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.access.JavaLangAccess;
29 import jdk.internal.access.SharedSecrets;
30 import jdk.internal.vm.ContinuationSupport;
31
32 /**
33 * Default PollerProvider for Linux.
34 */
35 class DefaultPollerProvider extends PollerProvider {
36 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
37
38 private static final boolean USE_IOURING;
39 private static final boolean USE_IORING_OP_READ;
40 private static final boolean USE_IORING_OP_WRITE;
41 static {
42 String s = System.getProperty("jdk.io_uring");
43 if ("".equals(s) || Boolean.parseBoolean(s)) {
44 USE_IOURING = true;
45 s = System.getProperty("jdk.io_uring.read");
46 USE_IORING_OP_READ = "".equals(s) || Boolean.parseBoolean(s);
47 s = System.getProperty("jdk.io_uring.write");
48 USE_IORING_OP_WRITE = "".equals(s) || Boolean.parseBoolean(s);
49 } else {
50 USE_IOURING = false;
51 USE_IORING_OP_READ = false;
52 USE_IORING_OP_WRITE = false;
53 }
54 }
55
56 DefaultPollerProvider(Poller.Mode mode) {
57 super(mode);
58 }
59
60 DefaultPollerProvider() {
61 this(ContinuationSupport.isSupported() && !JLA.isCustomDefaultVirtualThreadScheduler()
62 ? Poller.Mode.VTHREAD_POLLERS
63 : Poller.Mode.SYSTEM_THREADS);
64 }
65
66 @Override
67 int defaultReadPollers() {
68 int ncpus = Runtime.getRuntime().availableProcessors();
69 return switch (pollerMode()) {
70 case SYSTEM_THREADS -> Math.max(Integer.highestOneBit(ncpus / 4), 1);
71 case VTHREAD_POLLERS -> Math.min(Integer.highestOneBit(ncpus), 32);
72 default -> super.defaultReadPollers();
73 };
74 }
75
76 @Override
77 Poller readPoller(boolean subPoller) throws IOException {
78 Poller.Mode mode = pollerMode();
79 if (USE_IOURING) {
80 // read poller is system thread in SYSTEM_THREADS mode
81 boolean supportReadOps = USE_IORING_OP_READ
82 && ((mode == Poller.Mode.SYSTEM_THREADS) || subPoller);
83 return new IoUringPoller(mode, subPoller, true, supportReadOps);
84 } else {
85 return new EPollPoller(mode, subPoller, true);
86 }
87 }
88
89 @Override
90 Poller writePoller(boolean subPoller) throws IOException {
91 Poller.Mode mode = pollerMode();
92 if (USE_IOURING) {
93 // write poller is system thread in SYSTEM_THREADS and POLLER_PER_CARRIER modes
94 boolean supportWriteOps = USE_IORING_OP_WRITE
95 && ((mode != Poller.Mode.VTHREAD_POLLERS) || subPoller);
96 return new IoUringPoller(mode, subPoller, false, supportWriteOps);
97 } else {
98 return new EPollPoller(mode, subPoller, false);
99 }
100 }
101
102 @Override
103 boolean supportReadOps() {
104 return USE_IORING_OP_READ;
105 }
106
107 @Override
108 boolean supportWriteOps() {
109 return USE_IORING_OP_WRITE;
110 }
111 }