From 1a66f5f232d6c2869ef4e439eafe5a820f61a976 Mon Sep 17 00:00:00 2001
From: Thierry Bordaz <tbordaz@redhat.com>
Date: Wed, 15 Feb 2017 11:31:27 +0100
Subject: [PATCH] Ticket 49076 - To debug DB_DEADLOCK condition, allow to reset
DB_TXN_NOWAIT flag on txn_begin
Bug Description:
For debug reason it is interesting to have a new configuration ldbm backend config
option (nsslapd-db-transaction-wait) that allows to hang on deadlock
rather to let the server handling retries.
Fix Description:
The fix introduce a new attribute nsslapd-db-transaction-wait under
"cn=config,cn=ldbm database,cn=plugins,cn=config".
By default it is "off" (ldbm returns DB_DEADLOCK) and can be changed
online.
It is taken into account when a new transcation begin.
https://pagure.io/389-ds-base/issue/49076
Reviewed by: William Brown, Ludwig Krispenz
Platforms tested: F23
Flag Day: no
Doc impact: no
---
dirsrvtests/tests/tickets/ticket49076_test.py | 103 ++++++++++++++++++++++++++
ldap/servers/slapd/back-ldbm/dblayer.c | 9 ++-
ldap/servers/slapd/back-ldbm/dblayer.h | 3 +
ldap/servers/slapd/back-ldbm/ldbm_config.c | 22 ++++++
ldap/servers/slapd/back-ldbm/ldbm_config.h | 1 +
5 files changed, 137 insertions(+), 1 deletion(-)
create mode 100644 dirsrvtests/tests/tickets/ticket49076_test.py
diff --git a/dirsrvtests/tests/tickets/ticket49076_test.py b/dirsrvtests/tests/tickets/ticket49076_test.py
new file mode 100644
index 0000000..c4a2c1b
--- /dev/null
+++ b/dirsrvtests/tests/tickets/ticket49076_test.py
@@ -0,0 +1,103 @@
+import time
+import ldap
+import logging
+import pytest
+from lib389 import DirSrv, Entry, tools, tasks
+from lib389.tools import DirSrvTools
+from lib389._constants import *
+from lib389.properties import *
+from lib389.tasks import *
+from lib389.utils import *
+from lib389.topologies import topology_st as topo
+
+DEBUGGING = os.getenv("DEBUGGING", default=False)
+if DEBUGGING:
+ logging.getLogger(__name__).setLevel(logging.DEBUG)
+else:
+ logging.getLogger(__name__).setLevel(logging.INFO)
+log = logging.getLogger(__name__)
+
+ldbm_config = "cn=config,%s" % (DN_LDBM)
+txn_begin_flag = "nsslapd-db-transaction-wait"
+TEST_USER_DN = 'cn=test,%s' % SUFFIX
+TEST_USER = "test"
+
+def _check_configured_value(topology_st, attr=txn_begin_flag, expected_value=None, required=False):
+ entries = topology_st.standalone.search_s(ldbm_config, ldap.SCOPE_BASE, 'cn=config')
+ if required:
+ assert (entries[0].hasValue(attr))
+ if entries[0].hasValue(attr):
+ topology_st.standalone.log.info('Current value is %s' % entries[0].getValue(attr))
+ assert (entries[0].getValue(attr) == expected_value)
+
+def _update_db(topology_st):
+ topology_st.standalone.add_s(
+ Entry((TEST_USER_DN, {'objectclass': "top person organizationalPerson inetOrgPerson".split(),
+ 'cn': TEST_USER,
+ 'sn': TEST_USER,
+ 'givenname': TEST_USER})))
+ topology_st.standalone.delete_s(TEST_USER_DN)
+
+def test_ticket49076(topo):
+ """Write your testcase here...
+
+ Also, if you need any testcase initialization,
+ please, write additional fixture for that(include finalizer).
+ """
+
+ # check default value is DB_TXN_NOWAIT
+ _check_configured_value(topo, expected_value="off")
+
+ # tests we are able to update DB
+ _update_db(topo)
+
+ # switch to wait mode
+ topo.standalone.modify_s(ldbm_config,
+ [(ldap.MOD_REPLACE, txn_begin_flag, "on")])
+ # check default value is DB_TXN_NOWAIT
+ _check_configured_value(topo, expected_value="on")
+ _update_db(topo)
+
+
+ # switch back to "normal mode"
+ topo.standalone.modify_s(ldbm_config,
+ [(ldap.MOD_REPLACE, txn_begin_flag, "off")])
+ # check default value is DB_TXN_NOWAIT
+ _check_configured_value(topo, expected_value="off")
+ # tests we are able to update DB
+ _update_db(topo)
+
+ # check that settings are not reset by restart
+ topo.standalone.modify_s(ldbm_config,
+ [(ldap.MOD_REPLACE, txn_begin_flag, "on")])
+ # check default value is DB_TXN_NOWAIT
+ _check_configured_value(topo, expected_value="on")
+ _update_db(topo)
+ topo.standalone.restart(timeout=10)
+ _check_configured_value(topo, expected_value="on")
+ _update_db(topo)
+
+ # switch default value
+ topo.standalone.modify_s(ldbm_config,
+ [(ldap.MOD_DELETE, txn_begin_flag, None)])
+ # check default value is DB_TXN_NOWAIT
+ _check_configured_value(topo, expected_value="off")
+ # tests we are able to update DB
+ _update_db(topo)
+ topo.standalone.restart(timeout=10)
+ _check_configured_value(topo, expected_value="off")
+ # tests we are able to update DB
+ _update_db(topo)
+
+
+ if DEBUGGING:
+ # Add debugging steps(if any)...
+ pass
+
+
+if __name__ == '__main__':
+ # Run isolated
+ # -s for DEBUG mode
+ CURRENT_FILE = os.path.realpath(__file__)
+ pytest.main("-s %s" % CURRENT_FILE)
+
diff --git a/ldap/servers/slapd/back-ldbm/dblayer.c b/ldap/servers/slapd/back-ldbm/dblayer.c
index 683994f..507a3cc 100644
--- a/ldap/servers/slapd/back-ldbm/dblayer.c
+++ b/ldap/servers/slapd/back-ldbm/dblayer.c
@@ -3374,6 +3374,8 @@ dblayer_txn_begin_ext(struct ldbminfo *li, back_txnid parent_txn, back_txn *txn,
if (priv->dblayer_enable_transactions)
{
+ int txn_begin_flags;
+
dblayer_private_env *pEnv = priv->dblayer_env;
if(use_lock) slapi_rwlock_rdlock(pEnv->dblayer_env_lock);
if (!parent_txn)
@@ -3383,11 +3385,16 @@ dblayer_txn_begin_ext(struct ldbminfo *li, back_txnid parent_txn, back_txn *txn,
if (par_txn_txn) {
parent_txn = par_txn_txn->back_txn_txn;
}
+ }
+ if (priv->dblayer_txn_wait) {
+ txn_begin_flags = 0;
+ } else {
+ txn_begin_flags = DB_TXN_NOWAIT;
}
return_value = TXN_BEGIN(pEnv->dblayer_DB_ENV,
(DB_TXN*)parent_txn,
&new_txn.back_txn_txn,
- DB_TXN_NOWAIT);
+ txn_begin_flags);
if (0 != return_value)
{
if(use_lock) slapi_rwlock_unlock(priv->dblayer_env->dblayer_env_lock);
diff --git a/ldap/servers/slapd/back-ldbm/dblayer.h b/ldap/servers/slapd/back-ldbm/dblayer.h
index e02e6e0..e4307fc 100644
--- a/ldap/servers/slapd/back-ldbm/dblayer.h
+++ b/ldap/servers/slapd/back-ldbm/dblayer.h
@@ -104,6 +104,9 @@ struct dblayer_private
* the mpool */
int dblayer_recovery_required;
int dblayer_enable_transactions;
+ int dblayer_txn_wait; /* Default is "off" (DB_TXN_NOWAIT) but for
+ * support purpose it could be helpful to set
+ * "on" so that backend hang on deadlock */
int dblayer_durable_transactions;
int dblayer_checkpoint_interval;
int dblayer_circular_logging;
diff --git a/ldap/servers/slapd/back-ldbm/ldbm_config.c b/ldap/servers/slapd/back-ldbm/ldbm_config.c
index 8541224..dfe7a13 100644
--- a/ldap/servers/slapd/back-ldbm/ldbm_config.c
+++ b/ldap/servers/slapd/back-ldbm/ldbm_config.c
@@ -636,6 +636,27 @@ static int ldbm_config_db_transaction_logging_set(void *arg, void *value, char *
return retval;
}
+
+static void *ldbm_config_db_transaction_wait_get(void *arg)
+{
+ struct ldbminfo *li = (struct ldbminfo *) arg;
+
+ return (void *) ((uintptr_t)li->li_dblayer_private->dblayer_txn_wait);
+}
+
+static int ldbm_config_db_transaction_wait_set(void *arg, void *value, char *errorbuf, int phase, int apply)
+{
+ struct ldbminfo *li = (struct ldbminfo *) arg;
+ int retval = LDAP_SUCCESS;
+ int val = (int) ((uintptr_t)value);
+
+ if (apply) {
+ li->li_dblayer_private->dblayer_txn_wait = val;
+ }
+
+ return retval;
+}
+
static void *ldbm_config_db_logbuf_size_get(void *arg)
{
struct ldbminfo *li = (struct ldbminfo *) arg;
@@ -1517,6 +1538,7 @@ static config_info ldbm_config[] = {
{CONFIG_DB_DURABLE_TRANSACTIONS, CONFIG_TYPE_ONOFF, "on", &ldbm_config_db_durable_transactions_get, &ldbm_config_db_durable_transactions_set, CONFIG_FLAG_ALWAYS_SHOW},
{CONFIG_DB_CIRCULAR_LOGGING, CONFIG_TYPE_ONOFF, "on", &ldbm_config_db_circular_logging_get, &ldbm_config_db_circular_logging_set, 0},
{CONFIG_DB_TRANSACTION_LOGGING, CONFIG_TYPE_ONOFF, "on", &ldbm_config_db_transaction_logging_get, &ldbm_config_db_transaction_logging_set, 0},
+ {CONFIG_DB_TRANSACTION_WAIT, CONFIG_TYPE_ONOFF, "off", &ldbm_config_db_transaction_wait_get, &ldbm_config_db_transaction_wait_set, CONFIG_FLAG_ALWAYS_SHOW|CONFIG_FLAG_ALLOW_RUNNING_CHANGE},
{CONFIG_DB_CHECKPOINT_INTERVAL, CONFIG_TYPE_INT, "60", &ldbm_config_db_checkpoint_interval_get, &ldbm_config_db_checkpoint_interval_set, CONFIG_FLAG_ALWAYS_SHOW|CONFIG_FLAG_ALLOW_RUNNING_CHANGE},
{CONFIG_DB_COMPACTDB_INTERVAL, CONFIG_TYPE_INT, "2592000"/*30days*/, &ldbm_config_db_compactdb_interval_get, &ldbm_config_db_compactdb_interval_set, CONFIG_FLAG_ALWAYS_SHOW|CONFIG_FLAG_ALLOW_RUNNING_CHANGE},
{CONFIG_DB_TRANSACTION_BATCH, CONFIG_TYPE_INT, "0", &dblayer_get_batch_transactions, &dblayer_set_batch_transactions, CONFIG_FLAG_ALWAYS_SHOW|CONFIG_FLAG_ALLOW_RUNNING_CHANGE},
diff --git a/ldap/servers/slapd/back-ldbm/ldbm_config.h b/ldap/servers/slapd/back-ldbm/ldbm_config.h
index f481937..ddec3a8 100644
--- a/ldap/servers/slapd/back-ldbm/ldbm_config.h
+++ b/ldap/servers/slapd/back-ldbm/ldbm_config.h
@@ -80,6 +80,7 @@ struct config_info {
#define CONFIG_DB_DURABLE_TRANSACTIONS "nsslapd-db-durable-transaction"
#define CONFIG_DB_CIRCULAR_LOGGING "nsslapd-db-circular-logging"
#define CONFIG_DB_TRANSACTION_LOGGING "nsslapd-db-transaction-logging"
+#define CONFIG_DB_TRANSACTION_WAIT "nsslapd-db-transaction-wait"
#define CONFIG_DB_CHECKPOINT_INTERVAL "nsslapd-db-checkpoint-interval"
#define CONFIG_DB_COMPACTDB_INTERVAL "nsslapd-db-compactdb-interval"
#define CONFIG_DB_TRANSACTION_BATCH "nsslapd-db-transaction-batch-val"
--
2.9.3