io.earcam.instrumental.agent.InstrumentationServiceProvider Maven / Gradle / Ivy

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Dynamically load a Java Agent or acquire java.lang.instrument.Instrumentation via SPI

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/*-
 * #%L
 * io.earcam.instrumental.agent
 * %%
 * Copyright (C) 2018 earcam
 * %%
 * SPDX-License-Identifier: (BSD-3-Clause OR EPL-1.0 OR Apache-2.0 OR MIT)
 * 
 * You must choose to accept, in full - any individual or combination of 
 * the following licenses:
 * 
 * 	BSD-3-Clause
 * 	EPL-1.0
 * 	Apache-2.0
 * 	MIT
 * 
 * #L%
 */
package io.earcam.instrumental.agent;

import java.lang.instrument.Instrumentation;
import java.nio.file.Path;
import java.util.Objects;

import io.earcam.unexceptional.Exceptional;

/**
 * 
 * InstrumentationServiceProvider class.
 * 
 *
 */
public final class InstrumentationServiceProvider extends InstrumentationWrapper {

	static volatile Instrumentation instance;


	/**
	 * 
	 * Constructor for InstrumentationServiceProvider.
	 * 
	 */
	public InstrumentationServiceProvider()
	{
		attach();
		setDelegate(instance);
	}


	private static void attach()
	{
		if(instance == null) {
			Path agentJar = StubAgentJar.stubAgentJar("fake-agent-", FakeAgent.class);
			Exceptional.accept(Attach::attach, agentJar.toUri(), "");

			Objects.requireNonNull(instance);
		}
	}
}