blob: 7b5a459ec684e9a8cfe356078e8c710e9022ce80 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
/*******************************************************************************
* Copyright (c) 2008, 2009 Oracle. 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:
* Oracle - initial API and implementation
******************************************************************************/
package org.eclipse.jpt.utility.internal.synchronizers;
import java.io.Serializable;
/**
* This interface defines the protocol for starting, stopping, and executing a
* long-running, repeatable, and possibly recursive "synchronization" process.
* The intent is for the synchronizer to synchronize a "secondary" model with
* a "primary" model. Any change to the "primary" model will trigger the
* synchronization. The synchronizer implementation will determine whether the
* "secondary" model remains in sync synchronously or asynchronously.
* <p>
* The assumption is that the {@link #start()} and {@link #stop()} methods will be called from
* a single master thread that would control the synchronizer's lifecycle and
* the {@link #synchronize()} method will be called multiple times, possibly from
* multiple threads.
*/
public interface Synchronizer {
/**
* Enable the synchronizer to allow future synchronizations as requested
* by calls to {@link #synchronize()}.
*/
void start();
/**
* Synchronize the dependent model with the primary model. Do nothing if
* {@link #start()} has not previously been called. Do nothing if {@link #stop}
* has been called (without any intermediate call to {@link #start()}.
*/
void synchronize();
/**
* Stop the synchronizer immediately or, if a synchronization is currently
* in progress, when it completes. Return when the synchronizer is stopped.
* No further synchonizations will performed until {@link #start()} is called.
*/
void stop();
/**
* Singleton implementation of the {@link Synchronizer} interface that will do
* nothing.
*/
final class Null implements Synchronizer, Serializable {
public static final Synchronizer INSTANCE = new Null();
public static Synchronizer instance() {
return INSTANCE;
}
// ensure single instance
private Null() {
super();
}
public void start() {
// do nothing
}
public void synchronize() {
// do nothing
}
public void stop() {
// do nothing
}
@Override
public String toString() {
return "Synchronizer.Null"; //$NON-NLS-1$
}
private static final long serialVersionUID = 1L;
private Object readResolve() {
// replace this object with the singleton
return INSTANCE;
}
}
}
|
