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