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| 1 | /* | ||
| 2 | * Copyright (c) 2003, 2011, 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 | /* | ||
| 27 | * Written by Doug Lea with assistance from members of JCP JSR-166 | ||
| 28 | * Expert Group. Adapted and released, under explicit permission, | ||
| 29 | * from JDK ArrayList.java which carries the following copyright: | ||
| 30 | * | ||
| 31 | * Copyright 1997 by Sun Microsystems, Inc., | ||
| 32 | * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A. | ||
| 33 | * All rights reserved. | ||
| 34 | */ | ||
| 35 | |||
| 36 | package java.util.concurrent; | ||
| 37 | import java.util.*; | ||
| 38 | import java.util.concurrent.locks.*; | ||
| 39 | import sun.misc.Unsafe; | ||
| 40 | |||
| 41 | /** | ||
| 42 | * A thread-safe variant of {@link java.util.ArrayList} in which all mutative | ||
| 43 | * operations (<tt>add</tt>, <tt>set</tt>, and so on) are implemented by | ||
| 44 | * making a fresh copy of the underlying array. | ||
| 45 | * | ||
| 46 | * <p> This is ordinarily too costly, but may be <em>more</em> efficient | ||
| 47 | * than alternatives when traversal operations vastly outnumber | ||
| 48 | * mutations, and is useful when you cannot or don't want to | ||
| 49 | * synchronize traversals, yet need to preclude interference among | ||
| 50 | * concurrent threads. The "snapshot" style iterator method uses a | ||
| 51 | * reference to the state of the array at the point that the iterator | ||
| 52 | * was created. This array never changes during the lifetime of the | ||
| 53 | * iterator, so interference is impossible and the iterator is | ||
| 54 | * guaranteed not to throw <tt>ConcurrentModificationException</tt>. | ||
| 55 | * The iterator will not reflect additions, removals, or changes to | ||
| 56 | * the list since the iterator was created. Element-changing | ||
| 57 | * operations on iterators themselves (<tt>remove</tt>, <tt>set</tt>, and | ||
| 58 | * <tt>add</tt>) are not supported. These methods throw | ||
| 59 | * <tt>UnsupportedOperationException</tt>. | ||
| 60 | * | ||
| 61 | * <p>All elements are permitted, including <tt>null</tt>. | ||
| 62 | * | ||
| 63 | * <p>Memory consistency effects: As with other concurrent | ||
| 64 | * collections, actions in a thread prior to placing an object into a | ||
| 65 | * {@code CopyOnWriteArrayList} | ||
| 66 | * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a> | ||
| 67 | * actions subsequent to the access or removal of that element from | ||
| 68 | * the {@code CopyOnWriteArrayList} in another thread. | ||
| 69 | * | ||
| 70 | * <p>This class is a member of the | ||
| 71 | * <a href="{@docRoot}/../technotes/guides/collections/index.html"> | ||
| 72 | * Java Collections Framework</a>. | ||
| 73 | * | ||
| 74 | * @since 1.5 | ||
| 75 | * @author Doug Lea | ||
| 76 | * @param <E> the type of elements held in this collection | ||
| 77 | */ | ||
| 78 | public class CopyOnWriteArrayList<E> | ||
| 79 | implements List<E>, RandomAccess, Cloneable, java.io.Serializable { | ||
| 80 | private static final long serialVersionUID = 8673264195747942595L; | ||
| 81 | |||
| 82 | /** The lock protecting all mutators */ | ||
| 83 | transient final ReentrantLock lock = new ReentrantLock(); | ||
| 84 | |||
| 85 | /** The array, accessed only via getArray/setArray. */ | ||
| 86 | private volatile transient Object[] array; | ||
| 87 | |||
| 88 | /** | ||
| 89 | * Gets the array. Non-private so as to also be accessible | ||
| 90 | * from CopyOnWriteArraySet class. | ||
| 91 | */ | ||
| 92 | final Object[] getArray() { | ||
| 93 | return array; | ||
| 94 | } | ||
| 95 | |||
| 96 | /** | ||
| 97 | * Sets the array. | ||
| 98 | */ | ||
| 99 | final void setArray(Object[] a) { | ||
| 100 | array = a; | ||
| 101 | } | ||
| 102 | |||
| 103 | /** | ||
| 104 | * Creates an empty list. | ||
| 105 | */ | ||
| 106 | public CopyOnWriteArrayList() { | ||
| 107 | setArray(new Object[0]); | ||
| 108 | } | ||
| 109 | |||
| 110 | /** | ||
| 111 | * Creates a list containing the elements of the specified | ||
| 112 | * collection, in the order they are returned by the collection's | ||
| 113 | * iterator. | ||
| 114 | * | ||
| 115 | * @param c the collection of initially held elements | ||
| 116 | * @throws NullPointerException if the specified collection is null | ||
| 117 | */ | ||
| 118 | public CopyOnWriteArrayList(Collection<? extends E> c) { | ||
| 119 | Object[] elements = c.toArray(); | ||
| 120 | // c.toArray might (incorrectly) not return Object[] (see 6260652) | ||
| 121 | if (elements.getClass() != Object[].class) | ||
| 122 | elements = Arrays.copyOf(elements, elements.length, Object[].class); | ||
| 123 | setArray(elements); | ||
| 124 | } | ||
| 125 | |||
| 126 | /** | ||
| 127 | * Creates a list holding a copy of the given array. | ||
| 128 | * | ||
| 129 | * @param toCopyIn the array (a copy of this array is used as the | ||
| 130 | * internal array) | ||
| 131 | * @throws NullPointerException if the specified array is null | ||
| 132 | */ | ||
| 133 | public CopyOnWriteArrayList(E[] toCopyIn) { | ||
| 134 | setArray(Arrays.copyOf(toCopyIn, toCopyIn.length, Object[].class)); | ||
| 135 | } | ||
| 136 | |||
| 137 | /** | ||
| 138 | * Returns the number of elements in this list. | ||
| 139 | * | ||
| 140 | * @return the number of elements in this list | ||
| 141 | */ | ||
| 142 | public int size() { | ||
| 143 | return getArray().length; | ||
| 144 | } | ||
| 145 | |||
| 146 | /** | ||
| 147 | * Returns <tt>true</tt> if this list contains no elements. | ||
| 148 | * | ||
| 149 | * @return <tt>true</tt> if this list contains no elements | ||
| 150 | */ | ||
| 151 | public boolean isEmpty() { | ||
| 152 | return size() == 0; | ||
| 153 | } | ||
| 154 | |||
| 155 | /** | ||
| 156 | * Test for equality, coping with nulls. | ||
| 157 | */ | ||
| 158 | private static boolean eq(Object o1, Object o2) { | ||
| 159 | return (o1 == null ? o2 == null : o1.equals(o2)); | ||
| 160 | } | ||
| 161 | |||
| 162 | /** | ||
| 163 | * static version of indexOf, to allow repeated calls without | ||
| 164 | * needing to re-acquire array each time. | ||
| 165 | * @param o element to search for | ||
| 166 | * @param elements the array | ||
| 167 | * @param index first index to search | ||
| 168 | * @param fence one past last index to search | ||
| 169 | * @return index of element, or -1 if absent | ||
| 170 | */ | ||
| 171 | private static int indexOf(Object o, Object[] elements, | ||
| 172 | int index, int fence) { | ||
| 173 | if (o == null) { | ||
| 174 | for (int i = index; i < fence; i++) | ||
| 175 | if (elements[i] == null) | ||
| 176 | return i; | ||
| 177 | } else { | ||
| 178 | for (int i = index; i < fence; i++) | ||
| 179 | if (o.equals(elements[i])) | ||
| 180 | return i; | ||
| 181 | } | ||
| 182 | return -1; | ||
| 183 | } | ||
| 184 | |||
| 185 | /** | ||
| 186 | * static version of lastIndexOf. | ||
| 187 | * @param o element to search for | ||
| 188 | * @param elements the array | ||
| 189 | * @param index first index to search | ||
| 190 | * @return index of element, or -1 if absent | ||
| 191 | */ | ||
| 192 | private static int lastIndexOf(Object o, Object[] elements, int index) { | ||
| 193 | if (o == null) { | ||
| 194 | for (int i = index; i >= 0; i--) | ||
| 195 | if (elements[i] == null) | ||
| 196 | return i; | ||
| 197 | } else { | ||
| 198 | for (int i = index; i >= 0; i--) | ||
| 199 | if (o.equals(elements[i])) | ||
| 200 | return i; | ||
| 201 | } | ||
| 202 | return -1; | ||
| 203 | } | ||
| 204 | |||
| 205 | /** | ||
| 206 | * Returns <tt>true</tt> if this list contains the specified element. | ||
| 207 | * More formally, returns <tt>true</tt> if and only if this list contains | ||
| 208 | * at least one element <tt>e</tt> such that | ||
| 209 | * <tt>(o==null ? e==null : o.equals(e))</tt>. | ||
| 210 | * | ||
| 211 | * @param o element whose presence in this list is to be tested | ||
| 212 | * @return <tt>true</tt> if this list contains the specified element | ||
| 213 | */ | ||
| 214 | public boolean contains(Object o) { | ||
| 215 | Object[] elements = getArray(); | ||
| 216 | return indexOf(o, elements, 0, elements.length) >= 0; | ||
| 217 | } | ||
| 218 | |||
| 219 | /** | ||
| 220 | * {@inheritDoc} | ||
| 221 | */ | ||
| 222 | public int indexOf(Object o) { | ||
| 223 | Object[] elements = getArray(); | ||
| 224 | return indexOf(o, elements, 0, elements.length); | ||
| 225 | } | ||
| 226 | |||
| 227 | /** | ||
| 228 | * Returns the index of the first occurrence of the specified element in | ||
| 229 | * this list, searching forwards from <tt>index</tt>, or returns -1 if | ||
| 230 | * the element is not found. | ||
| 231 | * More formally, returns the lowest index <tt>i</tt> such that | ||
| 232 | * <tt>(i >= index && (e==null ? get(i)==null : e.equals(get(i))))</tt>, | ||
| 233 | * or -1 if there is no such index. | ||
| 234 | * | ||
| 235 | * @param e element to search for | ||
| 236 | * @param index index to start searching from | ||
| 237 | * @return the index of the first occurrence of the element in | ||
| 238 | * this list at position <tt>index</tt> or later in the list; | ||
| 239 | * <tt>-1</tt> if the element is not found. | ||
| 240 | * @throws IndexOutOfBoundsException if the specified index is negative | ||
| 241 | */ | ||
| 242 | public int indexOf(E e, int index) { | ||
| 243 | Object[] elements = getArray(); | ||
| 244 | return indexOf(e, elements, index, elements.length); | ||
| 245 | } | ||
| 246 | |||
| 247 | /** | ||
| 248 | * {@inheritDoc} | ||
| 249 | */ | ||
| 250 | public int lastIndexOf(Object o) { | ||
| 251 | Object[] elements = getArray(); | ||
| 252 | return lastIndexOf(o, elements, elements.length - 1); | ||
| 253 | } | ||
| 254 | |||
| 255 | /** | ||
| 256 | * Returns the index of the last occurrence of the specified element in | ||
| 257 | * this list, searching backwards from <tt>index</tt>, or returns -1 if | ||
| 258 | * the element is not found. | ||
| 259 | * More formally, returns the highest index <tt>i</tt> such that | ||
| 260 | * <tt>(i <= index && (e==null ? get(i)==null : e.equals(get(i))))</tt>, | ||
| 261 | * or -1 if there is no such index. | ||
| 262 | * | ||
| 263 | * @param e element to search for | ||
| 264 | * @param index index to start searching backwards from | ||
| 265 | * @return the index of the last occurrence of the element at position | ||
| 266 | * less than or equal to <tt>index</tt> in this list; | ||
| 267 | * -1 if the element is not found. | ||
| 268 | * @throws IndexOutOfBoundsException if the specified index is greater | ||
| 269 | * than or equal to the current size of this list | ||
| 270 | */ | ||
| 271 | public int lastIndexOf(E e, int index) { | ||
| 272 | Object[] elements = getArray(); | ||
| 273 | return lastIndexOf(e, elements, index); | ||
| 274 | } | ||
| 275 | |||
| 276 | /** | ||
| 277 | * Returns a shallow copy of this list. (The elements themselves | ||
| 278 | * are not copied.) | ||
| 279 | * | ||
| 280 | * @return a clone of this list | ||
| 281 | */ | ||
| 282 | public Object clone() { | ||
| 283 | try { | ||
| 284 | CopyOnWriteArrayList c = (CopyOnWriteArrayList)(super.clone()); | ||
| 285 | c.resetLock(); | ||
| 286 | return c; | ||
| 287 | } catch (CloneNotSupportedException e) { | ||
| 288 | // this shouldn't happen, since we are Cloneable | ||
| 289 | throw new InternalError(); | ||
| 290 | } | ||
| 291 | } | ||
| 292 | |||
| 293 | /** | ||
| 294 | * Returns an array containing all of the elements in this list | ||
| 295 | * in proper sequence (from first to last element). | ||
| 296 | * | ||
| 297 | * <p>The returned array will be "safe" in that no references to it are | ||
| 298 | * maintained by this list. (In other words, this method must allocate | ||
| 299 | * a new array). The caller is thus free to modify the returned array. | ||
| 300 | * | ||
| 301 | * <p>This method acts as bridge between array-based and collection-based | ||
| 302 | * APIs. | ||
| 303 | * | ||
| 304 | * @return an array containing all the elements in this list | ||
| 305 | */ | ||
| 306 | public Object[] toArray() { | ||
| 307 | Object[] elements = getArray(); | ||
| 308 | return Arrays.copyOf(elements, elements.length); | ||
| 309 | } | ||
| 310 | |||
| 311 | /** | ||
| 312 | * Returns an array containing all of the elements in this list in | ||
| 313 | * proper sequence (from first to last element); the runtime type of | ||
| 314 | * the returned array is that of the specified array. If the list fits | ||
| 315 | * in the specified array, it is returned therein. Otherwise, a new | ||
| 316 | * array is allocated with the runtime type of the specified array and | ||
| 317 | * the size of this list. | ||
| 318 | * | ||
| 319 | * <p>If this list fits in the specified array with room to spare | ||
| 320 | * (i.e., the array has more elements than this list), the element in | ||
| 321 | * the array immediately following the end of the list is set to | ||
| 322 | * <tt>null</tt>. (This is useful in determining the length of this | ||
| 323 | * list <i>only</i> if the caller knows that this list does not contain | ||
| 324 | * any null elements.) | ||
| 325 | * | ||
| 326 | * <p>Like the {@link #toArray()} method, this method acts as bridge between | ||
| 327 | * array-based and collection-based APIs. Further, this method allows | ||
| 328 | * precise control over the runtime type of the output array, and may, | ||
| 329 | * under certain circumstances, be used to save allocation costs. | ||
| 330 | * | ||
| 331 | * <p>Suppose <tt>x</tt> is a list known to contain only strings. | ||
| 332 | * The following code can be used to dump the list into a newly | ||
| 333 | * allocated array of <tt>String</tt>: | ||
| 334 | * | ||
| 335 | * <pre> | ||
| 336 | * String[] y = x.toArray(new String[0]);</pre> | ||
| 337 | * | ||
| 338 | * Note that <tt>toArray(new Object[0])</tt> is identical in function to | ||
| 339 | * <tt>toArray()</tt>. | ||
| 340 | * | ||
| 341 | * @param a the array into which the elements of the list are to | ||
| 342 | * be stored, if it is big enough; otherwise, a new array of the | ||
| 343 | * same runtime type is allocated for this purpose. | ||
| 344 | * @return an array containing all the elements in this list | ||
| 345 | * @throws ArrayStoreException if the runtime type of the specified array | ||
| 346 | * is not a supertype of the runtime type of every element in | ||
| 347 | * this list | ||
| 348 | * @throws NullPointerException if the specified array is null | ||
| 349 | */ | ||
| 350 | @SuppressWarnings("unchecked") | ||
| 351 | public <T> T[] toArray(T a[]) { | ||
| 352 | Object[] elements = getArray(); | ||
| 353 | int len = elements.length; | ||
| 354 | if (a.length < len) | ||
| 355 | return (T[]) Arrays.copyOf(elements, len, a.getClass()); | ||
| 356 | else { | ||
| 357 | System.arraycopy(elements, 0, a, 0, len); | ||
| 358 | if (a.length > len) | ||
| 359 | a[len] = null; | ||
| 360 | return a; | ||
| 361 | } | ||
| 362 | } | ||
| 363 | |||
| 364 | // Positional Access Operations | ||
| 365 | |||
| 366 | @SuppressWarnings("unchecked") | ||
| 367 | private E get(Object[] a, int index) { | ||
| 368 | return (E) a[index]; | ||
| 369 | } | ||
| 370 | |||
| 371 | /** | ||
| 372 | * {@inheritDoc} | ||
| 373 | * | ||
| 374 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 375 | */ | ||
| 376 | public E get(int index) { | ||
| 377 | return get(getArray(), index); | ||
| 378 | } | ||
| 379 | |||
| 380 | /** | ||
| 381 | * Replaces the element at the specified position in this list with the | ||
| 382 | * specified element. | ||
| 383 | * | ||
| 384 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 385 | */ | ||
| 386 | public E set(int index, E element) { | ||
| 387 | final ReentrantLock lock = this.lock; | ||
| 388 | lock.lock(); | ||
| 389 | try { | ||
| 390 | Object[] elements = getArray(); | ||
| 391 | E oldValue = get(elements, index); | ||
| 392 | |||
| 393 | if (oldValue != element) { | ||
| 394 | int len = elements.length; | ||
| 395 | Object[] newElements = Arrays.copyOf(elements, len); | ||
| 396 | newElements[index] = element; | ||
| 397 | setArray(newElements); | ||
| 398 | } else { | ||
| 399 | // Not quite a no-op; ensures volatile write semantics | ||
| 400 | setArray(elements); | ||
| 401 | } | ||
| 402 | return oldValue; | ||
| 403 | } finally { | ||
| 404 | lock.unlock(); | ||
| 405 | } | ||
| 406 | } | ||
| 407 | |||
| 408 | /** | ||
| 409 | * Appends the specified element to the end of this list. | ||
| 410 | * | ||
| 411 | * @param e element to be appended to this list | ||
| 412 | * @return <tt>true</tt> (as specified by {@link Collection#add}) | ||
| 413 | */ | ||
| 414 | public boolean add(E e) { | ||
| 415 | final ReentrantLock lock = this.lock; | ||
| 416 | lock.lock(); | ||
| 417 | try { | ||
| 418 | Object[] elements = getArray(); | ||
| 419 | int len = elements.length; | ||
| 420 | Object[] newElements = Arrays.copyOf(elements, len + 1); | ||
| 421 | newElements[len] = e; | ||
| 422 | setArray(newElements); | ||
| 423 | return true; | ||
| 424 | } finally { | ||
| 425 | lock.unlock(); | ||
| 426 | } | ||
| 427 | } | ||
| 428 | |||
| 429 | /** | ||
| 430 | * Inserts the specified element at the specified position in this | ||
| 431 | * list. Shifts the element currently at that position (if any) and | ||
| 432 | * any subsequent elements to the right (adds one to their indices). | ||
| 433 | * | ||
| 434 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 435 | */ | ||
| 436 | public void add(int index, E element) { | ||
| 437 | final ReentrantLock lock = this.lock; | ||
| 438 | lock.lock(); | ||
| 439 | try { | ||
| 440 | Object[] elements = getArray(); | ||
| 441 | int len = elements.length; | ||
| 442 | if (index > len || index < 0) | ||
| 443 | throw new IndexOutOfBoundsException("Index: "+index+ | ||
| 444 | ", Size: "+len); | ||
| 445 | Object[] newElements; | ||
| 446 | int numMoved = len - index; | ||
| 447 | if (numMoved == 0) | ||
| 448 | newElements = Arrays.copyOf(elements, len + 1); | ||
| 449 | else { | ||
| 450 | newElements = new Object[len + 1]; | ||
| 451 | System.arraycopy(elements, 0, newElements, 0, index); | ||
| 452 | System.arraycopy(elements, index, newElements, index + 1, | ||
| 453 | numMoved); | ||
| 454 | } | ||
| 455 | newElements[index] = element; | ||
| 456 | setArray(newElements); | ||
| 457 | } finally { | ||
| 458 | lock.unlock(); | ||
| 459 | } | ||
| 460 | } | ||
| 461 | |||
| 462 | /** | ||
| 463 | * Removes the element at the specified position in this list. | ||
| 464 | * Shifts any subsequent elements to the left (subtracts one from their | ||
| 465 | * indices). Returns the element that was removed from the list. | ||
| 466 | * | ||
| 467 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 468 | */ | ||
| 469 | public E remove(int index) { | ||
| 470 | final ReentrantLock lock = this.lock; | ||
| 471 | lock.lock(); | ||
| 472 | try { | ||
| 473 | Object[] elements = getArray(); | ||
| 474 | int len = elements.length; | ||
| 475 | E oldValue = get(elements, index); | ||
| 476 | int numMoved = len - index - 1; | ||
| 477 | if (numMoved == 0) | ||
| 478 | setArray(Arrays.copyOf(elements, len - 1)); | ||
| 479 | else { | ||
| 480 | Object[] newElements = new Object[len - 1]; | ||
| 481 | System.arraycopy(elements, 0, newElements, 0, index); | ||
| 482 | System.arraycopy(elements, index + 1, newElements, index, | ||
| 483 | numMoved); | ||
| 484 | setArray(newElements); | ||
| 485 | } | ||
| 486 | return oldValue; | ||
| 487 | } finally { | ||
| 488 | lock.unlock(); | ||
| 489 | } | ||
| 490 | } | ||
| 491 | |||
| 492 | /** | ||
| 493 | * Removes the first occurrence of the specified element from this list, | ||
| 494 | * if it is present. If this list does not contain the element, it is | ||
| 495 | * unchanged. More formally, removes the element with the lowest index | ||
| 496 | * <tt>i</tt> such that | ||
| 497 | * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> | ||
| 498 | * (if such an element exists). Returns <tt>true</tt> if this list | ||
| 499 | * contained the specified element (or equivalently, if this list | ||
| 500 | * changed as a result of the call). | ||
| 501 | * | ||
| 502 | * @param o element to be removed from this list, if present | ||
| 503 | * @return <tt>true</tt> if this list contained the specified element | ||
| 504 | */ | ||
| 505 | public boolean remove(Object o) { | ||
| 506 | final ReentrantLock lock = this.lock; | ||
| 507 | lock.lock(); | ||
| 508 | try { | ||
| 509 | Object[] elements = getArray(); | ||
| 510 | int len = elements.length; | ||
| 511 | if (len != 0) { | ||
| 512 | // Copy while searching for element to remove | ||
| 513 | // This wins in the normal case of element being present | ||
| 514 | int newlen = len - 1; | ||
| 515 | Object[] newElements = new Object[newlen]; | ||
| 516 | |||
| 517 | for (int i = 0; i < newlen; ++i) { | ||
| 518 | if (eq(o, elements[i])) { | ||
| 519 | // found one; copy remaining and exit | ||
| 520 | for (int k = i + 1; k < len; ++k) | ||
| 521 | newElements[k-1] = elements[k]; | ||
| 522 | setArray(newElements); | ||
| 523 | return true; | ||
| 524 | } else | ||
| 525 | newElements[i] = elements[i]; | ||
| 526 | } | ||
| 527 | |||
| 528 | // special handling for last cell | ||
| 529 | if (eq(o, elements[newlen])) { | ||
| 530 | setArray(newElements); | ||
| 531 | return true; | ||
| 532 | } | ||
| 533 | } | ||
| 534 | return false; | ||
| 535 | } finally { | ||
| 536 | lock.unlock(); | ||
| 537 | } | ||
| 538 | } | ||
| 539 | |||
| 540 | /** | ||
| 541 | * Removes from this list all of the elements whose index is between | ||
| 542 | * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive. | ||
| 543 | * Shifts any succeeding elements to the left (reduces their index). | ||
| 544 | * This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements. | ||
| 545 | * (If <tt>toIndex==fromIndex</tt>, this operation has no effect.) | ||
| 546 | * | ||
| 547 | * @param fromIndex index of first element to be removed | ||
| 548 | * @param toIndex index after last element to be removed | ||
| 549 | * @throws IndexOutOfBoundsException if fromIndex or toIndex out of range | ||
| 550 | * ({@code{fromIndex < 0 || toIndex > size() || toIndex < fromIndex}) | ||
| 551 | */ | ||
| 552 | private void removeRange(int fromIndex, int toIndex) { | ||
| 553 | final ReentrantLock lock = this.lock; | ||
| 554 | lock.lock(); | ||
| 555 | try { | ||
| 556 | Object[] elements = getArray(); | ||
| 557 | int len = elements.length; | ||
| 558 | |||
| 559 | if (fromIndex < 0 || toIndex > len || toIndex < fromIndex) | ||
| 560 | throw new IndexOutOfBoundsException(); | ||
| 561 | int newlen = len - (toIndex - fromIndex); | ||
| 562 | int numMoved = len - toIndex; | ||
| 563 | if (numMoved == 0) | ||
| 564 | setArray(Arrays.copyOf(elements, newlen)); | ||
| 565 | else { | ||
| 566 | Object[] newElements = new Object[newlen]; | ||
| 567 | System.arraycopy(elements, 0, newElements, 0, fromIndex); | ||
| 568 | System.arraycopy(elements, toIndex, newElements, | ||
| 569 | fromIndex, numMoved); | ||
| 570 | setArray(newElements); | ||
| 571 | } | ||
| 572 | } finally { | ||
| 573 | lock.unlock(); | ||
| 574 | } | ||
| 575 | } | ||
| 576 | |||
| 577 | /** | ||
| 578 | * Append the element if not present. | ||
| 579 | * | ||
| 580 | * @param e element to be added to this list, if absent | ||
| 581 | * @return <tt>true</tt> if the element was added | ||
| 582 | */ | ||
| 583 | public boolean addIfAbsent(E e) { | ||
| 584 | final ReentrantLock lock = this.lock; | ||
| 585 | lock.lock(); | ||
| 586 | try { | ||
| 587 | // Copy while checking if already present. | ||
| 588 | // This wins in the most common case where it is not present | ||
| 589 | Object[] elements = getArray(); | ||
| 590 | int len = elements.length; | ||
| 591 | Object[] newElements = new Object[len + 1]; | ||
| 592 | for (int i = 0; i < len; ++i) { | ||
| 593 | if (eq(e, elements[i])) | ||
| 594 | return false; // exit, throwing away copy | ||
| 595 | else | ||
| 596 | newElements[i] = elements[i]; | ||
| 597 | } | ||
| 598 | newElements[len] = e; | ||
| 599 | setArray(newElements); | ||
| 600 | return true; | ||
| 601 | } finally { | ||
| 602 | lock.unlock(); | ||
| 603 | } | ||
| 604 | } | ||
| 605 | |||
| 606 | /** | ||
| 607 | * Returns <tt>true</tt> if this list contains all of the elements of the | ||
| 608 | * specified collection. | ||
| 609 | * | ||
| 610 | * @param c collection to be checked for containment in this list | ||
| 611 | * @return <tt>true</tt> if this list contains all of the elements of the | ||
| 612 | * specified collection | ||
| 613 | * @throws NullPointerException if the specified collection is null | ||
| 614 | * @see #contains(Object) | ||
| 615 | */ | ||
| 616 | public boolean containsAll(Collection<?> c) { | ||
| 617 | Object[] elements = getArray(); | ||
| 618 | int len = elements.length; | ||
| 619 | for (Object e : c) { | ||
| 620 | if (indexOf(e, elements, 0, len) < 0) | ||
| 621 | return false; | ||
| 622 | } | ||
| 623 | return true; | ||
| 624 | } | ||
| 625 | |||
| 626 | /** | ||
| 627 | * Removes from this list all of its elements that are contained in | ||
| 628 | * the specified collection. This is a particularly expensive operation | ||
| 629 | * in this class because of the need for an internal temporary array. | ||
| 630 | * | ||
| 631 | * @param c collection containing elements to be removed from this list | ||
| 632 | * @return <tt>true</tt> if this list changed as a result of the call | ||
| 633 | * @throws ClassCastException if the class of an element of this list | ||
| 634 | * is incompatible with the specified collection | ||
| 635 | * (<a href="../Collection.html#optional-restrictions">optional</a>) | ||
| 636 | * @throws NullPointerException if this list contains a null element and the | ||
| 637 | * specified collection does not permit null elements | ||
| 638 | * (<a href="../Collection.html#optional-restrictions">optional</a>), | ||
| 639 | * or if the specified collection is null | ||
| 640 | * @see #remove(Object) | ||
| 641 | */ | ||
| 642 | public boolean removeAll(Collection<?> c) { | ||
| 643 | final ReentrantLock lock = this.lock; | ||
| 644 | lock.lock(); | ||
| 645 | try { | ||
| 646 | Object[] elements = getArray(); | ||
| 647 | int len = elements.length; | ||
| 648 | if (len != 0) { | ||
| 649 | // temp array holds those elements we know we want to keep | ||
| 650 | int newlen = 0; | ||
| 651 | Object[] temp = new Object[len]; | ||
| 652 | for (int i = 0; i < len; ++i) { | ||
| 653 | Object element = elements[i]; | ||
| 654 | if (!c.contains(element)) | ||
| 655 | temp[newlen++] = element; | ||
| 656 | } | ||
| 657 | if (newlen != len) { | ||
| 658 | setArray(Arrays.copyOf(temp, newlen)); | ||
| 659 | return true; | ||
| 660 | } | ||
| 661 | } | ||
| 662 | return false; | ||
| 663 | } finally { | ||
| 664 | lock.unlock(); | ||
| 665 | } | ||
| 666 | } | ||
| 667 | |||
| 668 | /** | ||
| 669 | * Retains only the elements in this list that are contained in the | ||
| 670 | * specified collection. In other words, removes from this list all of | ||
| 671 | * its elements that are not contained in the specified collection. | ||
| 672 | * | ||
| 673 | * @param c collection containing elements to be retained in this list | ||
| 674 | * @return <tt>true</tt> if this list changed as a result of the call | ||
| 675 | * @throws ClassCastException if the class of an element of this list | ||
| 676 | * is incompatible with the specified collection | ||
| 677 | * (<a href="../Collection.html#optional-restrictions">optional</a>) | ||
| 678 | * @throws NullPointerException if this list contains a null element and the | ||
| 679 | * specified collection does not permit null elements | ||
| 680 | * (<a href="../Collection.html#optional-restrictions">optional</a>), | ||
| 681 | * or if the specified collection is null | ||
| 682 | * @see #remove(Object) | ||
| 683 | */ | ||
| 684 | public boolean retainAll(Collection<?> c) { | ||
| 685 | final ReentrantLock lock = this.lock; | ||
| 686 | lock.lock(); | ||
| 687 | try { | ||
| 688 | Object[] elements = getArray(); | ||
| 689 | int len = elements.length; | ||
| 690 | if (len != 0) { | ||
| 691 | // temp array holds those elements we know we want to keep | ||
| 692 | int newlen = 0; | ||
| 693 | Object[] temp = new Object[len]; | ||
| 694 | for (int i = 0; i < len; ++i) { | ||
| 695 | Object element = elements[i]; | ||
| 696 | if (c.contains(element)) | ||
| 697 | temp[newlen++] = element; | ||
| 698 | } | ||
| 699 | if (newlen != len) { | ||
| 700 | setArray(Arrays.copyOf(temp, newlen)); | ||
| 701 | return true; | ||
| 702 | } | ||
| 703 | } | ||
| 704 | return false; | ||
| 705 | } finally { | ||
| 706 | lock.unlock(); | ||
| 707 | } | ||
| 708 | } | ||
| 709 | |||
| 710 | /** | ||
| 711 | * Appends all of the elements in the specified collection that | ||
| 712 | * are not already contained in this list, to the end of | ||
| 713 | * this list, in the order that they are returned by the | ||
| 714 | * specified collection's iterator. | ||
| 715 | * | ||
| 716 | * @param c collection containing elements to be added to this list | ||
| 717 | * @return the number of elements added | ||
| 718 | * @throws NullPointerException if the specified collection is null | ||
| 719 | * @see #addIfAbsent(Object) | ||
| 720 | */ | ||
| 721 | public int addAllAbsent(Collection<? extends E> c) { | ||
| 722 | Object[] cs = c.toArray(); | ||
| 723 | if (cs.length == 0) | ||
| 724 | return 0; | ||
| 725 | Object[] uniq = new Object[cs.length]; | ||
| 726 | final ReentrantLock lock = this.lock; | ||
| 727 | lock.lock(); | ||
| 728 | try { | ||
| 729 | Object[] elements = getArray(); | ||
| 730 | int len = elements.length; | ||
| 731 | int added = 0; | ||
| 732 | for (int i = 0; i < cs.length; ++i) { // scan for duplicates | ||
| 733 | Object e = cs[i]; | ||
| 734 | if (indexOf(e, elements, 0, len) < 0 && | ||
| 735 | indexOf(e, uniq, 0, added) < 0) | ||
| 736 | uniq[added++] = e; | ||
| 737 | } | ||
| 738 | if (added > 0) { | ||
| 739 | Object[] newElements = Arrays.copyOf(elements, len + added); | ||
| 740 | System.arraycopy(uniq, 0, newElements, len, added); | ||
| 741 | setArray(newElements); | ||
| 742 | } | ||
| 743 | return added; | ||
| 744 | } finally { | ||
| 745 | lock.unlock(); | ||
| 746 | } | ||
| 747 | } | ||
| 748 | |||
| 749 | /** | ||
| 750 | * Removes all of the elements from this list. | ||
| 751 | * The list will be empty after this call returns. | ||
| 752 | */ | ||
| 753 | public void clear() { | ||
| 754 | final ReentrantLock lock = this.lock; | ||
| 755 | lock.lock(); | ||
| 756 | try { | ||
| 757 | setArray(new Object[0]); | ||
| 758 | } finally { | ||
| 759 | lock.unlock(); | ||
| 760 | } | ||
| 761 | } | ||
| 762 | |||
| 763 | /** | ||
| 764 | * Appends all of the elements in the specified collection to the end | ||
| 765 | * of this list, in the order that they are returned by the specified | ||
| 766 | * collection's iterator. | ||
| 767 | * | ||
| 768 | * @param c collection containing elements to be added to this list | ||
| 769 | * @return <tt>true</tt> if this list changed as a result of the call | ||
| 770 | * @throws NullPointerException if the specified collection is null | ||
| 771 | * @see #add(Object) | ||
| 772 | */ | ||
| 773 | public boolean addAll(Collection<? extends E> c) { | ||
| 774 | Object[] cs = c.toArray(); | ||
| 775 | if (cs.length == 0) | ||
| 776 | return false; | ||
| 777 | final ReentrantLock lock = this.lock; | ||
| 778 | lock.lock(); | ||
| 779 | try { | ||
| 780 | Object[] elements = getArray(); | ||
| 781 | int len = elements.length; | ||
| 782 | Object[] newElements = Arrays.copyOf(elements, len + cs.length); | ||
| 783 | System.arraycopy(cs, 0, newElements, len, cs.length); | ||
| 784 | setArray(newElements); | ||
| 785 | return true; | ||
| 786 | } finally { | ||
| 787 | lock.unlock(); | ||
| 788 | } | ||
| 789 | } | ||
| 790 | |||
| 791 | /** | ||
| 792 | * Inserts all of the elements in the specified collection into this | ||
| 793 | * list, starting at the specified position. Shifts the element | ||
| 794 | * currently at that position (if any) and any subsequent elements to | ||
| 795 | * the right (increases their indices). The new elements will appear | ||
| 796 | * in this list in the order that they are returned by the | ||
| 797 | * specified collection's iterator. | ||
| 798 | * | ||
| 799 | * @param index index at which to insert the first element | ||
| 800 | * from the specified collection | ||
| 801 | * @param c collection containing elements to be added to this list | ||
| 802 | * @return <tt>true</tt> if this list changed as a result of the call | ||
| 803 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 804 | * @throws NullPointerException if the specified collection is null | ||
| 805 | * @see #add(int,Object) | ||
| 806 | */ | ||
| 807 | public boolean addAll(int index, Collection<? extends E> c) { | ||
| 808 | Object[] cs = c.toArray(); | ||
| 809 | final ReentrantLock lock = this.lock; | ||
| 810 | lock.lock(); | ||
| 811 | try { | ||
| 812 | Object[] elements = getArray(); | ||
| 813 | int len = elements.length; | ||
| 814 | if (index > len || index < 0) | ||
| 815 | throw new IndexOutOfBoundsException("Index: "+index+ | ||
| 816 | ", Size: "+len); | ||
| 817 | if (cs.length == 0) | ||
| 818 | return false; | ||
| 819 | int numMoved = len - index; | ||
| 820 | Object[] newElements; | ||
| 821 | if (numMoved == 0) | ||
| 822 | newElements = Arrays.copyOf(elements, len + cs.length); | ||
| 823 | else { | ||
| 824 | newElements = new Object[len + cs.length]; | ||
| 825 | System.arraycopy(elements, 0, newElements, 0, index); | ||
| 826 | System.arraycopy(elements, index, | ||
| 827 | newElements, index + cs.length, | ||
| 828 | numMoved); | ||
| 829 | } | ||
| 830 | System.arraycopy(cs, 0, newElements, index, cs.length); | ||
| 831 | setArray(newElements); | ||
| 832 | return true; | ||
| 833 | } finally { | ||
| 834 | lock.unlock(); | ||
| 835 | } | ||
| 836 | } | ||
| 837 | |||
| 838 | /** | ||
| 839 | * Saves the state of the list to a stream (that is, serializes it). | ||
| 840 | * | ||
| 841 | * @serialData The length of the array backing the list is emitted | ||
| 842 | * (int), followed by all of its elements (each an Object) | ||
| 843 | * in the proper order. | ||
| 844 | * @param s the stream | ||
| 845 | */ | ||
| 846 | private void writeObject(java.io.ObjectOutputStream s) | ||
| 847 | throws java.io.IOException{ | ||
| 848 | |||
| 849 | s.defaultWriteObject(); | ||
| 850 | |||
| 851 | Object[] elements = getArray(); | ||
| 852 | // Write out array length | ||
| 853 | s.writeInt(elements.length); | ||
| 854 | |||
| 855 | // Write out all elements in the proper order. | ||
| 856 | for (Object element : elements) | ||
| 857 | s.writeObject(element); | ||
| 858 | } | ||
| 859 | |||
| 860 | /** | ||
| 861 | * Reconstitutes the list from a stream (that is, deserializes it). | ||
| 862 | * | ||
| 863 | * @param s the stream | ||
| 864 | */ | ||
| 865 | private void readObject(java.io.ObjectInputStream s) | ||
| 866 | throws java.io.IOException, ClassNotFoundException { | ||
| 867 | |||
| 868 | s.defaultReadObject(); | ||
| 869 | |||
| 870 | // bind to new lock | ||
| 871 | resetLock(); | ||
| 872 | |||
| 873 | // Read in array length and allocate array | ||
| 874 | int len = s.readInt(); | ||
| 875 | Object[] elements = new Object[len]; | ||
| 876 | |||
| 877 | // Read in all elements in the proper order. | ||
| 878 | for (int i = 0; i < len; i++) | ||
| 879 | elements[i] = s.readObject(); | ||
| 880 | setArray(elements); | ||
| 881 | } | ||
| 882 | |||
| 883 | /** | ||
| 884 | * Returns a string representation of this list. The string | ||
| 885 | * representation consists of the string representations of the list's | ||
| 886 | * elements in the order they are returned by its iterator, enclosed in | ||
| 887 | * square brackets (<tt>"[]"</tt>). Adjacent elements are separated by | ||
| 888 | * the characters <tt>", "</tt> (comma and space). Elements are | ||
| 889 | * converted to strings as by {@link String#valueOf(Object)}. | ||
| 890 | * | ||
| 891 | * @return a string representation of this list | ||
| 892 | */ | ||
| 893 | public String toString() { | ||
| 894 | return Arrays.toString(getArray()); | ||
| 895 | } | ||
| 896 | |||
| 897 | /** | ||
| 898 | * Compares the specified object with this list for equality. | ||
| 899 | * Returns {@code true} if the specified object is the same object | ||
| 900 | * as this object, or if it is also a {@link List} and the sequence | ||
| 901 | * of elements returned by an {@linkplain List#iterator() iterator} | ||
| 902 | * over the specified list is the same as the sequence returned by | ||
| 903 | * an iterator over this list. The two sequences are considered to | ||
| 904 | * be the same if they have the same length and corresponding | ||
| 905 | * elements at the same position in the sequence are <em>equal</em>. | ||
| 906 | * Two elements {@code e1} and {@code e2} are considered | ||
| 907 | * <em>equal</em> if {@code (e1==null ? e2==null : e1.equals(e2))}. | ||
| 908 | * | ||
| 909 | * @param o the object to be compared for equality with this list | ||
| 910 | * @return {@code true} if the specified object is equal to this list | ||
| 911 | */ | ||
| 912 | public boolean equals(Object o) { | ||
| 913 | if (o == this) | ||
| 914 | return true; | ||
| 915 | if (!(o instanceof List)) | ||
| 916 | return false; | ||
| 917 | |||
| 918 | List<?> list = (List<?>)(o); | ||
| 919 | Iterator<?> it = list.iterator(); | ||
| 920 | Object[] elements = getArray(); | ||
| 921 | int len = elements.length; | ||
| 922 | for (int i = 0; i < len; ++i) | ||
| 923 | if (!it.hasNext() || !eq(elements[i], it.next())) | ||
| 924 | return false; | ||
| 925 | if (it.hasNext()) | ||
| 926 | return false; | ||
| 927 | return true; | ||
| 928 | } | ||
| 929 | |||
| 930 | /** | ||
| 931 | * Returns the hash code value for this list. | ||
| 932 | * | ||
| 933 | * <p>This implementation uses the definition in {@link List#hashCode}. | ||
| 934 | * | ||
| 935 | * @return the hash code value for this list | ||
| 936 | */ | ||
| 937 | public int hashCode() { | ||
| 938 | int hashCode = 1; | ||
| 939 | Object[] elements = getArray(); | ||
| 940 | int len = elements.length; | ||
| 941 | for (int i = 0; i < len; ++i) { | ||
| 942 | Object obj = elements[i]; | ||
| 943 | hashCode = 31*hashCode + (obj==null ? 0 : obj.hashCode()); | ||
| 944 | } | ||
| 945 | return hashCode; | ||
| 946 | } | ||
| 947 | |||
| 948 | /** | ||
| 949 | * Returns an iterator over the elements in this list in proper sequence. | ||
| 950 | * | ||
| 951 | * <p>The returned iterator provides a snapshot of the state of the list | ||
| 952 | * when the iterator was constructed. No synchronization is needed while | ||
| 953 | * traversing the iterator. The iterator does <em>NOT</em> support the | ||
| 954 | * <tt>remove</tt> method. | ||
| 955 | * | ||
| 956 | * @return an iterator over the elements in this list in proper sequence | ||
| 957 | */ | ||
| 958 | public Iterator<E> iterator() { | ||
| 959 | return new COWIterator<E>(getArray(), 0); | ||
| 960 | } | ||
| 961 | |||
| 962 | /** | ||
| 963 | * {@inheritDoc} | ||
| 964 | * | ||
| 965 | * <p>The returned iterator provides a snapshot of the state of the list | ||
| 966 | * when the iterator was constructed. No synchronization is needed while | ||
| 967 | * traversing the iterator. The iterator does <em>NOT</em> support the | ||
| 968 | * <tt>remove</tt>, <tt>set</tt> or <tt>add</tt> methods. | ||
| 969 | */ | ||
| 970 | public ListIterator<E> listIterator() { | ||
| 971 | return new COWIterator<E>(getArray(), 0); | ||
| 972 | } | ||
| 973 | |||
| 974 | /** | ||
| 975 | * {@inheritDoc} | ||
| 976 | * | ||
| 977 | * <p>The returned iterator provides a snapshot of the state of the list | ||
| 978 | * when the iterator was constructed. No synchronization is needed while | ||
| 979 | * traversing the iterator. The iterator does <em>NOT</em> support the | ||
| 980 | * <tt>remove</tt>, <tt>set</tt> or <tt>add</tt> methods. | ||
| 981 | * | ||
| 982 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 983 | */ | ||
| 984 | public ListIterator<E> listIterator(final int index) { | ||
| 985 | Object[] elements = getArray(); | ||
| 986 | int len = elements.length; | ||
| 987 | if (index<0 || index>len) | ||
| 988 | throw new IndexOutOfBoundsException("Index: "+index); | ||
| 989 | |||
| 990 | return new COWIterator<E>(elements, index); | ||
| 991 | } | ||
| 992 | |||
| 993 | private static class COWIterator<E> implements ListIterator<E> { | ||
| 994 | /** Snapshot of the array */ | ||
| 995 | private final Object[] snapshot; | ||
| 996 | /** Index of element to be returned by subsequent call to next. */ | ||
| 997 | private int cursor; | ||
| 998 | |||
| 999 | private COWIterator(Object[] elements, int initialCursor) { | ||
| 1000 | cursor = initialCursor; | ||
| 1001 | snapshot = elements; | ||
| 1002 | } | ||
| 1003 | |||
| 1004 | public boolean hasNext() { | ||
| 1005 | return cursor < snapshot.length; | ||
| 1006 | } | ||
| 1007 | |||
| 1008 | public boolean hasPrevious() { | ||
| 1009 | return cursor > 0; | ||
| 1010 | } | ||
| 1011 | |||
| 1012 | @SuppressWarnings("unchecked") | ||
| 1013 | public E next() { | ||
| 1014 | if (! hasNext()) | ||
| 1015 | throw new NoSuchElementException(); | ||
| 1016 | return (E) snapshot[cursor++]; | ||
| 1017 | } | ||
| 1018 | |||
| 1019 | @SuppressWarnings("unchecked") | ||
| 1020 | public E previous() { | ||
| 1021 | if (! hasPrevious()) | ||
| 1022 | throw new NoSuchElementException(); | ||
| 1023 | return (E) snapshot[--cursor]; | ||
| 1024 | } | ||
| 1025 | |||
| 1026 | public int nextIndex() { | ||
| 1027 | return cursor; | ||
| 1028 | } | ||
| 1029 | |||
| 1030 | public int previousIndex() { | ||
| 1031 | return cursor-1; | ||
| 1032 | } | ||
| 1033 | |||
| 1034 | /** | ||
| 1035 | * Not supported. Always throws UnsupportedOperationException. | ||
| 1036 | * @throws UnsupportedOperationException always; <tt>remove</tt> | ||
| 1037 | * is not supported by this iterator. | ||
| 1038 | */ | ||
| 1039 | public void remove() { | ||
| 1040 | throw new UnsupportedOperationException(); | ||
| 1041 | } | ||
| 1042 | |||
| 1043 | /** | ||
| 1044 | * Not supported. Always throws UnsupportedOperationException. | ||
| 1045 | * @throws UnsupportedOperationException always; <tt>set</tt> | ||
| 1046 | * is not supported by this iterator. | ||
| 1047 | */ | ||
| 1048 | public void set(E e) { | ||
| 1049 | throw new UnsupportedOperationException(); | ||
| 1050 | } | ||
| 1051 | |||
| 1052 | /** | ||
| 1053 | * Not supported. Always throws UnsupportedOperationException. | ||
| 1054 | * @throws UnsupportedOperationException always; <tt>add</tt> | ||
| 1055 | * is not supported by this iterator. | ||
| 1056 | */ | ||
| 1057 | public void add(E e) { | ||
| 1058 | throw new UnsupportedOperationException(); | ||
| 1059 | } | ||
| 1060 | } | ||
| 1061 | |||
| 1062 | /** | ||
| 1063 | * Returns a view of the portion of this list between | ||
| 1064 | * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive. | ||
| 1065 | * The returned list is backed by this list, so changes in the | ||
| 1066 | * returned list are reflected in this list. | ||
| 1067 | * | ||
| 1068 | * <p>The semantics of the list returned by this method become | ||
| 1069 | * undefined if the backing list (i.e., this list) is modified in | ||
| 1070 | * any way other than via the returned list. | ||
| 1071 | * | ||
| 1072 | * @param fromIndex low endpoint (inclusive) of the subList | ||
| 1073 | * @param toIndex high endpoint (exclusive) of the subList | ||
| 1074 | * @return a view of the specified range within this list | ||
| 1075 | * @throws IndexOutOfBoundsException {@inheritDoc} | ||
| 1076 | */ | ||
| 1077 | public List<E> subList(int fromIndex, int toIndex) { | ||
| 1078 | final ReentrantLock lock = this.lock; | ||
| 1079 | lock.lock(); | ||
| 1080 | try { | ||
| 1081 | Object[] elements = getArray(); | ||
| 1082 | int len = elements.length; | ||
| 1083 | if (fromIndex < 0 || toIndex > len || fromIndex > toIndex) | ||
| 1084 | throw new IndexOutOfBoundsException(); | ||
| 1085 | return new COWSubList<E>(this, fromIndex, toIndex); | ||
| 1086 | } finally { | ||
| 1087 | lock.unlock(); | ||
| 1088 | } | ||
| 1089 | } | ||
| 1090 | |||
| 1091 | /** | ||
| 1092 | * Sublist for CopyOnWriteArrayList. | ||
| 1093 | * This class extends AbstractList merely for convenience, to | ||
| 1094 | * avoid having to define addAll, etc. This doesn't hurt, but | ||
| 1095 | * is wasteful. This class does not need or use modCount | ||
| 1096 | * mechanics in AbstractList, but does need to check for | ||
| 1097 | * concurrent modification using similar mechanics. On each | ||
| 1098 | * operation, the array that we expect the backing list to use | ||
| 1099 | * is checked and updated. Since we do this for all of the | ||
| 1100 | * base operations invoked by those defined in AbstractList, | ||
| 1101 | * all is well. While inefficient, this is not worth | ||
| 1102 | * improving. The kinds of list operations inherited from | ||
| 1103 | * AbstractList are already so slow on COW sublists that | ||
| 1104 | * adding a bit more space/time doesn't seem even noticeable. | ||
| 1105 | */ | ||
| 1106 | private static class COWSubList<E> | ||
| 1107 | extends AbstractList<E> | ||
| 1108 | implements RandomAccess | ||
| 1109 | { | ||
| 1110 | private final CopyOnWriteArrayList<E> l; | ||
| 1111 | private final int offset; | ||
| 1112 | private int size; | ||
| 1113 | private Object[] expectedArray; | ||
| 1114 | |||
| 1115 | // only call this holding l's lock | ||
| 1116 | COWSubList(CopyOnWriteArrayList<E> list, | ||
| 1117 | int fromIndex, int toIndex) { | ||
| 1118 | l = list; | ||
| 1119 | expectedArray = l.getArray(); | ||
| 1120 | offset = fromIndex; | ||
| 1121 | size = toIndex - fromIndex; | ||
| 1122 | } | ||
| 1123 | |||
| 1124 | // only call this holding l's lock | ||
| 1125 | private void checkForComodification() { | ||
| 1126 | if (l.getArray() != expectedArray) | ||
| 1127 | throw new ConcurrentModificationException(); | ||
| 1128 | } | ||
| 1129 | |||
| 1130 | // only call this holding l's lock | ||
| 1131 | private void rangeCheck(int index) { | ||
| 1132 | if (index<0 || index>=size) | ||
| 1133 | throw new IndexOutOfBoundsException("Index: "+index+ | ||
| 1134 | ",Size: "+size); | ||
| 1135 | } | ||
| 1136 | |||
| 1137 | public E set(int index, E element) { | ||
| 1138 | final ReentrantLock lock = l.lock; | ||
| 1139 | lock.lock(); | ||
| 1140 | try { | ||
| 1141 | rangeCheck(index); | ||
| 1142 | checkForComodification(); | ||
| 1143 | E x = l.set(index+offset, element); | ||
| 1144 | expectedArray = l.getArray(); | ||
| 1145 | return x; | ||
| 1146 | } finally { | ||
| 1147 | lock.unlock(); | ||
| 1148 | } | ||
| 1149 | } | ||
| 1150 | |||
| 1151 | public E get(int index) { | ||
| 1152 | final ReentrantLock lock = l.lock; | ||
| 1153 | lock.lock(); | ||
| 1154 | try { | ||
| 1155 | rangeCheck(index); | ||
| 1156 | checkForComodification(); | ||
| 1157 | return l.get(index+offset); | ||
| 1158 | } finally { | ||
| 1159 | lock.unlock(); | ||
| 1160 | } | ||
| 1161 | } | ||
| 1162 | |||
| 1163 | public int size() { | ||
| 1164 | final ReentrantLock lock = l.lock; | ||
| 1165 | lock.lock(); | ||
| 1166 | try { | ||
| 1167 | checkForComodification(); | ||
| 1168 | return size; | ||
| 1169 | } finally { | ||
| 1170 | lock.unlock(); | ||
| 1171 | } | ||
| 1172 | } | ||
| 1173 | |||
| 1174 | public void add(int index, E element) { | ||
| 1175 | final ReentrantLock lock = l.lock; | ||
| 1176 | lock.lock(); | ||
| 1177 | try { | ||
| 1178 | checkForComodification(); | ||
| 1179 | if (index<0 || index>size) | ||
| 1180 | throw new IndexOutOfBoundsException(); | ||
| 1181 | l.add(index+offset, element); | ||
| 1182 | expectedArray = l.getArray(); | ||
| 1183 | size++; | ||
| 1184 | } finally { | ||
| 1185 | lock.unlock(); | ||
| 1186 | } | ||
| 1187 | } | ||
| 1188 | |||
| 1189 | public void clear() { | ||
| 1190 | final ReentrantLock lock = l.lock; | ||
| 1191 | lock.lock(); | ||
| 1192 | try { | ||
| 1193 | checkForComodification(); | ||
| 1194 | l.removeRange(offset, offset+size); | ||
| 1195 | expectedArray = l.getArray(); | ||
| 1196 | size = 0; | ||
| 1197 | } finally { | ||
| 1198 | lock.unlock(); | ||
| 1199 | } | ||
| 1200 | } | ||
| 1201 | |||
| 1202 | public E remove(int index) { | ||
| 1203 | final ReentrantLock lock = l.lock; | ||
| 1204 | lock.lock(); | ||
| 1205 | try { | ||
| 1206 | rangeCheck(index); | ||
| 1207 | checkForComodification(); | ||
| 1208 | E result = l.remove(index+offset); | ||
| 1209 | expectedArray = l.getArray(); | ||
| 1210 | size--; | ||
| 1211 | return result; | ||
| 1212 | } finally { | ||
| 1213 | lock.unlock(); | ||
| 1214 | } | ||
| 1215 | } | ||
| 1216 | |||
| 1217 | public boolean remove(Object o) { | ||
| 1218 | int index = indexOf(o); | ||
| 1219 | if (index == -1) | ||
| 1220 | return false; | ||
| 1221 | remove(index); | ||
| 1222 | return true; | ||
| 1223 | } | ||
| 1224 | |||
| 1225 | public Iterator<E> iterator() { | ||
| 1226 | final ReentrantLock lock = l.lock; | ||
| 1227 | lock.lock(); | ||
| 1228 | try { | ||
| 1229 | checkForComodification(); | ||
| 1230 | return new COWSubListIterator<E>(l, 0, offset, size); | ||
| 1231 | } finally { | ||
| 1232 | lock.unlock(); | ||
| 1233 | } | ||
| 1234 | } | ||
| 1235 | |||
| 1236 | public ListIterator<E> listIterator(final int index) { | ||
| 1237 | final ReentrantLock lock = l.lock; | ||
| 1238 | lock.lock(); | ||
| 1239 | try { | ||
| 1240 | checkForComodification(); | ||
| 1241 | if (index<0 || index>size) | ||
| 1242 | throw new IndexOutOfBoundsException("Index: "+index+ | ||
| 1243 | ", Size: "+size); | ||
| 1244 | return new COWSubListIterator<E>(l, index, offset, size); | ||
| 1245 | } finally { | ||
| 1246 | lock.unlock(); | ||
| 1247 | } | ||
| 1248 | } | ||
| 1249 | |||
| 1250 | public List<E> subList(int fromIndex, int toIndex) { | ||
| 1251 | final ReentrantLock lock = l.lock; | ||
| 1252 | lock.lock(); | ||
| 1253 | try { | ||
| 1254 | checkForComodification(); | ||
| 1255 | if (fromIndex<0 || toIndex>size) | ||
| 1256 | throw new IndexOutOfBoundsException(); | ||
| 1257 | return new COWSubList<E>(l, fromIndex + offset, | ||
| 1258 | toIndex + offset); | ||
| 1259 | } finally { | ||
| 1260 | lock.unlock(); | ||
| 1261 | } | ||
| 1262 | } | ||
| 1263 | |||
| 1264 | } | ||
| 1265 | |||
| 1266 | |||
| 1267 | private static class COWSubListIterator<E> implements ListIterator<E> { | ||
| 1268 | private final ListIterator<E> i; | ||
| 1269 | private final int index; | ||
| 1270 | private final int offset; | ||
| 1271 | private final int size; | ||
| 1272 | |||
| 1273 | COWSubListIterator(List<E> l, int index, int offset, | ||
| 1274 | int size) { | ||
| 1275 | this.index = index; | ||
| 1276 | this.offset = offset; | ||
| 1277 | this.size = size; | ||
| 1278 | i = l.listIterator(index+offset); | ||
| 1279 | } | ||
| 1280 | |||
| 1281 | public boolean hasNext() { | ||
| 1282 | return nextIndex() < size; | ||
| 1283 | } | ||
| 1284 | |||
| 1285 | public E next() { | ||
| 1286 | if (hasNext()) | ||
| 1287 | return i.next(); | ||
| 1288 | else | ||
| 1289 | throw new NoSuchElementException(); | ||
| 1290 | } | ||
| 1291 | |||
| 1292 | public boolean hasPrevious() { | ||
| 1293 | return previousIndex() >= 0; | ||
| 1294 | } | ||
| 1295 | |||
| 1296 | public E previous() { | ||
| 1297 | if (hasPrevious()) | ||
| 1298 | return i.previous(); | ||
| 1299 | else | ||
| 1300 | throw new NoSuchElementException(); | ||
| 1301 | } | ||
| 1302 | |||
| 1303 | public int nextIndex() { | ||
| 1304 | return i.nextIndex() - offset; | ||
| 1305 | } | ||
| 1306 | |||
| 1307 | public int previousIndex() { | ||
| 1308 | return i.previousIndex() - offset; | ||
| 1309 | } | ||
| 1310 | |||
| 1311 | public void remove() { | ||
| 1312 | throw new UnsupportedOperationException(); | ||
| 1313 | } | ||
| 1314 | |||
| 1315 | public void set(E e) { | ||
| 1316 | throw new UnsupportedOperationException(); | ||
| 1317 | } | ||
| 1318 | |||
| 1319 | public void add(E e) { | ||
| 1320 | throw new UnsupportedOperationException(); | ||
| 1321 | } | ||
| 1322 | } | ||
| 1323 | |||
| 1324 | // Support for resetting lock while deserializing | ||
| 1325 | private void resetLock() { | ||
| 1326 | UNSAFE.putObjectVolatile(this, lockOffset, new ReentrantLock()); | ||
| 1327 | } | ||
| 1328 | private static final sun.misc.Unsafe UNSAFE; | ||
| 1329 | private static final long lockOffset; | ||
| 1330 | static { | ||
| 1331 | try { | ||
| 1332 | UNSAFE = sun.misc.Unsafe.getUnsafe(); | ||
| 1333 | Class k = CopyOnWriteArrayList.class; | ||
| 1334 | lockOffset = UNSAFE.objectFieldOffset | ||
| 1335 | (k.getDeclaredField("lock")); | ||
| 1336 | } catch (Exception e) { | ||
| 1337 | throw new Error(e); | ||
| 1338 | } | ||
| 1339 | } | ||
| 1340 | } | ||