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1 | /* |
2 | * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com> | |
3 | * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com> | |
4 | * | |
5 | * This library is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU Lesser General Public License, version 2.1 only, | |
7 | * as published by the Free Software Foundation. | |
8 | * | |
9 | * This library is distributed in the hope that it will be useful, but WITHOUT | |
10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License | |
12 | * for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU Lesser General Public License | |
15 | * along with this library; if not, write to the Free Software Foundation, | |
16 | * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
17 | */ | |
18 | ||
19 | package org.lttng.ust.agent; | |
20 | ||
21 | import java.util.HashSet; | |
22 | import java.util.LinkedList; | |
23 | import java.util.List; | |
24 | import java.util.Map; | |
25 | import java.util.NavigableMap; | |
26 | import java.util.Set; | |
27 | import java.util.concurrent.ConcurrentHashMap; | |
28 | import java.util.concurrent.ConcurrentSkipListMap; | |
29 | import java.util.concurrent.atomic.AtomicInteger; | |
30 | ||
3165c2f5 | 31 | import org.lttng.ust.agent.client.ILttngTcpClientListener; |
d60dfbe4 AM |
32 | import org.lttng.ust.agent.client.LttngTcpSessiondClient; |
33 | ||
34 | /** | |
35 | * Base implementation of a {@link ILttngAgent}. | |
36 | * | |
37 | * @author Alexandre Montplaisir | |
38 | * @param <T> | |
39 | * The type of logging handler that should register to this agent | |
40 | */ | |
3165c2f5 AM |
41 | public abstract class AbstractLttngAgent<T extends ILttngHandler> |
42 | implements ILttngAgent<T>, ILttngTcpClientListener { | |
d60dfbe4 AM |
43 | |
44 | private static final String WILDCARD = "*"; | |
45 | private static final int INIT_TIMEOUT = 3; /* Seconds */ | |
46 | ||
47 | /** The handlers registered to this agent */ | |
48 | private final Set<T> registeredHandlers = new HashSet<T>(); | |
49 | ||
50 | /** | |
51 | * The trace events currently enabled in the sessions. | |
52 | * | |
53 | * The key represents the event name, the value is the ref count (how many | |
54 | * different sessions currently have this event enabled). Once the ref count | |
55 | * falls to 0, this means we can avoid sending log events through JNI | |
56 | * because nobody wants them. | |
57 | * | |
58 | * It uses a concurrent hash set", so that the {@link #isEventEnabled} and | |
59 | * read methods do not need to take a synchronization lock. | |
60 | */ | |
61 | private final Map<String, Integer> enabledEvents = new ConcurrentHashMap<String, Integer>(); | |
62 | ||
63 | /** | |
64 | * The trace events prefixes currently enabled in the sessions, which means | |
65 | * the event names finishing in *, like "abcd*". We track them separately | |
66 | * from the standard event names, so that we can use {@link String#equals} | |
67 | * and {@link String#startsWith} appropriately. | |
68 | * | |
69 | * We track the lone wildcard "*" separately, in {@link #enabledWildcards}. | |
70 | */ | |
71 | private final NavigableMap<String, Integer> enabledEventPrefixes = | |
72 | new ConcurrentSkipListMap<String, Integer>(); | |
73 | ||
74 | /** Number of sessions currently enabling the wildcard "*" event */ | |
75 | private final AtomicInteger enabledWildcards = new AtomicInteger(0); | |
76 | ||
77 | /** Tracing domain. Defined by the sub-classes via the constructor. */ | |
78 | private final Domain domain; | |
79 | ||
80 | /* Lazy-loaded sessiond clients and their thread objects */ | |
81 | private LttngTcpSessiondClient rootSessiondClient = null; | |
82 | private LttngTcpSessiondClient userSessiondClient = null; | |
83 | private Thread rootSessiondClientThread = null; | |
84 | private Thread userSessiondClientThread = null; | |
85 | ||
86 | /** Indicates if this agent has been initialized. */ | |
87 | private boolean initialized = false; | |
88 | ||
89 | /** | |
90 | * Constructor. Should only be called by sub-classes via super(...); | |
91 | * | |
92 | * @param domain | |
93 | * The tracing domain of this agent. | |
94 | */ | |
95 | protected AbstractLttngAgent(Domain domain) { | |
96 | this.domain = domain; | |
97 | } | |
98 | ||
99 | @Override | |
100 | public Domain getDomain() { | |
101 | return domain; | |
102 | } | |
103 | ||
104 | @Override | |
105 | public void registerHandler(T handler) { | |
106 | synchronized (registeredHandlers) { | |
107 | if (registeredHandlers.isEmpty()) { | |
108 | /* | |
109 | * This is the first handler that registers, we will initialize | |
110 | * the agent. | |
111 | */ | |
112 | init(); | |
113 | } | |
114 | registeredHandlers.add(handler); | |
115 | } | |
116 | } | |
117 | ||
118 | @Override | |
119 | public void unregisterHandler(T handler) { | |
120 | synchronized (registeredHandlers) { | |
121 | registeredHandlers.remove(handler); | |
122 | if (registeredHandlers.isEmpty()) { | |
123 | /* There are no more registered handlers, close the connection. */ | |
124 | dispose(); | |
125 | } | |
126 | } | |
127 | } | |
128 | ||
129 | private void init() { | |
130 | /* | |
131 | * Only called from a synchronized (registeredHandlers) block, should | |
132 | * not need additional synchronization. | |
133 | */ | |
134 | if (initialized) { | |
135 | return; | |
136 | } | |
137 | String rootClientThreadName = "Root sessiond client started by agent: " + this.getClass().getSimpleName(); | |
138 | ||
3165c2f5 | 139 | rootSessiondClient = new LttngTcpSessiondClient(this, getDomain().value(), true); |
d60dfbe4 AM |
140 | rootSessiondClientThread = new Thread(rootSessiondClient, rootClientThreadName); |
141 | rootSessiondClientThread.setDaemon(true); | |
142 | rootSessiondClientThread.start(); | |
143 | ||
144 | String userClientThreadName = "User sessiond client started by agent: " + this.getClass().getSimpleName(); | |
145 | ||
3165c2f5 | 146 | userSessiondClient = new LttngTcpSessiondClient(this, getDomain().value(), false); |
d60dfbe4 AM |
147 | userSessiondClientThread = new Thread(userSessiondClient, userClientThreadName); |
148 | userSessiondClientThread.setDaemon(true); | |
149 | userSessiondClientThread.start(); | |
150 | ||
151 | /* Give the threads' registration a chance to end. */ | |
152 | if (!rootSessiondClient.waitForConnection(INIT_TIMEOUT)) { | |
153 | userSessiondClient.waitForConnection(INIT_TIMEOUT); | |
154 | } | |
155 | ||
156 | initialized = true; | |
157 | } | |
158 | ||
159 | /** | |
160 | * Dispose the agent | |
161 | */ | |
162 | private void dispose() { | |
163 | /* | |
164 | * Only called from a synchronized (registeredHandlers) block, should | |
165 | * not need additional synchronization. | |
166 | */ | |
167 | rootSessiondClient.close(); | |
168 | userSessiondClient.close(); | |
169 | ||
170 | try { | |
171 | rootSessiondClientThread.join(); | |
172 | userSessiondClientThread.join(); | |
173 | ||
174 | } catch (InterruptedException e) { | |
175 | e.printStackTrace(); | |
176 | } | |
177 | rootSessiondClient = null; | |
178 | rootSessiondClientThread = null; | |
179 | userSessiondClient = null; | |
180 | userSessiondClientThread = null; | |
181 | ||
182 | /* Reset all enabled event counts to 0 */ | |
183 | enabledEvents.clear(); | |
184 | enabledEventPrefixes.clear(); | |
185 | enabledWildcards.set(0); | |
186 | ||
187 | initialized = false; | |
188 | ||
189 | } | |
190 | ||
3165c2f5 | 191 | @Override |
d60dfbe4 AM |
192 | public boolean eventEnabled(String eventName) { |
193 | if (eventName.equals(WILDCARD)) { | |
194 | enabledWildcards.incrementAndGet(); | |
195 | return true; | |
196 | } | |
197 | ||
198 | if (eventName.endsWith(WILDCARD)) { | |
199 | /* Strip the "*" from the name. */ | |
200 | String prefix = eventName.substring(0, eventName.length() - 1); | |
201 | return incrementEventCount(prefix, enabledEventPrefixes); | |
202 | } | |
203 | ||
204 | return incrementEventCount(eventName, enabledEvents); | |
205 | } | |
206 | ||
3165c2f5 | 207 | @Override |
d60dfbe4 AM |
208 | public boolean eventDisabled(String eventName) { |
209 | if (eventName.equals(WILDCARD)) { | |
210 | int newCount = enabledWildcards.decrementAndGet(); | |
211 | if (newCount < 0) { | |
212 | /* Event was not enabled, bring the count back to 0 */ | |
213 | enabledWildcards.incrementAndGet(); | |
214 | return false; | |
215 | } | |
cbaa5167 | 216 | return true; |
d60dfbe4 AM |
217 | } |
218 | ||
219 | if (eventName.endsWith(WILDCARD)) { | |
220 | /* Strip the "*" from the name. */ | |
221 | String prefix = eventName.substring(0, eventName.length() - 1); | |
222 | return decrementEventCount(prefix, enabledEventPrefixes); | |
223 | } | |
224 | ||
225 | return decrementEventCount(eventName, enabledEvents); | |
226 | } | |
227 | ||
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228 | @Override |
229 | public Iterable<String> listEnabledEvents() { | |
230 | List<String> events = new LinkedList<String>(); | |
231 | ||
232 | if (enabledWildcards.get() > 0) { | |
233 | events.add(WILDCARD); | |
234 | } | |
235 | for (String prefix : enabledEventPrefixes.keySet()) { | |
236 | events.add(new String(prefix + WILDCARD)); | |
237 | } | |
238 | events.addAll(enabledEvents.keySet()); | |
239 | return events; | |
240 | } | |
241 | ||
d60dfbe4 AM |
242 | @Override |
243 | public boolean isEventEnabled(String eventName) { | |
244 | /* If at least one session enabled the "*" wildcard, send the event */ | |
245 | if (enabledWildcards.get() > 0) { | |
246 | return true; | |
247 | } | |
248 | ||
249 | /* Check if at least one session wants this exact event name */ | |
250 | if (enabledEvents.containsKey(eventName)) { | |
251 | return true; | |
252 | } | |
253 | ||
254 | /* Look in the enabled prefixes if one of them matches the event */ | |
255 | String potentialMatch = enabledEventPrefixes.floorKey(eventName); | |
256 | if (potentialMatch != null && eventName.startsWith(potentialMatch)) { | |
257 | return true; | |
258 | } | |
259 | ||
260 | return false; | |
261 | } | |
262 | ||
d60dfbe4 AM |
263 | private static boolean incrementEventCount(String eventName, Map<String, Integer> eventMap) { |
264 | synchronized (eventMap) { | |
265 | Integer count = eventMap.get(eventName); | |
266 | if (count == null) { | |
267 | /* This is the first instance of this event being enabled */ | |
268 | eventMap.put(eventName, Integer.valueOf(1)); | |
269 | return true; | |
270 | } | |
271 | if (count.intValue() <= 0) { | |
272 | /* It should not have been in the map in the first place! */ | |
273 | throw new IllegalStateException(); | |
274 | } | |
275 | /* The event was already enabled, increment its refcount */ | |
276 | eventMap.put(eventName, Integer.valueOf(count.intValue() + 1)); | |
277 | return true; | |
278 | } | |
279 | } | |
280 | ||
281 | private static boolean decrementEventCount(String eventName, Map<String, Integer> eventMap) { | |
282 | synchronized (eventMap) { | |
283 | Integer count = eventMap.get(eventName); | |
284 | if (count == null || count.intValue() <= 0) { | |
285 | /* | |
286 | * The sessiond asked us to disable an event that was not | |
287 | * enabled previously. Command error? | |
288 | */ | |
289 | return false; | |
290 | } | |
291 | if (count.intValue() == 1) { | |
292 | /* | |
293 | * This is the last instance of this event being disabled, | |
294 | * remove it from the map so that we stop sending it. | |
295 | */ | |
296 | eventMap.remove(eventName); | |
297 | return true; | |
298 | } | |
299 | /* | |
300 | * Other sessions are still looking for this event, simply decrement | |
301 | * its refcount. | |
302 | */ | |
303 | eventMap.put(eventName, Integer.valueOf(count.intValue() - 1)); | |
304 | return true; | |
305 | } | |
306 | } | |
307 | } | |
308 |