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/*
* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package org.reactivestreams;
/**
* A {@link Subscription} represents a one-to-one lifecycle of a {@link Subscriber} subscribing to a {@link Publisher}.
* <p>
* It can only be used once by a single {@link Subscriber}.
* <p>
* It is used to both signal desire for data and cancel demand (and allow resource cleanup).
*
*/
public interface Subscription {
/**
* No events will be sent by a {@link Publisher} until demand is signaled via this method.
* <p>
* It can be called however often and whenever needed—but if the outstanding cumulative demand ever becomes Long.MAX_VALUE or more,
* it may be treated by the {@link Publisher} as "effectively unbounded".
* <p>
* Whatever has been requested can be sent by the {@link Publisher} so only signal demand for what can be safely handled.
* <p>
* A {@link Publisher} can send less than is requested if the stream ends but
* then must emit either {@link Subscriber#onError(Throwable)} or {@link Subscriber#onComplete()}.
*
* @param n the strictly positive number of elements to requests to the upstream {@link Publisher}
*/
public void request(long n);
/**
* Request the {@link Publisher} to stop sending data and clean up resources.
* <p>
* Data may still be sent to meet previously signalled demand after calling cancel.
*/
public void cancel();
}
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