1 /*
2 * Copyright (c) 2000, 2017, 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 sun.nio.ch;
27
28 import java.io.IOException;
29 import java.net.SocketException;
30 import java.nio.channels.ClosedSelectorException;
31 import java.nio.channels.IllegalSelectorException;
32 import java.nio.channels.SelectionKey;
33 import java.nio.channels.Selector;
34 import java.nio.channels.spi.AbstractSelectableChannel;
35 import java.nio.channels.spi.AbstractSelector;
36 import java.nio.channels.spi.SelectorProvider;
37 import java.util.Collections;
38 import java.util.HashSet;
39 import java.util.Iterator;
40 import java.util.Set;
41
42
43 /**
44 * Base Selector implementation class.
45 */
46
47 public abstract class SelectorImpl
48 extends AbstractSelector
49 {
50
51 // The set of keys with data ready for an operation
52 protected Set<SelectionKey> selectedKeys;
53
54 // The set of keys registered with this Selector
55 protected HashSet<SelectionKey> keys;
56
57 // Public views of the key sets
58 private Set<SelectionKey> publicKeys; // Immutable
59 private Set<SelectionKey> publicSelectedKeys; // Removal allowed, but not addition
60
61 protected SelectorImpl(SelectorProvider sp) {
62 super(sp);
63 keys = new HashSet<>();
64 selectedKeys = new HashSet<>();
65 publicKeys = Collections.unmodifiableSet(keys);
66 publicSelectedKeys = Util.ungrowableSet(selectedKeys);
67 }
68
69 public Set<SelectionKey> keys() {
70 if (!isOpen())
71 throw new ClosedSelectorException();
72 return publicKeys;
73 }
74
75 public Set<SelectionKey> selectedKeys() {
76 if (!isOpen())
77 throw new ClosedSelectorException();
78 return publicSelectedKeys;
79 }
80
81 protected abstract int doSelect(long timeout) throws IOException;
82
83 private int lockAndDoSelect(long timeout) throws IOException {
84 synchronized (this) {
85 if (!isOpen())
86 throw new ClosedSelectorException();
87 synchronized (publicKeys) {
88 synchronized (publicSelectedKeys) {
89 return doSelect(timeout);
90 }
91 }
92 }
93 }
94
95 public int select(long timeout)
96 throws IOException
97 {
98 if (timeout < 0)
99 throw new IllegalArgumentException("Negative timeout");
100 return lockAndDoSelect((timeout == 0) ? -1 : timeout);
101 }
102
103 public int select() throws IOException {
104 return select(0);
105 }
106
107 public int selectNow() throws IOException {
108 return lockAndDoSelect(0);
109 }
110
111 public void implCloseSelector() throws IOException {
112 wakeup();
113 synchronized (this) {
114 synchronized (publicKeys) {
115 synchronized (publicSelectedKeys) {
116 implClose();
117 }
118 }
119 }
120 }
121
122 protected abstract void implClose() throws IOException;
123
124 public void putEventOps(SelectionKeyImpl sk, int ops) { }
125
126 protected final SelectionKey register(AbstractSelectableChannel ch,
127 int ops,
128 Object attachment)
129 {
130 if (!(ch instanceof SelChImpl))
131 throw new IllegalSelectorException();
132 SelectionKeyImpl k = new SelectionKeyImpl((SelChImpl)ch, this);
133 k.attach(attachment);
134 synchronized (publicKeys) {
135 implRegister(k);
136 }
137 k.interestOps(ops);
138 return k;
139 }
140
141 protected abstract void implRegister(SelectionKeyImpl ski);
142
143 void processDeregisterQueue() throws IOException {
144 // Precondition: Synchronized on this, keys, and selectedKeys
145 Set<SelectionKey> cks = cancelledKeys();
146 synchronized (cks) {
147 if (!cks.isEmpty()) {
148 Iterator<SelectionKey> i = cks.iterator();
149 while (i.hasNext()) {
150 SelectionKeyImpl ski = (SelectionKeyImpl)i.next();
151 try {
152 implDereg(ski);
153 } catch (SocketException se) {
154 throw new IOException("Error deregistering key", se);
155 } finally {
156 i.remove();
157 }
158 }
159 }
160 }
161 }
162
163 protected abstract void implDereg(SelectionKeyImpl ski) throws IOException;
164
165 public abstract Selector wakeup();
166
167 }