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.observers;

import java.util.concurrent.*;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.util.*;

import static io.reactivex.internal.util.ExceptionHelper.timeoutMessage;

A combined Observer that awaits the success or error signal via a CountDownLatch.
Type parameters:
<T> – the value type/**
 * A combined Observer that awaits the success or error signal via a CountDownLatch.
 * @param <T> the value type
 */
public final class BlockingMultiObserver<T>
extends CountDownLatch
implements SingleObserver<T>, CompletableObserver, MaybeObserver<T> {

    T value;
    Throwable error;

    Disposable upstream;

    volatile boolean cancelled;

    public BlockingMultiObserver() {
        super(1);
    }

    void dispose() {
        cancelled = true;
        Disposable d = this.upstream;
        if (d != null) {
            d.dispose();
        }
    }

    @Override
    public void onSubscribe(Disposable d) {
        this.upstream = d;
        if (cancelled) {
            d.dispose();
        }
    }

    @Override
    public void onSuccess(T value) {
        this.value = value;
        countDown();
    }

    @Override
    public void onError(Throwable e) {
        error = e;
        countDown();
    }

    @Override
    public void onComplete() {
        countDown();
    }

    
Block until the latch is counted down then rethrow any exception received (wrapped if checked)
or return the received value (null if none).
Returns:
the value received or null if no value received/**
     * Block until the latch is counted down then rethrow any exception received (wrapped if checked)
     * or return the received value (null if none).
     * @return the value received or null if no value received
     */
    public T blockingGet() {
        if (getCount() != 0) {
            try {
                BlockingHelper.verifyNonBlocking();
                await();
            } catch (InterruptedException ex) {
                dispose();
                throw ExceptionHelper.wrapOrThrow(ex);
            }
        }
        Throwable ex = error;
        if (ex != null) {
            throw ExceptionHelper.wrapOrThrow(ex);
        }
        return value;
    }

    
Block until the latch is counted down then rethrow any exception received (wrapped if checked)
or return the received value (the defaultValue if none).
Params:
defaultValue – the default value to return if no value was received
Returns:
the value received or defaultValue if no value received/**
     * Block until the latch is counted down then rethrow any exception received (wrapped if checked)
     * or return the received value (the defaultValue if none).
     * @param defaultValue the default value to return if no value was received
     * @return the value received or defaultValue if no value received
     */
    public T blockingGet(T defaultValue) {
        if (getCount() != 0) {
            try {
                BlockingHelper.verifyNonBlocking();
                await();
            } catch (InterruptedException ex) {
                dispose();
                throw ExceptionHelper.wrapOrThrow(ex);
            }
        }
        Throwable ex = error;
        if (ex != null) {
            throw ExceptionHelper.wrapOrThrow(ex);
        }
        T v = value;
        return v != null ? v : defaultValue;
    }

    
Block until the latch is counted down and return the error received or null if no
error happened.
Returns:
the error received or null/**
     * Block until the latch is counted down and return the error received or null if no
     * error happened.
     * @return the error received or null
     */
    public Throwable blockingGetError() {
        if (getCount() != 0) {
            try {
                BlockingHelper.verifyNonBlocking();
                await();
            } catch (InterruptedException ex) {
                dispose();
                return ex;
            }
        }
        return error;
    }

    
Block until the latch is counted down and return the error received or
when the wait is interrupted or times out, null otherwise.
Params:
timeout – the timeout value
unit – the time unit
Returns:
the error received or null/**
     * Block until the latch is counted down and return the error received or
     * when the wait is interrupted or times out, null otherwise.
     * @param timeout the timeout value
     * @param unit the time unit
     * @return the error received or null
     */
    public Throwable blockingGetError(long timeout, TimeUnit unit) {
        if (getCount() != 0) {
            try {
                BlockingHelper.verifyNonBlocking();
                if (!await(timeout, unit)) {
                    dispose();
                    throw ExceptionHelper.wrapOrThrow(new TimeoutException(timeoutMessage(timeout, unit)));
                }
            } catch (InterruptedException ex) {
                dispose();
                throw ExceptionHelper.wrapOrThrow(ex);
            }
        }
        return error;
    }

    
Block until the observer terminates and return true; return false if
the wait times out.
Params:
timeout – the timeout value
unit – the time unit
Returns:
true if the observer terminated in time, false otherwise/**
     * Block until the observer terminates and return true; return false if
     * the wait times out.
     * @param timeout the timeout value
     * @param unit the time unit
     * @return true if the observer terminated in time, false otherwise
     */
    public boolean blockingAwait(long timeout, TimeUnit unit) {
        if (getCount() != 0) {
            try {
                BlockingHelper.verifyNonBlocking();
                if (!await(timeout, unit)) {
                    dispose();
                    return false;
                }
            } catch (InterruptedException ex) {
                dispose();
                throw ExceptionHelper.wrapOrThrow(ex);
            }
        }
        Throwable ex = error;
        if (ex != null) {
            throw ExceptionHelper.wrapOrThrow(ex);
        }
        return true;
    }
}