Package com.sleepycat.db

Class LockMode

java.lang.Object

com.sleepycat.db.LockMode

public final class LockMode
extends java.lang.Object

Locking modes for database operations. Locking modes are required parameters for operations that retrieve data or modify the database.

Field Summary

Fields

Modifier and Type	Field	Description
static LockMode	DEFAULT	Acquire read locks for read operations and write locks for write operations.
static LockMode	DEGREE_2	Deprecated. This has been replaced by READ_COMMITTED to conform to ANSI database isolation terminology.
static LockMode	DIRTY_READ	Deprecated. This has been replaced by READ_UNCOMMITTED to conform to ANSI database isolation terminology.
static LockMode	IGNORE_LEASES	Return the data item irrespective of the state of master leases.
static LockMode	READ_COMMITTED	Read committed isolation provides for cursor stability but not repeatable reads.
static LockMode	READ_UNCOMMITTED	Read modified but not yet committed data.
static LockMode	RMW	Acquire write locks instead of read locks when doing the retrieval.

Method Summary

Modifier and Type	Method	Description
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT

public static final LockMode DEFAULT

Acquire read locks for read operations and write locks for write operations.

READ_UNCOMMITTED

public static final LockMode READ_UNCOMMITTED

Read modified but not yet committed data.

READ_COMMITTED

public static final LockMode READ_COMMITTED

Read committed isolation 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 the cursor is closed or the transaction completes.

Note that this LockMode may only be passed to Database get methods, not to Cursor methods. To configure a cursor for Read committed isolation, use CursorConfig.setReadCommitted(boolean).

RMW

public static final LockMode RMW

Acquire write locks instead of read locks when doing the retrieval. Setting this flag can eliminate deadlock during a read-modify-write cycle by acquiring the write lock during the read part of the cycle so that another thread of control acquiring a read lock for the same item, in its own read-modify-write cycle, will not result in deadlock.

DIRTY_READ

@Deprecated
public static final LockMode DIRTY_READ

Deprecated.

This has been replaced by READ_UNCOMMITTED to conform to ANSI database isolation terminology.

Read modified but not yet committed data.

DEGREE_2

@Deprecated
public static final LockMode DEGREE_2

Deprecated.

This has been replaced by READ_COMMITTED to conform to ANSI database isolation terminology.

Read committed isolation 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 the cursor is closed or the transaction completes.

Note that this LockMode may only be passed to Database get methods, not to Cursor methods. To configure a cursor for Read committed isolation, use CursorConfig.setReadCommitted(boolean).

IGNORE_LEASES

public static final LockMode IGNORE_LEASES

Return the data item irrespective of the state of master leases. The item will be returned 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.

Method Detail

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object