| 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 | |
| 31 | import org.lttng.ust.agent.client.LttngTcpSessiondClient; |
| 32 | |
| 33 | /** |
| 34 | * Base implementation of a {@link ILttngAgent}. |
| 35 | * |
| 36 | * @author Alexandre Montplaisir |
| 37 | * @param <T> |
| 38 | * The type of logging handler that should register to this agent |
| 39 | */ |
| 40 | public abstract class AbstractLttngAgent<T extends ILttngHandler> implements ILttngAgent<T> { |
| 41 | |
| 42 | private static final String WILDCARD = "*"; |
| 43 | private static final int INIT_TIMEOUT = 3; /* Seconds */ |
| 44 | |
| 45 | /** The handlers registered to this agent */ |
| 46 | private final Set<T> registeredHandlers = new HashSet<T>(); |
| 47 | |
| 48 | /** |
| 49 | * The trace events currently enabled in the sessions. |
| 50 | * |
| 51 | * The key represents the event name, the value is the ref count (how many |
| 52 | * different sessions currently have this event enabled). Once the ref count |
| 53 | * falls to 0, this means we can avoid sending log events through JNI |
| 54 | * because nobody wants them. |
| 55 | * |
| 56 | * It uses a concurrent hash set", so that the {@link #isEventEnabled} and |
| 57 | * read methods do not need to take a synchronization lock. |
| 58 | */ |
| 59 | private final Map<String, Integer> enabledEvents = new ConcurrentHashMap<String, Integer>(); |
| 60 | |
| 61 | /** |
| 62 | * The trace events prefixes currently enabled in the sessions, which means |
| 63 | * the event names finishing in *, like "abcd*". We track them separately |
| 64 | * from the standard event names, so that we can use {@link String#equals} |
| 65 | * and {@link String#startsWith} appropriately. |
| 66 | * |
| 67 | * We track the lone wildcard "*" separately, in {@link #enabledWildcards}. |
| 68 | */ |
| 69 | private final NavigableMap<String, Integer> enabledEventPrefixes = |
| 70 | new ConcurrentSkipListMap<String, Integer>(); |
| 71 | |
| 72 | /** Number of sessions currently enabling the wildcard "*" event */ |
| 73 | private final AtomicInteger enabledWildcards = new AtomicInteger(0); |
| 74 | |
| 75 | /** Tracing domain. Defined by the sub-classes via the constructor. */ |
| 76 | private final Domain domain; |
| 77 | |
| 78 | /* Lazy-loaded sessiond clients and their thread objects */ |
| 79 | private LttngTcpSessiondClient rootSessiondClient = null; |
| 80 | private LttngTcpSessiondClient userSessiondClient = null; |
| 81 | private Thread rootSessiondClientThread = null; |
| 82 | private Thread userSessiondClientThread = null; |
| 83 | |
| 84 | /** Indicates if this agent has been initialized. */ |
| 85 | private boolean initialized = false; |
| 86 | |
| 87 | /** |
| 88 | * Constructor. Should only be called by sub-classes via super(...); |
| 89 | * |
| 90 | * @param domain |
| 91 | * The tracing domain of this agent. |
| 92 | */ |
| 93 | protected AbstractLttngAgent(Domain domain) { |
| 94 | this.domain = domain; |
| 95 | } |
| 96 | |
| 97 | @Override |
| 98 | public Domain getDomain() { |
| 99 | return domain; |
| 100 | } |
| 101 | |
| 102 | @Override |
| 103 | public void registerHandler(T handler) { |
| 104 | synchronized (registeredHandlers) { |
| 105 | if (registeredHandlers.isEmpty()) { |
| 106 | /* |
| 107 | * This is the first handler that registers, we will initialize |
| 108 | * the agent. |
| 109 | */ |
| 110 | init(); |
| 111 | } |
| 112 | registeredHandlers.add(handler); |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | @Override |
| 117 | public void unregisterHandler(T handler) { |
| 118 | synchronized (registeredHandlers) { |
| 119 | registeredHandlers.remove(handler); |
| 120 | if (registeredHandlers.isEmpty()) { |
| 121 | /* There are no more registered handlers, close the connection. */ |
| 122 | dispose(); |
| 123 | } |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | private void init() { |
| 128 | /* |
| 129 | * Only called from a synchronized (registeredHandlers) block, should |
| 130 | * not need additional synchronization. |
| 131 | */ |
| 132 | if (initialized) { |
| 133 | return; |
| 134 | } |
| 135 | String rootClientThreadName = "Root sessiond client started by agent: " + this.getClass().getSimpleName(); |
| 136 | |
| 137 | rootSessiondClient = new LttngTcpSessiondClient(this, true); |
| 138 | rootSessiondClientThread = new Thread(rootSessiondClient, rootClientThreadName); |
| 139 | rootSessiondClientThread.setDaemon(true); |
| 140 | rootSessiondClientThread.start(); |
| 141 | |
| 142 | String userClientThreadName = "User sessiond client started by agent: " + this.getClass().getSimpleName(); |
| 143 | |
| 144 | userSessiondClient = new LttngTcpSessiondClient(this, false); |
| 145 | userSessiondClientThread = new Thread(userSessiondClient, userClientThreadName); |
| 146 | userSessiondClientThread.setDaemon(true); |
| 147 | userSessiondClientThread.start(); |
| 148 | |
| 149 | /* Give the threads' registration a chance to end. */ |
| 150 | if (!rootSessiondClient.waitForConnection(INIT_TIMEOUT)) { |
| 151 | userSessiondClient.waitForConnection(INIT_TIMEOUT); |
| 152 | } |
| 153 | |
| 154 | initialized = true; |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Dispose the agent |
| 159 | */ |
| 160 | private void dispose() { |
| 161 | /* |
| 162 | * Only called from a synchronized (registeredHandlers) block, should |
| 163 | * not need additional synchronization. |
| 164 | */ |
| 165 | rootSessiondClient.close(); |
| 166 | userSessiondClient.close(); |
| 167 | |
| 168 | try { |
| 169 | rootSessiondClientThread.join(); |
| 170 | userSessiondClientThread.join(); |
| 171 | |
| 172 | } catch (InterruptedException e) { |
| 173 | e.printStackTrace(); |
| 174 | } |
| 175 | rootSessiondClient = null; |
| 176 | rootSessiondClientThread = null; |
| 177 | userSessiondClient = null; |
| 178 | userSessiondClientThread = null; |
| 179 | |
| 180 | /* Reset all enabled event counts to 0 */ |
| 181 | enabledEvents.clear(); |
| 182 | enabledEventPrefixes.clear(); |
| 183 | enabledWildcards.set(0); |
| 184 | |
| 185 | initialized = false; |
| 186 | |
| 187 | } |
| 188 | |
| 189 | /** |
| 190 | * Callback for the TCP clients to notify the agent that a request for |
| 191 | * enabling an event was sent from the session daemon. |
| 192 | * |
| 193 | * @param eventName |
| 194 | * The name of the event that was requested to be enabled. |
| 195 | * @return Since we do not track individual sessions, right now this command |
| 196 | * cannot fail. It will always return true. |
| 197 | */ |
| 198 | public boolean eventEnabled(String eventName) { |
| 199 | if (eventName.equals(WILDCARD)) { |
| 200 | enabledWildcards.incrementAndGet(); |
| 201 | return true; |
| 202 | } |
| 203 | |
| 204 | if (eventName.endsWith(WILDCARD)) { |
| 205 | /* Strip the "*" from the name. */ |
| 206 | String prefix = eventName.substring(0, eventName.length() - 1); |
| 207 | return incrementEventCount(prefix, enabledEventPrefixes); |
| 208 | } |
| 209 | |
| 210 | return incrementEventCount(eventName, enabledEvents); |
| 211 | } |
| 212 | |
| 213 | /** |
| 214 | * Callback for the TCP clients to notify the agent that a request for |
| 215 | * disabling an event was sent from the session daemon. |
| 216 | * |
| 217 | * @param eventName |
| 218 | * The name of the event that was requested to be disabled. |
| 219 | * @return True if the command completed successfully, false if we should |
| 220 | * report an error (event was not enabled, etc.) |
| 221 | */ |
| 222 | public boolean eventDisabled(String eventName) { |
| 223 | if (eventName.equals(WILDCARD)) { |
| 224 | int newCount = enabledWildcards.decrementAndGet(); |
| 225 | if (newCount < 0) { |
| 226 | /* Event was not enabled, bring the count back to 0 */ |
| 227 | enabledWildcards.incrementAndGet(); |
| 228 | return false; |
| 229 | } |
| 230 | return true; |
| 231 | } |
| 232 | |
| 233 | if (eventName.endsWith(WILDCARD)) { |
| 234 | /* Strip the "*" from the name. */ |
| 235 | String prefix = eventName.substring(0, eventName.length() - 1); |
| 236 | return decrementEventCount(prefix, enabledEventPrefixes); |
| 237 | } |
| 238 | |
| 239 | return decrementEventCount(eventName, enabledEvents); |
| 240 | } |
| 241 | |
| 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 | |
| 263 | @Override |
| 264 | public Iterable<String> listEnabledEvents() { |
| 265 | List<String> events = new LinkedList<String>(); |
| 266 | |
| 267 | if (enabledWildcards.get() > 0) { |
| 268 | events.add(WILDCARD); |
| 269 | } |
| 270 | for (String prefix : enabledEventPrefixes.keySet()) { |
| 271 | events.add(new String(prefix + WILDCARD)); |
| 272 | } |
| 273 | events.addAll(enabledEvents.keySet()); |
| 274 | return events; |
| 275 | } |
| 276 | |
| 277 | private static boolean incrementEventCount(String eventName, Map<String, Integer> eventMap) { |
| 278 | synchronized (eventMap) { |
| 279 | Integer count = eventMap.get(eventName); |
| 280 | if (count == null) { |
| 281 | /* This is the first instance of this event being enabled */ |
| 282 | eventMap.put(eventName, Integer.valueOf(1)); |
| 283 | return true; |
| 284 | } |
| 285 | if (count.intValue() <= 0) { |
| 286 | /* It should not have been in the map in the first place! */ |
| 287 | throw new IllegalStateException(); |
| 288 | } |
| 289 | /* The event was already enabled, increment its refcount */ |
| 290 | eventMap.put(eventName, Integer.valueOf(count.intValue() + 1)); |
| 291 | return true; |
| 292 | } |
| 293 | } |
| 294 | |
| 295 | private static boolean decrementEventCount(String eventName, Map<String, Integer> eventMap) { |
| 296 | synchronized (eventMap) { |
| 297 | Integer count = eventMap.get(eventName); |
| 298 | if (count == null || count.intValue() <= 0) { |
| 299 | /* |
| 300 | * The sessiond asked us to disable an event that was not |
| 301 | * enabled previously. Command error? |
| 302 | */ |
| 303 | return false; |
| 304 | } |
| 305 | if (count.intValue() == 1) { |
| 306 | /* |
| 307 | * This is the last instance of this event being disabled, |
| 308 | * remove it from the map so that we stop sending it. |
| 309 | */ |
| 310 | eventMap.remove(eventName); |
| 311 | return true; |
| 312 | } |
| 313 | /* |
| 314 | * Other sessions are still looking for this event, simply decrement |
| 315 | * its refcount. |
| 316 | */ |
| 317 | eventMap.put(eventName, Integer.valueOf(count.intValue() - 1)); |
| 318 | return true; |
| 319 | } |
| 320 | } |
| 321 | } |
| 322 | |