| 15 |
|
* subtask of a given parent task. In this case, completion of this |
| 16 |
|
* task will propagate to its parent. If the parent's pending subtask |
| 17 |
|
* completion count becomes zero, it too will complete. |
| 18 |
< |
* LinkedAsyncActions rarely use methods <tt>join</tt> or |
| 19 |
< |
* <tt>invoke</tt> but instead propagate completion to parents |
| 20 |
< |
* implicitly via <tt>complete</tt>. While typical, it is not necessary |
| 21 |
< |
* for each task to <tt>complete</tt> itself. For example, it is |
| 18 |
> |
* LinkedAsyncActions rarely use methods {@code join} or |
| 19 |
> |
* {@code invoke} but instead propagate completion to parents |
| 20 |
> |
* implicitly via {@code complete}. While typical, it is not necessary |
| 21 |
> |
* for each task to {@code complete} itself. For example, it is |
| 22 |
|
* possible to treat one subtask as a continuation of the current task |
| 23 |
|
* by not registering it on construction. In this case, a |
| 24 |
< |
* <tt>complete</tt> of the subtask will trigger <tt>complete</tt> of the |
| 24 |
> |
* {@code complete} of the subtask will trigger {@code complete} of the |
| 25 |
|
* parent without the parent explicitly doing so. |
| 26 |
|
* |
| 27 |
|
* <p>In addition to supporting these different computation styles |
| 32 |
|
* <p><b>Sample Usage.</b> Here is a sketch of a LinkedAsyncAction |
| 33 |
|
* that visits all of the nodes of a graph. The details of the graph's |
| 34 |
|
* Node and Edge classes are omitted, but we assume each node contains |
| 35 |
< |
* an <tt>AtomicBoolean</tt> mark that starts out false. To execute |
| 35 |
> |
* an {@code AtomicBoolean} mark that starts out false. To execute |
| 36 |
|
* this, you would create a GraphVisitor for the root node with null |
| 37 |
< |
* parent, and <tt>invoke</tt> in a ForkJoinPool. Upon return, all |
| 37 |
> |
* parent, and {@code invoke} in a ForkJoinPool. Upon return, all |
| 38 |
|
* reachable nodes will have been visited. |
| 39 |
|
* |
| 40 |
|
* <pre> |
| 77 |
|
|
| 78 |
|
/** |
| 79 |
|
* Creates a new action with no parent. (You can add a parent |
| 80 |
< |
* later (but before forking) via <tt>reinitialize</tt>). |
| 80 |
> |
* later (but before forking) via {@code reinitialize}). |
| 81 |
|
*/ |
| 82 |
|
protected LinkedAsyncAction() { |
| 83 |
|
} |
| 97 |
|
/** |
| 98 |
|
* Creates a new action with the given parent, optionally |
| 99 |
|
* registering with the parent. If the parent is non-null and |
| 100 |
< |
* <tt>register</tt> is true, this task registers with the |
| 100 |
> |
* {@code register} is true, this task registers with the |
| 101 |
|
* parent, in which case, the parent task cannot complete until |
| 102 |
|
* this task completes. |
| 103 |
|
* @param parent the parent task, or null if none |
| 114 |
|
* Creates a new action with the given parent, optionally |
| 115 |
|
* registering with the parent, and setting the pending join count |
| 116 |
|
* to the given value. If the parent is non-null and |
| 117 |
< |
* <tt>register</tt> is true, this task registers with the |
| 117 |
> |
* {@code register} is true, this task registers with the |
| 118 |
|
* parent, in which case, the parent task cannot complete until |
| 119 |
|
* this task completes. Setting the pending join count requires |
| 120 |
|
* care -- it is correct only if child tasks do not themselves |
| 137 |
|
protected final void setRawResult(Void mustBeNull) { } |
| 138 |
|
|
| 139 |
|
/** |
| 140 |
< |
* Overridable callback action triggered by <tt>complete</tt>. Upon |
| 140 |
> |
* Overridable callback action triggered by {@code complete}. Upon |
| 141 |
|
* invocation, all subtasks have completed. After return, this |
| 142 |
< |
* task <tt>isDone</tt> and is joinable by other tasks. The |
| 142 |
> |
* task {@code isDone} and is joinable by other tasks. The |
| 143 |
|
* default version of this method does nothing. But it may be |
| 144 |
|
* overridden in subclasses to perform some action when this task |
| 145 |
|
* is about to complete. |
| 149 |
|
|
| 150 |
|
/** |
| 151 |
|
* Overridable callback action triggered by |
| 152 |
< |
* <tt>completeExceptionally</tt>. Upon invocation, this task has |
| 152 |
> |
* {@code completeExceptionally}. Upon invocation, this task has |
| 153 |
|
* aborted due to an exception (accessible via |
| 154 |
< |
* <tt>getException</tt>). If this method returns <tt>true</tt>, |
| 154 |
> |
* {@code getException}). If this method returns {@code true}, |
| 155 |
|
* the exception propagates to the current task's |
| 156 |
|
* parent. Otherwise, normal completion is propagated. The |
| 157 |
|
* default version of this method does nothing and returns |
| 158 |
< |
* <tt>true</tt>. |
| 158 |
> |
* {@code true}. |
| 159 |
|
* @return true if this task's exception should be propagated to |
| 160 |
|
* this task's parent. |
| 161 |
|
*/ |
| 175 |
|
|
| 176 |
|
/** |
| 177 |
|
* Completes this task. If the pending subtask completion count is |
| 178 |
< |
* zero, invokes <tt>onCompletion</tt>, then causes this task to |
| 179 |
< |
* be joinable (<tt>isDone</tt> becomes true), and then |
| 178 |
> |
* zero, invokes {@code onCompletion}, then causes this task to |
| 179 |
> |
* be joinable ({@code isDone} becomes true), and then |
| 180 |
|
* recursively applies to this task's parent, if it exists. If an |
| 181 |
< |
* exception is encountered in any <tt>onCompletion</tt> |
| 181 |
> |
* exception is encountered in any {@code onCompletion} |
| 182 |
|
* invocation, that task and its ancestors |
| 183 |
< |
* <tt>completeExceptionally</tt>. |
| 183 |
> |
* {@code completeExceptionally}. |
| 184 |
|
*/ |
| 185 |
|
public final void complete() { |
| 186 |
|
LinkedAsyncAction a = this; |
| 204 |
|
/** |
| 205 |
|
* Completes this task abnormally. Unless this task already |
| 206 |
|
* cancelled or aborted, upon invocation, this method invokes |
| 207 |
< |
* <tt>onException</tt>, and then, depending on its return value, |
| 207 |
> |
* {@code onException}, and then, depending on its return value, |
| 208 |
|
* completees parent (if one exists) exceptionally or normally. To |
| 209 |
|
* avoid unbounded exception loops, this method aborts if an |
| 210 |
< |
* exception is encountered in any <tt>onException</tt> |
| 210 |
> |
* exception is encountered in any {@code onException} |
| 211 |
|
* invocation. |
| 212 |
|
* @param ex the exception to throw when joining this task |
| 213 |
|
* @throws NullPointerException if ex is null |
| 214 |
|
* @throws Throwable if any invocation of |
| 215 |
< |
* <tt>onException</tt> does so. |
| 215 |
> |
* {@code onException} does so. |
| 216 |
|
*/ |
| 217 |
|
public final void completeExceptionally(Throwable ex) { |
| 218 |
|
LinkedAsyncAction a = this; |
