1 /*

     2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package jdk.jfr;

    27 

    28 import static jdk.jfr.internal.LogLevel.DEBUG;

    29 import static jdk.jfr.internal.LogLevel.INFO;

    30 import static jdk.jfr.internal.LogTag.JFR;

    31 

    32 import java.security.AccessControlContext;

    33 import java.security.AccessController;

    34 import java.util.ArrayList;

    35 import java.util.Collections;

    36 import java.util.List;

    37 import java.util.Map;

    38 import java.util.Objects;

    39 

    40 import jdk.jfr.internal.JVM;

    41 import jdk.jfr.internal.JVMSupport;

    42 import jdk.jfr.internal.LogLevel;

    43 import jdk.jfr.internal.Logger;

    44 import jdk.jfr.internal.MetadataRepository;

    45 import jdk.jfr.internal.Options;

    46 import jdk.jfr.internal.PlatformRecorder;

    47 import jdk.jfr.internal.PlatformRecording;

    48 import jdk.jfr.internal.Repository;

    49 import jdk.jfr.internal.RequestEngine;

    50 import jdk.jfr.internal.Utils;

    51 

    52 /**

    53  * Class for accessing, controlling, and managing Flight Recorder.

    54  * <p>

    55  * This class provides the methods necessary for creating, starting, stopping,

    56  * and destroying recordings.

    57  *

    58  * @since 9

    59  */

    60 public final class FlightRecorder {

    61     private static volatile FlightRecorder platformRecorder;

    62     private static volatile boolean initialized;

    63     private final PlatformRecorder internal;

    64 

    65     private FlightRecorder(PlatformRecorder internal) {

    66         this.internal = internal;

    67     }

    68 

    69     /**

    70      * Returns an immutable list of the available recordings.

    71      * <p>

    72      * A recording becomes available when it is created. It becomes unavailable when it

    73      * is in the {@code CLOSED} state, typically after a call to

    74      * {@link Recording#close()}.

    75      *

    76      * @return a list of recordings, not {@code null}

    77      */

    78     public List<Recording> getRecordings() {

    79         List<Recording> recs = new ArrayList<>();

    80         for (PlatformRecording internal : internal.getRecordings()) {

    81             recs.add(internal.getRecording());

    82         }

    83         return Collections.unmodifiableList(recs);

    84     }

    85 

    86     /**

    87      * Creates a snapshot of all available recorded data.

    88      * <p>

    89      * A snapshot is a synthesized recording in a {@code STOPPPED} state. If no data is

    90      * available, a recording with size {@code 0} is returned.

    91      * <p>

    92      * A snapshot provides stable access to data for later operations (for example,

    93      * operations to change the interval or to reduce the data size).

    94      * <p>

    95      * The following example shows how to create a snapshot and write a subset of the data to a file.

    96      *

    97      * <pre>

    98      * <code>

    99      * try (Recording snapshot = FlightRecorder.getFlightRecorder().takeSnapshot()) {

   100      *   if (snapshot.getSize() > 0) {

   101      *     snapshot.setMaxSize(100_000_000);

   102      *     snapshot.setMaxAge(Duration.ofMinutes(5));

   103      *     snapshot.dump(Paths.get("snapshot.jfr"));

   104      *   }

   105      * }

   106      * </code>

   107      * </pre>

   108      *

   109      * The caller must close the recording when access to the data is no longer

   110      * needed.

   111      *

   112      * @return a snapshot of all available recording data, not {@code null}

   113      */

   114     public Recording takeSnapshot() {

   115         return internal.newSnapshot();

   116     }

   117 

   118     /**

   119      * Registers an event class.

   120      * <p>

   121      * If the event class is already registered, then the invocation of this method is

   122      * ignored.

   123      *

   124      * @param eventClass the event class to register, not {@code null}

   125      *

   126      * @throws IllegalArgumentException if class is abstract or not a subclass

   127      *         of {@link Event}

   128      * @throws SecurityException if a security manager exists and the caller

   129      *         does not have {@code FlightRecorderPermission("registerEvent")}

   130      */

   131     public static void register(Class<? extends Event> eventClass) {

   132         Objects.requireNonNull(eventClass);

   133         if (JVMSupport.isNotAvailable()) {

   134             return;

   135         }

   136         Utils.ensureValidEventSubclass(eventClass);

   137         MetadataRepository.getInstance().register(eventClass);

   138     }

   139 

   140     /**

   141      * Unregisters an event class.

   142      * <p>

   143      * If the event class is not registered, then the invocation of this method is

   144      * ignored.

   145      *

   146      * @param eventClass the event class to unregistered, not {@code null}

   147      * @throws IllegalArgumentException if a class is abstract or not a subclass

   148      *         of {@link Event}

   149      *

   150      * @throws SecurityException if a security manager exists and the caller

   151      *         does not have {@code FlightRecorderPermission("registerEvent")}

   152      */

   153     public static void unregister(Class<? extends Event> eventClass) {

   154         Objects.requireNonNull(eventClass);

   155         if (JVMSupport.isNotAvailable()) {

   156             return;

   157         }

   158         Utils.ensureValidEventSubclass(eventClass);

   159         MetadataRepository.getInstance().unregister(eventClass);

   160     }

   161 

   162     /**

   163      * Returns the Flight Recorder for the platform.

   164      *

   165      * @return a Flight Recorder instance, not {@code null}

   166      *

   167      * @throws IllegalStateException if Flight Recorder can't be created (for

   168      *         example, if the Java Virtual Machine (JVM) lacks Flight Recorder

   169      *         support, or if the file repository can't be created or accessed)

   170      *

   171      * @throws SecurityException if a security manager exists and the caller does

   172      *         not have {@code FlightRecorderPermission("accessFlightRecorder")}

   173      */

   174     public static FlightRecorder getFlightRecorder() throws IllegalStateException, SecurityException {

   175         synchronized (PlatformRecorder.class) {

   176             Utils.checkAccessFlightRecorder();

   177             JVMSupport.ensureWithIllegalStateException();

   178             if (platformRecorder == null) {

   179                 try {

   180                     platformRecorder = new FlightRecorder(new PlatformRecorder());

   181                 } catch (IllegalStateException ise) {

   182                     throw ise;

   183                 } catch (Exception e) {

   184                     throw new IllegalStateException("Can't create Flight Recorder. " + e.getMessage(), e);

   185                 }

   186                 // Must be in synchronized block to prevent instance leaking out

   187                 // before initialization is done

   188                 initialized = true;

   189                 Logger.log(JFR, INFO, "Flight Recorder initialized");

   190                 Logger.log(JFR, DEBUG, "maxchunksize: " + Options.getMaxChunkSize()+ " bytes");

   191                 Logger.log(JFR, DEBUG, "memorysize: " + Options.getMemorySize()+ " bytes");

   192                 Logger.log(JFR, DEBUG, "globalbuffersize: " + Options.getGlobalBufferSize()+ " bytes");

   193                 Logger.log(JFR, DEBUG, "globalbuffercount: " + Options.getGlobalBufferCount());

   194                 Logger.log(JFR, DEBUG, "dumppath: " + Options.getDumpPath());

   195                 Logger.log(JFR, DEBUG, "samplethreads: " + Options.getSampleThreads());

   196                 Logger.log(JFR, DEBUG, "stackdepth: " + Options.getStackDepth());

   197                 Logger.log(JFR, DEBUG, "threadbuffersize: " + Options.getThreadBufferSize());

   198                 Logger.log(JFR, LogLevel.INFO, "Created repository " + Repository.getRepository().getRepositoryPath().toString());

   199                 PlatformRecorder.notifyRecorderInitialized(platformRecorder);

   200             }

   201         }

   202         return platformRecorder;

   203     }

   204 

   205     /**

   206      * Adds a hook for a periodic event.

   207      * <p>

   208      * The implementation of the hook should return as soon as possible, to

   209      * avoid blocking other Flight Recorder operations. The hook should emit

   210      * one or more events of the specified type. When a hook is added, the

   211      * interval at which the call is invoked is configurable using the

   212      * {@code "period"} setting.

   213      *

   214      * @param eventClass the class that the hook should run for, not {@code null}

   215      * @param hook the hook, not {@code null}

   216      * @throws IllegalArgumentException if a class is not a subclass of

   217      *         {@link Event}, is abstract, or the hook is already added

   218      * @throws IllegalStateException if the event class has the

   219      *         {@code Registered(false)} annotation and is not registered manually

   220      * @throws SecurityException if a security manager exists and the caller

   221      *         does not have {@code FlightRecorderPermission("registerEvent")}

   222      */

   223     public static void addPeriodicEvent(Class<? extends Event> eventClass, Runnable hook) throws SecurityException {

   224         Objects.requireNonNull(eventClass);

   225         Objects.requireNonNull(hook);

   226         if (JVMSupport.isNotAvailable()) {

   227             return;

   228         }

   229 

   230         Utils.ensureValidEventSubclass(eventClass);

   231         Utils.checkRegisterPermission();

   232         AccessControlContext acc = AccessController.getContext();

   233         RequestEngine.addHook(acc, EventType.getEventType(eventClass).getPlatformEventType(), hook);

   234     }

   235 

   236     /**

   237      * Removes a hook for a periodic event.

   238      *

   239      * @param hook the hook to remove, not {@code null}

   240      * @return {@code true} if hook is removed, {@code false} otherwise

   241      * @throws SecurityException if a security manager exists and the caller

   242      *         does not have {@code FlightRecorderPermission("registerEvent")}

   243      */

   244     public static boolean removePeriodicEvent(Runnable hook) throws SecurityException {

   245         Objects.requireNonNull(hook);

   246         Utils.checkRegisterPermission();

   247         if (JVMSupport.isNotAvailable()) {

   248             return false;

   249         }

   250         return RequestEngine.removeHook(hook);

   251     }

   252 

   253     /**

   254      * Returns an immutable list that contains all currently registered events.

   255      * <p>

   256      * By default, events are registered when they are first used, typically

   257      * when an event object is allocated. To ensure an event is visible early,

   258      * registration can be triggered by invoking the

   259      * {@link FlightRecorder#register(Class)} method.

   260      *

   261      * @return list of events, not {@code null}

   262      */

   263     public List<EventType> getEventTypes() {

   264         return Collections.unmodifiableList(MetadataRepository.getInstance().getRegisteredEventTypes());

   265     }

   266 

   267     /**

   268      * Adds a recorder listener and captures the {@code AccessControlContext} to

   269      * use when invoking the listener.

   270      * <p>

   271      * If Flight Recorder is already initialized when the listener is added, then the method

   272      * {@link FlightRecorderListener#recorderInitialized(FlightRecorder)} method is

   273      * invoked before returning from this method.

   274      *

   275      * @param changeListener the listener to add, not {@code null}

   276      *

   277      * @throws SecurityException if a security manager exists and the caller

   278      *         does not have

   279      *         {@code FlightRecorderPermission("accessFlightRecorder")}

   280      */

   281     public static void addListener(FlightRecorderListener changeListener) {

   282         Objects.requireNonNull(changeListener);

   283         Utils.checkAccessFlightRecorder();

   284         if (JVMSupport.isNotAvailable()) {

   285             return;

   286         }

   287         PlatformRecorder.addListener(changeListener);

   288     }

   289 

   290     /**

   291      * Removes a recorder listener.

   292      * <p>

   293      * If the same listener is added multiple times, only one instance is

   294      * removed.

   295      *

   296      * @param changeListener listener to remove, not {@code null}

   297      *

   298      * @throws SecurityException if a security manager exists and the caller

   299      *         does not have

   300      *         {@code FlightRecorderPermission("accessFlightRecorder")}

   301      *

   302      * @return {@code true}, if the listener could be removed, {@code false}

   303      *         otherwise

   304      */

   305     public static boolean removeListener(FlightRecorderListener changeListener) {

   306         Objects.requireNonNull(changeListener);

   307         Utils.checkAccessFlightRecorder();

   308         if (JVMSupport.isNotAvailable()) {

   309             return false;

   310         }

   311 

   312         return PlatformRecorder.removeListener(changeListener);

   313     }

   314 

   315     /**

   316      * Returns {@code true} if the Java Virtual Machine (JVM) has Flight Recorder capabilities.

   317      * <p>

   318      * This method can quickly check whether Flight Recorder can be

   319      * initialized, without actually doing the initialization work. The value may

   320      * change during runtime and it is not safe to cache it.

   321      *

   322      * @return {@code true}, if Flight Recorder is available, {@code false}

   323      *         otherwise

   324      *

   325      * @see FlightRecorderListener for callback when Flight Recorder is

   326      *      initialized

   327      */

   328     public static boolean isAvailable() {

   329         if (JVMSupport.isNotAvailable()) {

   330             return false;

   331         }

   332         return JVM.getJVM().isAvailable();

   333     }

   334 

   335     /**

   336      * Returns {@code true} if Flight Recorder is initialized.

   337      *

   338      * @return {@code true}, if Flight Recorder is initialized,

   339      *         {@code false} otherwise

   340      *

   341      * @see FlightRecorderListener for callback when Flight Recorder is

   342      *      initialized

   343      */

   344     public static boolean isInitialized() {

   345         return initialized;

   346     }

   347 

   348     // package private

   349     PlatformRecording newInternalRecording(Map<String, String> settings) {

   350         return internal.newRecording(settings);

   351     }

   352 

   353 }