--- a/src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/BufferingSubscriber.java	Wed Nov 22 16:27:08 2017 +0000
+++ b/src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/BufferingSubscriber.java	Wed Nov 22 21:29:20 2017 +0000
@@ -155,13 +155,15 @@
 
         @Override
         public void request(long n) {
+            if (cancelled.get()) {
+                return;
+            }
             if (n <= 0L) {
+                cancel();
                 onError(new IllegalArgumentException(
                         "non-positive subscription request"));
                 return;
             }
-            if (cancelled.get())
-                return;
 
             demand.increase(n);
 
@@ -274,7 +276,7 @@
     public void onError(Throwable throwable) {
         Objects.requireNonNull(throwable);
         int s = state;
-        assert s == ACTIVE : "Expected ACTIVE, got:" + s;
+        assert s == ACTIVE || s == CANCELLED: "Expected ACTIVE||CANCELLED, got:" + s;
         state = ERROR;
         downstreamSubscriber.onError(throwable);
     }

--- a/test/jdk/java/net/httpclient/BufferingSubscriberCancelTest.java	Wed Nov 22 16:27:08 2017 +0000
+++ b/test/jdk/java/net/httpclient/BufferingSubscriberCancelTest.java	Wed Nov 22 21:29:20 2017 +0000
@@ -35,6 +35,7 @@
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
 import static java.lang.Long.MAX_VALUE;
+import static java.lang.Long.MIN_VALUE;
 import static java.lang.System.out;
 import static java.nio.ByteBuffer.wrap;
 import static java.util.concurrent.TimeUnit.SECONDS;
@@ -68,7 +69,6 @@
         BodySubscriber subscriber = buffering(exposingSubscriber, bufferSize);
         publisher.subscribe(subscriber);
         gate.await(30, SECONDS);
-       // while (publisher.getNumberOfSubscribers() != 0)
         assertEqualsWithRetry(publisher::getNumberOfSubscribers, 1);
         exposingSubscriber.subscription.cancel();
         assertEqualsWithRetry(publisher::getNumberOfSubscribers, 0);
@@ -80,6 +80,7 @@
         s.cancel(); s.request(MAX_VALUE); s.cancel(); s.cancel();
         s.cancel(); s.cancel(); s.cancel(); s.cancel();
         s.request(MAX_VALUE); s.request(MAX_VALUE); s.request(MAX_VALUE);
+        s.request(-1); s.request(-100); s.request(MIN_VALUE);
         assertEqualsWithRetry(publisher::getNumberOfSubscribers, 0);
     }
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/net/httpclient/BufferingSubscriberErrorCompleteTest.java	Wed Nov 22 21:29:20 2017 +0000
@@ -0,0 +1,223 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.Phaser;
+import java.util.concurrent.SubmissionPublisher;
+import java.util.function.IntSupplier;
+import java.util.stream.IntStream;
+import jdk.incubator.http.HttpResponse.BodySubscriber;
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+import static java.lang.Long.MAX_VALUE;
+import static java.lang.Long.MIN_VALUE;
+import static java.lang.System.out;
+import static java.nio.ByteBuffer.wrap;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static jdk.incubator.http.HttpResponse.BodySubscriber.buffering;
+import static org.testng.Assert.*;
+
+/*
+ * @test
+ * @summary Test for HttpResponse.BodySubscriber.buffering() onError/onComplete
+ * @run testng/othervm BufferingSubscriberErrorCompleteTest
+ */
+
+public class BufferingSubscriberErrorCompleteTest {
+
+    @DataProvider(name = "illegalDemand")
+    public Object[][] illegalDemand() {
+        return new Object[][]{
+            {0L}, {-1L}, {-5L}, {-100L}, {-101L}, {-100_001L}, {MIN_VALUE}
+        };
+    }
+
+    @Test(dataProvider = "illegalDemand")
+    public void illegalRequest(long demand) throws Exception {
+        ExecutorService executor = Executors.newFixedThreadPool(1);
+        SubmissionPublisher<List<ByteBuffer>> publisher =
+                new SubmissionPublisher<>(executor, 1);
+
+        Phaser gate = new Phaser(2);  // single onSubscribe and onError
+        ExposingSubscriber exposingSubscriber = new ExposingSubscriber(gate);
+        BodySubscriber subscriber = buffering(exposingSubscriber, 1);
+        publisher.subscribe(subscriber);
+        gate.arriveAndAwaitAdvance();
+
+        Subscription s = exposingSubscriber.subscription;
+        int previous = exposingSubscriber.onErrorInvocations;
+        s.request(demand);
+        gate.arriveAndAwaitAdvance();
+
+        assertEquals(previous + 1, exposingSubscriber.onErrorInvocations);
+        assertTrue(exposingSubscriber.throwable instanceof IllegalArgumentException,
+                "Expected IAE, got:" + exposingSubscriber.throwable);
+
+        furtherCancelsRequestsShouldBeNoOp(s);
+        assertEquals(exposingSubscriber.onErrorInvocations, 1);
+    }
+
+
+    @DataProvider(name = "bufferAndItemSizes")
+    public Object[][] bufferAndItemSizes() {
+        List<Object[]> values = new ArrayList<>();
+
+        for (int bufferSize : new int[] { 1, 5, 10, 100, 1000 })
+            for (int items : new int[]  { 0, 1, 2, 5, 9, 10, 11, 15, 29, 99 })
+                values.add(new Object[] { bufferSize, items });
+
+        return values.stream().toArray(Object[][]::new);
+    }
+
+    @Test(dataProvider = "bufferAndItemSizes")
+    public void onErrorFromPublisher(int bufferSize,
+                                     int numberOfItems)
+        throws Exception
+    {
+        ExecutorService executor = Executors.newFixedThreadPool(1);
+        SubmissionPublisher<List<ByteBuffer>> publisher =
+                new SubmissionPublisher<>(executor, 1);
+
+        // onSubscribe + onError + this thread
+        Phaser gate = new Phaser(3);
+        ExposingSubscriber exposingSubscriber = new ExposingSubscriber(gate);
+        BodySubscriber subscriber = buffering(exposingSubscriber, bufferSize);
+        publisher.subscribe(subscriber);
+
+        List<ByteBuffer> item = List.of(wrap(new byte[] { 1 }));
+        IntStream.range(0, numberOfItems).forEach(x -> publisher.submit(item));
+        Throwable t = new Throwable("a message from me to me");
+        publisher.closeExceptionally(t);
+
+        gate.arriveAndAwaitAdvance();
+
+        Subscription s = exposingSubscriber.subscription;
+
+        assertEquals(exposingSubscriber.onErrorInvocations, 1);
+        assertEquals(exposingSubscriber.onCompleteInvocations, 0);
+        assertEquals(exposingSubscriber.throwable, t);
+        assertEquals(exposingSubscriber.throwable.getMessage(),
+                     "a message from me to me");
+
+        furtherCancelsRequestsShouldBeNoOp(s);
+        assertEquals(exposingSubscriber.onErrorInvocations, 1);
+        assertEquals(exposingSubscriber.onCompleteInvocations, 0);
+    }
+
+    @Test(dataProvider = "bufferAndItemSizes")
+    public void onCompleteFromPublisher(int bufferSize,
+                                        int numberOfItems)
+            throws Exception
+    {
+        ExecutorService executor = Executors.newFixedThreadPool(1);
+        SubmissionPublisher<List<ByteBuffer>> publisher =
+                new SubmissionPublisher<>(executor, 1);
+
+        // onSubscribe + onComplete + this thread
+        Phaser gate = new Phaser(3);
+        ExposingSubscriber exposingSubscriber = new ExposingSubscriber(gate);
+        BodySubscriber subscriber = buffering(exposingSubscriber, bufferSize);
+        publisher.subscribe(subscriber);
+
+        List<ByteBuffer> item = List.of(wrap(new byte[] { 1 }));
+        IntStream.range(0, numberOfItems).forEach(x -> publisher.submit(item));
+        publisher.close();
+
+        gate.arriveAndAwaitAdvance();
+
+        Subscription s = exposingSubscriber.subscription;
+
+        assertEquals(exposingSubscriber.onErrorInvocations, 0);
+        assertEquals(exposingSubscriber.onCompleteInvocations, 1);
+        assertEquals(exposingSubscriber.throwable, null);
+
+        furtherCancelsRequestsShouldBeNoOp(s);
+        assertEquals(exposingSubscriber.onErrorInvocations, 0);
+        assertEquals(exposingSubscriber.onCompleteInvocations, 1);
+        assertEquals(exposingSubscriber.throwable, null);
+    }
+
+    static class ExposingSubscriber implements BodySubscriber<Void> {
+        final Phaser gate;
+        volatile Subscription subscription;
+        volatile int onNextInvocations;
+        volatile int onErrorInvocations;
+        volatile int onCompleteInvocations;
+        volatile Throwable throwable;
+
+        ExposingSubscriber(Phaser gate) {
+            this.gate = gate;
+        }
+
+        @Override
+        public void onSubscribe(Subscription subscription) {
+            //out.println("onSubscribe " + subscription);
+            this.subscription = subscription;
+            subscription.request(MAX_VALUE);
+            gate.arrive();
+        }
+
+        @Override
+        public void onNext(List<ByteBuffer> item) {
+            //out.println("onNext " + item);
+            onNextInvocations++;
+        }
+
+        @Override
+        public void onError(Throwable throwable) {
+            //out.println("onError " + throwable);
+            this.throwable = throwable;
+            onErrorInvocations++;
+            gate.arrive();
+        }
+
+        @Override
+        public void onComplete() {
+            //out.println("onComplete ");
+            onCompleteInvocations++;
+            gate.arrive();
+        }
+
+        @Override
+        public CompletionStage<Void> getBody() {
+            throw new UnsupportedOperationException("getBody is unsupported");
+        }
+    }
+
+    static void furtherCancelsRequestsShouldBeNoOp(Subscription s) {
+        s.cancel(); s.request(1);
+        s.cancel(); s.request(100); s.cancel();
+        s.cancel(); s.request(MAX_VALUE); s.cancel(); s.cancel();
+        s.cancel(); s.cancel(); s.cancel(); s.cancel();
+        s.request(MAX_VALUE); s.request(MAX_VALUE); s.request(MAX_VALUE);
+        s.request(-1); s.request(-100); s.request(MIN_VALUE);
+    }
+}