TaskChain PureBasic Reference Documentation

TaskChain

Current Version: 10.1.2

Requires Chilkat Bundle License

Represents a chain of asynchronous tasks to be run in sequence in a background thread.

Object Creation

obj.i = CkTaskChain::ckCreate()

; Make sure to dispose of the object when finished like this:
CkTaskChain::ckDispose(obj);

Properties

DebugLogFilePath

Declare.s ckDebugLogFilePath(obj.i)
Declare setCkDebugLogFilePath(obj.i, value.s)

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

A timeout property set to 0, indicating an infinite timeout.
A hang occurring within an event callback in the application code.
An internal bug in the Chilkat code causing the hang.

More Information and Examples

Example showing how to use DebugLogFilePath.

Finished

Declare.i ckFinished(obj.i) ; (read-only)

Introduced in version 9.5.0.52

1 if the task status is "canceled", "aborted", or "completed". A task chain can only reach the "canceled" status if it was activated via the Run method, made it onto the internal thread pool thread's queue, was waiting for a pool thread to become available, and was then canceled prior to the task actually starting.

Inert

Declare.i ckInert(obj.i) ; (read-only)

Introduced in version 9.5.0.52

1 if the task status is "empty" or "loaded". When a task chain is inert, it has been loaded but is not scheduled to run yet.

LastErrorHtml

Declare.s ckLastErrorHtml(obj.i) ; (read-only)

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

LastErrorText

Declare.s ckLastErrorText(obj.i) ; (read-only)

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

LastErrorXml

Declare.s ckLastErrorXml(obj.i) ; (read-only)

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

LastMethodSuccess

Declare.i ckLastMethodSuccess(obj.i)
Declare setCkLastMethodSuccess(obj.i, value.i)

Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.

Live

Declare.i ckLive(obj.i) ; (read-only)

Introduced in version 9.5.0.52

1 if the task status is "queued" or "running". When a task chain is live, it is either already running, or is on the thread pool thread's queue waiting for a thread to become available.

NumTasks

Declare.i ckNumTasks(obj.i) ; (read-only)

Introduced in version 9.5.0.52

The number of tasks contained within the task chain.

Status

Declare.s ckStatus(obj.i) ; (read-only)

Introduced in version 9.5.0.52

The current status of the task chain. Possible values are:

"empty" -- No tasks have yet been appended to the task chain.
"loaded" -- The task chain has been loaded (appended) with one or more task objects.
"queued" -- The task chain is in the thread pool's queue of tasks awaiting to be run.
"running" -- The task chain is currently running.
"canceled" -- The task chain was canceled before it entered the "running" state.
"aborted" -- The task chain was canceled while it was in the running state.
"completed" -- The task chain completed.

StatusInt

Declare.i ckStatusInt(obj.i) ; (read-only)

Introduced in version 9.5.0.52

The current status of the task as an integer value. Possible values are:

1 -- "empty" -- No tasks have yet been appended to the task chain.
2 -- "loaded" -- The task chain has been loaded (appended) with one or more task objects.
3 -- "queued" -- The task chain is in the thread pool's queue of tasks awaiting to be run.
4 -- "running" -- The task chain is currently running.
5 -- "canceled" -- The task chain was canceled before it entered the "running" state.
6 -- "aborted" -- The task chain was canceled while it was in the running state.
7 -- "completed" -- The task chain completed.

StopOnFailedTask

Declare.i ckStopOnFailedTask(obj.i)
Declare setCkStopOnFailedTask(obj.i, value.i)

Introduced in version 9.5.0.52

If 1 then stops execution of the task chain if any individual task fails. Task failure is defined by the standard LastMethodSuccess property. If 0, then all of the tasks in the chain will be run even if some fail. The default value of this property is 1.

More Information and Examples

Async Methods Returning an Object

VerboseLogging

Declare.i ckVerboseLogging(obj.i)
Declare setCkVerboseLogging(obj.i, value.i)

If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

Version

Declare.s ckVersion(obj.i) ; (read-only)

Version of the component/library, such as "10.1.0"

More Information and Examples

How to get the Chilkat version at runtime.

Methods

Append

Declare.i ckAppend(obj.i, task.i)

Introduced in version 9.5.0.52

Appends a task to the task chain. Can fail if the task is already part of another chain. (A task can only be part of a single chain.)

Returns 1 for success, 0 for failure.

More Information and Examples

Async Task Chain

Cancel

Declare.i ckCancel(obj.i)

Introduced in version 9.5.0.52

Cancels execution of the asynchronous task chain.

Returns 1 for success, 0 for failure.

GetTask

Declare.i ckGetTask(obj.i, index.l)

Introduced in version 9.5.0.52

Returns the Nth task in the chain. The 1st task is at index 0.

Returns 0 on failure

More Information and Examples

Async Methods Returning an Object

Run

Declare.i ckRun(obj.i)

Introduced in version 9.5.0.52

Queues the task chain to run on the internal Chilkat thread pool. Each task in the chain will run, one after the other.

Returns 1 for success, 0 for failure.

RunSynchronously

Declare.i ckRunSynchronously(obj.i)

Introduced in version 9.5.0.52

Runs the task chain synchronously. Then this method returns after all the tasks in the chain have been run.

Returns 1 for success, 0 for failure.

SleepMs

Declare ckSleepMs(obj.i, numMs.l)

Introduced in version 9.5.0.52

Convenience method to force the calling thread to sleep for a number of milliseconds.

Wait

Declare.i ckWait(obj.i, maxWaitMs.l)

Introduced in version 9.5.0.52

Waits for the task chain to complete. Returns when all of the tasks in the chain have completed, or after maxWaitMs milliseconds have elapsed. (A maxWaitMs value of 0 is to wait indefinitely.) Returns (0) if the task chain has not yet been started by calling the Run method, or if the maxWaitMs expired. If the task chain completed, was already completed, was canceled, or aborted, then this method returns 1.

Returns 1 for success, 0 for failure.