| Package | flash.concurrent |
| Class | public final class Condition |
| Inheritance | Condition  Object |
| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 11.5, AIR 3.5 |
The following is one possible workflow for using a Condition object:
- Before using a Condition object, the first worker must take ownership
of the condition's associated mutex by calling the Mutex object's
lock()ortryLock()methods. - The worker's code operates on the shared resource until some condition becomes false, preventing the worker from doing more work with the shared resource. For example, if the shared resource is a set of data to process, when there is no more data to process the worker can't do any more work.
- At that point, call the Condition object's
wait()method to pause the worker's execution and release ownership of the mutex. - At some point, a second worker takes ownership of the mutex. Because the mutex is available, it is safe for the second worker's code to operate on the shared resource. The second worker does whatever is necessary to satisfy the condition so that the first worker can do its work again. For example, if the first worker has no data to process, the second worker could pass more data to process into the shared resource.
- At that point, the condition related to the first worker's work is now
true, so the first worker needs to be notified that the condition is
fulfilled. To notify the first worker, the second worker's code calls
the Condition object's
notify()method or itsnotifyAll()method. - In addition to calling
notify(), the second worker needs to release ownership of the mutex. It does this either by calling the Mutex object'sunlock()method or the Condition object'swait()method. Since the first worker called thewait()method, ownership of the mutex returns to the first worker. Code execution in the first worker then continues again with the next line of code following thewait()call.
The Condition class is one of the special object types that are shared
between workers rather than copied between them. When you pass a condition
from one worker to another worker either by calling the Worker object's
setSharedProperty() method or by using a MessageChannel object,
both workers have a reference to the same Condition object in the runtime's
memory.
Related API Elements
Hide Inherited Public Properties
Show Inherited Public Properties| Property | Defined By | ||
|---|---|---|---|
 | constructor : Object
A reference to the class object or constructor function for a given object instance. | Object | |
| isSupported : Boolean [static] [read-only]
Indicates whether the Condition class is supported for the current platform. | Condition | ||
| mutex : Mutex [read-only]
The mutex associated with this condition. | Condition | ||
| Method | Defined By | ||
|---|---|---|---|
Creates a new Condition instance. | Condition | ||
|
Indicates whether an object has a specified property defined. | Object | |
|
Indicates whether an instance of the Object class is in the prototype chain of the object specified
as the parameter. | Object | |
Specifes that the condition that this Condition object represents has
been satisfied and that ownership of the mutex will be returned to the
next worker (if any) that's waiting on this condition. | Condition | ||
Specifies that the condition that this Condition object represents has
been satisfied and that ownership of the mutex will be returned to all
workers that are waiting on this condition. | Condition | ||
|
Indicates whether the specified property exists and is enumerable. | Object | |
|
Sets the availability of a dynamic property for loop operations. | Object | |
|
Returns the string representation of this object, formatted according to locale-specific conventions. | Object | |
|
Returns the string representation of the specified object. | Object | |
|
Returns the primitive value of the specified object. | Object | |
Specifies that the condition that this Condition object represents isn't
satisfied, and the current worker needs to wait until it is satisfied
before executing more code. | Condition | ||
isSupported | property |
isSupported:Boolean [read-only] | Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 11.5, AIR 3.5 |
Indicates whether the Condition class is supported for the current platform.
Note: if the Mutex class is not supported, creation
of a Condition instance is not possible and this property is false.
Implementation
public static function get isSupported():Booleanmutex | property |
Condition | () | Constructor |
notify | () | method |
public function notify():void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 11.5, AIR 3.5 |
Specifes that the condition that this Condition object represents has been satisfied and that ownership of the mutex will be returned to the next worker (if any) that's waiting on this condition.
Calling this method doesn't automatically release ownership of the
mutex. After calling notify(), you should explicitly
release ownership of the mutex in one of two ways: call the
Mutex.unlock() method if the current worker doesn't need the
mutex again, or call wait() if the worker should get
ownership of the mutex again after other workers have completed their work.
One the mutex's lock is released, the next worker in the queue of
workers that have called the wait() method acquires the
mutex and resumes code execution.
Throws
IllegalOperationError — if the current worker doesn't
own this condition's mutex
|
notifyAll | () | method |
public function notifyAll():void| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 11.5, AIR 3.5 |
Specifies that the condition that this Condition object represents has been satisfied and that ownership of the mutex will be returned to all workers that are waiting on this condition.
Calling this method doesn't automatically release ownership of the
mutex. After calling notify(), you should explicitly release
ownership of the mutex in one of two ways: call the
Mutex.unlock() method if the current worker doesn't need the
mutex again, or call wait() if the worker should get
ownership of the mutex again after other workers have completed their work.
Once the mutex's lock is released, the waiting workers receive
ownership one at a time in the order they called the wait()
method. Each worker that has called the wait() method
acquires the mutex in turn and resumes code execution. When that worker
calls the Mutex.unlock() method or the wait()
method, mutex ownership then switches to the next waiting worker. Each
time mutex ownership switches between workers, the transition is performed
as a single atomic operation.
Throws
IllegalOperationError — if the current worker doesn't
own this condition's mutex
|
wait | () | method |
public function wait(timeout:Number = -1):Boolean| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 11.5, AIR 3.5 |
Specifies that the condition that this Condition object represents isn't
satisfied, and the current worker needs to wait until it is satisfied
before executing more code. Calling this method pauses the current
worker's execution thread and releases ownership of the condition's mutex.
These steps are performed as a single atomic operation. The worker remains
paused until another worker calls this Condition object's
notify() or notifyAll() methods.
Parameters
timeout:Number (default = -1) |
Boolean — true if the method returned because the timeout
time elapsed. Otherwise the method returns false.
|
Throws
IllegalOperationError — if the current worker doesn't
own this condition's mutex
| |
ArgumentError — if the timeout argument is less than
0 and not -1
| |
ScriptTimeoutError — if the method is called from
code in the primordial worker in Flash Player and worker pauses
longer than the script timeout limit (15 seconds by default)
| |
Error — if the method is called and, while the calling
worker's execution is paused, the waiting worker is terminated.
|
Wed Nov 21 2018, 06:34 AM -08:00