Merge pull request #1727 from benjchristensen/groupByWithBackpressure

Proposed groupBy/groupByUntil Changes

Author: benjchristensen

src/main/java/rx/Observable.java

@@ -4708,15 +4708,6 @@ public final void forEach(final Action1<? super T> onNext, final Action1<Throwab
      * is subscribed to. For this reason, in order to avoid memory leaks, you should not simply ignore those
      * {@code GroupedObservable}s that do not concern you. Instead, you can signal to them that they may
      * discard their buffers by applying an operator like {@link #take}{@code (0)} to them.
-     * <dl>
-     *  <dt><b>Backpressure Support:</b></dt>
-     *  <dd>This operator does not support backpressure as splitting a stream effectively turns it into a "hot
-     *      observable" and blocking any one group would block the entire parent stream. If you need
-     *      backpressure on individual groups then you should use operators such as {@link #onBackpressureDrop}
-     *      or {@link #onBackpressureBuffer}.</dd>
-     *  <dt><b>Scheduler:</b></dt>
-     *  <dd>{@code groupBy} does not operate by default on a particular {@link Scheduler}.</dd>
-     * </dl>
      * 
      * @param keySelector
      *            a function that extracts the key for each item
@@ -4746,15 +4737,6 @@ public final <K, R> Observable<GroupedObservable<K, R>> groupBy(final Func1<? su
      * is subscribed to. For this reason, in order to avoid memory leaks, you should not simply ignore those
      * {@code GroupedObservable}s that do not concern you. Instead, you can signal to them that they may
      * discard their buffers by applying an operator like {@link #take}{@code (0)} to them.
-     * <dl>
-     *  <dt><b>Backpressure Support:</b></dt>
-     *  <dd>This operator does not support backpressure as splitting a stream effectively turns it into a "hot
-     *      observable" and blocking any one group would block the entire parent stream. If you need
-     *      backpressure on individual groups then you should use operators such as {@link #onBackpressureDrop}
-     *      or {@link #onBackpressureBuffer}.</dd>
-     *  <dt><b>Scheduler:</b></dt>
-     *  <dd>{@code groupBy} does not operate by default on a particular {@link Scheduler}.</dd>
-     * </dl>
      * 
      * @param keySelector
      *            a function that extracts the key for each item
@@ -4770,77 +4752,6 @@ public final <K> Observable<GroupedObservable<K, T>> groupBy(final Func1<? super
         return lift(new OperatorGroupBy<T, K, T>(keySelector));
     }
 
-    /**
-     * Groups the items emitted by an {@code Observable} according to a specified key selector function until
-     * the duration {@code Observable} expires for the key.
-     * <p>
-     * <img width="640" height="375" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/groupByUntil.png" alt="">
-     * <p>
-     * <em>Note:</em> A {@link GroupedObservable} will cache the items it is to emit until such time as it
-     * is subscribed to. For this reason, in order to avoid memory leaks, you should not simply ignore those
-     * {@code GroupedObservable}s that do not concern you. Instead, you can signal to them that they may
-     * discard their buffers by applying an operator like {@link #take}{@code (0)} to them.
-     * <dl>
-     *  <dt><b>Backpressure Support:</b></dt>
-     *  <dd>This operator does not support backpressure as splitting a stream effectively turns it into a "hot
-     *      observable" and blocking any one group would block the entire parent stream. If you need
-     *      backpressure on individual groups then you should use operators such as {@link #onBackpressureDrop}
-     *      or {@link #onBackpressureBuffer}.</dd>
-     *  <dt><b>Scheduler:</b></dt>
-     *  <dd>{@code groupByUntil} does not operate by default on a particular {@link Scheduler}.</dd>
-     * </dl>
-     * 
-     * @param keySelector
-     *            a function to extract the key for each item
-     * @param durationSelector
-     *            a function to signal the expiration of a group
-     * @return an {@code Observable} that emits {@link GroupedObservable}s, each of which corresponds to a key
-     *         value and each of which emits all items emitted by the source {@code Observable} during that
-     *         key's duration that share that same key value
-     * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Transforming-Observables#groupby-and-groupbyuntil">RxJava wiki: groupByUntil</a>
-     * @see <a href="http://msdn.microsoft.com/en-us/library/hh211932.aspx">MSDN: Observable.GroupByUntil</a>
-     */
-    public final <TKey, TDuration> Observable<GroupedObservable<TKey, T>> groupByUntil(Func1<? super T, ? extends TKey> keySelector, Func1<? super GroupedObservable<TKey, T>, ? extends Observable<? extends TDuration>> durationSelector) {
-        return groupByUntil(keySelector, Functions.<T> identity(), durationSelector);
-    }
-
-    /**
-     * Groups the items emitted by an {@code Observable} (transformed by a selector) according to a specified
-     * key selector function until the duration Observable expires for the key.
-     * <p>
-     * <img width="640" height="375" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/groupByUntil.png" alt="">
-     * <p>
-     * <em>Note:</em> A {@link GroupedObservable} will cache the items it is to emit until such time as it
-     * is subscribed to. For this reason, in order to avoid memory leaks, you should not simply ignore those
-     * {@code GroupedObservable}s that do not concern you. Instead, you can signal to them that they may
-     * discard their buffers by applying an operator like {@link #take}{@code (0)} to them.
-     * <dl>
-     *  <dt><b>Backpressure Support:</b></dt>
-     *  <dd>This operator does not support backpressure as splitting a stream effectively turns it into a "hot
-     *      observable" and blocking any one group would block the entire parent stream. If you need
-     *      backpressure on individual groups then you should use operators such as {@link #onBackpressureDrop}
-     *      or {@link #onBackpressureBuffer}.</dd>
-     *  <dt><b>Scheduler:</b></dt>
-     *  <dd>{@code groupByUntil} does not operate by default on a particular {@link Scheduler}.</dd>
-     * </dl>
-     * 
-     * @param keySelector
-     *            a function to extract the key for each item
-     * @param valueSelector
-     *            a function to map each item emitted by the source {@code Observable} to an item emitted by one
-     *            of the resulting {@link GroupedObservable}s
-     * @param durationSelector
-     *            a function to signal the expiration of a group
-     * @return an {@code Observable} that emits {@link GroupedObservable}s, each of which corresponds to a key
-     *         value and each of which emits all items emitted by the source {@code Observable} during that
-     *         key's duration that share that same key value, transformed by the value selector
-     * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Transforming-Observables#groupby-and-groupbyuntil">RxJava wiki: groupByUntil</a>
-     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229433.aspx">MSDN: Observable.GroupByUntil</a>
-     */
-    public final <TKey, TValue, TDuration> Observable<GroupedObservable<TKey, TValue>> groupByUntil(Func1<? super T, ? extends TKey> keySelector, Func1<? super T, ? extends TValue> valueSelector, Func1<? super GroupedObservable<TKey, TValue>, ? extends Observable<? extends TDuration>> durationSelector) {
-        return lift(new OperatorGroupByUntil<T, TKey, TValue, TDuration>(keySelector, valueSelector, durationSelector));
-    }
-
     /**
      * Returns an Observable that correlates two Observables when they overlap in time and groups the results.
      * <p>