Package org.eclipse.core.runtime

Interface IProgressMonitor

All Known Subinterfaces:
IProgressMonitorWithBlocking
All Known Implementing Classes:
NullProgressMonitor, ProgressMonitorPart, ProgressMonitorWrapper, SlicedProgressMonitor, SubMonitor, SubProgressMonitor
public interface IProgressMonitor
The IProgressMonitor interface is implemented by objects that monitor the progress of an activity; the methods in this interface are invoked by code that performs the activity.

All activity is broken down into a linear sequence of tasks against which progress is reported. When a task begins, a beginTask(String, int) notification is reported, followed by any number and mixture of progress reports (worked()) and subtask notifications (subTask(String)). When the task is eventually completed, a done() notification is reported. After the done() notification, the progress monitor cannot be reused; i.e., beginTask(String, int) cannot be called again after the call to done().

A request to cancel an operation can be signaled using the setCanceled method. Operations taking a progress monitor are expected to poll the monitor (using isCanceled) periodically and abort at their earliest convenience. Operation can however choose to ignore cancelation requests.

Since notification is synchronous with the activity itself, the listener should provide a fast and robust implementation. If the handling of notifications would involve blocking operations, or operations which might throw uncaught exceptions, the notifications should be queued, and the actual processing deferred (or perhaps delegated to a separate thread).

CALLER/CALLEE RESPONSIBILITIES:

Methods that receive an IProgressMonitor ("callees") must either obey the following conventions or include JavaDoc explaining how it differs from these rules. The called method:

The caller:

The responsibilities described above were introduced in Eclipse 4.7 (Oxygen). Prior to Eclipse 4.7, it was common practice for the callee to invoke done() on its monitor and for the caller to rely upon this fact. As of Eclipse 4.6, all the important top-level entry points have been updated to call done(), meaning they work with both methods that invoke done() and methods that don't.

Since this convention was introduced in Eclipse 4.7, some plugin code may need to change. In particular, callers that pass a monitor are no longer allowed to rely upon the callee invoking done() and must do so themselves if necessary.

This interface can be used without OSGi running.

Clients may implement this interface.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    UNKNOWN
    Constant indicating an unknown amount of work.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    beginTask(String name, int totalWork)
    Notifies that the main task is beginning.
    default void
    clearBlocked()
    Clears the blocked state of the running operation.
    void
    done()
    Notifies that the work is done; that is, either the main task is completed or the user canceled it.
    static void
    done(IProgressMonitor monitor)
    Calls done() on the given monitor if is non-null.
    void
    internalWorked(double work)
    Internal method to handle scaling correctly.
    boolean
    isCanceled()
    Returns whether cancelation of current operation has been requested.
    static IProgressMonitor
    nullSafe(IProgressMonitor monitor)
    Returns a null safe access to the given monitor, for example in cases where a monitor is passed to a function the implementation can call this method to get a guaranteed non-null monitor reference
    default void
    setBlocked(IStatus reason)
    Indicates that this operation is blocked by some background activity.
    void
    setCanceled(boolean value)
    Sets the cancel state to the given value.
    void
    setTaskName(String name)
    Sets the task name to the given value.
    default IProgressMonitor
    slice(int work)
    This method creates a slice out of this monitor.
    void
    subTask(String name)
    Notifies that a subtask of the main task is beginning.
    void
    worked(int work)
    Notifies that a given number of work unit of the main task has been completed.

  • Field Details

    • UNKNOWN

      static final int UNKNOWN
      Constant indicating an unknown amount of work.
      See Also:

  • Method Details

    • beginTask

      void beginTask(String name, int totalWork)
      Notifies that the main task is beginning. This must only be called once on a given progress monitor instance.
      Parameters:
      name - the name (or description) of the main task
      totalWork - the total number of work units into which the main task is been subdivided. If the value is UNKNOWN the implementation is free to indicate progress in a way which doesn't require the total number of work units in advance.

    • done

      void done()
      Notifies that the work is done; that is, either the main task is completed or the user canceled it. This method may be called more than once (implementations should be prepared to handle this case).

    • internalWorked

      void internalWorked(double work)
      Internal method to handle scaling correctly. This method must not be called by a client. Clients should always use the method worked(int).
      Parameters:
      work - the amount of work done

    • isCanceled

      boolean isCanceled()
      Returns whether cancelation of current operation has been requested. Long-running operations should poll to see if cancelation has been requested.
      Returns:
      true if cancellation has been requested, and false otherwise
      See Also:

    • setCanceled

      void setCanceled(boolean value)
      Sets the cancel state to the given value.
      Parameters:
      value - true indicates that cancelation has been requested (but not necessarily acknowledged); false clears this flag
      See Also:

    • setTaskName

      void setTaskName(String name)
      Sets the task name to the given value. This method is used to restore the task label after a nested operation was executed. Normally there is no need for clients to call this method.
      Parameters:
      name - the name (or description) of the main task
      See Also:

    • subTask

      void subTask(String name)
      Notifies that a subtask of the main task is beginning. Subtasks are optional; the main task might not have subtasks.
      Parameters:
      name - the name (or description) of the subtask

    • worked

      void worked(int work)
      Notifies that a given number of work unit of the main task has been completed. Note that this amount represents an installment, as opposed to a cumulative amount of work done to date.
      Parameters:
      work - a non-negative number of work units just completed

    • setBlocked

      default void setBlocked(IStatus reason)
      Indicates that this operation is blocked by some background activity. If a running operation ever calls setBlocked, it must eventually call clearBlocked before the operation completes.

      If the caller is blocked by a currently executing job, this method will return an IJobStatus indicating the job that is currently blocking the caller. If this blocking job is not known, this method will return a plain informational IStatus object.

      Parameters:
      reason - an optional status object whose message describes the reason why this operation is blocked, or null if this information is not available.
      Since:
      3.13
      See Also:

    • clearBlocked

      default void clearBlocked()
      Clears the blocked state of the running operation. If a running operation ever calls setBlocked, it must eventually call clearBlocked before the operation completes.
      Since:
      3.13
      See Also:

    • slice

      default IProgressMonitor slice(int work)
      This method creates a slice out of this monitor. The slice behaves as if a new monitor instance is created that simply reports work back to its parent monitor. Even though it is safe to pass the sliced instance to another thread, instance itself might not be thread-safe and each slice should therefore only be used by one thread at once. To account for this, if sliced instances are passed to another thread, only sliced instances should be used like in this example: 
       IProgressMonitor monitor = ...
 
 processAsync(monitor.slice(70));
 monitor = monitor.slice(30); // get a local slice so we can use the monitor
                                                                // without interference with the async processing
 monitor.beginTask("Working on private slice", 1);
 ...
 monitor.worked(1);           // this is now safe to be called further on
 ...
 monitor.done();                                // mark our part as done, 
                                                                // the other slice will be finished by processAsync(...)
                                                                // ... and the original monitor by the caller of this method
      The caller of this method (or the Thread that gets this instance passed) is responsible to make sure that done() is called once the monitor is no longer needed.
      Parameters:
      work - the amount of work for this IProgressMonitor to slice
      Returns:
      a IProgressMonitor slice for the given amount, the default implementation suppress any strings passed to setTaskName(String), subTask(String) and beginTask(String, int), and does not propagate setCanceled(boolean) (but reports cancelation of the parent
      Since:
      3.14

    • done

      static void done(IProgressMonitor monitor)
      Calls done() on the given monitor if is non-null. If the given monitor is null, this is a no-op.
      Parameters:
      monitor - the monitor to make done, might be null
      Since:
      3.14

    • nullSafe

      static IProgressMonitor nullSafe(IProgressMonitor monitor)
      Returns a null safe access to the given monitor, for example in cases where a monitor is passed to a function the implementation can call this method to get a guaranteed non-null monitor reference
      Parameters:
      monitor - the monitor to check
      Returns:
      the passed monitor instance or NullProgressMonitor if monitor was null
      Since:
      3.14