13 |
|
* have smaller stack space footprints and faster completion mechanics |
14 |
|
* but higher per-task footprints. Compared to LinkedAsyncActions, |
15 |
|
* BinaryAsyncActions are simpler to use and have less overhead in |
16 |
< |
* typical uasges but are restricted to binary computation trees. |
16 |
> |
* typical usages but are restricted to binary computation trees. |
17 |
|
* |
18 |
|
* <p>Upon construction, a BinaryAsyncAction does not bear any |
19 |
|
* linkages. For non-root tasks, links must be established using |
38 |
|
* } |
39 |
|
* } |
40 |
|
* </pre> |
41 |
< |
* An alternative, and usually faster strategy is to instead use a |
41 |
> |
* An alternative, and usually faster, strategy is to instead use a |
42 |
|
* loop to fork subtasks: |
43 |
|
* <pre> |
44 |
|
* protected void compute() { |
57 |
|
* </pre> |
58 |
|
*/ |
59 |
|
public abstract class BinaryAsyncAction extends ForkJoinTask<Void> { |
60 |
< |
private volatile int controlState; |
61 |
< |
|
62 |
< |
static final AtomicIntegerFieldUpdater<BinaryAsyncAction> controlStateUpdater = |
60 |
> |
private volatile int controlState; |
61 |
> |
|
62 |
> |
static final AtomicIntegerFieldUpdater<BinaryAsyncAction> controlStateUpdater = |
63 |
|
AtomicIntegerFieldUpdater.newUpdater(BinaryAsyncAction.class, "controlState"); |
64 |
< |
|
64 |
> |
|
65 |
|
/** |
66 |
|
* Parent to propagate completion; nulled after completion to |
67 |
|
* avoid retaining entire tree as garbage |
89 |
|
* as parent, and each other as siblings. |
90 |
|
* @param x one subtask |
91 |
|
* @param y the other subtask |
92 |
< |
* @throws NullPointerException if either argument is null. |
92 |
> |
* @throws NullPointerException if either argument is null |
93 |
|
*/ |
94 |
|
public final void linkSubtasks(BinaryAsyncAction x, BinaryAsyncAction y) { |
95 |
|
x.parent = y.parent = this; |
120 |
|
* default version of this method does nothing and returns |
121 |
|
* {@code true}. |
122 |
|
* @return true if this task's exception should be propagated to |
123 |
< |
* this task's parent. |
123 |
> |
* this task's parent |
124 |
|
*/ |
125 |
|
protected boolean onException() { |
126 |
|
return true; |
169 |
|
a.sibling = null; |
170 |
|
a.parent = null; |
171 |
|
a.completeThis(); |
172 |
< |
if (p == null || p.compareAndSetControlState(0, 1)) |
172 |
> |
if (p == null || p.compareAndSetControlState(0, 1)) |
173 |
|
break; |
174 |
|
try { |
175 |
|
p.onComplete(a, s); |
192 |
|
* @param ex the exception to throw when joining this task |
193 |
|
* @throws NullPointerException if ex is null |
194 |
|
* @throws Throwable if any invocation of |
195 |
< |
* {@code onException} does so. |
195 |
> |
* {@code onException} does so |
196 |
|
*/ |
197 |
|
public final void completeExceptionally(Throwable ex) { |
198 |
|
BinaryAsyncAction a = this; |
209 |
|
/** |
210 |
|
* Returns this task's parent, or null if none or this task |
211 |
|
* is already complete. |
212 |
< |
* @return this task's parent, or null if none. |
212 |
> |
* @return this task's parent, or null if none |
213 |
|
*/ |
214 |
|
public final BinaryAsyncAction getParent() { |
215 |
|
return parent; |
218 |
|
/** |
219 |
|
* Returns this task's sibling, or null if none or this task is |
220 |
|
* already complete. |
221 |
< |
* @return this task's sibling, or null if none. |
221 |
> |
* @return this task's sibling, or null if none |
222 |
|
*/ |
223 |
|
public BinaryAsyncAction getSibling() { |
224 |
|
return sibling; |
267 |
|
} |
268 |
|
|
269 |
|
/** |
270 |
< |
* Sets the control state to the given value, |
270 |
> |
* Increments the control state. |
271 |
|
* @param value the new value |
272 |
|
*/ |
273 |
|
protected final void incrementControlState() { |
275 |
|
} |
276 |
|
|
277 |
|
/** |
278 |
< |
* Decrement the control state |
278 |
> |
* Decrements the control state. |
279 |
|
* @return true if successful |
280 |
|
*/ |
281 |
|
protected final void decrementControlState() { |
282 |
|
controlStateUpdater.decrementAndGet(this); |
283 |
|
} |
284 |
|
|
285 |
+ |
|
286 |
|
} |