1 /*
2 * Copyright (c) 2017, 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 import jdk.internal.vm.ContinuationSupport;
29
30 /**
31 * Default PollerProvider for Linux.
32 */
33 class DefaultPollerProvider extends PollerProvider {
34 private static final boolean USE_IOURING;
35 private static final boolean USE_IORING_OP_READ;
36 private static final boolean USE_IORING_OP_WRITE;
37 static {
38 String s = System.getProperty("jdk.io_uring");
39 if ("".equals(s) || Boolean.parseBoolean(s)) {
40 USE_IOURING = true;
41 s = System.getProperty("jdk.io_uring.read");
42 USE_IORING_OP_READ = "".equals(s) || Boolean.parseBoolean(s);
43 s = System.getProperty("jdk.io_uring.write");
44 USE_IORING_OP_WRITE = "".equals(s) || Boolean.parseBoolean(s);
45 } else {
46 USE_IOURING = false;
47 USE_IORING_OP_READ = false;
48 USE_IORING_OP_WRITE = false;
49 }
50 }
51
52 DefaultPollerProvider(Poller.Mode mode) {
53 super(mode);
54 }
55
56 DefaultPollerProvider() {
57 this(ContinuationSupport.isSupported()
58 ? Poller.Mode.VTHREAD_POLLERS
59 : Poller.Mode.SYSTEM_THREADS);
60 }
61
62 @Override
63 int defaultReadPollers() {
64 int ncpus = Runtime.getRuntime().availableProcessors();
65 return switch (pollerMode()) {
66 case SYSTEM_THREADS -> Math.max(Integer.highestOneBit(ncpus / 4), 1);
67 case VTHREAD_POLLERS -> Math.min(Integer.highestOneBit(ncpus), 32);
68 default -> super.defaultReadPollers();
69 };
70 }
71
72 @Override
73 Poller readPoller(boolean subPoller) throws IOException {
74 Poller.Mode mode = pollerMode();
75 if (USE_IOURING) {
76 // read poller is system thread in SYSTEM_THREADS mode
77 boolean supportReadOps = USE_IORING_OP_READ
78 && ((mode == Poller.Mode.SYSTEM_THREADS) || subPoller);
79 return new IoUringPoller(mode, subPoller, true, supportReadOps);
80 } else {
81 return new EPollPoller(mode, subPoller, true);
82 }
83 }
84
85 @Override
86 Poller writePoller(boolean subPoller) throws IOException {
87 Poller.Mode mode = pollerMode();
88 if (USE_IOURING) {
89 // write poller is system thread in SYSTEM_THREADS and POLLER_PER_CARRIER modes
90 boolean supportWriteOps = USE_IORING_OP_WRITE
91 && ((mode != Poller.Mode.VTHREAD_POLLERS) || subPoller);
92 return new IoUringPoller(mode, subPoller, false, supportWriteOps);
93 } else {
94 return new EPollPoller(mode, subPoller, false);
95 }
96 }
97
98 @Override
99 boolean supportReadOps() {
100 return USE_IORING_OP_READ;
101 }
102
103 @Override
104 boolean supportWriteOps() {
105 return USE_IORING_OP_WRITE;
106 }
107 }