Copyright (c) 2000, 2007 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2007 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.core.runtime;

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: 

Will call beginTask on the argument 0 or 1 times, at its option.
Will not promise to invoke done() on the monitor.
Will not call setCanceled on the monitor.
May rely on the monitor not being null.
May rely on the monitor ignoring the string passed to beginTask.


The caller:

Will either pass in a fresh instance of IProgressMonitor that has not had beginTask invoked on it yet, or will select an implementation of IProgressMonitor that explicitly permits multiple calls to beginTask.
Will not rely on the callee to invoke done() on the monitor. It must either select an implementation of IProgressMonitor that does not require done() to be called, for example SubMonitor, or it must invoke done() itself after the method returns.
Will not pass in a null monitor unless the JavaDoc of the callee says that it
    accepts null.
Will pass in a monitor that ignores the name argument to beginTask unless the JavaDoc for the callee states otherwise. 
 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.

/**
 * The <code>IProgressMonitor</code> 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.
 * <p>
 * All activity is broken down into a linear sequence of tasks against
 * which progress is reported. When a task begins, a <code>beginTask(String, int)
 * </code> notification is reported, followed by any number and mixture of 
 * progress reports (<code>worked()</code>) and subtask notifications 
 * (<code>subTask(String)</code>).  When the task is eventually completed, a 
 * <code>done()</code> notification is reported.  After the <code>done()</code>
 * notification, the progress monitor cannot be reused;  i.e., <code>
 * beginTask(String, int)</code> cannot be called again after the call to 
 * <code>done()</code>.
 * </p>
 * <p>
 * A request to cancel an operation can be signaled using the 
 * <code>setCanceled</code> method.  Operations taking a progress
 * monitor are expected to poll the monitor (using <code>isCanceled</code>)
 * periodically and abort at their earliest convenience.  Operation can however 
 * choose to ignore cancelation requests.
 * </p>
 * <p>
 * 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).
 * </p>
 * <p><b>CALLER/CALLEE RESPONSIBILITIES:</b></p>
 * <p>
 * Methods that receive an {@link IProgressMonitor} ("callees") must either obey the following
 * conventions or include JavaDoc explaining how it differs from these rules.
 * The called method:
 * <ul>
 * <li>Will call {@link #beginTask} on the argument 0 or 1 times, at its option.</li>
 * <li>Will not promise to invoke {@link #done()} on the monitor.</li>
 * <li>Will not call {@link #setCanceled} on the monitor.</li>
 * <li>May rely on the monitor not being null.</li>
 * <li>May rely on the monitor ignoring the string passed to {@link #beginTask}.</li>
 * </ul>
 * <p>
 * The caller:
 * <ul>
 * <li>Will either pass in a fresh instance of {@link IProgressMonitor} that has
 *     not had {@link #beginTask} invoked on it yet, or will select an
 *     implementation of {@link IProgressMonitor} that explicitly permits multiple calls
 *     to {@link #beginTask}.</li>
 * <li>Will not rely on the callee to invoke {@link #done()} on the monitor.
 *     It must either select an implementation of {@link IProgressMonitor} that
 *     does not require {@link #done()} to be called, for example {@link SubMonitor},
 *     or it must invoke {@link #done()} itself after the method returns.</li>
 * <li>Will not pass in a null monitor unless the JavaDoc of the callee says that it
 *     accepts null.</li>
 * <li>Will pass in a monitor that ignores the name argument to {@link #beginTask}
 *     unless the JavaDoc for the callee states otherwise.
 * </ul>
 * 
 * <p>
 * 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 {@link #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 {@link #done()},
 * meaning they work with both methods that invoke {@link #done()} and methods
 * that don't.
 * </p>
 * <p>
 * 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 {@link #done()} and must do so themselves if necessary.
 * </p>
 * <p>
 * This interface can be used without OSGi running.
 * </p><p>
 * Clients may implement this interface.
 * </p>
 */
public interface IProgressMonitor {

	
Constant indicating an unknown amount of work.
/** Constant indicating an unknown amount of work.
	 */
	public final static int UNKNOWN = -1;

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

	
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).
/**
	 * 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).
	 */
	public void done();

	
Internal method to handle scaling correctly. This method
must not be called by a client. Clients should 
always use the method worked(int).
Params:
work – the amount of work done/**
	 * Internal method to handle scaling correctly. This method
	 * must not be called by a client. Clients should 
	 * always use the method <code>worked(int)</code>.
	 * 
	 * @param work the amount of work done
	 */
	public void internalWorked(double work);

	
Returns whether cancelation of current operation has been requested.
Long-running operations should poll to see if cancelation
has been requested.
See Also:
setCanceled(boolean)
Returns:
true if cancellation has been requested,
   and false otherwise/**
	 * Returns whether cancelation of current operation has been requested.
	 * Long-running operations should poll to see if cancelation
	 * has been requested.
	 *
	 * @return <code>true</code> if cancellation has been requested,
	 *    and <code>false</code> otherwise
	 * @see #setCanceled(boolean)
	 */
	public boolean isCanceled();

	
Sets the cancel state to the given value.
Params:
value – true indicates that cancelation has
    been requested (but not necessarily acknowledged);
    false clears this flag
See Also:
isCanceled()/**
	 * Sets the cancel state to the given value.
	 * 
	 * @param value <code>true</code> indicates that cancelation has
	 *     been requested (but not necessarily acknowledged);
	 *     <code>false</code> clears this flag
	 * @see #isCanceled()
	 */
	public void setCanceled(boolean value);

	
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.
Params:
name – the name (or description) of the main task
See Also:
beginTask(String, int)/**
	 * 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.
	 *
	 * @param name the name (or description) of the main task
	 * @see #beginTask(java.lang.String, int)
	 */
	public void setTaskName(String name);

	
Notifies that a subtask of the main task is beginning.
Subtasks are optional; the main task might not have subtasks.
Params:
name – the name (or description) of the subtask/**
	 * Notifies that a subtask of the main task is beginning.
	 * Subtasks are optional; the main task might not have subtasks.
	 *
	 * @param name the name (or description) of the subtask
	 */
	public void subTask(String name);

	
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.
Params:
work – a non-negative number of work units just completed/**
	 * 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.
	 *
	 * @param work a non-negative number of work units just completed
	 */
	public void worked(int work);
}