net.jpountz.xxhash.StreamingXXHash32 Maven / Gradle / Ivy
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package net.jpountz.xxhash;
import java.util.zip.Checksum;
import java.io.Closeable;
/*
* Copyright 2020 Adrien Grand and the lz4-java contributors.
*
* Licensed 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.
*/
/**
* Streaming interface for {@link XXHash32}.
*
* This API is compatible with the {@link XXHash32 block API} and the following
* code samples are equivalent:
*
* int hash(XXHashFactory xxhashFactory, byte[] buf, int off, int len, int seed) {
* return xxhashFactory.hash32().hash(buf, off, len, seed);
* }
*
*
* int hash(XXHashFactory xxhashFactory, byte[] buf, int off, int len, int seed) {
* StreamingXXHash32 sh32 = xxhashFactory.newStreamingHash32(seed);
* sh32.update(buf, off, len);
* return sh32.getValue();
* }
*
*
* Instances of this class are not thread-safe.
*/
public abstract class StreamingXXHash32 implements Closeable {
interface Factory {
StreamingXXHash32 newStreamingHash(int seed);
}
final int seed;
StreamingXXHash32(int seed) {
this.seed = seed;
}
/**
* Returns the value of the checksum.
*
* @return the checksum
*/
public abstract int getValue();
/**
* Updates the value of the hash with buf[off:off+len].
*
* @param buf the input data
* @param off the start offset in buf
* @param len the number of bytes to hash
*/
public abstract void update(byte[] buf, int off, int len);
/**
* Resets this instance to the state it had right after instantiation. The
* seed remains unchanged.
*/
public abstract void reset();
/**
* Releases any system resources associated with this instance.
* It is not mandatory to call this method after using this instance
* because the system resources are released anyway when this instance
* is reclaimed by GC.
*/
@Override
public void close() {
}
@Override
public String toString() {
return getClass().getSimpleName() + "(seed=" + seed + ")";
}
/**
* Returns a {@link Checksum} view of this instance. Modifications to the view
* will modify this instance too and vice-versa.
*
* @return the {@link Checksum} object representing this instance
*/
public final Checksum asChecksum() {
return new Checksum() {
@Override
public long getValue() {
return StreamingXXHash32.this.getValue() & 0xFFFFFFFL;
}
@Override
public void reset() {
StreamingXXHash32.this.reset();
}
@Override
public void update(int b) {
StreamingXXHash32.this.update(new byte[] {(byte) b}, 0, 1);
}
@Override
public void update(byte[] b, int off, int len) {
StreamingXXHash32.this.update(b, off, len);
}
@Override
public String toString() {
return StreamingXXHash32.this.toString();
}
};
}
}