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java.lang.Objectorg.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
A locking policy that implements row level locking with isolation degree 2. The approach is to place all "write" container and row locks on the transaction group lock list. Locks on this group will last until end of transaction. All "read" container and row locks will be placed on a group list, key'd by the ContainerId of the lock. Locks on this list will either be released explicitly by the caller, or will be released as a group when the unlockContainer() call is made. Note that write operations extend from the RowLocking3 implementations.
LockingPolicy
Field Summary | |
private static LockingPolicy |
NO_LOCK
|
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 |
Constructor Summary | |
protected |
RowLocking2(LockFactory lf)
|
Method Summary | |
boolean |
lockContainer(Transaction t,
ContainerHandle container,
boolean waitForLock,
boolean forUpdate)
Obtain container level intent lock. |
void |
lockRecordForRead(Latch latch,
RecordHandle record,
boolean forUpdate)
Obtain lock on record being read while holding a latch. |
boolean |
lockRecordForRead(Transaction t,
ContainerHandle container_handle,
RecordHandle record,
boolean waitForLock,
boolean forUpdate)
Obtain lock on record being read. |
void |
unlockContainer(Transaction t,
ContainerHandle container_handle)
Unlock read locks. |
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.RowLockingRR |
getReadLockType, getUpdateLockType, getWriteLockType |
Methods inherited from class org.apache.derby.impl.store.raw.xact.RowLocking3 |
getMode, lockRecordForWrite, lockRecordForWrite, zeroDurationLockRecordForWrite |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
private static final LockingPolicy NO_LOCK
Constructor Detail |
protected RowLocking2(LockFactory lf)
Method Detail |
public boolean lockContainer(Transaction t, ContainerHandle container, boolean waitForLock, boolean forUpdate) throws StandardException
This implementation of row locking is 2 level, ie. table and row locking. It will interact correctly with tables opened with ContainerLocking3 locking mode.
Updater's will get table level IX locks, and X row locks.
Reader's will get table level IS locks, and S row locks.
Read locks are put in a separate "group" from the transaction, so that when the container is closed it can release these read locks.
lockContainer
in interface LockingPolicy
lockContainer
in class RowLocking3
t
- Transaction to associate lock with.container
- Container to lock.waitForLock
- Should lock request wait until granted?forUpdate
- Should container be locked for update, or read?
StandardException
- Standard exception policy.public boolean lockRecordForRead(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean waitForLock, boolean forUpdate) throws StandardException
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 placed on separate group from transaction.
lockRecordForRead
in interface LockingPolicy
lockRecordForRead
in class RowLocking3
t
- The transaction to associate the lock with.record
- The record to be locked.waitForLock
- Should lock request wait until granted?forUpdate
- Whether to open for read or write access.
StandardException
- Standard exception policy.public void lockRecordForRead(Latch latch, RecordHandle record, boolean forUpdate) throws StandardException
Assumes that a table level IS has been acquired. Will acquire a Shared or Update lock on the row, depending on the "forUpdate" parameter.
lockRecordForRead
in interface LockingPolicy
lockRecordForRead
in class RowLocking3
latch
- The latch being held.record
- The record to be locked.forUpdate
- Whether to open for read or write access.
StandardException
- Standard exception policy.public void unlockRecordAfterRead(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean forUpdate, boolean row_qualified) throws StandardException
RowLockingRR
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.
unlockRecordAfterRead
in interface LockingPolicy
unlockRecordAfterRead
in class RowLockingRR
StandardException
- Standard exception policy.public void unlockContainer(Transaction t, ContainerHandle container_handle)
In Cursor stability release all read locks obtained. unlockContainer() will be called when the container is closed.
unlockContainer
in interface LockingPolicy
unlockContainer
in class NoLocking
t
- The transaction to associate the lock with.
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