute) LDAP_P(( Operation *op, Entry *target,
 	struct berval *entry_ndn, AttributeDescription *entry_at,
 	BerVarray *vals, slap_access_t access ));
+#ifdef LDAP_X_TXN
+struct OpExtra;
+typedef int (BI_op_txn) LDAP_P(( Operation *op, int txnop, struct OpExtra **ptr ));
+#define SLAP_TXN_BEGIN	1
+#define SLAP_TXN_COMMIT	2
+#define SLAP_TXN_ABORT	3
+#endif
 
 typedef int (BI_conn_func) LDAP_P(( BackendDB *bd, Connection *c ));
 typedef BI_conn_func BI_connection_init;
@@ -2279,6 +2286,9 @@ struct BackendInfo {
 	BI_operational		*bi_operational;
 	BI_chk_referrals	*bi_chk_referrals;
 	BI_chk_controls		*bi_chk_controls;
+#ifdef LDAP_X_TXN
+	BI_op_txn			*bi_op_txn;
+#endif
 	BI_entry_get_rw		*bi_entry_get_rw;
 	BI_entry_release_rw	*bi_entry_release_rw;
 
@@ -2402,6 +2412,9 @@ typedef enum slap_operation_e {
 	op_aux_operational,
 	op_aux_chk_referrals,
 	op_aux_chk_controls,
+#ifdef LDAP_X_TXN
+	op_txn,
+#endif
 	op_last
 } slap_operation_t;
 

servers/slapd/txn.c

@@ -111,6 +111,11 @@ int txn_spec_ctrl(
 	return LDAP_SUCCESS;
 }
 
+static int txn_result( Operation *op, SlapReply *rs )
+{
+	return rs->sr_err;
+}
+
 int txn_end_extop(
 	Operation *op, SlapReply *rs )
 {
@@ -121,6 +126,8 @@ int txn_end_extop(
 	ber_len_t len;
 	ber_int_t commit=1;
 	struct berval txnid;
+	Operation *o, *p;
+	Connection *c = op->o_conn;
 
 	Statslog( LDAP_DEBUG_STATS, "%s TXN END\n",
 		op->o_log_prefix, 0, 0, 0, 0 );
@@ -134,7 +141,7 @@ int txn_end_extop(
 		return LDAP_PROTOCOL_ERROR;
 	}
 
-	op->o_bd = op->o_conn->c_authz_backend;
+	op->o_bd = c->c_authz_backend;
 	if( backend_check_restrictions( op, rs,
 		(struct berval *)&slap_EXOP_TXN_END ) != LDAP_SUCCESS )
 	{
@@ -170,48 +177,140 @@ int txn_end_extop(
 	}
 
 	/* acquire connection lock */
-	ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
+	ldap_pvt_thread_mutex_lock( &c->c_mutex );
 
-	if( op->o_conn->c_txn != CONN_TXN_SPECIFY ) {
+	if( c->c_txn != CONN_TXN_SPECIFY ) {
 		rs->sr_text = "invalid transaction identifier";
 		rc = LDAP_X_TXN_ID_INVALID;
 		goto done;
 	}
-	op->o_conn->c_txn = CONN_TXN_SETTLE;
+	c->c_txn = CONN_TXN_SETTLE;
 
 	if( commit ) {
+		slap_callback cb = {0};
+		OpExtra *txn = NULL;
 		if ( op->o_abandon ) {
+			goto drain;
 		}
 
-		if( LDAP_STAILQ_EMPTY(&op->o_conn->c_txn_ops) ) {
+		if( LDAP_STAILQ_EMPTY(&c->c_txn_ops) ) {
 			/* no updates to commit */
 			rs->sr_text = "no updates to commit";
 			rc = LDAP_OPERATIONS_ERROR;
 			goto settled;
 		}
 
-		rs->sr_text = "not yet implemented";
-		rc = LDAP_UNWILLING_TO_PERFORM;
-
+		cb.sc_response = txn_result;
+		LDAP_STAILQ_FOREACH( o, &c->c_txn_ops, o_next ) {
+			o->o_bd = c->c_txn_backend;
+			p = o;
+			if ( !txn ) {
+				rc = o->o_bd->bd_info->bi_op_txn(o, SLAP_TXN_BEGIN, &txn );
+				if ( rc ) {
+					rs->sr_text = "couldn't start DB transaction";
+					rc = LDAP_OTHER;
+					goto drain;
+				}
+			} else {
+				LDAP_SLIST_INSERT_HEAD( &o->o_extra, txn, oe_next );
+			}
+			cb.sc_next = o->o_callback;
+			o->o_callback = &cb;
+			{
+				SlapReply rs = {REP_RESULT};
+				int opidx = slap_req2op( o->o_tag );
+				assert( opidx != SLAP_OP_LAST );
+				o->o_threadctx = op->o_threadctx;
+				o->o_tid = op->o_tid;
+				ldap_pvt_thread_mutex_unlock( &c->c_mutex );
+				rc = (&o->o_bd->bd_info->bi_op_bind)[opidx]( o, &rs );
+				ldap_pvt_thread_mutex_lock( &c->c_mutex );
+			}
+			if ( rc ) {
+				struct berval *bv = NULL;
+				BerElementBuffer berbuf;
+				BerElement *ber = (BerElement *)&berbuf;
+
+				ber_init_w_nullc( ber, LBER_USE_DER );
+				ber_printf( ber, "{i}", o->o_msgid );
+				ber_flatten( ber, &bv );
+				ber_free_buf( ber );
+				rs->sr_rspdata = bv;
+				o->o_bd->bd_info->bi_op_txn(o, SLAP_TXN_ABORT, &txn );
+				goto drain;
+			}
+		}
+		o = p;
+		rc = o->o_bd->bd_info->bi_op_txn(o, SLAP_TXN_COMMIT, &txn );
+		if ( rc ) {
+			rs->sr_text = "transaction commit failed";
+			rc = LDAP_OTHER;
+		}
 	} else {
 		rs->sr_text = "transaction aborted";
-		rc = LDAP_SUCCESS;;
+		rc = LDAP_SUCCESS;
 	}
 
 drain:
 	/* drain txn ops list */
+	while (( o = LDAP_STAILQ_FIRST( &c->c_txn_ops )) != NULL ) {
+		LDAP_STAILQ_REMOVE_HEAD( &c->c_txn_ops, o_next );
+		LDAP_STAILQ_NEXT( o, o_next ) = NULL;
+		slap_op_free( o, NULL );
+	}
 
 settled:
-	assert( LDAP_STAILQ_EMPTY(&op->o_conn->c_txn_ops) );
-	assert( op->o_conn->c_txn == CONN_TXN_SETTLE );
-	op->o_conn->c_txn = CONN_TXN_INACTIVE;
-	op->o_conn->c_txn_backend = NULL;
+	assert( LDAP_STAILQ_EMPTY(&c->c_txn_ops) );
+	assert( c->c_txn == CONN_TXN_SETTLE );
+	c->c_txn = CONN_TXN_INACTIVE;
+	c->c_txn_backend = NULL;
 
 done:
 	/* release connection lock */
-	ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
+	ldap_pvt_thread_mutex_unlock( &c->c_mutex );
 
 	return rc;
 }
 
+int txn_preop( Operation *op, SlapReply *rs )
+{
+	int settle = 0;
+
+	/* acquire connection lock */
+	ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
+	if( op->o_conn->c_txn == CONN_TXN_INACTIVE ) {
+		rs->sr_text = "invalid transaction identifier";
+		rs->sr_err = LDAP_X_TXN_ID_INVALID;
+		goto txnReturn;
+	} else if( op->o_conn->c_txn == CONN_TXN_SETTLE ) {
+		settle=1;
+		goto txnReturn;
+	}
+
+	if( op->o_conn->c_txn_backend == NULL ) {
+		op->o_conn->c_txn_backend = op->o_bd;
+
+	} else if( op->o_conn->c_txn_backend != op->o_bd ) {
+		rs->sr_text = "transaction cannot span multiple database contexts";
+		rs->sr_err = LDAP_AFFECTS_MULTIPLE_DSAS;
+		goto txnReturn;
+	}
+
+	/* insert operation into transaction */
+	LDAP_STAILQ_REMOVE( &op->o_conn->c_ops, op, Operation, o_next );
+	LDAP_STAILQ_INSERT_TAIL( &op->o_conn->c_txn_ops, op, o_next );
+
+txnReturn:
+	/* release connection lock */
+	ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
+
+	if( !settle ) {
+		send_ldap_result( op, rs );
+		if ( !rs->sr_err )
+			rs->sr_err = LDAP_X_TXN_SPECIFY_OKAY;
+		return rs->sr_err;
+	}
+	return LDAP_SUCCESS;	/* proceed with operation */
+}
+
 #endif /* LDAP_X_TXN */