2
|
1 |
/*
|
|
2 |
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
|
|
3 |
*
|
|
4 |
* This code is free software; you can redistribute it and/or modify it
|
|
5 |
* under the terms of the GNU General Public License version 2 only, as
|
5506
|
6 |
* published by the Free Software Foundation. Oracle designates this
|
2
|
7 |
* particular file as subject to the "Classpath" exception as provided
|
5506
|
8 |
* by Oracle in the LICENSE file that accompanied this code.
|
2
|
9 |
*
|
|
10 |
* This code is distributed in the hope that it will be useful, but WITHOUT
|
|
11 |
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
12 |
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
13 |
* version 2 for more details (a copy is included in the LICENSE file that
|
|
14 |
* accompanied this code).
|
|
15 |
*
|
|
16 |
* You should have received a copy of the GNU General Public License version
|
|
17 |
* 2 along with this work; if not, write to the Free Software Foundation,
|
|
18 |
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
19 |
*
|
5506
|
20 |
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
|
|
21 |
* or visit www.oracle.com if you need additional information or have any
|
|
22 |
* questions.
|
2
|
23 |
*/
|
|
24 |
|
|
25 |
/*
|
|
26 |
* This file is available under and governed by the GNU General Public
|
|
27 |
* License version 2 only, as published by the Free Software Foundation.
|
|
28 |
* However, the following notice accompanied the original version of this
|
|
29 |
* file:
|
|
30 |
*
|
|
31 |
* Written by Doug Lea with assistance from members of JCP JSR-166
|
|
32 |
* Expert Group and released to the public domain, as explained at
|
|
33 |
* http://creativecommons.org/licenses/publicdomain
|
|
34 |
*/
|
|
35 |
|
|
36 |
package java.util.concurrent.atomic;
|
|
37 |
import sun.misc.Unsafe;
|
|
38 |
import java.lang.reflect.*;
|
|
39 |
|
|
40 |
/**
|
|
41 |
* A reflection-based utility that enables atomic updates to
|
|
42 |
* designated {@code volatile long} fields of designated classes.
|
|
43 |
* This class is designed for use in atomic data structures in which
|
|
44 |
* several fields of the same node are independently subject to atomic
|
|
45 |
* updates.
|
|
46 |
*
|
|
47 |
* <p>Note that the guarantees of the {@code compareAndSet}
|
|
48 |
* method in this class are weaker than in other atomic classes.
|
|
49 |
* Because this class cannot ensure that all uses of the field
|
|
50 |
* are appropriate for purposes of atomic access, it can
|
|
51 |
* guarantee atomicity only with respect to other invocations of
|
|
52 |
* {@code compareAndSet} and {@code set} on the same updater.
|
|
53 |
*
|
|
54 |
* @since 1.5
|
|
55 |
* @author Doug Lea
|
|
56 |
* @param <T> The type of the object holding the updatable field
|
|
57 |
*/
|
|
58 |
public abstract class AtomicLongFieldUpdater<T> {
|
|
59 |
/**
|
|
60 |
* Creates and returns an updater for objects with the given field.
|
|
61 |
* The Class argument is needed to check that reflective types and
|
|
62 |
* generic types match.
|
|
63 |
*
|
|
64 |
* @param tclass the class of the objects holding the field
|
|
65 |
* @param fieldName the name of the field to be updated.
|
|
66 |
* @return the updater
|
|
67 |
* @throws IllegalArgumentException if the field is not a
|
|
68 |
* volatile long type.
|
|
69 |
* @throws RuntimeException with a nested reflection-based
|
|
70 |
* exception if the class does not hold field or is the wrong type.
|
|
71 |
*/
|
|
72 |
public static <U> AtomicLongFieldUpdater<U> newUpdater(Class<U> tclass, String fieldName) {
|
|
73 |
if (AtomicLong.VM_SUPPORTS_LONG_CAS)
|
|
74 |
return new CASUpdater<U>(tclass, fieldName);
|
|
75 |
else
|
|
76 |
return new LockedUpdater<U>(tclass, fieldName);
|
|
77 |
}
|
|
78 |
|
|
79 |
/**
|
|
80 |
* Protected do-nothing constructor for use by subclasses.
|
|
81 |
*/
|
|
82 |
protected AtomicLongFieldUpdater() {
|
|
83 |
}
|
|
84 |
|
|
85 |
/**
|
|
86 |
* Atomically sets the field of the given object managed by this updater
|
|
87 |
* to the given updated value if the current value {@code ==} the
|
|
88 |
* expected value. This method is guaranteed to be atomic with respect to
|
|
89 |
* other calls to {@code compareAndSet} and {@code set}, but not
|
|
90 |
* necessarily with respect to other changes in the field.
|
|
91 |
*
|
|
92 |
* @param obj An object whose field to conditionally set
|
|
93 |
* @param expect the expected value
|
|
94 |
* @param update the new value
|
|
95 |
* @return true if successful.
|
|
96 |
* @throws ClassCastException if {@code obj} is not an instance
|
|
97 |
* of the class possessing the field established in the constructor.
|
|
98 |
*/
|
|
99 |
public abstract boolean compareAndSet(T obj, long expect, long update);
|
|
100 |
|
|
101 |
/**
|
|
102 |
* Atomically sets the field of the given object managed by this updater
|
|
103 |
* to the given updated value if the current value {@code ==} the
|
|
104 |
* expected value. This method is guaranteed to be atomic with respect to
|
|
105 |
* other calls to {@code compareAndSet} and {@code set}, but not
|
|
106 |
* necessarily with respect to other changes in the field.
|
|
107 |
*
|
|
108 |
* <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
|
|
109 |
* and does not provide ordering guarantees, so is only rarely an
|
|
110 |
* appropriate alternative to {@code compareAndSet}.
|
|
111 |
*
|
|
112 |
* @param obj An object whose field to conditionally set
|
|
113 |
* @param expect the expected value
|
|
114 |
* @param update the new value
|
|
115 |
* @return true if successful.
|
|
116 |
* @throws ClassCastException if {@code obj} is not an instance
|
|
117 |
* of the class possessing the field established in the constructor.
|
|
118 |
*/
|
|
119 |
public abstract boolean weakCompareAndSet(T obj, long expect, long update);
|
|
120 |
|
|
121 |
/**
|
|
122 |
* Sets the field of the given object managed by this updater to the
|
|
123 |
* given updated value. This operation is guaranteed to act as a volatile
|
|
124 |
* store with respect to subsequent invocations of {@code compareAndSet}.
|
|
125 |
*
|
|
126 |
* @param obj An object whose field to set
|
|
127 |
* @param newValue the new value
|
|
128 |
*/
|
|
129 |
public abstract void set(T obj, long newValue);
|
|
130 |
|
|
131 |
/**
|
|
132 |
* Eventually sets the field of the given object managed by this
|
|
133 |
* updater to the given updated value.
|
|
134 |
*
|
|
135 |
* @param obj An object whose field to set
|
|
136 |
* @param newValue the new value
|
|
137 |
* @since 1.6
|
|
138 |
*/
|
|
139 |
public abstract void lazySet(T obj, long newValue);
|
|
140 |
|
|
141 |
/**
|
|
142 |
* Gets the current value held in the field of the given object managed
|
|
143 |
* by this updater.
|
|
144 |
*
|
|
145 |
* @param obj An object whose field to get
|
|
146 |
* @return the current value
|
|
147 |
*/
|
|
148 |
public abstract long get(T obj);
|
|
149 |
|
|
150 |
/**
|
|
151 |
* Atomically sets the field of the given object managed by this updater
|
|
152 |
* to the given value and returns the old value.
|
|
153 |
*
|
|
154 |
* @param obj An object whose field to get and set
|
|
155 |
* @param newValue the new value
|
|
156 |
* @return the previous value
|
|
157 |
*/
|
|
158 |
public long getAndSet(T obj, long newValue) {
|
|
159 |
for (;;) {
|
|
160 |
long current = get(obj);
|
|
161 |
if (compareAndSet(obj, current, newValue))
|
|
162 |
return current;
|
|
163 |
}
|
|
164 |
}
|
|
165 |
|
|
166 |
/**
|
|
167 |
* Atomically increments by one the current value of the field of the
|
|
168 |
* given object managed by this updater.
|
|
169 |
*
|
|
170 |
* @param obj An object whose field to get and set
|
|
171 |
* @return the previous value
|
|
172 |
*/
|
|
173 |
public long getAndIncrement(T obj) {
|
|
174 |
for (;;) {
|
|
175 |
long current = get(obj);
|
|
176 |
long next = current + 1;
|
|
177 |
if (compareAndSet(obj, current, next))
|
|
178 |
return current;
|
|
179 |
}
|
|
180 |
}
|
|
181 |
|
|
182 |
/**
|
|
183 |
* Atomically decrements by one the current value of the field of the
|
|
184 |
* given object managed by this updater.
|
|
185 |
*
|
|
186 |
* @param obj An object whose field to get and set
|
|
187 |
* @return the previous value
|
|
188 |
*/
|
|
189 |
public long getAndDecrement(T obj) {
|
|
190 |
for (;;) {
|
|
191 |
long current = get(obj);
|
|
192 |
long next = current - 1;
|
|
193 |
if (compareAndSet(obj, current, next))
|
|
194 |
return current;
|
|
195 |
}
|
|
196 |
}
|
|
197 |
|
|
198 |
/**
|
|
199 |
* Atomically adds the given value to the current value of the field of
|
|
200 |
* the given object managed by this updater.
|
|
201 |
*
|
|
202 |
* @param obj An object whose field to get and set
|
|
203 |
* @param delta the value to add
|
|
204 |
* @return the previous value
|
|
205 |
*/
|
|
206 |
public long getAndAdd(T obj, long delta) {
|
|
207 |
for (;;) {
|
|
208 |
long current = get(obj);
|
|
209 |
long next = current + delta;
|
|
210 |
if (compareAndSet(obj, current, next))
|
|
211 |
return current;
|
|
212 |
}
|
|
213 |
}
|
|
214 |
|
|
215 |
/**
|
|
216 |
* Atomically increments by one the current value of the field of the
|
|
217 |
* given object managed by this updater.
|
|
218 |
*
|
|
219 |
* @param obj An object whose field to get and set
|
|
220 |
* @return the updated value
|
|
221 |
*/
|
|
222 |
public long incrementAndGet(T obj) {
|
|
223 |
for (;;) {
|
|
224 |
long current = get(obj);
|
|
225 |
long next = current + 1;
|
|
226 |
if (compareAndSet(obj, current, next))
|
|
227 |
return next;
|
|
228 |
}
|
|
229 |
}
|
|
230 |
|
|
231 |
/**
|
|
232 |
* Atomically decrements by one the current value of the field of the
|
|
233 |
* given object managed by this updater.
|
|
234 |
*
|
|
235 |
* @param obj An object whose field to get and set
|
|
236 |
* @return the updated value
|
|
237 |
*/
|
|
238 |
public long decrementAndGet(T obj) {
|
|
239 |
for (;;) {
|
|
240 |
long current = get(obj);
|
|
241 |
long next = current - 1;
|
|
242 |
if (compareAndSet(obj, current, next))
|
|
243 |
return next;
|
|
244 |
}
|
|
245 |
}
|
|
246 |
|
|
247 |
/**
|
|
248 |
* Atomically adds the given value to the current value of the field of
|
|
249 |
* the given object managed by this updater.
|
|
250 |
*
|
|
251 |
* @param obj An object whose field to get and set
|
|
252 |
* @param delta the value to add
|
|
253 |
* @return the updated value
|
|
254 |
*/
|
|
255 |
public long addAndGet(T obj, long delta) {
|
|
256 |
for (;;) {
|
|
257 |
long current = get(obj);
|
|
258 |
long next = current + delta;
|
|
259 |
if (compareAndSet(obj, current, next))
|
|
260 |
return next;
|
|
261 |
}
|
|
262 |
}
|
|
263 |
|
|
264 |
private static class CASUpdater<T> extends AtomicLongFieldUpdater<T> {
|
|
265 |
private static final Unsafe unsafe = Unsafe.getUnsafe();
|
|
266 |
private final long offset;
|
|
267 |
private final Class<T> tclass;
|
|
268 |
private final Class cclass;
|
|
269 |
|
|
270 |
CASUpdater(Class<T> tclass, String fieldName) {
|
|
271 |
Field field = null;
|
|
272 |
Class caller = null;
|
|
273 |
int modifiers = 0;
|
|
274 |
try {
|
|
275 |
field = tclass.getDeclaredField(fieldName);
|
|
276 |
caller = sun.reflect.Reflection.getCallerClass(3);
|
|
277 |
modifiers = field.getModifiers();
|
|
278 |
sun.reflect.misc.ReflectUtil.ensureMemberAccess(
|
|
279 |
caller, tclass, null, modifiers);
|
|
280 |
sun.reflect.misc.ReflectUtil.checkPackageAccess(tclass);
|
|
281 |
} catch(Exception ex) {
|
|
282 |
throw new RuntimeException(ex);
|
|
283 |
}
|
|
284 |
|
|
285 |
Class fieldt = field.getType();
|
|
286 |
if (fieldt != long.class)
|
|
287 |
throw new IllegalArgumentException("Must be long type");
|
|
288 |
|
|
289 |
if (!Modifier.isVolatile(modifiers))
|
|
290 |
throw new IllegalArgumentException("Must be volatile type");
|
|
291 |
|
|
292 |
this.cclass = (Modifier.isProtected(modifiers) &&
|
|
293 |
caller != tclass) ? caller : null;
|
|
294 |
this.tclass = tclass;
|
|
295 |
offset = unsafe.objectFieldOffset(field);
|
|
296 |
}
|
|
297 |
|
|
298 |
private void fullCheck(T obj) {
|
|
299 |
if (!tclass.isInstance(obj))
|
|
300 |
throw new ClassCastException();
|
|
301 |
if (cclass != null)
|
|
302 |
ensureProtectedAccess(obj);
|
|
303 |
}
|
|
304 |
|
|
305 |
public boolean compareAndSet(T obj, long expect, long update) {
|
|
306 |
if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
|
|
307 |
return unsafe.compareAndSwapLong(obj, offset, expect, update);
|
|
308 |
}
|
|
309 |
|
|
310 |
public boolean weakCompareAndSet(T obj, long expect, long update) {
|
|
311 |
if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
|
|
312 |
return unsafe.compareAndSwapLong(obj, offset, expect, update);
|
|
313 |
}
|
|
314 |
|
|
315 |
public void set(T obj, long newValue) {
|
|
316 |
if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
|
|
317 |
unsafe.putLongVolatile(obj, offset, newValue);
|
|
318 |
}
|
|
319 |
|
|
320 |
public void lazySet(T obj, long newValue) {
|
|
321 |
if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
|
|
322 |
unsafe.putOrderedLong(obj, offset, newValue);
|
|
323 |
}
|
|
324 |
|
|
325 |
public long get(T obj) {
|
|
326 |
if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
|
|
327 |
return unsafe.getLongVolatile(obj, offset);
|
|
328 |
}
|
|
329 |
|
|
330 |
private void ensureProtectedAccess(T obj) {
|
|
331 |
if (cclass.isInstance(obj)) {
|
|
332 |
return;
|
|
333 |
}
|
|
334 |
throw new RuntimeException (
|
|
335 |
new IllegalAccessException("Class " +
|
|
336 |
cclass.getName() +
|
|
337 |
" can not access a protected member of class " +
|
|
338 |
tclass.getName() +
|
|
339 |
" using an instance of " +
|
|
340 |
obj.getClass().getName()
|
|
341 |
)
|
|
342 |
);
|
|
343 |
}
|
|
344 |
}
|
|
345 |
|
|
346 |
|
|
347 |
private static class LockedUpdater<T> extends AtomicLongFieldUpdater<T> {
|
|
348 |
private static final Unsafe unsafe = Unsafe.getUnsafe();
|
|
349 |
private final long offset;
|
|
350 |
private final Class<T> tclass;
|
|
351 |
private final Class cclass;
|
|
352 |
|
|
353 |
LockedUpdater(Class<T> tclass, String fieldName) {
|
|
354 |
Field field = null;
|
|
355 |
Class caller = null;
|
|
356 |
int modifiers = 0;
|
|
357 |
try {
|
|
358 |
field = tclass.getDeclaredField(fieldName);
|
|
359 |
caller = sun.reflect.Reflection.getCallerClass(3);
|
|
360 |
modifiers = field.getModifiers();
|
|
361 |
sun.reflect.misc.ReflectUtil.ensureMemberAccess(
|
|
362 |
caller, tclass, null, modifiers);
|
|
363 |
sun.reflect.misc.ReflectUtil.checkPackageAccess(tclass);
|
|
364 |
} catch(Exception ex) {
|
|
365 |
throw new RuntimeException(ex);
|
|
366 |
}
|
|
367 |
|
|
368 |
Class fieldt = field.getType();
|
|
369 |
if (fieldt != long.class)
|
|
370 |
throw new IllegalArgumentException("Must be long type");
|
|
371 |
|
|
372 |
if (!Modifier.isVolatile(modifiers))
|
|
373 |
throw new IllegalArgumentException("Must be volatile type");
|
|
374 |
|
|
375 |
this.cclass = (Modifier.isProtected(modifiers) &&
|
|
376 |
caller != tclass) ? caller : null;
|
|
377 |
this.tclass = tclass;
|
|
378 |
offset = unsafe.objectFieldOffset(field);
|
|
379 |
}
|
|
380 |
|
|
381 |
private void fullCheck(T obj) {
|
|
382 |
if (!tclass.isInstance(obj))
|
|
383 |
throw new ClassCastException();
|
|
384 |
if (cclass != null)
|
|
385 |
ensureProtectedAccess(obj);
|
|
386 |
}
|
|
387 |
|
|
388 |
public boolean compareAndSet(T obj, long expect, long update) {
|
|
389 |
if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
|
|
390 |
synchronized(this) {
|
|
391 |
long v = unsafe.getLong(obj, offset);
|
|
392 |
if (v != expect)
|
|
393 |
return false;
|
|
394 |
unsafe.putLong(obj, offset, update);
|
|
395 |
return true;
|
|
396 |
}
|
|
397 |
}
|
|
398 |
|
|
399 |
public boolean weakCompareAndSet(T obj, long expect, long update) {
|
|
400 |
return compareAndSet(obj, expect, update);
|
|
401 |
}
|
|
402 |
|
|
403 |
public void set(T obj, long newValue) {
|
|
404 |
if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
|
|
405 |
synchronized(this) {
|
|
406 |
unsafe.putLong(obj, offset, newValue);
|
|
407 |
}
|
|
408 |
}
|
|
409 |
|
|
410 |
public void lazySet(T obj, long newValue) {
|
|
411 |
set(obj, newValue);
|
|
412 |
}
|
|
413 |
|
|
414 |
public long get(T obj) {
|
|
415 |
if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
|
|
416 |
synchronized(this) {
|
|
417 |
return unsafe.getLong(obj, offset);
|
|
418 |
}
|
|
419 |
}
|
|
420 |
|
|
421 |
private void ensureProtectedAccess(T obj) {
|
|
422 |
if (cclass.isInstance(obj)) {
|
|
423 |
return;
|
|
424 |
}
|
|
425 |
throw new RuntimeException (
|
|
426 |
new IllegalAccessException("Class " +
|
|
427 |
cclass.getName() +
|
|
428 |
" can not access a protected member of class " +
|
|
429 |
tclass.getName() +
|
|
430 |
" using an instance of " +
|
|
431 |
obj.getClass().getName()
|
|
432 |
)
|
|
433 |
);
|
|
434 |
}
|
|
435 |
}
|
|
436 |
}
|