net.corda.core.utilities

## Class ProgressTracker

- net.corda.core.utilities.ProgressTracker

-     public class ProgressTracker

  A progress tracker helps surface information about the progress of an operation to a user interface or API of some kind. It lets you define a set of steps that represent an operation. A step is represented by an object (typically a singleton).

  Steps may logically be children of other steps, which models the case where a large top level operation involves sub-operations which may also have a notion of progress. If a step has children, then the tracker will report the steps children as the "next step" after the parent. In other words, a parent step is considered to involve actual reportable work and is a thing. If the parent step simply groups other steps, then you'll have to step over it manually.

  Each step has a label. It is assumed by default that the label does not change. If you want a label to change, then you can emit a `class Change.Rendering` object on the ProgressTracker.Step.changes observable stream after it changes. That object will propagate through to the top level trackers changes stream, which renderers can subscribe to in order to learn about progress.

  An operation can move both forwards and backwards through steps, thus, a `class ProgressTracker` can represent operations that include loops.

  A progress tracker is not thread safe. You may move events from the thread making progress to another thread by using the Observable subscribeOn call.

  See Also:
    `class Change.Rendering`, `class ProgressTracker`

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `ProgressTracker.Change`
    `static class` | `ProgressTracker.DONE`
    `class` | `ProgressTracker.RelabelableStep` This class makes it easier to relabel a step on the fly, to provide transient information.
    `static class` | `ProgressTracker.Step` The superclass of all step objects.
    `static class` | `ProgressTracker.UNSTARTED`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `ProgressTracker(net.corda.core.utilities.ProgressTracker.Step steps)` A progress tracker helps surface information about the progress of an operation to a user interface or API of some kind. It lets you define a set of steps that represent an operation. A step is represented by an object (typically a singleton).

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `endWithError(java.lang.Throwable error)` Ends the progress tracker with the given error, bypassing any remaining steps. changes will emit the exception as an error.
    `java.util.List<kotlin.Pair>` | `getAllSteps()` A list of all steps in this ProgressTracker and the children, with the indent level provided starting at zero. Note that UNSTARTED is never counted, and DONE is only counted at the calling level.
    `rx.Observable<net.corda.core.utilities.ProgressTracker.Change>` | `getChanges()` An observable stream of changes: includes child steps, resets and any changes emitted by individual steps (e.g. if a step changed its label or rendering).
    `ProgressTracker` | `getChildProgressTracker(ProgressTracker.Step step)`
    `ProgressTracker.Step` | `getCurrentStep()` Reading returns the value of stepsstepIndex, writing moves the position of the current tracker. Once moved to the `class ProgressTracker.DONE` state, this tracker is finished and the current step cannot be moved again.
    `ProgressTracker.Step` | `getCurrentStepRecursive()` Returns the current step, descending into children to find the deepest step we are up to.
    `boolean` | `getHasEnded()` Returns true if the progress tracker has ended, either by reaching the `class ProgressTracker.DONE` step or prematurely with an error
    `ProgressTracker` | `getParent()` The parent of this tracker: set automatically by the parent when a tracker is added as a child
    `int` | `getStepIndex()` The zero-based index of the current step in the steps array (i.e. with UNSTARTED and DONE)
    `ProgressTracker.Step[]` | `getSteps()` The steps in this tracker, same as the steps passed to the constructor but with UNSTARTED and DONE inserted.
    `ProgressTracker` | `getTopLevelTracker()` Walks up the tree to find the top level tracker. If this is the top level tracker, returns 'this'
    `ProgressTracker.Step` | `nextStep()` Iterates the progress tracker. If the current step has a child, the child is iterated instead (recursively). Returns the latest step at the bottom of the step tree.
    `void` | `setChildProgressTracker(ProgressTracker.Step step, ProgressTracker childProgressTracker)`
    `void` | `setCurrentStep(ProgressTracker.Step value)` Reading returns the value of stepsstepIndex, writing moves the position of the current tracker. Once moved to the `class ProgressTracker.DONE` state, this tracker is finished and the current step cannot be moved again.

- - ### Constructor Detail

    - #### ProgressTracker

          public ProgressTracker(net.corda.core.utilities.ProgressTracker.Step steps)

      A progress tracker helps surface information about the progress of an operation to a user interface or API of some kind. It lets you define a set of steps that represent an operation. A step is represented by an object (typically a singleton).

      Steps may logically be children of other steps, which models the case where a large top level operation involves sub-operations which may also have a notion of progress. If a step has children, then the tracker will report the steps children as the "next step" after the parent. In other words, a parent step is considered to involve actual reportable work and is a thing. If the parent step simply groups other steps, then you'll have to step over it manually.

      Each step has a label. It is assumed by default that the label does not change. If you want a label to change, then you can emit a `class Change.Rendering` object on the ProgressTracker.Step.changes observable stream after it changes. That object will propagate through to the top level trackers changes stream, which renderers can subscribe to in order to learn about progress.

      An operation can move both forwards and backwards through steps, thus, a `class ProgressTracker` can represent operations that include loops.

      A progress tracker is not thread safe. You may move events from the thread making progress to another thread by using the Observable subscribeOn call.

      See Also:
        `class Change.Rendering`, `class ProgressTracker`

  - ### Method Detail

    - #### getSteps

          public ProgressTracker.Step[] getSteps()

      The steps in this tracker, same as the steps passed to the constructor but with UNSTARTED and DONE inserted.

    - #### getStepIndex

          public int getStepIndex()

      The zero-based index of the current step in the steps array (i.e. with UNSTARTED and DONE)

    - #### getCurrentStep

          public ProgressTracker.Step getCurrentStep()

      Reading returns the value of stepsstepIndex, writing moves the position of the current tracker. Once moved to the `class ProgressTracker.DONE` state, this tracker is finished and the current step cannot be moved again.

      See Also:
        `class ProgressTracker.DONE`

    - #### setCurrentStep

          public void setCurrentStep(ProgressTracker.Step value)

      Reading returns the value of stepsstepIndex, writing moves the position of the current tracker. Once moved to the `class ProgressTracker.DONE` state, this tracker is finished and the current step cannot be moved again.

      See Also:
        `class ProgressTracker.DONE`

    - #### getCurrentStepRecursive

          public ProgressTracker.Step getCurrentStepRecursive()

      Returns the current step, descending into children to find the deepest step we are up to.

    - #### getChildProgressTracker

          public ProgressTracker getChildProgressTracker(ProgressTracker.Step step)

    - #### setChildProgressTracker

          public void setChildProgressTracker(ProgressTracker.Step step,
                                              ProgressTracker childProgressTracker)

    - #### endWithError

          public void endWithError(java.lang.Throwable error)

      Ends the progress tracker with the given error, bypassing any remaining steps. changes will emit the exception as an error.

    - #### getParent

          public ProgressTracker getParent()

      The parent of this tracker: set automatically by the parent when a tracker is added as a child

    - #### getTopLevelTracker

          public ProgressTracker getTopLevelTracker()

      Walks up the tree to find the top level tracker. If this is the top level tracker, returns 'this'

    - #### getAllSteps

          public java.util.List<kotlin.Pair> getAllSteps()

      A list of all steps in this ProgressTracker and the children, with the indent level provided starting at zero. Note that UNSTARTED is never counted, and DONE is only counted at the calling level.

    - #### nextStep

          public ProgressTracker.Step nextStep()

      Iterates the progress tracker. If the current step has a child, the child is iterated instead (recursively). Returns the latest step at the bottom of the step tree.

    - #### getChanges

          public rx.Observable<net.corda.core.utilities.ProgressTracker.Change> getChanges()

      An observable stream of changes: includes child steps, resets and any changes emitted by individual steps (e.g. if a step changed its label or rendering).

    - #### getHasEnded

          public boolean getHasEnded()

      Returns true if the progress tracker has ended, either by reaching the `class ProgressTracker.DONE` step or prematurely with an error

      See Also:
        `class ProgressTracker.DONE`