| /* |
| * Copyright 2017, OpenCensus Authors |
| * |
| * 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. |
| */ |
| |
| package io.opencensus.contrib.agent; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| import static com.google.common.base.Preconditions.checkState; |
| import static net.bytebuddy.matcher.ElementMatchers.none; |
| |
| import io.opencensus.contrib.agent.bootstrap.ContextStrategy; |
| import io.opencensus.contrib.agent.bootstrap.ContextTrampoline; |
| import io.opencensus.contrib.agent.instrumentation.Instrumenter; |
| import java.lang.instrument.Instrumentation; |
| import java.util.ServiceLoader; |
| import java.util.jar.JarFile; |
| import java.util.logging.Logger; |
| import net.bytebuddy.agent.builder.AgentBuilder; |
| |
| /** |
| * The <b>OpenCensus Agent for Java</b> collects and sends latency data about your Java process to |
| * OpenCensus backends such as Stackdriver Trace for analysis and visualization. |
| * |
| * <p>To enable the *OpenCensus Agent for Java* for your application, add the option {@code |
| * -javaagent:path/to/opencensus-contrib-agent.jar} to the invocation of the {@code java} executable |
| * as shown in the following example: |
| * |
| * <pre> |
| * java -javaagent:path/to/opencensus-contrib-agent.jar ... |
| * </pre> |
| * |
| * @see <a |
| * href="https://github.com/census-instrumentation/instrumentation-java/tree/master/agent">https://github.com/census-instrumentation/instrumentation-java/tree/master/agent</a> |
| * @since 0.6 |
| */ |
| public final class AgentMain { |
| |
| private static final Logger logger = Logger.getLogger(AgentMain.class.getName()); |
| |
| private AgentMain() {} |
| |
| /** |
| * Initializes the OpenCensus Agent for Java. |
| * |
| * @param agentArgs agent options, passed as a single string by the JVM |
| * @param instrumentation the {@link Instrumentation} object provided by the JVM for instrumenting |
| * Java programming language code |
| * @throws Exception if initialization of the agent fails |
| * @see java.lang.instrument |
| * @since 0.6 |
| */ |
| public static void premain(String agentArgs, Instrumentation instrumentation) throws Exception { |
| checkNotNull(instrumentation, "instrumentation"); |
| |
| logger.fine("Initializing."); |
| |
| // The classes in bootstrap.jar, such as ContextManger and ContextStrategy, will be referenced |
| // from classes loaded by the bootstrap classloader. Thus, these classes have to be loaded by |
| // the bootstrap classloader, too. |
| instrumentation.appendToBootstrapClassLoaderSearch( |
| new JarFile(Resources.getResourceAsTempFile("bootstrap.jar"))); |
| |
| checkLoadedByBootstrapClassloader(ContextTrampoline.class); |
| checkLoadedByBootstrapClassloader(ContextStrategy.class); |
| |
| Settings settings = Settings.load(); |
| AgentBuilder agentBuilder = |
| new AgentBuilder.Default() |
| .disableClassFormatChanges() |
| .with(AgentBuilder.RedefinitionStrategy.RETRANSFORMATION) |
| .with(new AgentBuilderListener()) |
| .ignore(none()); |
| for (Instrumenter instrumenter : ServiceLoader.load(Instrumenter.class)) { |
| agentBuilder = instrumenter.instrument(agentBuilder, settings); |
| } |
| agentBuilder.installOn(instrumentation); |
| |
| logger.fine("Initialized."); |
| } |
| |
| private static void checkLoadedByBootstrapClassloader(Class<?> clazz) { |
| checkState( |
| clazz.getClassLoader() == null, "%s must be loaded by the bootstrap classloader", clazz); |
| } |
| } |