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
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
|
/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.drools.system.internal;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import lombok.AccessLevel;
import lombok.Getter;
import org.onap.policy.drools.core.lock.AlwaysFailLock;
import org.onap.policy.drools.core.lock.Lock;
import org.onap.policy.drools.core.lock.LockCallback;
import org.onap.policy.drools.core.lock.LockState;
import org.onap.policy.drools.core.lock.PolicyResourceLockManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Super class for Lock Features.
*
* <p/>
* Note: this implementation does <i>not</i> honor the waitForLocks={@code true}
* parameter.
*
* <p/>
* When a lock is deserialized, it will not initially appear in this feature's map; it
* will be added to the map once free() or extend() is invoked, provided there isn't
* already an entry.
*/
public abstract class LockManager<T extends FeatureLockImpl> implements PolicyResourceLockManager {
private static final Logger logger = LoggerFactory.getLogger(LockManager.class);
public static final String NOT_LOCKED_MSG = "not locked";
/**
* Maps a resource to the lock that owns it.
*/
@Getter(AccessLevel.PROTECTED)
private final Map<String, T> resource2lock = new ConcurrentHashMap<>();
/**
* {@code True} if this feature is running, {@code false} otherwise.
*/
private boolean alive = false;
/**
* {@code True} if this feature is locked, {@code false} otherwise.
*/
private boolean locked = false;
/**
* Constructs the object.
*/
protected LockManager() {
super();
}
@Override
public boolean isAlive() {
return alive;
}
@Override
public synchronized boolean start() {
if (alive) {
return false;
}
alive = true;
return true;
}
/**
* Stops the expiration checker. Does <i>not</i> invoke any lock call-backs.
*/
@Override
public synchronized boolean stop() {
if (!alive) {
return false;
}
alive = false;
return true;
}
@Override
public void shutdown() {
stop();
}
@Override
public boolean isLocked() {
return locked;
}
@Override
public synchronized boolean lock() {
if (locked) {
return false;
}
locked = true;
return true;
}
@Override
public synchronized boolean unlock() {
if (!locked) {
return false;
}
locked = false;
return true;
}
/**
* After performing checks, this invokes
* {@link #makeLock(LockState, String, String, int, LockCallback)} to create a lock
* object, inserts it into the map, and then invokes {@link #finishLock(MgrLock)}.
*/
@Override
public Lock createLock(String resourceId, String ownerKey, int holdSec, LockCallback callback,
boolean waitForLock) {
if (hasInstanceChanged()) {
AlwaysFailLock lock = new AlwaysFailLock(resourceId, ownerKey, holdSec, callback);
lock.notifyUnavailable();
return lock;
}
T lock = makeLock(LockState.WAITING, resourceId, ownerKey, holdSec, callback);
T existingLock = resource2lock.putIfAbsent(resourceId, lock);
if (existingLock == null) {
logger.debug("added lock to map {}", lock);
finishLock(lock);
} else {
lock.deny("resource is busy");
}
return lock;
}
/**
* Determines if this object is no longer the current instance of this feature type.
*
* @return {@code true} if this object is no longer the current instance,
* {@code false} otherwise
*/
protected abstract boolean hasInstanceChanged();
/**
* Finishes the steps required to establish a lock, changing its state to ACTIVE, when
* appropriate.
*
* @param lock the lock to be locked
*/
protected abstract void finishLock(T lock);
// these may be overridden by junit tests
/**
* Makes a lock of the appropriate type.
*
* @param state initial state of the lock
* @param resourceId identifier of the resource to be locked
* @param ownerKey information identifying the owner requesting the lock
* @param holdSec amount of time, in seconds, for which the lock should be held, after
* which it will automatically be released
* @param callback callback to be invoked once the lock is granted, or subsequently
* lost; must not be {@code null}
* @return a new lock
*/
protected abstract T makeLock(LockState waiting, String resourceId, String ownerKey, int holdSec,
LockCallback callback);
}
|
