/*
 * Copyright (c) 2016-present, RxJava 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.
 */

package io.reactivex.rxjava3.core;

import io.reactivex.rxjava3.annotations.NonNull;

/**
 * A functional interface that has a {@code subscribe()} method that receives
 * an {@link ObservableEmitter} instance that allows pushing
 * events in a cancellation-safe manner.
 *
 * @param <T> the value type pushed
 */
@FunctionalInterface
public interface ObservableOnSubscribe<@NonNull T> {

    /**
     * Called for each {@link Observer} that subscribes.
     * @param emitter the safe emitter instance, never {@code null}
     * @throws Throwable on error
     */
    void subscribe(@NonNull ObservableEmitter<T> emitter) throws Throwable;
}

