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/*
* 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 com.datastax.dse.driver.internal.core.cql.reactive;
import java.util.Objects;
import org.reactivestreams.Publisher;
import org.reactivestreams.Subscriber;
/**
* A {@link Publisher} that immediately signals the error passed at instantiation to all its
* subscribers.
*/
public class FailedPublisher implements Publisher {
protected final Throwable error;
public FailedPublisher(Throwable error) {
this.error = error;
}
@Override
public void subscribe(Subscriber subscriber) {
Objects.requireNonNull(subscriber, "Subscriber cannot be null");
// Per rule 1.9, we need to call onSubscribe before any other signal. Pass a dummy
// subscription since we know it will never be used.
subscriber.onSubscribe(EmptySubscription.INSTANCE);
// Signal the error to the subscriber right away. This is safe to do because per rule 2.10,
// a Subscriber MUST be prepared to receive an onError signal without a preceding
// Subscription.request(long n) call.
// Also, per rule 2.13: onError MUST return normally except when any provided parameter
// is null (which is not the case here); so we don't need care about catching errors here.
subscriber.onError(error);
}
}