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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

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1+/*
2+ * Copyright (c) 2000, 2008, 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 java.nio.channels;
27+
28+import java.io.IOException;
29+import java.nio.channels.spi.AbstractInterruptibleChannel;
30+import java.nio.channels.spi.SelectorProvider;
31+
32+
33+/**
34+ * A channel that can be multiplexed via a {@link Selector}.
35+ *
36+ * <p> In order to be used with a selector, an instance of this class must
37+ * first be <i>registered</i> via the {@link #register(Selector,int,Object)
38+ * register} method. This method returns a new {@link SelectionKey} object
39+ * that represents the channel's registration with the selector.
40+ *
41+ * <p> Once registered with a selector, a channel remains registered until it
42+ * is <i>deregistered</i>. This involves deallocating whatever resources were
43+ * allocated to the channel by the selector.
44+ *
45+ * <p> A channel cannot be deregistered directly; instead, the key representing
46+ * its registration must be <i>cancelled</i>. Cancelling a key requests that
47+ * the channel be deregistered during the selector's next selection operation.
48+ * A key may be cancelled explicitly by invoking its {@link
49+ * SelectionKey#cancel() cancel} method. All of a channel's keys are cancelled
50+ * implicitly when the channel is closed, whether by invoking its {@link
51+ * Channel#close close} method or by interrupting a thread blocked in an I/O
52+ * operation upon the channel.
53+ *
54+ * <p> If the selector itself is closed then the channel will be deregistered,
55+ * and the key representing its registration will be invalidated, without
56+ * further delay.
57+ *
58+ * <p> A channel may be registered at most once with any particular selector.
59+ *
60+ * <p> Whether or not a channel is registered with one or more selectors may be
61+ * determined by invoking the {@link #isRegistered isRegistered} method.
62+ *
63+ * <p> Selectable channels are safe for use by multiple concurrent
64+ * threads. </p>
65+ *
66+ *
67+ * <a name="bm">
68+ * <h4>Blocking mode</h4>
69+ *
70+ * A selectable channel is either in <i>blocking</i> mode or in
71+ * <i>non-blocking</i> mode. In blocking mode, every I/O operation invoked
72+ * upon the channel will block until it completes. In non-blocking mode an I/O
73+ * operation will never block and may transfer fewer bytes than were requested
74+ * or possibly no bytes at all. The blocking mode of a selectable channel may
75+ * be determined by invoking its {@link #isBlocking isBlocking} method.
76+ *
77+ * <p> Newly-created selectable channels are always in blocking mode.
78+ * Non-blocking mode is most useful in conjunction with selector-based
79+ * multiplexing. A channel must be placed into non-blocking mode before being
80+ * registered with a selector, and may not be returned to blocking mode until
81+ * it has been deregistered.
82+ *
83+ *
84+ * @author Mark Reinhold
85+ * @author JSR-51 Expert Group
86+ * @since 1.4
87+ *
88+ * @see SelectionKey
89+ * @see Selector
90+ */
91+
92+public abstract class SelectableChannel
93+ extends AbstractInterruptibleChannel
94+ implements Channel
95+{
96+
97+ /**
98+ * Initializes a new instance of this class.
99+ */
100+ protected SelectableChannel() { }
101+
102+ /**
103+ * Returns the provider that created this channel.
104+ *
105+ * @return The provider that created this channel
106+ */
107+ public abstract SelectorProvider provider();
108+
109+ /**
110+ * Returns an <a href="SelectionKey.html#opsets">operation set</a>
111+ * identifying this channel's supported operations. The bits that are set
112+ * in this integer value denote exactly the operations that are valid for
113+ * this channel. This method always returns the same value for a given
114+ * concrete channel class. </p>
115+ *
116+ * @return The valid-operation set
117+ */
118+ public abstract int validOps();
119+
120+ // Internal state:
121+ // keySet, may be empty but is never null, typ. a tiny array
122+ // boolean isRegistered, protected by key set
123+ // regLock, lock object to prevent duplicate registrations
124+ // boolean isBlocking, protected by regLock
125+
126+ /**
127+ * Tells whether or not this channel is currently registered with any
128+ * selectors. A newly-created channel is not registered.
129+ *
130+ * <p> Due to the inherent delay between key cancellation and channel
131+ * deregistration, a channel may remain registered for some time after all
132+ * of its keys have been cancelled. A channel may also remain registered
133+ * for some time after it is closed. </p>
134+ *
135+ * @return <tt>true</tt> if, and only if, this channel is registered
136+ */
137+ public abstract boolean isRegistered();
138+ //
139+ // sync(keySet) { return isRegistered; }
140+
141+ /**
142+ * Retrieves the key representing the channel's registration with the given
143+ * selector. </p>
144+ *
145+ * @return The key returned when this channel was last registered with the
146+ * given selector, or <tt>null</tt> if this channel is not
147+ * currently registered with that selector
148+ */
149+ public abstract SelectionKey keyFor(Selector sel);
150+ //
151+ // sync(keySet) { return findKey(sel); }
152+
153+ /**
154+ * Registers this channel with the given selector, returning a selection
155+ * key.
156+ *
157+ * <p> If this channel is currently registered with the given selector then
158+ * the selection key representing that registration is returned. The key's
159+ * interest set will have been changed to <tt>ops</tt>, as if by invoking
160+ * the {@link SelectionKey#interestOps(int) interestOps(int)} method. If
161+ * the <tt>att</tt> argument is not <tt>null</tt> then the key's attachment
162+ * will have been set to that value. A {@link CancelledKeyException} will
163+ * be thrown if the key has already been cancelled.
164+ *
165+ * <p> Otherwise this channel has not yet been registered with the given
166+ * selector, so it is registered and the resulting new key is returned.
167+ * The key's initial interest set will be <tt>ops</tt> and its attachment
168+ * will be <tt>att</tt>.
169+ *
170+ * <p> This method may be invoked at any time. If this method is invoked
171+ * while another invocation of this method or of the {@link
172+ * #configureBlocking(boolean) configureBlocking} method is in progress
173+ * then it will first block until the other operation is complete. This
174+ * method will then synchronize on the selector's key set and therefore may
175+ * block if invoked concurrently with another registration or selection
176+ * operation involving the same selector. </p>
177+ *
178+ * <p> If this channel is closed while this operation is in progress then
179+ * the key returned by this method will have been cancelled and will
180+ * therefore be invalid. </p>
181+ *
182+ * @param sel
183+ * The selector with which this channel is to be registered
184+ *
185+ * @param ops
186+ * The interest set for the resulting key
187+ *
188+ * @param att
189+ * The attachment for the resulting key; may be <tt>null</tt>
190+ *
191+ * @throws ClosedChannelException
192+ * If this channel is closed
193+ *
194+ * @throws ClosedSelectorException
195+ * If the selector is closed
196+ *
197+ * @throws IllegalBlockingModeException
198+ * If this channel is in blocking mode
199+ *
200+ * @throws IllegalSelectorException
201+ * If this channel was not created by the same provider
202+ * as the given selector
203+ *
204+ * @throws CancelledKeyException
205+ * If this channel is currently registered with the given selector
206+ * but the corresponding key has already been cancelled
207+ *
208+ * @throws IllegalArgumentException
209+ * If a bit in the <tt>ops</tt> set does not correspond to an
210+ * operation that is supported by this channel, that is, if
211+ * <tt>set & ~validOps() != 0</tt>
212+ *
213+ * @return A key representing the registration of this channel with
214+ * the given selector
215+ */
216+ public abstract SelectionKey register(Selector sel, int ops, Object att)
217+ throws ClosedChannelException;
218+ //
219+ // sync(regLock) {
220+ // sync(keySet) { look for selector }
221+ // if (channel found) { set interest ops -- may block in selector;
222+ // return key; }
223+ // create new key -- may block somewhere in selector;
224+ // sync(keySet) { add key; }
225+ // attach(attachment);
226+ // return key;
227+ // }
228+
229+ /**
230+ * Registers this channel with the given selector, returning a selection
231+ * key.
232+ *
233+ * <p> An invocation of this convenience method of the form
234+ *
235+ * <blockquote><tt>sc.register(sel, ops)</tt></blockquote>
236+ *
237+ * behaves in exactly the same way as the invocation
238+ *
239+ * <blockquote><tt>sc.{@link
240+ * #register(java.nio.channels.Selector,int,java.lang.Object)
241+ * register}(sel, ops, null)</tt></blockquote>
242+ *
243+ * @param sel
244+ * The selector with which this channel is to be registered
245+ *
246+ * @param ops
247+ * The interest set for the resulting key
248+ *
249+ * @throws ClosedChannelException
250+ * If this channel is closed
251+ *
252+ * @throws ClosedSelectorException
253+ * If the selector is closed
254+ *
255+ * @throws IllegalBlockingModeException
256+ * If this channel is in blocking mode
257+ *
258+ * @throws IllegalSelectorException
259+ * If this channel was not created by the same provider
260+ * as the given selector
261+ *
262+ * @throws CancelledKeyException
263+ * If this channel is currently registered with the given selector
264+ * but the corresponding key has already been cancelled
265+ *
266+ * @throws IllegalArgumentException
267+ * If a bit in <tt>ops</tt> does not correspond to an operation
268+ * that is supported by this channel, that is, if <tt>set &
269+ * ~validOps() != 0</tt>
270+ *
271+ * @return A key representing the registration of this channel with
272+ * the given selector
273+ */
274+ public final SelectionKey register(Selector sel, int ops)
275+ throws ClosedChannelException
276+ {
277+ return register(sel, ops, null);
278+ }
279+
280+ /**
281+ * Adjusts this channel's blocking mode.
282+ *
283+ * <p> If this channel is registered with one or more selectors then an
284+ * attempt to place it into blocking mode will cause an {@link
285+ * IllegalBlockingModeException} to be thrown.
286+ *
287+ * <p> This method may be invoked at any time. The new blocking mode will
288+ * only affect I/O operations that are initiated after this method returns.
289+ * For some implementations this may require blocking until all pending I/O
290+ * operations are complete.
291+ *
292+ * <p> If this method is invoked while another invocation of this method or
293+ * of the {@link #register(Selector, int) register} method is in progress
294+ * then it will first block until the other operation is complete. </p>
295+ *
296+ * @param block If <tt>true</tt> then this channel will be placed in
297+ * blocking mode; if <tt>false</tt> then it will be placed
298+ * non-blocking mode
299+ *
300+ * @return This selectable channel
301+ *
302+ * @throws ClosedChannelException
303+ * If this channel is closed
304+ *
305+ * @throws IllegalBlockingModeException
306+ * If <tt>block</tt> is <tt>true</tt> and this channel is
307+ * registered with one or more selectors
308+ *
309+ * @throws IOException
310+ * If an I/O error occurs
311+ */
312+ public abstract SelectableChannel configureBlocking(boolean block)
313+ throws IOException;
314+ //
315+ // sync(regLock) {
316+ // sync(keySet) { throw IBME if block && isRegistered; }
317+ // change mode;
318+ // }
319+
320+ /**
321+ * Tells whether or not every I/O operation on this channel will block
322+ * until it completes. A newly-created channel is always in blocking mode.
323+ *
324+ * <p> If this channel is closed then the value returned by this method is
325+ * not specified. </p>
326+ *
327+ * @return <tt>true</tt> if, and only if, this channel is in blocking mode
328+ */
329+ public abstract boolean isBlocking();
330+
331+ /**
332+ * Retrieves the object upon which the {@link #configureBlocking
333+ * configureBlocking} and {@link #register register} methods synchronize.
334+ * This is often useful in the implementation of adaptors that require a
335+ * specific blocking mode to be maintained for a short period of time.
336+ * </p>
337+ *
338+ * @return The blocking-mode lock object
339+ */
340+ public abstract Object blockingLock();
341+
342+}