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1   /*
2    * junixsocket
3    *
4    * Copyright 2009-2024 Christian Kohlschütter
5    *
6    * Licensed under the Apache License, Version 2.0 (the "License");
7    * you may not use this file except in compliance with the License.
8    * You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.newsclub.net.unix;
19  
20  import java.io.Closeable;
21  import java.io.FileDescriptor;
22  import java.io.IOException;
23  import java.net.SocketTimeoutException;
24  import java.nio.channels.SelectionKey;
25  
26  /**
27   * Helper class to support polling "virtually blocked" file descriptors for virtual threads.
28   *
29   * @author Christian Kohlschütter
30   */
31  interface VirtualThreadPoller {
32    /**
33     * Returns the default instance best suited for the current system.
34     */
35    VirtualThreadPoller INSTANCE = new VirtualThreadPollerNaive();
36  
37    /**
38     * Parks the current thread until the given file descriptor is ready, with respect to the given
39     * readiness mode.
40     *
41     * @param fd The file descriptor to check.
42     * @param mode The mode (bitmask of {@link SelectionKey#OP_READ}, {@link SelectionKey#OP_WRITE},
43     *          {@link SelectionKey#OP_ACCEPT}, {@link SelectionKey#OP_CONNECT})
44     * @param now The refence time (in millis) for the timeout
45     * @param timeout (in seconds), or 0 for infinite
46     * @param closeOnInterrupt Callback to call upon interrupt (usually to close the resource working
47     *          on the file descriptor)
48     * @throws SocketTimeoutException on timeout
49     * @throws SocketClosedByInterruptException on interrupt.
50     * @throws IOException on other error
51     */
52    void parkThreadUntilReady(FileDescriptor fd, /* SelectionKey.OP_ */ int mode, long now,
53        AFSupplier<Integer> timeout, Closeable closeOnInterrupt) throws IOException;
54  }