ParallelTask (Type of variable)

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Declaration
Properties specific to the description of ParallelTask variables
WLanguage functions that use ParallelTask variables

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ParallelTask (Type of variable)

In french: TâcheParallèle

The ParallelTask type is used to handle a task, which means a procedure run by a thread in the parallel programming.

Remark: See Declaring a variable for more details on the declaration of this type of variable and the use of WLanguage properties.

Versions 21 and later

This type of variable is now available in Apple Watch mode.

New in version 21

This type of variable is now available in Apple Watch mode.

Versions 23 and later

This type of variable is now available for Java applications.

This type of variable is now available in Android Widget mode.

This type of variable is now available for Android applications.

New in version 23

This type of variable is now available for Java applications.

This type of variable is now available in Android Widget mode.

This type of variable is now available for Android applications.

This type of variable is now available for Java applications.

This type of variable is now available in Android Widget mode.

This type of variable is now available for Android applications.

Example

// Declares a variable to handle a parallel task
t is ParallelTask
// Builds a parallel task and triggers its execution on a procedure
t = ParallelTaskExecute(Proc, ("First parameter", 2))

// Builds a parallel task
t is ParallelTask(Proc, ("First parameter", 2))
// Triggers the execution of parallel task
ParallelTaskExecute(t)

// Describes a parallel task
d is Description of ParallelTask
d.Procedure = Proc
d.Parameter[1] = "First parameter"
d.Parameter[2] = 2
// Builds a parallel task and triggers its execution
t is ParallelTask = ParallelTaskExecute(d)

Declaration

Declaring a parallel task that is not described Hide the details

MyVariable is ParallelTask

In this case, the task is not described. The variable will have to be assigned with an existing task or with the result of one of the functions for running parallel tasks.

Describing a parallel task via the ParallelTask type Hide the details

MyVariable is ParallelTask (<Procedure> [, <Parameters> [, <Options>]])

<Procedure>: Character string or Procedure variable

Procedure to run. This parameter can correspond to:
the name of procedure to run.
the name of Procedure variable corresponding to the procedure to run.

<Parameters>: List of values enclosed in brackets and separated by commas

Parameters of procedure to run. This list of parameters has the following format:

(<Parameter 1>, ..., <Parameter N>)

where:
<Parameter 1>: First procedure parameter.
...
<Parameter N>: Nth procedure parameter.

<Options>: Optional Integer constant

Options of task to run:
ptoFullCopyHFSQLContext Triggers the immediate copy of current HFSQL context.
Recommended, for example, if the parallel task must take into account the current positions in the files and queries of the context of the caller.
ptoDelayedCopyHFSQLContext
(Default value) Triggers a light copy of HFSQL context during the first access to the HFSQL data.
ptoLightCopyHFSQLContext Triggers the immediate copy of part of current HFSQL context.
Only the directories containing the data files in HFSQL Classic mode and/or the connections in HFSQL Client/Server mode are stored.
ptoMainThread Runs the task in the main thread.
Caution: This constant cannot be used to run a parallel task in the main thread from the main thread.

In this case, the task is described and its description cannot be modified anymore.
The task is not automatically scheduled therefore a single declaration will not trigger the execution of the task. You must call one of the functions for running tasks in order to trigger the execution of the task.

Describing a parallel task via a Description of ParallelTask Hide the details

MyVariable is ParallelTask (<Description>)

<Description>: Description of ParallelTask variable

Name of Description of ParallelTask variable describing the task.

In this case, the task is described and its description cannot be modified anymore.
The task is not automatically scheduled, therefore, a single declaration will not trigger the execution of the task. You must call one of the functions for running tasks in order to trigger the execution of the task.

Remarks

Properties specific to the description of ParallelTask variables

The following properties can be used to handle a parallel task:

Property name	Type used	Effect

Canceled	Boolean	True if the task is canceled, False otherwise. This property is available in read-only.
State	Integer constant	Task status: ptsCanceled: the parallel task is canceled (ParallelTaskCancel). ptsCancelationRequested: a cancelation request was performed on the parallel task (ParallelTaskRequestCancelation). ptsWaitingExecution: the parallel task is waiting to be run. ptsWaitingPrevious: the parallel task waits for the execution of a previous parallel task. ptsExecutionInProgress: the parallel task is currently run. ptsNotScheduled: the parallel task is not scheduled. ptsCompleted: the parallel task is ended. This property is available in read-only.
Identifier	Integer	Identifier of task. This identifier can be used for debugging purpose for example. This property is available in read-only.
Completed	Boolean	True if the task is completed, False otherwise. This property is available in read-only.
ReturnedValue	Value returned by the task.	Caution: If the task is still in progress, the ReturnedValue property waits for the end of the task If the task is completed without fatal error, the property returns the return values of the procedure of the task. This property is available in read-only.

WLanguage functions that use ParallelTask variables

Standard functions:


Versions 20 and later ParallelTaskExecute New in version 20 ParallelTaskExecute ParallelTaskExecute	Triggers the execution of a parallel task.
Versions 20 and later ParallelTaskExecuteAfter New in version 20 ParallelTaskExecuteAfter ParallelTaskExecuteAfter	Indicates a continuation parallel task that will be run when one of the specified parallel task is ended.
Versions 20 and later ParallelTaskExecuteAfterAll New in version 20 ParallelTaskExecuteAfterAll ParallelTaskExecuteAfterAll	Indicates a continuation parallel task that will be run when all the tasks found in an array of parallel tasks are ended.
Versions 20 and later ParallelTaskExecuteAfterOne New in version 20 ParallelTaskExecuteAfterOne ParallelTaskExecuteAfterOne	Indicates a continuation parallel task that will be run once the first task is ended in an array of parallel tasks.
Versions 20 and later ParallelTaskRequestCancelation New in version 20 ParallelTaskRequestCancelation ParallelTaskRequestCancelation	Requests the cancelation of a parallel task.
Versions 20 and later ParallelTaskWait New in version 20 ParallelTaskWait ParallelTaskWait	Waits for the execution of a parallel task.

Functions with prefixed syntax:


Versions 24 and later <ParallelTask variable>.RequestCancelation New in version 24 <ParallelTask variable>.RequestCancelation <ParallelTask variable>.RequestCancelation	Requests the cancelation of a parallel task.
Versions 24 and later <ParallelTask variable>.Wait New in version 24 <ParallelTask variable>.Wait <ParallelTask variable>.Wait	Waits for the execution of a parallel task.