X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=liblttng-ust-java-agent%2Fjava%2Flttng-ust-agent-common%2Forg%2Flttng%2Fust%2Fagent%2Fcontext%2FContextInfoManager.java;fp=liblttng-ust-java-agent%2Fjava%2Flttng-ust-agent-common%2Forg%2Flttng%2Fust%2Fagent%2Fcontext%2FContextInfoManager.java;h=7a8c80e9a83d6040f1ed630b2932870e65f4eb66;hb=831b4b0806c39463ab61b8ee82c1951cf252bcd4;hp=86ded59b346ab6984ca4594826d4d9f5716cb5d4;hpb=a548b3c1a329855ad7b2be6937a5a378419fb1b3;p=lttng-ust.git

diff --git a/liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/context/ContextInfoManager.java b/liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/context/ContextInfoManager.java
index 86ded59b..7a8c80e9 100644
--- a/liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/context/ContextInfoManager.java
+++ b/liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/context/ContextInfoManager.java
@@ -40,6 +40,10 @@ public final class ContextInfoManager {
 	private final Map<String, IContextInfoRetriever> contextInfoRetrievers = new ConcurrentHashMap<String, IContextInfoRetriever>();
 	private final Map<String, Long> contextInforRetrieverRefs = new HashMap<String, Long>();
 
+	/**
+	 * Lock used to keep the two maps above in sync when retrievers are
+	 * registered or unregistered.
+	 */
 	private final Object retrieverLock = new Object();
 
 	/** Singleton class, constructor should not be accessed directly */
@@ -163,6 +167,13 @@ public final class ContextInfoManager {
 	 *         was none
 	 */
 	public IContextInfoRetriever getContextInfoRetriever(String retrieverName) {
+		/*
+		 * Note that this method does not take the retrieverLock, it lets
+		 * concurrent threads access the ConcurrentHashMap directly.
+		 *
+		 * It's fine for a get() to happen during a registration or
+		 * unregistration, it's first-come-first-serve.
+		 */
 		return contextInfoRetrievers.get(retrieverName);
 	}