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| 1 | /* | ||
| 2 | * Copyright (c) 1997, 2003, 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.rmi.server; | ||
| 27 | |||
| 28 | import java.io.IOException; | ||
| 29 | import java.io.ObjectInput; | ||
| 30 | import java.io.ObjectOutput; | ||
| 31 | import java.lang.reflect.Proxy; | ||
| 32 | import java.net.MalformedURLException; | ||
| 33 | import java.net.URL; | ||
| 34 | import java.rmi.*; | ||
| 35 | import java.rmi.activation.*; | ||
| 36 | import java.rmi.server.Operation; | ||
| 37 | import java.rmi.server.RMIClassLoader; | ||
| 38 | import java.rmi.server.RemoteCall; | ||
| 39 | import java.rmi.server.RemoteObject; | ||
| 40 | import java.rmi.server.RemoteObjectInvocationHandler; | ||
| 41 | import java.rmi.server.RemoteRef; | ||
| 42 | import java.rmi.server.RemoteStub; | ||
| 43 | |||
| 44 | public class ActivatableRef implements RemoteRef { | ||
| 45 | |||
| 46 | private static final long serialVersionUID = 7579060052569229166L; | ||
| 47 | |||
| 48 | protected ActivationID id; | ||
| 49 | protected RemoteRef ref; | ||
| 50 | transient boolean force = false; | ||
| 51 | |||
| 52 | private static final int MAX_RETRIES = 3; | ||
| 53 | private static final String versionComplaint = | ||
| 54 | "activation requires 1.2 stubs"; | ||
| 55 | |||
| 56 | /** | ||
| 57 | * Create a new (empty) ActivatableRef | ||
| 58 | */ | ||
| 59 | public ActivatableRef() | ||
| 60 | {} | ||
| 61 | |||
| 62 | /** | ||
| 63 | * Create a ActivatableRef with the specified id | ||
| 64 | */ | ||
| 65 | public ActivatableRef(ActivationID id, RemoteRef ref) | ||
| 66 | { | ||
| 67 | this.id = id; | ||
| 68 | this.ref = ref; | ||
| 69 | } | ||
| 70 | |||
| 71 | /** | ||
| 72 | * Returns the stub for the remote object whose class is | ||
| 73 | * specified in the activation descriptor. The ActivatableRef | ||
| 74 | * in the resulting stub has its activation id set to the | ||
| 75 | * activation id supplied as the second argument. | ||
| 76 | */ | ||
| 77 | public static Remote getStub(ActivationDesc desc, ActivationID id) | ||
| 78 | throws StubNotFoundException | ||
| 79 | { | ||
| 80 | String className = desc.getClassName(); | ||
| 81 | |||
| 82 | try { | ||
| 83 | Class cl = | ||
| 84 | RMIClassLoader.loadClass(desc.getLocation(), className); | ||
| 85 | RemoteRef clientRef = new ActivatableRef(id, null); | ||
| 86 | return Util.createProxy(cl, clientRef, false); | ||
| 87 | |||
| 88 | } catch (IllegalArgumentException e) { | ||
| 89 | throw new StubNotFoundException( | ||
| 90 | "class implements an illegal remote interface", e); | ||
| 91 | |||
| 92 | } catch (ClassNotFoundException e) { | ||
| 93 | throw new StubNotFoundException("unable to load class: " + | ||
| 94 | className, e); | ||
| 95 | } catch (MalformedURLException e) { | ||
| 96 | throw new StubNotFoundException("malformed URL", e); | ||
| 97 | } | ||
| 98 | } | ||
| 99 | |||
| 100 | /** | ||
| 101 | * Invoke method on remote object. This method delegates remote | ||
| 102 | * method invocation to the underlying ref type. If the | ||
| 103 | * underlying reference is not known (is null), then the object | ||
| 104 | * must be activated first. If an attempt at method invocation | ||
| 105 | * fails, the object should force reactivation. Method invocation | ||
| 106 | * must preserve "at most once" call semantics. In RMI, "at most | ||
| 107 | * once" applies to parameter deserialization at the remote site | ||
| 108 | * and the remote object's method execution. "At most once" does | ||
| 109 | * not apply to parameter serialization at the client so the | ||
| 110 | * parameters of a call don't need to be buffered in anticipation | ||
| 111 | * of call retry. Thus, a method call is only be retried if the | ||
| 112 | * initial method invocation does not execute at all at the server | ||
| 113 | * (including parameter deserialization). | ||
| 114 | */ | ||
| 115 | public Object invoke(Remote obj, | ||
| 116 | java.lang.reflect.Method method, | ||
| 117 | Object[] params, | ||
| 118 | long opnum) | ||
| 119 | throws Exception | ||
| 120 | { | ||
| 121 | |||
| 122 | boolean force = false; | ||
| 123 | RemoteRef localRef; | ||
| 124 | Exception exception = null; | ||
| 125 | |||
| 126 | /* | ||
| 127 | * Attempt object activation if active ref is unknown. | ||
| 128 | * Throws a RemoteException if object can't be activated. | ||
| 129 | */ | ||
| 130 | synchronized (this) { | ||
| 131 | if (ref == null) { | ||
| 132 | localRef = activate(force); | ||
| 133 | force = true; | ||
| 134 | } else { | ||
| 135 | localRef = ref; | ||
| 136 | } | ||
| 137 | } | ||
| 138 | |||
| 139 | for (int retries = MAX_RETRIES; retries > 0; retries--) { | ||
| 140 | |||
| 141 | try { | ||
| 142 | return localRef.invoke(obj, method, params, opnum); | ||
| 143 | } catch (NoSuchObjectException e) { | ||
| 144 | /* | ||
| 145 | * Object is not active in VM; retry call | ||
| 146 | */ | ||
| 147 | exception = e; | ||
| 148 | } catch (ConnectException e) { | ||
| 149 | /* | ||
| 150 | * Failure during connection setup; retry call | ||
| 151 | */ | ||
| 152 | exception = e; | ||
| 153 | } catch (UnknownHostException e) { | ||
| 154 | /* | ||
| 155 | * Failure during connection setup; retry call. | ||
| 156 | */ | ||
| 157 | exception = e; | ||
| 158 | } catch (ConnectIOException e) { | ||
| 159 | /* | ||
| 160 | * Failure setting up multiplexed connection or reusing | ||
| 161 | * cached connection; retry call | ||
| 162 | */ | ||
| 163 | exception = e; | ||
| 164 | } catch (MarshalException e) { | ||
| 165 | /* | ||
| 166 | * Failure during parameter serialization; call may | ||
| 167 | * have reached server, so call retry not possible. | ||
| 168 | */ | ||
| 169 | throw e; | ||
| 170 | } catch (ServerError e) { | ||
| 171 | /* | ||
| 172 | * Call reached server; propagate remote exception. | ||
| 173 | */ | ||
| 174 | throw e; | ||
| 175 | } catch (ServerException e) { | ||
| 176 | /* | ||
| 177 | * Call reached server; propagate remote exception | ||
| 178 | */ | ||
| 179 | throw e; | ||
| 180 | } catch (RemoteException e) { | ||
| 181 | /* | ||
| 182 | * This is a catch-all for other RemoteExceptions. | ||
| 183 | * UnmarshalException being the only one relevant. | ||
| 184 | * | ||
| 185 | * StubNotFoundException should never show up because | ||
| 186 | * it is generally thrown when attempting to locate | ||
| 187 | * a stub. | ||
| 188 | * | ||
| 189 | * UnexpectedException should never show up because | ||
| 190 | * it is only thrown by a stub and would be wrapped | ||
| 191 | * in a ServerException if it was propagated by a | ||
| 192 | * remote call. | ||
| 193 | */ | ||
| 194 | synchronized (this) { | ||
| 195 | if (localRef == ref) { | ||
| 196 | ref = null; // this may be overly conservative | ||
| 197 | } | ||
| 198 | } | ||
| 199 | |||
| 200 | throw e; | ||
| 201 | } | ||
| 202 | |||
| 203 | if (retries > 1) { | ||
| 204 | /* | ||
| 205 | * Activate object, since object could not be reached. | ||
| 206 | */ | ||
| 207 | synchronized (this) { | ||
| 208 | if (localRef.remoteEquals(ref) || ref == null) { | ||
| 209 | RemoteRef newRef = activate(force); | ||
| 210 | |||
| 211 | if (newRef.remoteEquals(localRef) && | ||
| 212 | exception instanceof NoSuchObjectException && | ||
| 213 | force == false) { | ||
| 214 | /* | ||
| 215 | * If last exception was NoSuchObjectException, | ||
| 216 | * then old value of ref is definitely wrong, | ||
| 217 | * so make sure that it is different. | ||
| 218 | */ | ||
| 219 | newRef = activate(true); | ||
| 220 | } | ||
| 221 | |||
| 222 | localRef = newRef; | ||
| 223 | force = true; | ||
| 224 | } else { | ||
| 225 | localRef = ref; | ||
| 226 | force = false; | ||
| 227 | } | ||
| 228 | } | ||
| 229 | } | ||
| 230 | } | ||
| 231 | |||
| 232 | /* | ||
| 233 | * Retries unsuccessful, so throw last exception | ||
| 234 | */ | ||
| 235 | throw exception; | ||
| 236 | } | ||
| 237 | |||
| 238 | /** | ||
| 239 | * private method to obtain the ref for a call. | ||
| 240 | */ | ||
| 241 | private synchronized RemoteRef getRef() | ||
| 242 | throws RemoteException | ||
| 243 | { | ||
| 244 | if (ref == null) { | ||
| 245 | ref = activate(false); | ||
| 246 | } | ||
| 247 | |||
| 248 | return ref; | ||
| 249 | } | ||
| 250 | |||
| 251 | /** | ||
| 252 | * private method to activate the remote object. | ||
| 253 | * | ||
| 254 | * NOTE: the caller must be synchronized on "this" before | ||
| 255 | * calling this method. | ||
| 256 | */ | ||
| 257 | private RemoteRef activate(boolean force) | ||
| 258 | throws RemoteException | ||
| 259 | { | ||
| 260 | assert Thread.holdsLock(this); | ||
| 261 | |||
| 262 | ref = null; | ||
| 263 | try { | ||
| 264 | /* | ||
| 265 | * Activate the object and retrieve the remote reference | ||
| 266 | * from inside the stub returned as the result. Then | ||
| 267 | * set this activatable ref's internal ref to be the | ||
| 268 | * ref inside the ref of the stub. In more clear terms, | ||
| 269 | * the stub returned from the activate call contains an | ||
| 270 | * ActivatableRef. We need to set the ref in *this* | ||
| 271 | * ActivatableRef to the ref inside the ActivatableRef | ||
| 272 | * retrieved from the stub. The ref type embedded in the | ||
| 273 | * ActivatableRef is typically a UnicastRef. | ||
| 274 | */ | ||
| 275 | |||
| 276 | Remote proxy = id.activate(force); | ||
| 277 | ActivatableRef newRef = null; | ||
| 278 | |||
| 279 | if (proxy instanceof RemoteStub) { | ||
| 280 | newRef = (ActivatableRef) ((RemoteStub) proxy).getRef(); | ||
| 281 | } else { | ||
| 282 | /* | ||
| 283 | * Assume that proxy is an instance of a dynamic proxy | ||
| 284 | * class. If that assumption is not correct, or either of | ||
| 285 | * the casts below fails, the resulting exception will be | ||
| 286 | * wrapped in an ActivateFailedException below. | ||
| 287 | */ | ||
| 288 | RemoteObjectInvocationHandler handler = | ||
| 289 | (RemoteObjectInvocationHandler) | ||
| 290 | Proxy.getInvocationHandler(proxy); | ||
| 291 | newRef = (ActivatableRef) handler.getRef(); | ||
| 292 | } | ||
| 293 | ref = newRef.ref; | ||
| 294 | return ref; | ||
| 295 | |||
| 296 | } catch (ConnectException e) { | ||
| 297 | throw new ConnectException("activation failed", e); | ||
| 298 | } catch (RemoteException e) { | ||
| 299 | throw new ConnectIOException("activation failed", e); | ||
| 300 | } catch (UnknownObjectException e) { | ||
| 301 | throw new NoSuchObjectException("object not registered"); | ||
| 302 | } catch (ActivationException e) { | ||
| 303 | throw new ActivateFailedException("activation failed", e); | ||
| 304 | } | ||
| 305 | } | ||
| 306 | |||
| 307 | /** | ||
| 308 | * This call is used by the old 1.1 stub protocol and is | ||
| 309 | * unsupported since activation requires 1.2 stubs. | ||
| 310 | */ | ||
| 311 | public synchronized RemoteCall newCall(RemoteObject obj, | ||
| 312 | Operation[] ops, | ||
| 313 | int opnum, | ||
| 314 | long hash) | ||
| 315 | throws RemoteException | ||
| 316 | { | ||
| 317 | throw new UnsupportedOperationException(versionComplaint); | ||
| 318 | } | ||
| 319 | |||
| 320 | /** | ||
| 321 | * This call is used by the old 1.1 stub protocol and is | ||
| 322 | * unsupported since activation requires 1.2 stubs. | ||
| 323 | */ | ||
| 324 | public void invoke(RemoteCall call) throws Exception | ||
| 325 | { | ||
| 326 | throw new UnsupportedOperationException(versionComplaint); | ||
| 327 | } | ||
| 328 | |||
| 329 | /** | ||
| 330 | * This call is used by the old 1.1 stub protocol and is | ||
| 331 | * unsupported since activation requires 1.2 stubs. | ||
| 332 | */ | ||
| 333 | public void done(RemoteCall call) throws RemoteException { | ||
| 334 | throw new UnsupportedOperationException(versionComplaint); | ||
| 335 | } | ||
| 336 | |||
| 337 | /** | ||
| 338 | * Returns the class of the ref type to be serialized | ||
| 339 | */ | ||
| 340 | public String getRefClass(ObjectOutput out) | ||
| 341 | { | ||
| 342 | return "ActivatableRef"; | ||
| 343 | } | ||
| 344 | |||
| 345 | /** | ||
| 346 | * Write out external representation for remote ref. | ||
| 347 | */ | ||
| 348 | public void writeExternal(ObjectOutput out) throws IOException | ||
| 349 | { | ||
| 350 | RemoteRef localRef = ref; | ||
| 351 | |||
| 352 | out.writeObject(id); | ||
| 353 | if (localRef == null) { | ||
| 354 | out.writeUTF(""); | ||
| 355 | } else { | ||
| 356 | out.writeUTF(localRef.getRefClass(out)); | ||
| 357 | localRef.writeExternal(out); | ||
| 358 | } | ||
| 359 | } | ||
| 360 | |||
| 361 | /** | ||
| 362 | * Read in external representation for remote ref. | ||
| 363 | * @exception ClassNotFoundException If the class for an object | ||
| 364 | * being restored cannot be found. | ||
| 365 | */ | ||
| 366 | public void readExternal(ObjectInput in) | ||
| 367 | throws IOException, ClassNotFoundException | ||
| 368 | { | ||
| 369 | id = (ActivationID)in.readObject(); | ||
| 370 | ref = null; | ||
| 371 | String className = in.readUTF(); | ||
| 372 | |||
| 373 | if (className.equals("")) return; | ||
| 374 | |||
| 375 | try { | ||
| 376 | Class refClass = Class.forName(RemoteRef.packagePrefix + "." + | ||
| 377 | className); | ||
| 378 | ref = (RemoteRef)refClass.newInstance(); | ||
| 379 | ref.readExternal(in); | ||
| 380 | } catch (InstantiationException e) { | ||
| 381 | throw new UnmarshalException("Unable to create remote reference", | ||
| 382 | e); | ||
| 383 | } catch (IllegalAccessException e) { | ||
| 384 | throw new UnmarshalException("Illegal access creating remote reference"); | ||
| 385 | } | ||
| 386 | } | ||
| 387 | |||
| 388 | //----------------------------------------------------------------------; | ||
| 389 | /** | ||
| 390 | * Method from object, forward from RemoteObject | ||
| 391 | */ | ||
| 392 | public String remoteToString() { | ||
| 393 | return Util.getUnqualifiedName(getClass()) + | ||
| 394 | " [remoteRef: " + ref + "]"; | ||
| 395 | } | ||
| 396 | |||
| 397 | /** | ||
| 398 | * default implementation of hashCode for remote objects | ||
| 399 | */ | ||
| 400 | public int remoteHashCode() { | ||
| 401 | return id.hashCode(); | ||
| 402 | } | ||
| 403 | |||
| 404 | /** default implementation of equals for remote objects | ||
| 405 | */ | ||
| 406 | public boolean remoteEquals(RemoteRef ref) { | ||
| 407 | if (ref instanceof ActivatableRef) | ||
| 408 | return id.equals(((ActivatableRef)ref).id); | ||
| 409 | return false; | ||
| 410 | } | ||
| 411 | } | ||