Class RowLocking2nohold
java.lang.Object
org.apache.derby.impl.store.raw.xact.NoLocking
org.apache.derby.impl.store.raw.xact.RowLocking3
org.apache.derby.impl.store.raw.xact.RowLockingRR
org.apache.derby.impl.store.raw.xact.RowLocking2
org.apache.derby.impl.store.raw.xact.RowLocking2nohold
- All Implemented Interfaces:
LockingPolicy
A locking policy that implements row level locking with isolation degree 2,
never holding read locks after they are granted.
Exactly the same as RowLocking2, except that read locks are acquired using
zeroDuration locks, which are immediately released by the lock manager
after they are granted.
- See Also:
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Field Summary
Fields inherited from class org.apache.derby.impl.store.raw.xact.RowLocking3
lf
Fields inherited from interface org.apache.derby.iapi.store.raw.LockingPolicy
MODE_CONTAINER, MODE_NONE, MODE_RECORD
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionboolean
lockRecordForRead
(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean waitForLock, boolean forUpdate) Obtain lock on record being read.void
unlockRecordAfterRead
(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean forUpdate, boolean row_qualified) Unlock a record after it has been locked for read.Methods inherited from class org.apache.derby.impl.store.raw.xact.RowLocking2
lockContainer, unlockContainer
Methods inherited from class org.apache.derby.impl.store.raw.xact.RowLockingRR
getReadLockType, getUpdateLockType, getWriteLockType
Methods inherited from class org.apache.derby.impl.store.raw.xact.RowLocking3
getMode, lockRecordForWrite, zeroDurationLockRecordForWrite
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Constructor Details
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RowLocking2nohold
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Method Details
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lockRecordForRead
public boolean lockRecordForRead(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean waitForLock, boolean forUpdate) throws StandardException Obtain lock on record being read.Assumes that a table level IS has been acquired. Will acquire a Shared or Update lock on the row, depending on the "forUpdate" parameter.
Read lock will be acquired using zeroDuration lock.
- Specified by:
lockRecordForRead
in interfaceLockingPolicy
- Overrides:
lockRecordForRead
in classRowLocking2
- Parameters:
t
- The transaction to associate the lock with.container_handle
- Open Container used to get record. Will be used to row locks by the container they belong to.record
- The record to be locked.waitForLock
- Should lock request wait until granted?forUpdate
- Whether to open for read or write access.- Returns:
- true if the lock was granted, false if waitForLock was false and the lock could not be granted.
- Throws:
StandardException
- Standard exception policy.- See Also:
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unlockRecordAfterRead
public void unlockRecordAfterRead(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean forUpdate, boolean row_qualified) Description copied from class:RowLockingRR
Unlock a record after it has been locked for read.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.
- Specified by:
unlockRecordAfterRead
in interfaceLockingPolicy
- Overrides:
unlockRecordAfterRead
in classRowLocking2
- See Also:
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