/*
* 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.
*/
package org.apache.beam.runners.direct;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.coders.CoderException;
import org.apache.beam.sdk.util.CoderUtils;
/**
* A (Key, Coder) pair that uses the structural value of the key (as provided by
* {@link Coder#structuralValue(Object)}) to perform equality and hashing.
*/
abstract class StructuralKey<K> {
private StructuralKey() {
// Prevents extending outside of this class
}
/**
* Returns the key that this {@link StructuralKey} was created from.
*/
public abstract K getKey();
/**
* Get the empty {@link StructuralKey}. All instances of the empty key are considered equal.
*/
static StructuralKey<?> empty() {
StructuralKey<Object> emptyKey = new StructuralKey<Object>() {
@Override
public Object getKey() {
return this;
}
};
return emptyKey;
}
/**
* Create a new Structural Key of the provided key that can be encoded by the provided coder.
*/
static <K> StructuralKey<K> of(K key, Coder<K> coder) {
try {
return new CoderStructuralKey<>(coder, key);
} catch (Exception e) {
throw new IllegalArgumentException(
"Could not encode a key with its provided coder " + coder.getClass().getSimpleName(), e);
}
}
private static class CoderStructuralKey<K> extends StructuralKey<K> {
private final Coder<K> coder;
private final Object structuralValue;
private final byte[] encoded;
private CoderStructuralKey(Coder<K> coder, K key) throws Exception {
this.coder = coder;
this.structuralValue = coder.structuralValue(key);
this.encoded = CoderUtils.encodeToByteArray(coder, key);
}
@Override
public K getKey() {
try {
return CoderUtils.decodeFromByteArray(coder, encoded);
} catch (CoderException e) {
throw new IllegalArgumentException(
"Could not decode Key with coder of type " + coder.getClass().getSimpleName(), e);
}
}
@Override
public boolean equals(Object other) {
if (other == this) {
return true;
}
if (other instanceof CoderStructuralKey) {
CoderStructuralKey<?> that = (CoderStructuralKey<?>) other;
return structuralValue.equals(that.structuralValue);
}
return false;
}
@Override
public int hashCode() {
return structuralValue.hashCode();
}
}
}