org.jetbrains.annotations.BlockingExecutor Maven / Gradle / Ivy

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/*
 * Copyright 2000-2021 JetBrains s.r.o.
 *
 * 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
 *
 * https://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.jetbrains.annotations;

import java.lang.annotation.*;

/**
 * Indicates that the annotated executor (CoroutineContext, Scheduler)
 * allows blocking methods execution.
 * 
 * If a given executor does not allow blocking calls, {@link NonBlockingExecutor} should be used.
 *
 * 

 * Example 1 (Kotlin coroutines):
 * 

 *  class BlockingExampleService {
 *      val dispatcher: @BlockingExecutor CoroutineContext
 *          get() { ... }
 *
 *      suspend fun foo() {
 *          val result = withContext(dispatcher) {
 *              blockingBuzz() // no IDE warning
 *          }
 *      }
 *
 *      @Blocking fun blockingBuzz() { ... }
 *  }
 * 
 *
 * 
 * Example 2 (Java with Reactor framework):
 * 

 * class BlockingExampleService {
 *     private static final @BlockingExecutor Scheduler blockingScheduler =
 *             Schedulers.newBoundedElastic(4, 10, "executor");
 *
 *     public Flux<String> foo(Flux<String> urls) {
 *         return urls.publishOn(blockingScheduler)
 *                 .map(url -> blockingBuzz(url));  // no IDE warning
 *     }
 *
 *     @Blocking
 *     private String blockingBuzz(String url) { ... }
 * }
 * 
 *
 * @see Blocking
 * @see NonBlocking
 */
@Documented
@Retention(RetentionPolicy.CLASS)
@Target({ElementType.TYPE, ElementType.TYPE_USE})
public @interface BlockingExecutor {
}