1 /*

     2  * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package jdk.incubator.http;

    27 

    28 import jdk.incubator.http.internal.common.ByteBufferReference;

    29 

    30 import java.io.IOException;

    31 import java.nio.ByteBuffer;

    32 import java.util.function.Consumer;

    33 import java.util.function.Supplier;

    34 

    35 /**

    36  * Implemented by classes that offer an asynchronous interface.

    37  *

    38  * PlainHttpConnection, AsyncSSLConnection AsyncSSLDelegate.

    39  *

    40  * setAsyncCallbacks() is called to set the callback for reading

    41  * and error notification. Reads all happen on the selector thread, which

    42  * must not block.

    43  *

    44  * Writing uses the same write() methods as used in blocking mode.

    45  * Queues are employed on the writing side to buffer data while it is waiting

    46  * to be sent. This strategy relies on HTTP/2 protocol flow control to stop

    47  * outgoing queue from continually growing. Writes can be initiated by the

    48  * calling thread, but if socket becomes full then the queue is emptied by

    49  * the selector thread

    50  */

    51 interface AsyncConnection {

    52 

    53     /**

    54      * Enables asynchronous sending and receiving mode. The given async

    55      * receiver will receive all incoming data. asyncInput() will be called

    56      * to trigger reads. asyncOutput() will be called to drive writes.

    57      *

    58      * The errorReceiver callback must be called when any fatal exception

    59      * occurs. Connection is assumed to be closed afterwards.

    60      */

    61     void setAsyncCallbacks(Consumer<ByteBufferReference> asyncReceiver,

    62                            Consumer<Throwable> errorReceiver,

    63                            Supplier<ByteBufferReference> readBufferSupplier);

    64 

    65 

    66 

    67     /**

    68      * Does whatever is required to start reading. Usually registers

    69      * an event with the selector thread.

    70      */

    71     void startReading();

    72 

    73     /**

    74      * Cancel asynchronous reading. Used to downgrade a HTTP/2 connection to HTTP/1

    75      */

    76     void stopAsyncReading();

    77 

    78     /**

    79      * In async mode, this method puts buffers at the end of the send queue.

    80      * When in async mode, calling this method should later be followed by

    81      * subsequent flushAsync invocation.

    82      * That allows multiple threads to put buffers into the queue while some other

    83      * thread is writing.

    84      */

    85     void writeAsync(ByteBufferReference[] buffers) throws IOException;

    86 

    87     /**

    88      * Re-enable asynchronous reads through the callback

    89      */

    90     void enableCallback();

    91 

    92     /**

    93      * In async mode, this method may put buffers at the beginning of send queue,

    94      * breaking frames sequence and allowing to write these buffers before other

    95      * buffers in the queue.

    96      * When in async mode, calling this method should later be followed by

    97      * subsequent flushAsync invocation.

    98      * That allows multiple threads to put buffers into the queue while some other

    99      * thread is writing.

   100      */

   101     void writeAsyncUnordered(ByteBufferReference[] buffers) throws IOException;

   102 

   103     /**

   104      * This method should be called after any writeAsync/writeAsyncUnordered

   105      * invocation.

   106      * If there is a race to flushAsync from several threads one thread

   107      * (race winner) capture flush operation and write the whole queue content.

   108      * Other threads (race losers) exits from the method (not blocking)

   109      * and continue execution.

   110      */

   111     void flushAsync() throws IOException;

   112 }