+++ /dev/null
-/*
- * SPDX-License-Identifier: LGPL-2.1-only
- *
- * Copyright (C) 2015 EfficiOS Inc.
- * Copyright (C) 2015 Alexandre Montplaisir <alexmonthy@efficios.com>
- */
-
-package org.lttng.ust.agent.context;
-
-import java.io.IOException;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
-/**
- * The singleton manager of {@link IContextInfoRetriever} objects.
- *
- * @author Alexandre Montplaisir
- */
-public final class ContextInfoManager {
-
- private static final String SHARED_LIBRARY_NAME = "lttng-ust-context-jni";
-
- private static final Pattern VALID_CONTEXT_NAME_PATTERN = Pattern.compile("^[a-zA-Z0-9_\\.]+$");
-
- private static ContextInfoManager instance;
-
- 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 */
- private ContextInfoManager() {
- }
-
- /**
- * Get the singleton instance.
- *
- * <p>
- * Usage of this class requires the "liblttng-ust-context-jni.so" native
- * library to be present on the system and available (passing
- * -Djava.library.path=path to the JVM may be needed).
- * </p>
- *
- * @return The singleton instance
- * @throws IOException
- * If the shared library cannot be found.
- * @throws SecurityException
- * We will forward any SecurityExcepion that may be thrown when
- * trying to load the JNI library.
- */
- public static synchronized ContextInfoManager getInstance() throws IOException, SecurityException {
- if (instance == null) {
- try {
- System.loadLibrary(SHARED_LIBRARY_NAME);
- } catch (UnsatisfiedLinkError e) {
- throw new IOException(e);
- }
- instance = new ContextInfoManager();
- }
- return instance;
- }
-
- /**
- * Register a new context info retriever.
- *
- * <p>
- * Each context info retriever is registered with a given "retriever name",
- * which specifies the namespace of the context elements. This name is
- * specified separately from the retriever objects, which would allow
- * register the same retriever under different namespaces for example.
- * </p>
- *
- * <p>
- * If the method returns false (indicating registration failure), then the
- * retriever object will *not* be used for context information.
- * </p>
- *
- * @param retrieverName
- * The name to register to the context retriever object with.
- * @param contextInfoRetriever
- * The context info retriever to register
- * @return True if the retriever was successfully registered, false if there
- * was an error, for example if a retriever is already registered
- * with that name.
- */
- public boolean registerContextInfoRetriever(String retrieverName, IContextInfoRetriever contextInfoRetriever) {
- synchronized (retrieverLock) {
- if (!validateRetrieverName(retrieverName)) {
- return false;
- }
-
- if (contextInfoRetrievers.containsKey(retrieverName)) {
- /*
- * There is already a retriever registered with that name,
- * refuse the new registration.
- */
- return false;
- }
- /*
- * Inform LTTng-UST of the new retriever. The names have to start
- * with "$app." on the UST side!
- */
- long ref = LttngContextApi.registerProvider("$app." + retrieverName);
- if (ref == 0) {
- return false;
- }
-
- contextInfoRetrievers.put(retrieverName, contextInfoRetriever);
- contextInforRetrieverRefs.put(retrieverName, Long.valueOf(ref));
-
- return true;
- }
- }
-
- /**
- * Unregister a previously added context info retriever.
- *
- * This method has no effect if the retriever was not already registered.
- *
- * @param retrieverName
- * The context info retriever to unregister
- * @return True if unregistration was successful, false if there was an
- * error
- */
- public boolean unregisterContextInfoRetriever(String retrieverName) {
- synchronized (retrieverLock) {
- if (!contextInfoRetrievers.containsKey(retrieverName)) {
- /*
- * There was no retriever registered with that name.
- */
- return false;
- }
- contextInfoRetrievers.remove(retrieverName);
- long ref = contextInforRetrieverRefs.remove(retrieverName).longValue();
-
- /* Unregister the retriever on the UST side too */
- LttngContextApi.unregisterProvider(ref);
-
- return true;
- }
- }
-
- /**
- * Return the context info retriever object registered with the given name.
- *
- * @param retrieverName
- * The retriever name to look for
- * @return The corresponding retriever object, or <code>null</code> if there
- * 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);
- }
-
- /**
- * Validate that the given retriever name contains only the allowed
- * characters, which are alphanumerical characters, period "." and
- * underscore "_". The name must also not start with a number.
- */
- private static boolean validateRetrieverName(String contextName) {
- if (contextName.isEmpty()) {
- return false;
- }
-
- /* First character must not be a number */
- if (Character.isDigit(contextName.charAt(0))) {
- return false;
- }
-
- /* Validate the other characters of the string */
- Matcher matcher = VALID_CONTEXT_NAME_PATTERN.matcher(contextName);
- return matcher.matches();
- }
-}
projects / lttng-ust.git / blobdiff