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	/*
	* Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package jdk.jfr;

	import static jdk.jfr.internal.LogLevel.DEBUG;
	import static jdk.jfr.internal.LogLevel.INFO;
	import static jdk.jfr.internal.LogTag.JFR;

	import java.security.AccessControlContext;
	import java.security.AccessController;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.List;
	import java.util.Objects;

	import jdk.jfr.internal.JVM;
	import jdk.jfr.internal.JVMSupport;
	import jdk.jfr.internal.LogLevel;
	import jdk.jfr.internal.Logger;
	import jdk.jfr.internal.MetadataRepository;
	import jdk.jfr.internal.Options;
	import jdk.jfr.internal.PlatformRecorder;
	import jdk.jfr.internal.PlatformRecording;
	import jdk.jfr.internal.Repository;
	import jdk.jfr.internal.RequestEngine;
	import jdk.jfr.internal.Utils;

	/**
	* Class for accessing, controlling, and managing Flight Recorder.
	* <p>
	* This class provides the methods necessary for creating, starting, stopping,
	* and destroying recordings.
	*
	* @since 8
	*/
	public final class FlightRecorder {
	private static volatile FlightRecorder platformRecorder;
	private static volatile boolean initialized;
	private final PlatformRecorder internal;

	private FlightRecorder(PlatformRecorder internal) {
	this.internal = internal;
	}

	/**
	* Returns an immutable list of the available recordings.
	* <p>
	* A recording becomes available when it is created. It becomes unavailable when it
	* is in the {@code CLOSED} state, typically after a call to
	* {@link Recording#close()}.
	*
	* @return a list of recordings, not {@code null}
	*/
	public List<Recording> getRecordings() {
	List<Recording> recs = new ArrayList<>();
	for (PlatformRecording r : internal.getRecordings()) {
	recs.add(r.getRecording());
	}
	return Collections.unmodifiableList(recs);
	}

	/**
	* Creates a snapshot of all available recorded data.
	* <p>
	* A snapshot is a synthesized recording in a {@code STOPPPED} state. If no data is
	* available, a recording with size {@code 0} is returned.
	* <p>
	* A snapshot provides stable access to data for later operations (for example,
	* operations to change the interval or to reduce the data size).
	* <p>
	* The following example shows how to create a snapshot and write a subset of the data to a file.
	*
	* <pre>
	* <code>
	* try (Recording snapshot = FlightRecorder.getFlightRecorder().takeSnapshot()) {
	* if (snapshot.getSize() > 0) {
	* snapshot.setMaxSize(100_000_000);
	* snapshot.setMaxAge(Duration.ofMinutes(5));
	* snapshot.dump(Paths.get("snapshot.jfr"));
	* }
	* }
	* </code>
	* </pre>
	*
	* The caller must close the recording when access to the data is no longer
	* needed.
	*
	* @return a snapshot of all available recording data, not {@code null}
	*/
	public Recording takeSnapshot() {
	Recording snapshot = new Recording();
	snapshot.setName("Snapshot");
	internal.fillWithRecordedData(snapshot.getInternal(), null);
	return snapshot;
	}

	/**
	* Registers an event class.
	* <p>
	* If the event class is already registered, then the invocation of this method is
	* ignored.
	*
	* @param eventClass the event class to register, not {@code null}
	*
	* @throws IllegalArgumentException if class is abstract or not a subclass
	* of {@link Event}
	* @throws SecurityException if a security manager exists and the caller
	* does not have {@code FlightRecorderPermission("registerEvent")}
	*/
	public static void register(Class<? extends Event> eventClass) {
	Objects.requireNonNull(eventClass);
	if (JVMSupport.isNotAvailable()) {
	return;
	}
	Utils.ensureValidEventSubclass(eventClass);
	MetadataRepository.getInstance().register(eventClass);
	}

	/**
	* Unregisters an event class.
	* <p>
	* If the event class is not registered, then the invocation of this method is
	* ignored.
	*
	* @param eventClass the event class to unregistered, not {@code null}
	* @throws IllegalArgumentException if a class is abstract or not a subclass
	* of {@link Event}
	*
	* @throws SecurityException if a security manager exists and the caller
	* does not have {@code FlightRecorderPermission("registerEvent")}
	*/
	public static void unregister(Class<? extends Event> eventClass) {
	Objects.requireNonNull(eventClass);
	if (JVMSupport.isNotAvailable()) {
	return;
	}
	Utils.ensureValidEventSubclass(eventClass);
	MetadataRepository.getInstance().unregister(eventClass);
	}

	/**
	* Returns the Flight Recorder for the platform.
	*
	* @return a Flight Recorder instance, not {@code null}
	*
	* @throws IllegalStateException if Flight Recorder can't be created (for
	* example, if the Java Virtual Machine (JVM) lacks Flight Recorder
	* support, or if the file repository can't be created or accessed)
	*
	* @throws SecurityException if a security manager exists and the caller does
	* not have {@code FlightRecorderPermission("accessFlightRecorder")}
	*/
	public static FlightRecorder getFlightRecorder() throws IllegalStateException, SecurityException {
	synchronized (PlatformRecorder.class) {
	Utils.checkAccessFlightRecorder();
	JVMSupport.ensureWithIllegalStateException();
	if (platformRecorder == null) {
	try {
	platformRecorder = new FlightRecorder(new PlatformRecorder());
	} catch (IllegalStateException ise) {
	throw ise;
	} catch (Exception e) {
	throw new IllegalStateException("Can't create Flight Recorder. " + e.getMessage(), e);
	}
	// Must be in synchronized block to prevent instance leaking out
	// before initialization is done
	initialized = true;
	Logger.log(JFR, INFO, "Flight Recorder initialized");
	Logger.log(JFR, DEBUG, "maxchunksize: " + Options.getMaxChunkSize()+ " bytes");
	Logger.log(JFR, DEBUG, "memorysize: " + Options.getMemorySize()+ " bytes");
	Logger.log(JFR, DEBUG, "globalbuffersize: " + Options.getGlobalBufferSize()+ " bytes");
	Logger.log(JFR, DEBUG, "globalbuffercount: " + Options.getGlobalBufferCount());
	Logger.log(JFR, DEBUG, "dumppath: " + Options.getDumpPath());
	Logger.log(JFR, DEBUG, "samplethreads: " + Options.getSampleThreads());
	Logger.log(JFR, DEBUG, "stackdepth: " + Options.getStackDepth());
	Logger.log(JFR, DEBUG, "threadbuffersize: " + Options.getThreadBufferSize());
	Logger.log(JFR, LogLevel.INFO, "Created repository " + Repository.getRepository().getRepositoryPath().toString());
	PlatformRecorder.notifyRecorderInitialized(platformRecorder);
	}
	}
	return platformRecorder;
	}

	/**
	* Adds a hook for a periodic event.
	* <p>
	* The implementation of the hook should return as soon as possible, to
	* avoid blocking other Flight Recorder operations. The hook should emit
	* one or more events of the specified type. When a hook is added, the
	* interval at which the call is invoked is configurable using the
	* {@code "period"} setting.
	*
	* @param eventClass the class that the hook should run for, not {@code null}
	* @param hook the hook, not {@code null}
	* @throws IllegalArgumentException if a class is not a subclass of
	* {@link Event}, is abstract, or the hook is already added
	* @throws IllegalStateException if the event class has the
	* {@code Registered(false)} annotation and is not registered manually
	* @throws SecurityException if a security manager exists and the caller
	* does not have {@code FlightRecorderPermission("registerEvent")}
	*/
	public static void addPeriodicEvent(Class<? extends Event> eventClass, Runnable hook) throws SecurityException {
	Objects.requireNonNull(eventClass);
	Objects.requireNonNull(hook);
	if (JVMSupport.isNotAvailable()) {
	return;
	}

	Utils.ensureValidEventSubclass(eventClass);
	Utils.checkRegisterPermission();
	AccessControlContext acc = AccessController.getContext();
	RequestEngine.addHook(acc, EventType.getEventType(eventClass).getPlatformEventType(), hook);
	}

	/**
	* Removes a hook for a periodic event.
	*
	* @param hook the hook to remove, not {@code null}
	* @return {@code true} if hook is removed, {@code false} otherwise
	* @throws SecurityException if a security manager exists and the caller
	* does not have {@code FlightRecorderPermission("registerEvent")}
	*/
	public static boolean removePeriodicEvent(Runnable hook) throws SecurityException {
	Objects.requireNonNull(hook);
	Utils.checkRegisterPermission();
	if (JVMSupport.isNotAvailable()) {
	return false;
	}
	return RequestEngine.removeHook(hook);
	}

	/**
	* Returns an immutable list that contains all currently registered events.
	* <p>
	* By default, events are registered when they are first used, typically
	* when an event object is allocated. To ensure an event is visible early,
	* registration can be triggered by invoking the
	* {@link FlightRecorder#register(Class)} method.
	*
	* @return list of events, not {@code null}
	*/
	public List<EventType> getEventTypes() {
	return Collections.unmodifiableList(MetadataRepository.getInstance().getRegisteredEventTypes());
	}

	/**
	* Adds a recorder listener and captures the {@code AccessControlContext} to
	* use when invoking the listener.
	* <p>
	* If Flight Recorder is already initialized when the listener is added, then the method
	* {@link FlightRecorderListener#recorderInitialized(FlightRecorder)} method is
	* invoked before returning from this method.
	*
	* @param changeListener the listener to add, not {@code null}
	*
	* @throws SecurityException if a security manager exists and the caller
	* does not have
	* {@code FlightRecorderPermission("accessFlightRecorder")}
	*/
	public static void addListener(FlightRecorderListener changeListener) {
	Objects.requireNonNull(changeListener);
	Utils.checkAccessFlightRecorder();
	if (JVMSupport.isNotAvailable()) {
	return;
	}
	PlatformRecorder.addListener(changeListener);
	}

	/**
	* Removes a recorder listener.
	* <p>
	* If the same listener is added multiple times, only one instance is
	* removed.
	*
	* @param changeListener listener to remove, not {@code null}
	*
	* @throws SecurityException if a security manager exists and the caller
	* does not have
	* {@code FlightRecorderPermission("accessFlightRecorder")}
	*
	* @return {@code true}, if the listener could be removed, {@code false}
	* otherwise
	*/
	public static boolean removeListener(FlightRecorderListener changeListener) {
	Objects.requireNonNull(changeListener);
	Utils.checkAccessFlightRecorder();
	if (JVMSupport.isNotAvailable()) {
	return false;
	}

	return PlatformRecorder.removeListener(changeListener);
	}

	/**
	* Returns {@code true} if the Java Virtual Machine (JVM) has Flight Recorder capabilities.
	* <p>
	* This method can quickly check whether Flight Recorder can be
	* initialized, without actually doing the initialization work. The value may
	* change during runtime and it is not safe to cache it.
	*
	* @return {@code true}, if Flight Recorder is available, {@code false}
	* otherwise
	*
	* @see FlightRecorderListener for callback when Flight Recorder is
	* initialized
	*/
	public static boolean isAvailable() {
	if (JVMSupport.isNotAvailable()) {
	return false;
	}
	return JVM.getJVM().isAvailable();
	}

	/**
	* Returns {@code true} if Flight Recorder is initialized.
	*
	* @return {@code true}, if Flight Recorder is initialized,
	* {@code false} otherwise
	*
	* @see FlightRecorderListener for callback when Flight Recorder is
	* initialized
	*/
	public static boolean isInitialized() {
	return initialized;
	}

	PlatformRecorder getInternal() {
	return internal;
	}
	}

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