src/java.net.http/share/classes/jdk/internal/net/http/common/BufferSupplier.java
changeset 49944 4690a2871b44
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.net.http/share/classes/jdk/internal/net/http/common/BufferSupplier.java	Wed May 02 02:36:17 2018 -0700
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 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.common;
+
+import java.nio.ByteBuffer;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.function.Supplier;
+
+/**
+ *  This interface allows to recycle buffers used for SSL decryption.
+ *  Buffers that are used for reading SSL encrypted data are typically
+ *  very short lived, as it is necessary to aggregate their content
+ *  before calling SSLEngine::unwrap.
+ *  Because both reading and copying happen in the SelectorManager
+ *  thread, then it makes it possible to pool these buffers and
+ *  recycle them for the next socket read, instead of simply
+ *  letting them be GC'ed. That also makes it possible to use
+ *  direct byte buffers, and avoid another layer of copying by
+ *  the SocketChannel implementation.
+ *
+ *  The HttpClientImpl has an implementation of this interface
+ *  that allows to reuse the same 3 direct buffers for reading
+ *  off SSL encrypted data from the socket.
+ *  The BufferSupplier::get method is called by SocketTube
+ *  (see SocketTube.SSLDirectBufferSource) and BufferSupplier::recycle
+ *  is called by SSLFlowDelegate.Reader.
+ **/
+public interface BufferSupplier extends Supplier<ByteBuffer> {
+    /**
+     * Returns a buffer to read encrypted data off the socket.
+     * @return a buffer to read encrypted data off the socket.
+     */
+    ByteBuffer get();
+
+    /**
+     * Returns a buffer to the pool.
+     *
+     * @param buffer This must be a buffer previously obtained
+     *               by calling BufferSupplier::get. The caller must
+     *               not touch the buffer after returning it to
+     *               the pool.
+     */
+    void recycle(ByteBuffer buffer);
+}
+