IProgressMonitor


1   /*******************************************************************************
2    * Copyright (c) 2000, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    * 
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.core.runtime;
12  
13  /**
14   * The <code>IProgressMonitor</code> interface is implemented
15   * by objects that monitor the progress of an activity; the methods
16   * in this interface are invoked by code that performs the activity.
17   * <p>
18   * All activity is broken down into a linear sequence of tasks against
19   * which progress is reported. When a task begins, a <code>beginTask(String, int)
20   * </code> notification is reported, followed by any number and mixture of 
21   * progress reports (<code>worked()</code>) and subtask notifications 
22   * (<code>subTask(String)</code>).  When the task is eventually completed, a 
23   * <code>done()</code> notification is reported.  After the <code>done()</code>
24   * notification, the progress monitor cannot be reused;  i.e., <code>
25   * beginTask(String, int)</code> cannot be called again after the call to 
26   * <code>done()</code>.
27   * </p>
28   * <p>
29   * A request to cancel an operation can be signaled using the 
30   * <code>setCanceled</code> method.  Operations taking a progress
31   * monitor are expected to poll the monitor (using <code>isCanceled</code>)
32   * periodically and abort at their earliest convenience.  Operation can however 
33   * choose to ignore cancelation requests.
34   * </p>
35   * <p>
36   * Since notification is synchronous with the activity itself, the listener should 
37   * provide a fast and robust implementation. If the handling of notifications would 
38   * involve blocking operations, or operations which might throw uncaught exceptions, 
39   * the notifications should be queued, and the actual processing deferred (or perhaps
40   * delegated to a separate thread).
41   * </p><p>
42   * This interface can be used without OSGi running.
43   * </p><p>
44   * Clients may implement this interface.
45   * </p>
46   */
47  public interface IProgressMonitor {
48  
49      /** Constant indicating an unknown amount of work.
50       */
51      public final static int UNKNOWN = -1;
52  
53      /**
54       * Notifies that the main task is beginning.  This must only be called once
55       * on a given progress monitor instance.
56       * 
57       * @param name the name (or description) of the main task
58       * @param totalWork the total number of work units into which
59       *  the main task is been subdivided. If the value is <code>UNKNOWN</code> 
60       *  the implementation is free to indicate progress in a way which 
61       *  doesn't require the total number of work units in advance.
62       */
63      public void beginTask(String   name, int totalWork);
64  
65      /**
66       * Notifies that the work is done; that is, either the main task is completed 
67       * or the user canceled it. This method may be called more than once 
68       * (implementations should be prepared to handle this case).
69       */
70      public void done();
71  
72      /**
73       * Internal method to handle scaling correctly. This method
74       * must not be called by a client. Clients should 
75       * always use the method </code>worked(int)</code>.
76       * 
77       * @param work the amount of work done
78       */
79      public void internalWorked(double work);
80  
81      /**
82       * Returns whether cancelation of current operation has been requested.
83       * Long-running operations should poll to see if cancelation
84       * has been requested.
85       *
86       * @return <code>true</code> if cancellation has been requested,
87       *    and <code>false</code> otherwise
88       * @see #setCanceled(boolean)
89       */
90      public boolean isCanceled();
91  
92      /**
93       * Sets the cancel state to the given value.
94       * 
95       * @param value <code>true</code> indicates that cancelation has
96       *     been requested (but not necessarily acknowledged);
97       *     <code>false</code> clears this flag
98       * @see #isCanceled()
99       */
100     public void setCanceled(boolean value);
101 
102     /**
103      * Sets the task name to the given value. This method is used to 
104      * restore the task label after a nested operation was executed. 
105      * Normally there is no need for clients to call this method.
106      *
107      * @param name the name (or description) of the main task
108      * @see #beginTask(java.lang.String, int)
109      */
110     public void setTaskName(String   name);
111 
112     /**
113      * Notifies that a subtask of the main task is beginning.
114      * Subtasks are optional; the main task might not have subtasks.
115      *
116      * @param name the name (or description) of the subtask
117      */
118     public void subTask(String   name);
119 
120     /**
121      * Notifies that a given number of work unit of the main task
122      * has been completed. Note that this amount represents an
123      * installment, as opposed to a cumulative amount of work done
124      * to date.
125      *
126      * @param work a non-negative number of work units just completed
127      */
128     public void worked(int work);
129 }
130
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