1 /*
 2  * Copyright (c) 2019, 2023, 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 package sun.nio.ch;
26 
27 import java.io.IOException;
28 
29 /**
30  * Default PollerProvider for Windows based on wepoll.
31  */
32 class DefaultPollerProvider extends PollerProvider {
33     DefaultPollerProvider(Poller.Mode mode) {
34         if (mode != Poller.Mode.SYSTEM_THREADS) {
35             throw new UnsupportedOperationException();
36         }
37         super(mode);
38     }
39 
40     DefaultPollerProvider() {
41         this(Poller.Mode.SYSTEM_THREADS);
42     }
43 
44     @Override
45     int defaultReadPollers() {
46         int ncpus = Runtime.getRuntime().availableProcessors();
47         return Math.max(Integer.highestOneBit(ncpus / 8), 1);
48     }
49 
50     @Override
51     int fdValToIndex(int fdVal, int toIndex) {
52         return (fdVal >> 2) & (toIndex - 1);
53     }
54 
55     @Override
56     Poller readPoller(boolean subPoller) throws IOException {
57         if (subPoller)
58             throw new UnsupportedOperationException();
59         return new WEPollPoller(true);
60     }
61 
62     @Override
63     Poller writePoller(boolean subPoller) throws IOException {
64         if (subPoller)
65             throw new UnsupportedOperationException();
66         return new WEPollPoller(false);
67     }
68 }