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com.tangosol.coherence.transaction
Class Isolation

java.lang.Object
java.lang.Enum
com.tangosol.coherence.transaction.Isolation

All Implemented Interfaces:

java.io.Serializable, java.lang.Comparable

public class Isolation

extends java.lang.Enum

Coherence transaction isolation levels.

Since:

Coherence 3.6

Author:

js 2009.02.01

Field Summary

static Isolation	READ_COMMITTED Read Committed isolation.
static Isolation	STMT_CONSISTENT_READ Statement Consistent Read isolation.
static Isolation	STMT_MONOTONIC_CONSISTENT_READ Statement Monotonic Consistent Read isolation.
static Isolation	TX_CONSISTENT_READ Transaction Consistent Read isolation.
static Isolation	TX_MONOTONIC_CONSISTENT_READ Transaction Monotonic Consistent Read isolation.

Method Summary

abstract boolean	isConsistent() Returns whether the isolation level guaranteed consistent reads.
abstract boolean	isMonotonic() Returns whether the isolation level guarantees monotonic reads.
java.lang.String	toString() Return a human-readable description for this Isolation.
static Isolation	valueOf(java.lang.String name)
static Isolation[]	values()

Methods inherited from class java.lang.Enum

clone, compareTo, equals, getDeclaringClass, hashCode, name, ordinal, valueOf

Field Detail

READ_COMMITTED

public static final Isolation READ_COMMITTED

Read Committed isolation.

This is the default isolation level if no level is specified. This isolation level guarantees that only committed data is visible and doesn't provide any consistency guarantees. Reads are guaranteed to be monotonic. All writes acquire a write lock and reads do not acquire any lock. Any attempt to write to a locked entry will result in an exception; the request will not block. This is the weakest of the isolation levels and will generally be the most performant at the cost of read consistency.

STMT_CONSISTENT_READ

public static final Isolation STMT_CONSISTENT_READ

Statement Consistent Read isolation.

Provides statement scoped read consistency. This isolation level guarantees that all the data read by a single operation comes from a single point in time; the time that the statement began execution. Reads are not guaranteed to be monotonic. All writes acquire a write lock and reads do not acquire any lock. Any attempt to write to a locked entry will result in an exception; the request will not block.

TX_CONSISTENT_READ

public static final Isolation TX_CONSISTENT_READ

Transaction Consistent Read isolation.

Provides transaction scoped read consistency. This isolation level guarantees that all the data read in a transaction comes from a single point in time; the time that the transaction began. Reads are not guaranteed to be monotonic. All writes acquire a write lock and reads do not acquire any lock. Any attempt to write to a locked entry will result in an exception; the request will not block.

Read operations with this isolation level may produce a VersionNotAvailableException if attempting to read a historical version of the data that is no longer available in storage.

STMT_MONOTONIC_CONSISTENT_READ

public static final Isolation STMT_MONOTONIC_CONSISTENT_READ

Statement Monotonic Consistent Read isolation.

Provides statement scoped read consistency and monotonic reads. This isolation level guarantees that all data read by a single operation comes from a single point in time; the time that the statement began execution. Reads are guaranteed to be monotonic. This means that a read is guaranteed to return a version that is equal to or greater than any version that was previously encountered while using the connection. Due to the monotinic read guarantee, reads with this isolation may block until the necessary versions are available. All writes acquire a write lock and reads do not acquire any lock. Any attempt to write to a locked entry will result in an exception; the request will not block waiting for a write lock.

TX_MONOTONIC_CONSISTENT_READ

public static final Isolation TX_MONOTONIC_CONSISTENT_READ

Transaction Monotonic Consistent Read isolation.

Provides transaction scoped read consistency and monotonic reads. This isolation level guarantees that all data read by a single operation comes from a single point in time; the time that the transaction began. Reads are guaranteed to be monotonic. This means that a read is guaranteed to return a version that is equal to or greater than any version that was previously encountered while using the connection. Due to the monotinic read guarantee, the initial read in a transaction with this isolation may block until the necessary versions are available. All writes acquire a write lock and reads do not acquire any lock. Any attempt to write to a locked entry will result in an exception; the request will not block waiting for a write lock.

Read operations with this isolation level may produce a VersionNotAvailableException if attempting to read a historical version of the data that is no longer available in storage.

Method Detail

values

public static Isolation[] values()

valueOf

public static Isolation valueOf(java.lang.String name)

isConsistent

public abstract boolean isConsistent()

Returns whether the isolation level guaranteed consistent reads.

Returns:

true if consistent reads are guaranteed, false otherwise

isMonotonic

public abstract boolean isMonotonic()

Returns whether the isolation level guarantees monotonic reads.

Returns:

true if monotonic reads are guaranteed, false otherwise

toString

public java.lang.String toString()

Return a human-readable description for this Isolation.

Overrides:

toString in class java.lang.Enum

Returns:

a String description of the Isolation

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