code: /*
   * 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
   * a {@link FlowableEmitter} instance that allows pushing
   * events in a backpressure-safe and cancellation-safe manner.
   *
   * @param <T> the value type pushed
   */
  @FunctionalInterface
  public interface FlowableOnSubscribe<@NonNull T> {
  
      /**
       * Called for each {@link org.reactivestreams.Subscriber Subscriber} that subscribes.
       * @param emitter the safe emitter instance, never {@code null}
       * @throws Throwable on error
       */
      void subscribe(@NonNull FlowableEmitter<T> emitter) throws Throwable;
  }
  
  