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/*******************************************************************************
* Copyright (c) 2000, 2007 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.runtime;
/**
* 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.
*/
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.
*
* @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).
*/
public void 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.
*
* @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.
*
* @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.
*
* @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.
*
* @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.
*
* @param work a non-negative number of work units just completed
*/
public void worked(int work);
}
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