90 lines
1.7 KiB
Java
90 lines
1.7 KiB
Java
package org.warp.jcwdb;
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import java.io.IOException;
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/**
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* You must have only a maximum of 1 reference for each index
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* @param <T>
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*/
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public class EntryReference<T> implements Castable, AutoCloseable {
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private final JCWDatabase db;
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private final long entryIndex;
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private final DBTypeParser<T> parser;
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public T value;
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private volatile boolean closed;
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private final Object closeLock = new Object();
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public EntryReference(JCWDatabase db, long entryId, DBTypeParser<T> parser) throws IOException {
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this.db = db;
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this.entryIndex = entryId;
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this.parser = parser;
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this.value = db.getIndexManager().get(entryId, parser.getReader());
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}
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public EntryReference(JCWDatabase db, long entryId, DBTypeParser<T> parser, T value) {
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this.db = db;
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this.entryIndex = entryId;
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this.parser = parser;
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this.value = value;
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}
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public DBTypeParser<T> getParser() {
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return parser;
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}
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public long getIndex() {
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return entryIndex;
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}
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public long calculateHash() {
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return parser.calculateHash(value);
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}
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/**
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* Note that this method won't be called when closing without saving
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* @throws IOException
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*/
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public void save() throws IOException {
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if (!closed) {
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db.getIndexManager().set(entryIndex, parser.getWriter(value));
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}
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}
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@Override
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public <T> T cast() {
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return (T) this;
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}
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@Override
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public void close() throws IOException {
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if (closed) {
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return;
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}
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synchronized (closeLock) {
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if (closed) {
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return;
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}
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save();
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db.removeEntryReference(entryIndex);
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closed = true;
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}
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}
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public void closeWithoutSaving() {
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if (closed) {
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return;
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}
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synchronized (closeLock) {
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if (closed) {
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return;
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}
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db.removeEntryReference(entryIndex);
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closed = true;
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}
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}
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}
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