package org.apache.lucene.index;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.IndexOutput;
/**
* Byte[] referencing is used because a new norm object needs
* to be created for each clone, and the byte array is all
* that is needed for sharing between cloned readers. The
* current norm referencing is for sharing between readers
* whereas the byte[] referencing is for copy on write which
* is independent of reader references (i.e. incRef, decRef).
*/
final class SegmentNorms implements Cloneable {
/** norms header placeholder */
static final byte[] NORMS_HEADER = new byte[]{'N','R','M',-1};
int refCount = 1;
// If this instance is a clone, the originalNorm
// references the Norm that has a real open IndexInput:
private SegmentNorms origNorm;
private IndexInput in;
private long normSeek;
// null until bytes is set
private AtomicInteger bytesRef;
private byte[] bytes;
private int number;
boolean dirty;
boolean rollbackDirty;
private final SegmentReader owner;
public SegmentNorms(IndexInput in, int number, long normSeek, SegmentReader owner) {
this.in = in;
this.number = number;
this.normSeek = normSeek;
this.owner = owner;
}
public synchronized void incRef() {
assert refCount > 0 && (origNorm == null || origNorm.refCount > 0);
refCount++;
}
private void closeInput() throws IOException {
if (in != null) {
if (in != owner.singleNormStream) {
// It's private to us -- just close it
in.close();
} else {
// We are sharing this with others -- decRef and
// maybe close the shared norm stream
if (owner.singleNormRef.decrementAndGet() == 0) {
owner.singleNormStream.close();
owner.singleNormStream = null;
}
}
in = null;
}
}
public synchronized void decRef() throws IOException {
assert refCount > 0 && (origNorm == null || origNorm.refCount > 0);
if (--refCount == 0) {
if (origNorm != null) {
origNorm.decRef();
origNorm = null;
} else {
closeInput();
}
if (bytes != null) {
assert bytesRef != null;
bytesRef.decrementAndGet();
bytes = null;
bytesRef = null;
} else {
assert bytesRef == null;
}
}
}
// Load bytes but do not cache them if they were not
// already cached
public synchronized void bytes(byte[] bytesOut, int offset, int len) throws IOException {
assert refCount > 0 && (origNorm == null || origNorm.refCount > 0);
if (bytes != null) {
// Already cached -- copy from cache:
assert len <= owner.maxDoc();
System.arraycopy(bytes, 0, bytesOut, offset, len);
} else {
// Not cached
if (origNorm != null) {
// Ask origNorm to load
origNorm.bytes(bytesOut, offset, len);
} else {
// We are orig -- read ourselves from disk:
synchronized(in) {
in.seek(normSeek);
in.readBytes(bytesOut, offset, len, false);
}
}
}
}
// Load & cache full bytes array. Returns bytes.
public synchronized byte[] bytes() throws IOException {
assert refCount > 0 && (origNorm == null || origNorm.refCount > 0);
if (bytes == null) { // value not yet read
assert bytesRef == null;
if (origNorm != null) {
// Ask origNorm to load so that for a series of
// reopened readers we share a single read-only
// byte[]
bytes = origNorm.bytes();
bytesRef = origNorm.bytesRef;
bytesRef.incrementAndGet();
// Once we've loaded the bytes we no longer need
// origNorm:
origNorm.decRef();
origNorm = null;
} else {
// We are the origNorm, so load the bytes for real
// ourself:
final int count = owner.maxDoc();
bytes = new byte[count];
// Since we are orig, in must not be null
assert in != null;
// Read from disk.
synchronized(in) {
in.seek(normSeek);
in.readBytes(bytes, 0, count, false);
}
bytesRef = new AtomicInteger(1);
closeInput();
}
}
return bytes;
}
// Only for testing
AtomicInteger bytesRef() {
return bytesRef;
}
// Called if we intend to change a norm value. We make a
// private copy of bytes if it's shared with others:
public synchronized byte[] copyOnWrite() throws IOException {
assert refCount > 0 && (origNorm == null || origNorm.refCount > 0);
bytes();
assert bytes != null;
assert bytesRef != null;
if (bytesRef.get() > 1) {
// I cannot be the origNorm for another norm
// instance if I'm being changed. Ie, only the
// "head Norm" can be changed:
assert refCount == 1;
final AtomicInteger oldRef = bytesRef;
bytes = owner.cloneNormBytes(bytes);
bytesRef = new AtomicInteger(1);
oldRef.decrementAndGet();
}
dirty = true;
return bytes;
}
// Returns a copy of this Norm instance that shares
// IndexInput & bytes with the original one
@Override
public synchronized Object clone() {
assert refCount > 0 && (origNorm == null || origNorm.refCount > 0);
SegmentNorms clone;
try {
clone = (SegmentNorms) super.clone();
} catch (CloneNotSupportedException cnse) {
// Cannot happen
throw new RuntimeException("unexpected CloneNotSupportedException", cnse);
}
clone.refCount = 1;
if (bytes != null) {
assert bytesRef != null;
assert origNorm == null;
// Clone holds a reference to my bytes:
clone.bytesRef.incrementAndGet();
} else {
assert bytesRef == null;
if (origNorm == null) {
// I become the origNorm for the clone:
clone.origNorm = this;
}
clone.origNorm.incRef();
}
// Only the origNorm will actually readBytes from in:
clone.in = null;
return clone;
}
// Flush all pending changes to the next generation
// separate norms file.
public void reWrite(SegmentInfo si) throws IOException {
assert refCount > 0 && (origNorm == null || origNorm.refCount > 0): "refCount=" + refCount + " origNorm=" + origNorm;
// NOTE: norms are re-written in regular directory, not cfs
si.advanceNormGen(this.number);
final String normFileName = si.getNormFileName(this.number);
IndexOutput out = owner.directory().createOutput(normFileName);
boolean success = false;
try {
try {
out.writeBytes(SegmentNorms.NORMS_HEADER, 0, SegmentNorms.NORMS_HEADER.length);
out.writeBytes(bytes, owner.maxDoc());
} finally {
out.close();
}
success = true;
} finally {
if (!success) {
try {
owner.directory().deleteFile(normFileName);
} catch (Throwable t) {
// suppress this so we keep throwing the
// original exception
}
}
}
this.dirty = false;
}
}