#include <DbXml.hpp> XmlTransaction XmlManager::createTransaction(DB_TXN *toAdopt) XmlTransaction XmlManager::createTransaction(u_int32_t flags = 0)
The XmlManager::createTransaction
method
method creates a new
XmlTransaction
object. If a DB_TXN
object
is not provided to this method, then a new transaction is begun (a
DB_TXN
object is instantiated and DbEnv::txn_begin
is called).
If transactions were not initialized when this
XmlManager
object was opened (that is,
DB_INIT_TXN was not specified) then this method throws an exception.
If a DB_TXN
handle is passed to this method, the new
XmlTransaction
is simply another reference for the DB_TXN
handle. In this case, if the
XmlTransaction
object is destroyed
or goes out of scope before XmlTransaction::commit or
XmlTransaction::abort are called, the state of the underlying
transaction is left unchanged. This allows a transaction to be
controlled external to its
XmlTransaction
object. If no DB_TXN
is passed, and the
XmlTransaction
object is destroyed or goes out
of scope, the transaction is implicitly aborted.
This parameter must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values:
DB_READ_COMMITTED
This operation will have degree 2 isolation. This provides for cursor stability but not repeatable reads. Data items which have been previously read by this transaction may be deleted or modified by other transactions before this transaction completes.
DB_READ_UNCOMMITTED
This operation will support degree 1 isolation; that is,
read operations may return data that has been modified
by other transactions but which has not yet been
committed. Silently ignored if the DB_READ_UNCOMMITTED
flag was not specified when the underlying container was
opened.
DB_TXN_NOSYNC
Do not synchronously flush the log when this transaction commits or prepares. This means the transaction will exhibit the ACI (atomic, consistent, and isolated) properties, but not D (durable); that is, database integrity will be maintained but it is possible that this transaction may be undone during recovery.
This behavior may be set for a Berkeley DB environment
using the DbEnv::set_flags()
method. Any value
specified to this method overrides that setting.
DBXML_IGNORE_LEASE
This flag is relevant only when using a replicated environment.
Perform transactional operations irrespective of the state of master leases. The transactional operations will perform under all conditions: if master leases are not configured, if the request is made to a client, if the request is made to a master with a valid lease, or if the request is made to a master without a valid lease.
Refer to Master Leases in the Berkeley DB Programmer's Reference Guide for more information.
DB_TXN_NOWAIT
If a lock is unavailable for any Berkeley DB operation
performed in the context of this transaction, cause the
operation to return DB_LOCK_DEADLOCK
or throw an
XmlException
with DB error code DB_LOCK_DEADLOCK
immediately instead of blocking on the lock.
DB_TXN_SNAPSHOT
This transaction will execute with snapshot isolation.
For containers with the DB_MULTIVERSION
flag set, data
values will be read as they are when the transaction
begins, without taking read locks. Silently ignored for
operations on databases with DB_MULTIVERSION
not set on
the underlying container (read locks are acquired).
The DB_LOCK_DEADLOCK
error is returned from update
operations if a snapshot transaction attempts to update
data which was modified after the snapshot transaction
read it.
DB_TXN_SYNC
Synchronously flush the log when this transaction commits or prepares. This means the transaction will exhibit all of the ACID (atomic, consistent, isolated, and durable) properties.
This behavior is the default for Berkeley DB
environments unless the DB_TXN_NOSYNC
flag was
specified to the DbEnv::set_flags()
method. Any
value specified to this method overrides that setting.
DBXML_IGNORE_LEASE
This flag is relevant only when using a replicated environment.
Perform transactional operations irrespective of the state of master leases. The transactional operations will perform under all conditions: if master leases are not configured, if the request is made to a client, if the request is made to a master with a valid lease, or if the request was made to a master without a valid lease.
For information on master leases, see Master Leases in the Berkeley DB Programmer's Reference Guide.
The XmlManager::createTransaction
method may
fail and throw
XmlException
, encapsulating one of the following
non-zero errors: