org.apache.derby.impl.store.access.btree.index
Class B2IRowLocking1
java.lang.Object
org.apache.derby.impl.store.access.btree.index.B2IRowLocking3
org.apache.derby.impl.store.access.btree.index.B2IRowLockingRR
org.apache.derby.impl.store.access.btree.index.B2IRowLocking2
org.apache.derby.impl.store.access.btree.index.B2IRowLocking1
- All Implemented Interfaces:
- BTreeLockingPolicy
class B2IRowLocking1
- extends B2IRowLocking2
- implements BTreeLockingPolicy
The btree locking policy which implements read uncommitted isolation level.
It inherits all functionality from B2IRowLocking2 except that it does not
get any read row locks (and thus does not release them). Note that table
level and table level intent locking remains the same as B2IRowLocking2 as
this is currently the way we prevent concurrent ddl from happening while a
read uncommitted scanner is operating in the btree.
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
B2IRowLocking1
B2IRowLocking1(Transaction rawtran,
int lock_level,
LockingPolicy locking_policy,
ConglomerateController base_cc,
OpenBTree open_btree)
- Constructors for This class:
lockScanRow
public boolean lockScanRow(OpenBTree open_btree,
BTree btree,
BTreeRowPosition pos,
FetchDescriptor lock_fetch_desc,
DataValueDescriptor[] lock_template,
RowLocation lock_row_loc,
boolean previous_key_lock,
boolean forUpdate,
int lock_operation)
throws StandardException
- Lock a row as part of doing the scan.
Lock the row at the given slot (or the previous row if slot is 0).
If this routine returns true all locks were acquired while maintaining
the latch on leaf. If this routine returns false, locks may or may
not have been acquired, and the routine should be called again after
the client has researched the tree to reget the latch on the
appropriate page.
- Specified by:
lockScanRow
in interface BTreeLockingPolicy
- Overrides:
lockScanRow
in class B2IRowLockingRR
- Parameters:
open_btree
- The open_btree to associate latches with -
used if routine has to scan backward.btree
- the conglomerate info.pos
- The position of the row to lock.lock_template
- A scratch area to use to read in rows.previous_key_lock
- Is this a previous key lock call?forUpdate
- Is the scan for update or for read only.lock_operation
- For what operation are we requesting the lock,
this should be one of the following 4 options:
LOCK_READ [read lock],
(LOCK_INS | LOCK_UPD) [ lock for insert],
(LOCK_INSERT_PREVKEY | LOCK_UPD) [lock for
previous key to insert],
(LOCK_UPD) [lock for delete or replace]
- Returns:
- Whether locks were acquired without releasing latch on leaf.
- Throws:
StandardException
- Standard exception policy.
unlockScanRecordAfterRead
public void unlockScanRecordAfterRead(BTreeRowPosition pos,
boolean forUpdate)
throws StandardException
- Release read lock on a row.
Because this is read uncommitted no S row locks will have been requested,
thus none need be released. The only locks that need to be released
are U locks requested if the scan was opened for update.
- Specified by:
unlockScanRecordAfterRead
in interface BTreeLockingPolicy
- Overrides:
unlockScanRecordAfterRead
in class B2IRowLocking2
- Parameters:
pos
- The position of the row to unlock.forUpdate
- Is the scan for update or for read only.
- Throws:
StandardException
- Standard exception policy.
Apache Derby V10.6 Internals - Copyright © 2004,2007 The Apache Software Foundation. All Rights Reserved.