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1   /*
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3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.core.session;
21  
22  import java.net.SocketAddress;
23  import java.util.Set;
24  
25  import org.apache.mina.core.filterchain.IoFilter;
26  import org.apache.mina.core.filterchain.IoFilterChain;
27  import org.apache.mina.core.future.CloseFuture;
28  import org.apache.mina.core.future.ReadFuture;
29  import org.apache.mina.core.future.WriteFuture;
30  import org.apache.mina.core.service.IoAcceptor;
31  import org.apache.mina.core.service.IoConnector;
32  import org.apache.mina.core.service.IoHandler;
33  import org.apache.mina.core.service.IoService;
34  import org.apache.mina.core.service.TransportMetadata;
35  import org.apache.mina.core.write.WriteRequest;
36  import org.apache.mina.core.write.WriteRequestQueue;
37  
38  /**
39   * A handle which represents connection between two end-points regardless of
40   * transport types.
41   * <p/>
42   * {@link IoSession} provides user-defined attributes.  User-defined attributes
43   * are application-specific data which are associated with a session.
44   * It often contains objects that represents the state of a higher-level protocol
45   * and becomes a way to exchange data between filters and handlers.
46   * <p/>
47   * <h3>Adjusting Transport Type Specific Properties</h3>
48   * <p/>
49   * You can simply downcast the session to an appropriate subclass.
50   * </p>
51   * <p/>
52   * <h3>Thread Safety</h3>
53   * <p/>
54   * {@link IoSession} is thread-safe.  But please note that performing
55   * more than one {@link #write(Object)} calls at the same time will
56   * cause the {@link IoFilter#filterWrite(IoFilter.NextFilter,IoSession,WriteRequest)}
57   * to be executed simultaneously, and therefore you have to make sure the
58   * {@link IoFilter} implementations you're using are thread-safe, too.
59   * </p>
60   * <p/>
61   * <h3>Equality of Sessions</h3>
62   * TODO : The getId() method is totally wrong. We can't base
63   * a method which is designed to create a unique ID on the hashCode method.
64   * {@link #equals(Object)} and {@link #hashCode()} shall not be overriden
65   * to the default behavior that is defined in {@link Object}.
66   *
67   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
68   */
69  public interface IoSession {
70      /**
71       * @return a unique identifier for this session.  Every session has its own
72       * ID which is different from each other.
73       * 
74       * TODO : The way it's implemented does not guarantee that the contract is
75       * respected. It uses the HashCode() method which don't guarantee the key
76       * unicity.
77       */
78      long getId();
79  
80      /**
81       * @return the {@link IoService} which provides I/O service to this session.
82       */
83      IoService getService();
84  
85      /**
86       * @return the {@link IoHandler} which handles this session.
87       */
88      IoHandler getHandler();
89  
90      /**
91       * @return the configuration of this session.
92       */
93      IoSessionConfig getConfig();
94  
95      /**
96       * @return the filter chain that only affects this session.
97       */
98      IoFilterChain getFilterChain();
99  
100     
101     /**
102      * TODO Add method documentation
103      */
104     WriteRequestQueue getWriteRequestQueue();
105 
106     /**
107      * @return the {@link TransportMetadata} that this session runs on.
108      */
109     TransportMetadata getTransportMetadata();
110 
111     /**
112      * TODO This javadoc is wrong. The return tag should be short.
113      * 
114      * @return a {@link ReadFuture} which is notified when a new message is
115      * received, the connection is closed or an exception is caught.  This
116      * operation is especially useful when you implement a client application.
117      * TODO : Describe here how we enable this feature.
118      * However, please note that this operation is disabled by default and
119      * throw {@link IllegalStateException} because all received events must be
120      * queued somewhere to support this operation, possibly leading to memory
121      * leak.  This means you have to keep calling {@link #read()} once you
122      * enabled this operation.  To enable this operation, please call
123      * {@link IoSessionConfig#setUseReadOperation(boolean)} with <tt>true</tt>.
124      *
125      * @throws IllegalStateException if
126      * {@link IoSessionConfig#setUseReadOperation(boolean) useReadOperation}
127      * option has not been enabled.
128      */
129     ReadFuture read();
130 
131     /**
132      * Writes the specified <code>message</code> to remote peer.  This
133      * operation is asynchronous; {@link IoHandler#messageSent(IoSession,Object)}
134      * will be invoked when the message is actually sent to remote peer.
135      * You can also wait for the returned {@link WriteFuture} if you want
136      * to wait for the message actually written.
137      */
138     WriteFuture write(Object message);
139 
140     /**
141      * (Optional) Writes the specified <tt>message</tt> to the specified <tt>destination</tt>.
142      * This operation is asynchronous; {@link IoHandler#messageSent(IoSession, Object)}
143      * will be invoked when the message is actually sent to remote peer. You can
144      * also wait for the returned {@link WriteFuture} if you want to wait for
145      * the message actually written.
146      * <p>
147      * When you implement a client that receives a broadcast message from a server
148      * such as DHCP server, the client might need to send a response message for the
149      * broadcast message the server sent.  Because the remote address of the session
150      * is not the address of the server in case of broadcasting, there should be a
151      * way to specify the destination when you write the response message.
152      * This interface provides {@link #write(Object, SocketAddress)} method so you
153      * can specify the destination.
154      *
155      * @param destination <tt>null</tt> if you want the message sent to the
156      *                    default remote address
157      *
158      * @throws UnsupportedOperationException if this operation is not supported
159      */
160     WriteFuture write(Object message, SocketAddress destination);
161 
162     /**
163      * Closes this session immediately or after all queued write requests
164      * are flushed.  This operation is asynchronous.  Wait for the returned
165      * {@link CloseFuture} if you want to wait for the session actually closed.
166      *
167      * @param immediately {@code true} to close this session immediately
168      *                    (i.e. {@link #close()}).
169      *                    {@code false} to close this session after all queued
170      *                    write requests are flushed (i.e. {@link #closeOnFlush()}).
171      */
172     CloseFuture close(boolean immediately);
173     
174     /**
175      * Closes this session after all queued write requests
176      * are flushed. This operation is asynchronous.  Wait for the returned
177      * {@link CloseFuture} if you want to wait for the session actually closed.
178      * @deprecated use {@link IoSession#close(boolean)}
179      */
180     @Deprecated CloseFuture close();
181 
182     /**
183      * Returns an attachment of this session.
184      * This method is identical with <tt>getAttribute( "" )</tt>.
185      *
186      * @deprecated Use {@link #getAttribute(Object)} instead.
187      */
188     @Deprecated Object getAttachment();
189 
190     /**
191      * Sets an attachment of this session.
192      * This method is identical with <tt>setAttribute( "", attachment )</tt>.
193      *
194      * @return Old attachment.  <tt>null</tt> if it is new.
195      * @deprecated Use {@link #setAttribute(Object, Object)} instead.
196      */
197     @Deprecated Object setAttachment(Object attachment);
198 
199     /**
200      * Returns the value of the user-defined attribute of this session.
201      *
202      * @param key the key of the attribute
203      * @return <tt>null</tt> if there is no attribute with the specified key
204      */
205     Object getAttribute(Object key);
206 
207     /**
208      * Returns the value of user defined attribute associated with the
209      * specified key.  If there's no such attribute, the specified default
210      * value is associated with the specified key, and the default value is
211      * returned.  This method is same with the following code except that the
212      * operation is performed atomically.
213      * <pre>
214      * if (containsAttribute(key)) {
215      *     return getAttribute(key);
216      * } else {
217      *     setAttribute(key, defaultValue);
218      *     return defaultValue;
219      * }
220      * </pre>
221      */
222     Object getAttribute(Object key, Object defaultValue);
223 
224     /**
225      * Sets a user-defined attribute.
226      *
227      * @param key   the key of the attribute
228      * @param value the value of the attribute
229      * @return The old value of the attribute.  <tt>null</tt> if it is new.
230      */
231     Object setAttribute(Object key, Object value);
232 
233     /**
234      * Sets a user defined attribute without a value.  This is useful when
235      * you just want to put a 'mark' attribute.  Its value is set to
236      * {@link Boolean#TRUE}.
237      *
238      * @param key the key of the attribute
239      * @return The old value of the attribute.  <tt>null</tt> if it is new.
240      */
241     Object setAttribute(Object key);
242 
243     /**
244      * Sets a user defined attribute if the attribute with the specified key
245      * is not set yet.  This method is same with the following code except
246      * that the operation is performed atomically.
247      * <pre>
248      * if (containsAttribute(key)) {
249      *     return getAttribute(key);
250      * } else {
251      *     return setAttribute(key, value);
252      * }
253      * </pre>
254      */
255     Object setAttributeIfAbsent(Object key, Object value);
256 
257     /**
258      * Sets a user defined attribute without a value if the attribute with
259      * the specified key is not set yet.  This is useful when you just want to
260      * put a 'mark' attribute.  Its value is set to {@link Boolean#TRUE}.
261      * This method is same with the following code except that the operation
262      * is performed atomically.
263      * <pre>
264      * if (containsAttribute(key)) {
265      *     return getAttribute(key);  // might not always be Boolean.TRUE.
266      * } else {
267      *     return setAttribute(key);
268      * }
269      * </pre>
270      */
271     Object setAttributeIfAbsent(Object key);
272 
273     /**
274      * Removes a user-defined attribute with the specified key.
275      *
276      * @return The old value of the attribute.  <tt>null</tt> if not found.
277      */
278     Object removeAttribute(Object key);
279 
280     /**
281      * Removes a user defined attribute with the specified key if the current
282      * attribute value is equal to the specified value.  This method is same
283      * with the following code except that the operation is performed
284      * atomically.
285      * <pre>
286      * if (containsAttribute(key) && getAttribute(key).equals(value)) {
287      *     removeAttribute(key);
288      *     return true;
289      * } else {
290      *     return false;
291      * }
292      * </pre>
293      */
294     boolean removeAttribute(Object key, Object value);
295 
296     /**
297      * Replaces a user defined attribute with the specified key if the
298      * value of the attribute is equals to the specified old value.
299      * This method is same with the following code except that the operation
300      * is performed atomically.
301      * <pre>
302      * if (containsAttribute(key) && getAttribute(key).equals(oldValue)) {
303      *     setAttribute(key, newValue);
304      *     return true;
305      * } else {
306      *     return false;
307      * }
308      * </pre>
309      */
310     boolean replaceAttribute(Object key, Object oldValue, Object newValue);
311 
312     /**
313      * Returns <tt>true</tt> if this session contains the attribute with
314      * the specified <tt>key</tt>.
315      */
316     boolean containsAttribute(Object key);
317 
318     /**
319      * Returns the set of keys of all user-defined attributes.
320      */
321     Set<Object> getAttributeKeys();
322 
323     /**
324      * Returns <code>true</code> if this session is connected with remote peer.
325      */
326     boolean isConnected();
327 
328     /**
329      * Returns <code>true</tt> if and only if this session is being closed
330      * (but not disconnected yet) or is closed.
331      */
332     boolean isClosing();
333 
334     /**
335      * Returns the {@link CloseFuture} of this session.  This method returns
336      * the same instance whenever user calls it.
337      */
338     CloseFuture getCloseFuture();
339 
340     /**
341      * Returns the socket address of remote peer.
342      */
343     SocketAddress getRemoteAddress();
344 
345     /**
346      * Returns the socket address of local machine which is associated with this
347      * session.
348      */
349     SocketAddress getLocalAddress();
350 
351     /**
352      * Returns the socket address of the {@link IoService} listens to to manage
353      * this session.  If this session is managed by {@link IoAcceptor}, it
354      * returns the {@link SocketAddress} which is specified as a parameter of
355      * {@link IoAcceptor#bind()}.  If this session is managed by
356      * {@link IoConnector}, this method returns the same address with
357      * that of {@link #getRemoteAddress()}.
358      */
359     SocketAddress getServiceAddress();
360 
361     /**
362      * 
363      * TODO setWriteRequestQueue.
364      *
365      * @param writeRequestQueue
366      */
367     void setCurrentWriteRequest(WriteRequest currentWriteRequest);
368     
369     /**
370      * Suspends read operations for this session.
371      */
372     void suspendRead();
373 
374     /**
375      * Suspends write operations for this session.
376      */
377     void suspendWrite();
378 
379     /**
380      * Resumes read operations for this session.
381      */
382     void resumeRead();
383 
384     /**
385      * Resumes write operations for this session.
386      */
387     void resumeWrite();
388     
389     /**
390      * Is read operation is suspended for this session. 
391      * @return <code>true</code> if suspended
392      */
393     boolean isReadSuspended();
394     
395     /**
396      * Is write operation is suspended for this session.
397      * @return <code>true</code> if suspended
398      */
399     boolean isWriteSuspended();
400     
401     /**
402      * Update all statistical properties related with throughput assuming
403      * the specified time is the current time.  By default this method returns
404      * silently without updating the throughput properties if they were
405      * calculated already within last
406      * {@link IoSessionConfig#getThroughputCalculationInterval() calculation interval}.
407      * If, however, <tt>force</tt> is specified as <tt>true</tt>, this method
408      * updates the throughput properties immediately.
409 
410      * @param currentTime the current time in milliseconds
411      */
412     void updateThroughput(long currentTime, boolean force);
413     
414     /**
415      * Returns the total number of bytes which were read from this session.
416      */
417     long getReadBytes();
418 
419     /**
420      * Returns the total number of bytes which were written to this session.
421      */
422     long getWrittenBytes();
423 
424     /**
425      * Returns the total number of messages which were read and decoded from this session.
426      */
427     long getReadMessages();
428 
429     /**
430      * Returns the total number of messages which were written and encoded by this session.
431      */
432     long getWrittenMessages();
433 
434     /**
435      * Returns the number of read bytes per second.
436      */
437     double getReadBytesThroughput();
438 
439     /**
440      * Returns the number of written bytes per second.
441      */
442     double getWrittenBytesThroughput();
443 
444     /**
445      * Returns the number of read messages per second.
446      */
447     double getReadMessagesThroughput();
448 
449     /**
450      * Returns the number of written messages per second.
451      */
452     double getWrittenMessagesThroughput();
453 
454     /**
455      * Returns the number of messages which are scheduled to be written to this session.
456      */
457     int getScheduledWriteMessages();
458 
459     /**
460      * Returns the number of bytes which are scheduled to be written to this
461      * session.
462      */
463     long getScheduledWriteBytes();
464 
465     /**
466      * Returns the message which is being written by {@link IoService}.
467      * @return <tt>null</tt> if and if only no message is being written
468      */
469     Object getCurrentWriteMessage();
470 
471     /**
472      * Returns the {@link WriteRequest} which is being processed by
473      * {@link IoService}.
474      *
475      * @return <tt>null</tt> if and if only no message is being written
476      */
477     WriteRequest getCurrentWriteRequest();
478 
479     /**
480      * @return the session's creation time in milliseconds
481      */
482     long getCreationTime();
483 
484     /**
485      * Returns the time in millis when I/O occurred lastly.
486      */
487     long getLastIoTime();
488 
489     /**
490      * Returns the time in millis when read operation occurred lastly.
491      */
492     long getLastReadTime();
493 
494     /**
495      * Returns the time in millis when write operation occurred lastly.
496      */
497     long getLastWriteTime();
498 
499     /**
500      * Returns <code>true</code> if this session is idle for the specified
501      * {@link IdleStatus}.
502      */
503     boolean isIdle(IdleStatus status);
504 
505     /**
506      * Returns <code>true</code> if this session is {@link IdleStatus#READER_IDLE}.
507      * @see #isIdle(IdleStatus)
508      */
509     boolean isReaderIdle();
510 
511     /**
512      * Returns <code>true</code> if this session is {@link IdleStatus#WRITER_IDLE}.
513      * @see #isIdle(IdleStatus)
514      */
515     boolean isWriterIdle();
516 
517     /**
518      * Returns <code>true</code> if this session is {@link IdleStatus#BOTH_IDLE}.
519      * @see #isIdle(IdleStatus)
520      */
521     boolean isBothIdle();
522 
523     /**
524      * Returns the number of the fired continuous <tt>sessionIdle</tt> events
525      * for the specified {@link IdleStatus}.
526      * <p/>
527      * If <tt>sessionIdle</tt> event is fired first after some time after I/O,
528      * <tt>idleCount</tt> becomes <tt>1</tt>.  <tt>idleCount</tt> resets to
529      * <tt>0</tt> if any I/O occurs again, otherwise it increases to
530      * <tt>2</tt> and so on if <tt>sessionIdle</tt> event is fired again without
531      * any I/O between two (or more) <tt>sessionIdle</tt> events.
532      */
533     int getIdleCount(IdleStatus status);
534 
535     /**
536      * Returns the number of the fired continuous <tt>sessionIdle</tt> events
537      * for {@link IdleStatus#READER_IDLE}.
538      * @see #getIdleCount(IdleStatus)
539      */
540     int getReaderIdleCount();
541 
542     /**
543      * Returns the number of the fired continuous <tt>sessionIdle</tt> events
544      * for {@link IdleStatus#WRITER_IDLE}.
545      * @see #getIdleCount(IdleStatus)
546      */
547     int getWriterIdleCount();
548 
549     /**
550      * Returns the number of the fired continuous <tt>sessionIdle</tt> events
551      * for {@link IdleStatus#BOTH_IDLE}.
552      * @see #getIdleCount(IdleStatus)
553      */
554     int getBothIdleCount();
555 
556     /**
557      * Returns the time in milliseconds when the last <tt>sessionIdle</tt> event
558      * is fired for the specified {@link IdleStatus}.
559      */
560     long getLastIdleTime(IdleStatus status);
561 
562 
563     /**
564      * Returns the time in milliseconds when the last <tt>sessionIdle</tt> event
565      * is fired for {@link IdleStatus#READER_IDLE}.
566      * @see #getLastIdleTime(IdleStatus)
567      */
568     long getLastReaderIdleTime();
569 
570     /**
571      * Returns the time in milliseconds when the last <tt>sessionIdle</tt> event
572      * is fired for {@link IdleStatus#WRITER_IDLE}.
573      * @see #getLastIdleTime(IdleStatus)
574      */
575     long getLastWriterIdleTime();
576 
577     /**
578      * Returns the time in milliseconds when the last <tt>sessionIdle</tt> event
579      * is fired for {@link IdleStatus#BOTH_IDLE}.
580      * @see #getLastIdleTime(IdleStatus)
581      */
582     long getLastBothIdleTime();
583 }