1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 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.polling; 21 22 import java.net.SocketAddress; 23 import java.util.Collections; 24 import java.util.HashMap; 25 import java.util.HashSet; 26 import java.util.Iterator; 27 import java.util.List; 28 import java.util.Map; 29 import java.util.Queue; 30 import java.util.Set; 31 import java.util.concurrent.ConcurrentLinkedQueue; 32 import java.util.concurrent.Executor; 33 import java.util.concurrent.Executors; 34 35 import org.apache.mina.core.RuntimeIoException; 36 import org.apache.mina.core.filterchain.IoFilter; 37 import org.apache.mina.core.future.IoFuture; 38 import org.apache.mina.core.service.AbstractIoAcceptor; 39 import org.apache.mina.core.service.IoAcceptor; 40 import org.apache.mina.core.service.IoHandler; 41 import org.apache.mina.core.service.IoProcessor; 42 import org.apache.mina.core.service.SimpleIoProcessorPool; 43 import org.apache.mina.core.session.AbstractIoSession; 44 import org.apache.mina.core.session.IoSession; 45 import org.apache.mina.core.session.IoSessionConfig; 46 import org.apache.mina.transport.socket.nio.NioSocketAcceptor; 47 import org.apache.mina.util.ExceptionMonitor; 48 49 /** 50 * A base class for implementing transport using a polling strategy. The 51 * underlying sockets will be checked in an active loop and woke up when an 52 * socket needed to be processed. This class handle the logic behind binding, 53 * accepting and disposing the server sockets. An {@link Executor} will be used 54 * for running client accepting and an {@link AbstractPollingIoProcessor} will 55 * be used for processing client I/O operations like reading, writing and 56 * closing. 57 * 58 * All the low level methods for binding, accepting, closing need to be provided 59 * by the subclassing implementation. 60 * 61 * @see NioSocketAcceptor for a example of implementation 62 * 63 * @author The Apache MINA Project (dev@mina.apache.org) 64 * @version $Rev: 751504 $, $Date: 2008-06-26 17:58:30 +0200 (jeu, 26 jun 2008) 65 * $ 66 */ 67 public abstract class AbstractPollingIoAcceptor<T extends AbstractIoSession, H> 68 extends AbstractIoAcceptor { 69 70 private final IoProcessor<T> processor; 71 72 private final boolean createdProcessor; 73 74 private final Object lock = new Object(); 75 76 private final Queue<AcceptorOperationFuture> registerQueue = new ConcurrentLinkedQueue<AcceptorOperationFuture>(); 77 78 private final Queue<AcceptorOperationFuture> cancelQueue = new ConcurrentLinkedQueue<AcceptorOperationFuture>(); 79 80 private final Map<SocketAddress, H> boundHandles = Collections 81 .synchronizedMap(new HashMap<SocketAddress, H>()); 82 83 private final ServiceOperationFuture disposalFuture = new ServiceOperationFuture(); 84 85 /** A flag set when the acceptor has been created and initialized */ 86 private volatile boolean selectable; 87 88 /** The thread responsible of accepting incoming requests */ 89 private Acceptor acceptor; 90 91 /** 92 * Constructor for {@link AbstractPollingIoAcceptor}. You need to provide a default 93 * session configuration, a class of {@link IoProcessor} which will be instantiated in a 94 * {@link SimpleIoProcessorPool} for better scaling in multiprocessor systems. The default 95 * pool size will be used. 96 * 97 * @see SimpleIoProcessorPool 98 * 99 * @param sessionConfig 100 * the default configuration for the managed {@link IoSession} 101 * @param processorClass a {@link Class} of {@link IoProcessor} for the associated {@link IoSession} 102 * type. 103 */ 104 protected AbstractPollingIoAcceptor(IoSessionConfig sessionConfig, 105 Class<? extends IoProcessor<T>> processorClass) { 106 this(sessionConfig, null, new SimpleIoProcessorPool<T>(processorClass), 107 true); 108 } 109 110 /** 111 * Constructor for {@link AbstractPollingIoAcceptor}. You need to provide a default 112 * session configuration, a class of {@link IoProcessor} which will be instantiated in a 113 * {@link SimpleIoProcessorPool} for using multiple thread for better scaling in multiprocessor 114 * systems. 115 * 116 * @see SimpleIoProcessorPool 117 * 118 * @param sessionConfig 119 * the default configuration for the managed {@link IoSession} 120 * @param processorClass a {@link Class} of {@link IoProcessor} for the associated {@link IoSession} 121 * type. 122 * @param processorCount the amount of processor to instantiate for the pool 123 */ 124 protected AbstractPollingIoAcceptor(IoSessionConfig sessionConfig, 125 Class<? extends IoProcessor<T>> processorClass, int processorCount) { 126 this(sessionConfig, null, new SimpleIoProcessorPool<T>(processorClass, 127 processorCount), true); 128 } 129 130 /** 131 * Constructor for {@link AbstractPollingIoAcceptor}. You need to provide a default 132 * session configuration, a default {@link Executor} will be created using 133 * {@link Executors#newCachedThreadPool()}. 134 * 135 * {@see AbstractIoService#AbstractIoService(IoSessionConfig, Executor)} 136 * 137 * @param sessionConfig 138 * the default configuration for the managed {@link IoSession} 139 * @param processor the {@link IoProcessor} for processing the {@link IoSession} of this transport, triggering 140 * events to the bound {@link IoHandler} and processing the chains of {@link IoFilter} 141 */ 142 protected AbstractPollingIoAcceptor(IoSessionConfig sessionConfig, 143 IoProcessor<T> processor) { 144 this(sessionConfig, null, processor, false); 145 } 146 147 /** 148 * Constructor for {@link AbstractPollingIoAcceptor}. You need to provide a default 149 * session configuration and an {@link Executor} for handling I/O events. If a 150 * null {@link Executor} is provided, a default one will be created using 151 * {@link Executors#newCachedThreadPool()}. 152 * 153 * {@see AbstractIoService#AbstractIoService(IoSessionConfig, Executor)} 154 * 155 * @param sessionConfig 156 * the default configuration for the managed {@link IoSession} 157 * @param executor 158 * the {@link Executor} used for handling asynchronous execution of I/O 159 * events. Can be <code>null</code>. 160 * @param processor the {@link IoProcessor} for processing the {@link IoSession} of this transport, triggering 161 * events to the bound {@link IoHandler} and processing the chains of {@link IoFilter} 162 */ 163 protected AbstractPollingIoAcceptor(IoSessionConfig sessionConfig, 164 Executor executor, IoProcessor<T> processor) { 165 this(sessionConfig, executor, processor, false); 166 } 167 168 /** 169 * Constructor for {@link AbstractPollingIoAcceptor}. You need to provide a default 170 * session configuration and an {@link Executor} for handling I/O events. If a 171 * null {@link Executor} is provided, a default one will be created using 172 * {@link Executors#newCachedThreadPool()}. 173 * 174 * {@see AbstractIoService#AbstractIoService(IoSessionConfig, Executor)} 175 * 176 * @param sessionConfig 177 * the default configuration for the managed {@link IoSession} 178 * @param executor 179 * the {@link Executor} used for handling asynchronous execution of I/O 180 * events. Can be <code>null</code>. 181 * @param processor the {@link IoProcessor} for processing the {@link IoSession} of 182 * this transport, triggering events to the bound {@link IoHandler} and processing 183 * the chains of {@link IoFilter} 184 * @param createdProcessor tagging the processor as automatically created, so it 185 * will be automatically disposed 186 */ 187 private AbstractPollingIoAcceptor(IoSessionConfig sessionConfig, 188 Executor executor, IoProcessor<T> processor, 189 boolean createdProcessor) { 190 super(sessionConfig, executor); 191 192 if (processor == null) { 193 throw new NullPointerException("processor"); 194 } 195 196 this.processor = processor; 197 this.createdProcessor = createdProcessor; 198 199 try { 200 // Initialize the selector 201 init(); 202 203 // The selector is now ready, we can switch the 204 // flag to true so that incoming connection can be accepted 205 selectable = true; 206 } catch (RuntimeException e) { 207 throw e; 208 } catch (Exception e) { 209 throw new RuntimeIoException("Failed to initialize.", e); 210 } finally { 211 if (!selectable) { 212 try { 213 destroy(); 214 } catch (Exception e) { 215 ExceptionMonitor.getInstance().exceptionCaught(e); 216 } 217 } 218 } 219 } 220 221 /** 222 * Initialize the polling system, will be called at construction time. 223 * @throws Exception any exception thrown by the underlying system calls 224 */ 225 protected abstract void init() throws Exception; 226 227 /** 228 * Destroy the polling system, will be called when this {@link IoAcceptor} 229 * implementation will be disposed. 230 * @throws Exception any exception thrown by the underlying systems calls 231 */ 232 protected abstract void destroy() throws Exception; 233 234 /** 235 * Check for acceptable connections, interrupt when at least a server is ready for accepting. 236 * All the ready server socket descriptors need to be returned by {@link #selectedHandles()} 237 * @return The number of sockets having got incoming client 238 * @throws Exception any exception thrown by the underlying systems calls 239 */ 240 protected abstract int select() throws Exception; 241 242 /** 243 * Interrupt the {@link #select()} method. Used when the poll set need to be modified. 244 */ 245 protected abstract void wakeup(); 246 247 /** 248 * {@link Iterator} for the set of server sockets found with acceptable incoming connections 249 * during the last {@link #select()} call. 250 * @return the list of server handles ready 251 */ 252 protected abstract Iterator<H> selectedHandles(); 253 254 /** 255 * Open a server socket for a given local address. 256 * @param localAddress the associated local address 257 * @return the opened server socket 258 * @throws Exception any exception thrown by the underlying systems calls 259 */ 260 protected abstract H open(SocketAddress localAddress) throws Exception; 261 262 /** 263 * Get the local address associated with a given server socket 264 * @param handle the server socket 265 * @return the local {@link SocketAddress} associated with this handle 266 * @throws Exception any exception thrown by the underlying systems calls 267 */ 268 protected abstract SocketAddress localAddress(H handle) throws Exception; 269 270 /** 271 * Accept a client connection for a server socket and return a new {@link IoSession} 272 * associated with the given {@link IoProcessor} 273 * @param processor the {@link IoProcessor} to associate with the {@link IoSession} 274 * @param handle the server handle 275 * @return the created {@link IoSession} 276 * @throws Exception any exception thrown by the underlying systems calls 277 */ 278 protected abstract T accept(IoProcessor<T> processor, H handle) 279 throws Exception; 280 281 /** 282 * Close a server socket. 283 * @param handle the server socket 284 * @throws Exception any exception thrown by the underlying systems calls 285 */ 286 protected abstract void close(H handle) throws Exception; 287 288 /** 289 * {@inheritDoc} 290 */ 291 @Override 292 protected IoFuture dispose0() throws Exception { 293 unbind(); 294 if (!disposalFuture.isDone()) { 295 startupAcceptor(); 296 wakeup(); 297 } 298 return disposalFuture; 299 } 300 301 /** 302 * {@inheritDoc} 303 */ 304 @Override 305 protected final Set<SocketAddress> bindInternal( 306 List<? extends SocketAddress> localAddresses) throws Exception { 307 // Create a bind request as a Future operation. When the selector 308 // have handled the registration, it will signal this future. 309 AcceptorOperationFuture request = new AcceptorOperationFuture( 310 localAddresses); 311 312 // adds the Registration request to the queue for the Workers 313 // to handle 314 registerQueue.add(request); 315 316 // creates the Acceptor instance and has the local 317 // executor kick it off. 318 startupAcceptor(); 319 320 // As we just started the acceptor, we have to unblock the select() 321 // in order to process the bind request we just have added to the 322 // registerQueue. 323 wakeup(); 324 325 // Now, we wait until this request is completed. 326 request.awaitUninterruptibly(); 327 328 if (request.getException() != null) { 329 throw request.getException(); 330 } 331 332 // Update the local addresses. 333 // setLocalAddresses() shouldn't be called from the worker thread 334 // because of deadlock. 335 Set<SocketAddress> newLocalAddresses = new HashSet<SocketAddress>(); 336 337 for (H handle:boundHandles.values()) { 338 newLocalAddresses.add(localAddress(handle)); 339 } 340 341 return newLocalAddresses; 342 } 343 344 /** 345 * This method is called by the doBind() and doUnbind() 346 * methods. If the acceptor is null, the acceptor object will 347 * be created and kicked off by the executor. If the acceptor 348 * object is null, probably already created and this class 349 * is now working, then nothing will happen and the method 350 * will just return. 351 */ 352 private void startupAcceptor() { 353 // If the acceptor is not ready, clear the queues 354 // TODO : they should already be clean : do we have to do that ? 355 if (!selectable) { 356 registerQueue.clear(); 357 cancelQueue.clear(); 358 } 359 360 // start the acceptor if not already started 361 synchronized (lock) { 362 if (acceptor == null) { 363 acceptor = new Acceptor(); 364 executeWorker(acceptor); 365 } 366 } 367 } 368 369 /** 370 * {@inheritDoc} 371 */ 372 @Override 373 protected final void unbind0(List<? extends SocketAddress> localAddresses) 374 throws Exception { 375 AcceptorOperationFuture future = new AcceptorOperationFuture( 376 localAddresses); 377 378 cancelQueue.add(future); 379 startupAcceptor(); 380 wakeup(); 381 382 future.awaitUninterruptibly(); 383 if (future.getException() != null) { 384 throw future.getException(); 385 } 386 } 387 388 /** 389 * This class is called by the startupAcceptor() method and is 390 * placed into a NamePreservingRunnable class. 391 * It's a thread accepting incoming connections from clients. 392 * The loop is stopped when all the bound handlers are unbound. 393 */ 394 private class Acceptor implements Runnable { 395 public void run() { 396 int nHandles = 0; 397 398 while (selectable) { 399 try { 400 // Detect if we have some keys ready to be processed 401 // The select() will be woke up if some new connection 402 // have occurred, or if the selector has been explicitly 403 // woke up 404 int selected = select(); 405 406 // this actually sets the selector to OP_ACCEPT, 407 // and binds to the port on which this class will 408 // listen on 409 nHandles += registerHandles(); 410 411 if (selected > 0) { 412 // We have some connection request, let's process 413 // them here. 414 processHandles(selectedHandles()); 415 } 416 417 // check to see if any cancellation request has been made. 418 nHandles -= unregisterHandles(); 419 420 // Now, if the number of registred handles is 0, we can 421 // quit the loop: we don't have any socket listening 422 // for incoming connection. 423 if (nHandles == 0) { 424 synchronized (lock) { 425 if (registerQueue.isEmpty() 426 && cancelQueue.isEmpty()) { 427 acceptor = null; 428 break; 429 } 430 } 431 } 432 } catch (Throwable e) { 433 ExceptionMonitor.getInstance().exceptionCaught(e); 434 435 try { 436 Thread.sleep(1000); 437 } catch (InterruptedException e1) { 438 ExceptionMonitor.getInstance().exceptionCaught(e1); 439 } 440 } 441 } 442 443 // Cleanup all the processors, and shutdown the acceptor. 444 if (selectable && isDisposing()) { 445 selectable = false; 446 try { 447 if (createdProcessor) { 448 processor.dispose(); 449 } 450 } finally { 451 try { 452 synchronized (disposalLock) { 453 if (isDisposing()) { 454 destroy(); 455 } 456 } 457 } catch (Exception e) { 458 ExceptionMonitor.getInstance().exceptionCaught(e); 459 } finally { 460 disposalFuture.setDone(); 461 } 462 } 463 } 464 } 465 466 /** 467 * This method will process new sessions for the Worker class. All 468 * keys that have had their status updates as per the Selector.selectedKeys() 469 * method will be processed here. Only keys that are ready to accept 470 * connections are handled here. 471 * <p/> 472 * Session objects are created by making new instances of SocketSessionImpl 473 * and passing the session object to the SocketIoProcessor class. 474 */ 475 @SuppressWarnings("unchecked") 476 private void processHandles(Iterator<H> handles) throws Exception { 477 while (handles.hasNext()) { 478 H handle = handles.next(); 479 handles.remove(); 480 481 // Associates a new created connection to a processor, 482 // and get back a session 483 T session = accept(processor, handle); 484 485 if (session == null) { 486 break; 487 } 488 489 initSession(session, null, null); 490 491 // add the session to the SocketIoProcessor 492 session.getProcessor().add(session); 493 } 494 } 495 } 496 497 /** 498 * Sets up the socket communications. Sets items such as: 499 * <p/> 500 * Blocking 501 * Reuse address 502 * Receive buffer size 503 * Bind to listen port 504 * Registers OP_ACCEPT for selector 505 */ 506 private int registerHandles() { 507 for (;;) { 508 // The register queue contains the list of services to manage 509 // in this acceptor. 510 AcceptorOperationFuture future = registerQueue.poll(); 511 512 if (future == null) { 513 return 0; 514 } 515 516 // We create a temporary map to store the bound handles, 517 // as we may have to remove them all if there is an exception 518 // during the sockets opening. 519 Map<SocketAddress, H> newHandles = new HashMap<SocketAddress, H>(); 520 List<SocketAddress> localAddresses = future.getLocalAddresses(); 521 522 try { 523 // Process all the addresses 524 for (SocketAddress a : localAddresses) { 525 H handle = open(a); 526 newHandles.put(localAddress(handle), handle); 527 } 528 529 // Everything went ok, we can now update the map storing 530 // all the bound sockets. 531 boundHandles.putAll(newHandles); 532 533 // and notify. 534 future.setDone(); 535 return newHandles.size(); 536 } catch (Exception e) { 537 // We store the exception in the future 538 future.setException(e); 539 } finally { 540 // Roll back if failed to bind all addresses. 541 if (future.getException() != null) { 542 for (H handle : newHandles.values()) { 543 try { 544 close(handle); 545 } catch (Exception e) { 546 ExceptionMonitor.getInstance().exceptionCaught(e); 547 } 548 } 549 550 // TODO : add some comment : what is the wakeup() waking up ? 551 wakeup(); 552 } 553 } 554 } 555 } 556 557 /** 558 * This method just checks to see if anything has been placed into the 559 * cancellation queue. The only thing that should be in the cancelQueue 560 * is CancellationRequest objects and the only place this happens is in 561 * the doUnbind() method. 562 */ 563 private int unregisterHandles() { 564 int cancelledHandles = 0; 565 for (;;) { 566 AcceptorOperationFuture future = cancelQueue.poll(); 567 if (future == null) { 568 break; 569 } 570 571 // close the channels 572 for (SocketAddress a : future.getLocalAddresses()) { 573 H handle = boundHandles.remove(a); 574 if (handle == null) { 575 continue; 576 } 577 578 try { 579 close(handle); 580 wakeup(); // wake up again to trigger thread death 581 } catch (Throwable e) { 582 ExceptionMonitor.getInstance().exceptionCaught(e); 583 } finally { 584 cancelledHandles++; 585 } 586 } 587 588 future.setDone(); 589 } 590 591 return cancelledHandles; 592 } 593 594 /** 595 * {@inheritDoc} 596 */ 597 public final IoSession newSession(SocketAddress remoteAddress, 598 SocketAddress localAddress) { 599 throw new UnsupportedOperationException(); 600 } 601 }