doOnUnsubscribe behaviour does not align with documentation

[rossdanderson]

Hi,

According to the documentation here, when my source observable is reference counted I should only be notified of the final subscriber's unsubscription, however, unless I am misunderstanding the term source - or misusing it, it appears to be called on every subscriber's unsubscription.

Below is a simple test which demonstrates what I mean - onUnsubscribeAfterRefCount will fail, while onUnsubscribeBeforeRefCount will pass

package streams;

import org.junit.Test;
import rx.Observable;
import rx.Subscription;
import rx.observers.TestSubscriber;
import rx.subjects.PublishSubject;

import java.util.concurrent.atomic.AtomicInteger;

import static org.junit.Assert.assertEquals;

public class UnsubscribeTest {

    @Test
    public void onUnsubscribeAfterRefCount() {
        AtomicInteger count = new AtomicInteger();

        Observable<String> publishSubject = PublishSubject.<String>create().publish().refCount().doOnUnsubscribe(count::getAndIncrement);

        TestSubscriber<String> testSubscriber1 = TestSubscriber.create();
        Subscription subscription1 = publishSubject.subscribe(testSubscriber1);

        TestSubscriber<String> testSubscriber2 = TestSubscriber.create();
        Subscription subscription2 = publishSubject.subscribe(testSubscriber2);

        subscription1.unsubscribe();
        subscription2.unsubscribe();

        assertEquals(1, count.get());
    }

    @Test
    public void onUnsubscribeBeforeRefCount() {
        AtomicInteger count = new AtomicInteger();

        Observable<String> publishSubject = PublishSubject.<String>create().doOnUnsubscribe(count::getAndIncrement).publish().refCount();

        TestSubscriber<String> testSubscriber1 = TestSubscriber.create();
        Subscription subscription1 = publishSubject.subscribe(testSubscriber1);

        TestSubscriber<String> testSubscriber2 = TestSubscriber.create();
        Subscription subscription2 = publishSubject.subscribe(testSubscriber2);

        subscription1.unsubscribe();
        subscription2.unsubscribe();

        assertEquals(1, count.get());
    }
}

[akarnokd]

You get two calls because the two subscribers create two separate chains up until the publish() stage and two unsubscribe calls are issued. In the second (synchronous) case, publish().refCount() makes sure the unsubscription happens only once and the preceding doOnUnsubscribe only gets called once.

[rossdanderson]

Yes I follow what is happening but this does not seem to align with the documentation where it says the source observable is modified to call doOnUnsubscribe, and that if the source observable is ref counted then it should only happen once.
The source observable is the one on the left I presume? In which case is this an invalid statement?

[akarnokd]

Ah, yes, that statement is invalid. Would you like to submit a PR and fix that?

[rossdanderson]

Certainly, is the intention to fix the documentation to match the actual behavour?
Cheers

[akarnokd]

Fix the documentation.

[akarnokd]

See my proposed updates to the javadoc in #3907

[akarnokd]

Closing via #3907.