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.
/**
 * 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.internal.util;

import java.util.concurrent.CountDownLatch;

import io.reactivex.disposables.Disposable;
import io.reactivex.internal.schedulers.NonBlockingThread;
import io.reactivex.plugins.RxJavaPlugins;

Utility methods for helping common blocking operations.
/**
 * Utility methods for helping common blocking operations.
 */
public final class BlockingHelper {
    
Utility class. /** Utility class. */
    private BlockingHelper() {
        throw new IllegalStateException("No instances!");
    }

    public static void awaitForComplete(CountDownLatch latch, Disposable subscription) {
        if (latch.getCount() == 0) {
            // Synchronous observable completes before awaiting for it.
            // Skip await so InterruptedException will never be thrown.
            return;
        }
        // block until the subscription completes and then return
        try {
            verifyNonBlocking();
            latch.await();
        } catch (InterruptedException e) {
            subscription.dispose();
            // set the interrupted flag again so callers can still get it
            // for more information see https://github.com/ReactiveX/RxJava/pull/147#issuecomment-13624780
            Thread.currentThread().interrupt();
            // using Runtime so it is not checked
            throw new IllegalStateException("Interrupted while waiting for subscription to complete.", e);
        }
    }

    
Checks if the failOnNonBlockingScheduler plugin setting is enabled and the current thread is a Scheduler sensitive to blocking operators. 
Throws:
IllegalStateException – if the failOnNonBlockingScheduler and the current thread is sensitive to blocking/**
     * Checks if the {@code failOnNonBlockingScheduler} plugin setting is enabled and the current
     * thread is a Scheduler sensitive to blocking operators.
     * @throws IllegalStateException if the {@code failOnNonBlockingScheduler} and the current thread is sensitive to blocking
     */
    public static void verifyNonBlocking() {
        if (RxJavaPlugins.isFailOnNonBlockingScheduler()
                && (Thread.currentThread() instanceof NonBlockingThread
                        || RxJavaPlugins.onBeforeBlocking())) {
            throw new IllegalStateException("Attempt to block on a Scheduler " + Thread.currentThread().getName() + " that doesn't support blocking operators as they may lead to deadlock");
        }
    }
}