IndexState.java
/*
** Module : IndexState.java
** Abstract : Tracks which indices have been updated for a transient, newly created record.
**
** Copyright (c) 2020-2024, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description---------------------------------------
** 001 ECF 20200820 First revision.
** 002 IAS 20200914 Re-work (de)serialization.
** ECF 20210924 Minor cleanup.
** 003 TJD 20240110 Implemented toString for easier debugging
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
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*/
package com.goldencode.p2j.persist.orm;
import java.io.*;
import java.util.*;
/**
* An object which tracks which indices have been updated for a newly created database record, before it is
* first flushed to the database.
*/
public final class IndexState
implements Externalizable
{
/** Map of unique indices which need to be updated */
private BitSet unique;
/** Map of non-unique indices which need to be updated */
private BitSet nonunique;
/** UID of primary index, if any (0 if none) */
private int primaryUid;
/** Default constructor */
public IndexState()
{
}
/**
* Constructor.
*
* @param ulen
* Number of unique indices. May be 0, but not negative.
* @param nlen
* Number of non-unique indices. May be 0, but not negative.
* @param primaryUid
* Optional UID of the primary index, if any. Must be set to 0 if there is no primary index.
*/
public IndexState(int ulen, int nlen, int primaryUid)
{
this.unique = new BitSet(ulen);
this.nonunique = new BitSet(nlen);
this.primaryUid = primaryUid;
}
/**
* Get the state of the index with the given index UID.
*
* @param idxUid
* UID of the desired index.
*
* @return {@code true} if the index has not yet been updated; {@code false} if it has been updated.
*/
public boolean get(int idxUid)
{
return bitSetFromUid(idxUid).get(offsetFromUid(idxUid));
}
/**
* Mark an index as needing to be updated.
*
* @param idxUid
* Identifier of a unique (positive value) or non-unique (negative value) index.
* @param value
* new value
*/
public void set(int idxUid, boolean value)
{
bitSetFromUid(idxUid).set(offsetFromUid(idxUid), value);
}
/**
* Mark an index as having been updated by clearing its corresponding bit in the appropriate bit set.
*
* @param idxUid
* Identifier of a unique (positive value) or non-unique (negative value) index.
*/
void clear(int idxUid)
{
bitSetFromUid(idxUid).clear(offsetFromUid(idxUid));
}
/**
* Indicate whether there are no indices remaining to be updated.
*
* @return {@code true} if there are no indices left to be updated, else {@code false}. {@code true}
* will naturally be reported for a table with no indices.
*/
public boolean isEmpty()
{
return unique.isEmpty() && nonunique.isEmpty();
}
/**
* Get the index identifier of the primary index, if any.
*
* @return Primary index UID.
*/
public boolean getPrimary()
{
return primaryUid != 0 && get(primaryUid);
}
/**
* Set all bits in both the unique and non-unique index bit sets.
*
* @param ulen
* Number of unique indices. May be 0, but not negative.
* @param nlen
* Number of non-unique indices. May be 0, but not negative.
*/
void setAll(int ulen, int nlen)
{
if (ulen > 0)
{
unique.set(0, ulen);
}
if (nlen > 0)
{
nonunique.set(0, nlen);
}
}
/**
* Clear all bits in both the unique and non-unique index bit sets.
*/
void clearAll()
{
unique.clear();
nonunique.clear();
}
/**
* Get the bit set associated with either the unique or non-unique indices.
*
* @param isUnique
* {@code true} to get the unique index bit set; {@code false} to get the non-unique index bit
* set.
*
* @return Index bit set as described above.
*/
BitSet getBitSet(boolean isUnique)
{
return isUnique ? unique : nonunique;
}
/**
* Get the bit set upon which to operate, based on the value of the given index UID. A positive UID
* returns the unique index bit set; a negative UID returns the non-unique index bit set.
*
* @param idxUid
* A positive or negative index UID. A value of 0 is considered invalid.
*
* @return The bit set representing the array of unique or non-unique indices, as described above.
*/
private BitSet bitSetFromUid(int idxUid)
{
return idxUid > 0 ? unique : nonunique;
}
/**
* Get the bit offset on which to operate, based on the value of the given index UID.
*
* @param idxUid
* A positive or negative index UID. A value of 0 is considered invalid.
*
* @return The bit offset associated with the UID.
*/
private int offsetFromUid(int idxUid)
{
return (idxUid < 0 ? -idxUid : idxUid) - 1;
}
/**
* Replacement for the default object writing method.
*
* @param out
* The output destination to which fields will be saved.
*
* @throws IOException
* In case of I/O errors.
*/
@Override
public void writeExternal(ObjectOutput out) throws IOException
{
out.writeObject(unique);
out.writeObject(nonunique);
out.writeInt(primaryUid);
}
/**
* Replacement for the default object reading method.
*
* @param in
* Input source from which fields will be restored.
*
* @throws IOException
* In case of I/O errors.
* @throws ClassNotFoundException
* If payload can't be instantiated.
*/
@Override
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
{
unique = (BitSet) in.readObject();
nonunique = (BitSet) in.readObject();
primaryUid = in.readInt();
}
/**
* Create a string representation of this IndexState for debugging purposes.
*
*/
@Override
public String toString()
{
return "IndexState [unique=" + unique + ", nonunique=" + nonunique + ", primaryUid="
+ primaryUid + ", isEmpty()=" + isEmpty() + ", getPrimary()=" + getPrimary() + "]";
}
}