BTreeLockingPolicy
B2IRowLocking2
class B2IRowLockingRR extends B2IRowLocking3 implements BTreeLockingPolicy
base_cc, open_btree
Constructor | Description |
---|---|
B2IRowLockingRR(Transaction rawtran,
int lock_level,
LockingPolicy locking_policy,
ConglomerateController base_cc,
OpenBTree open_btree) |
Constructors for This class:
|
Modifier and Type | Method | Description |
---|---|---|
boolean |
lockScanRow(OpenBTree open_btree,
BTreeRowPosition pos,
FetchDescriptor lock_fetch_desc,
DataValueDescriptor[] lock_template,
RowLocation lock_row_loc,
boolean previous_key_lock,
boolean forUpdate,
int lock_operation) |
Lock a row as part of doing the scan.
|
void |
unlockScanRecordAfterRead(BTreeRowPosition pos,
boolean forUpdate) |
Unlock a record after it has been locked for read.
|
_lockScanRow, lockNonScanPreviousRow, lockNonScanRow, lockNonScanRowOnPage, lockScanCommittedDeletedRow
lockNonScanPreviousRow, lockNonScanRow, lockNonScanRowOnPage, lockScanCommittedDeletedRow
B2IRowLockingRR(Transaction rawtran, int lock_level, LockingPolicy locking_policy, ConglomerateController base_cc, OpenBTree open_btree)
public boolean lockScanRow(OpenBTree open_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 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.
lockScanRow
in interface BTreeLockingPolicy
lockScanRow
in class B2IRowLocking3
open_btree
- The open_btree to associate latches with -
used if routine has to scan backward.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]StandardException
- Standard exception policy.public void unlockScanRecordAfterRead(BTreeRowPosition pos, boolean forUpdate) throws StandardException
In repeatable read only unlock records which "did not qualify". For example in a query like "select * from foo where a = 1" on a table with no index it is only necessary to hold locks on rows where a=1, but in the process of finding those rows the system will get locks on other rows to verify they are committed before applying the qualifier. Those locks can be released under repeatable read isolation.
if it is forUpdate then get S lock and release U lock, else there is nothing to do in serializable - we keep the S locks until end of transaction.
unlockScanRecordAfterRead
in interface BTreeLockingPolicy
unlockScanRecordAfterRead
in class B2IRowLocking3
forUpdate
- Is the scan for update or for read only.pos
- Data structure that defines the current position
in the scan to be unlocked.StandardException
- Standard exception policy.Apache Derby V10.14 Internals - Copyright © 2004,2018 The Apache Software Foundation. All Rights Reserved.