com.goldencode.p2j.persist.orm

Class UniqueTracker.UniqueIndex.Key

java.lang.Object

com.goldencode.p2j.persist.orm.UniqueTracker.UniqueIndex.Key

Enclosing class:

UniqueTracker.UniqueIndex

private class UniqueTracker.UniqueIndex.Key
extends java.lang.Object

The key used for tracking a record within an unique index.

Field Summary

Fields

Modifier and Type	Field and Description
private int[]	fieldPos The fields that the unique index is compounded of.
private int	hash The pre-computed hash code
private boolean	hasNulls Flags whether the record has null values for fields components of this unique index.
private java.lang.Object[]	snapshot The snapshot of the record at the moment of indexing.

Constructor Summary

Constructors

Constructor and Description
Key(UniqueTracker.UniqueIndex uniqueIndex, java.lang.Object[] data) Creates a new, immutable Key object.

Method Summary

Modifier and Type	Method and Description
(package private) void	addToIndex(java.lang.Long id) Add this key to its enclosing UniqueIndex.
private int	computeHash() Computes the hash code for this unique key.
boolean	equals(java.lang.Object o) Test for equality with a specified object.
int	hashCode() Obtain the hash code for this unique key.
(package private) void	removeFromIndex() Remove this key from its enclosing UniqueIndex.
java.lang.String	toString() Composes and return a short description of this object which includes the values of the indexed fields.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

snapshot

private final java.lang.Object[] snapshot

The snapshot of the record at the moment of indexing.

fieldPos

private final int[] fieldPos

The fields that the unique index is compounded of. Having the offsets in an int array is faster than computing them bitwise from a BitSet.

hash

private final int hash

The pre-computed hash code

hasNulls

private boolean hasNulls

Flags whether the record has null values for fields components of this unique index. In this case the record is unique.

Constructor Detail

Key

public Key(UniqueTracker.UniqueIndex uniqueIndex,
           java.lang.Object[] data)

Creates a new, immutable Key object. For performance reasons, the hash code will be computed only once and the hasNulls will also be evaluated.

Parameters:

uniqueIndex - The components of the index, by their position in data array.

data - The values of the fields in the record (a reference will be saved, not copied).

Method Detail

equals

public boolean equals(java.lang.Object o)

Test for equality with a specified object. The test is done using the 4GL uniqueness semantics: two records are unique from the point of view of an unique index if the compound fields (their index in data array is specified in the fieldPos) must be different except when one of them is null, in which case the records are unique.

Overrides:

equals in class java.lang.Object

Parameters:

o - The object to be tested against.

Returns:

true if and only if the two keys are equals from the point of view of the 4GL uniqueness semantics.

toString

public java.lang.String toString()

Composes and return a short description of this object which includes the values of the indexed fields.

Overrides:

toString in class java.lang.Object

Returns:

a short description of this object.

hashCode

public int hashCode()

Obtain the hash code for this unique key.

Overrides:

hashCode in class java.lang.Object

Returns:

the hash code for this unique key.

addToIndex

void addToIndex(java.lang.Long id)

Add this key to its enclosing UniqueIndex. The index is locked before the operation and released after.

Parameters:

id - Primary key to associate with this key.

removeFromIndex

void removeFromIndex()

Remove this key from its enclosing UniqueIndex. The index is locked before the operation and released after.

computeHash

private int computeHash()

Computes the hash code for this unique key. Only the compound fields of the current index from the record are taken into consideration, the other are ignored.

Returns:

the hash code for this unique key.