--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.net.http/share/classes/jdk/internal/net/http/PullPublisher.java	Wed Feb 07 21:45:37 2018 +0000
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2016, 2018, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package jdk.internal.net.http;
+
+import java.util.Iterator;
+import java.util.concurrent.Flow;
+import jdk.internal.net.http.common.Demand;
+import jdk.internal.net.http.common.SequentialScheduler;
+
+/**
+ * A Publisher that publishes items obtained from the given Iterable. Each new
+ * subscription gets a new Iterator.
+ */
+class PullPublisher<T> implements Flow.Publisher<T> {
+
+    // Only one of `iterable` and `throwable` can be non-null. throwable is
+    // non-null when an error has been encountered, by the creator of
+    // PullPublisher, while subscribing the subscriber, but before subscribe has
+    // completed.
+    private final Iterable<T> iterable;
+    private final Throwable throwable;
+
+    PullPublisher(Iterable<T> iterable, Throwable throwable) {
+        this.iterable = iterable;
+        this.throwable = throwable;
+    }
+
+    PullPublisher(Iterable<T> iterable) {
+        this(iterable, null);
+    }
+
+    @Override
+    public void subscribe(Flow.Subscriber<? super T> subscriber) {
+        Subscription sub;
+        if (throwable != null) {
+            assert iterable == null : "non-null iterable: " + iterable;
+            sub = new Subscription(subscriber, null, throwable);
+        } else {
+            assert throwable == null : "non-null exception: " + throwable;
+            sub = new Subscription(subscriber, iterable.iterator(), null);
+        }
+        subscriber.onSubscribe(sub);
+
+        if (throwable != null) {
+            sub.pullScheduler.runOrSchedule();
+        }
+    }
+
+    private class Subscription implements Flow.Subscription {
+
+        private final Flow.Subscriber<? super T> subscriber;
+        private final Iterator<T> iter;
+        private volatile boolean completed;
+        private volatile boolean cancelled;
+        private volatile Throwable error;
+        final SequentialScheduler pullScheduler = new SequentialScheduler(new PullTask());
+        private final Demand demand = new Demand();
+
+        Subscription(Flow.Subscriber<? super T> subscriber,
+                     Iterator<T> iter,
+                     Throwable throwable) {
+            this.subscriber = subscriber;
+            this.iter = iter;
+            this.error = throwable;
+        }
+
+        final class PullTask extends SequentialScheduler.CompleteRestartableTask {
+            @Override
+            protected void run() {
+                if (completed || cancelled) {
+                    return;
+                }
+
+                Throwable t = error;
+                if (t != null) {
+                    completed = true;
+                    pullScheduler.stop();
+                    subscriber.onError(t);
+                    return;
+                }
+
+                while (demand.tryDecrement() && !cancelled) {
+                    if (!iter.hasNext()) {
+                        break;
+                    } else {
+                        subscriber.onNext(iter.next());
+                    }
+                }
+                if (!iter.hasNext() && !cancelled) {
+                    completed = true;
+                    pullScheduler.stop();
+                    subscriber.onComplete();
+                }
+            }
+        }
+
+        @Override
+        public void request(long n) {
+            if (cancelled)
+                return;  // no-op
+
+            if (n <= 0) {
+                error = new IllegalArgumentException("illegal non-positive request:" + n);
+            } else {
+                demand.increase(n);
+            }
+            pullScheduler.runOrSchedule();
+        }
+
+        @Override
+        public void cancel() {
+            cancelled = true;
+        }
+    }
+}