1 /*
   2  * Copyright (c) 2016, 2019, 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
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   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
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  23  * questions.
  24  */
  25 
  26 package jdk.jfr;
  27 
  28 
  29 /**
  30  * Callback interface to monitor Flight Recorder's life cycle.
  31  *
  32  * @since 9
  33  */
  34 public interface FlightRecorderListener {
  35 
  36     /**
  37      * Receives notification when Flight Recorder is initialized.
  38      * <p>
  39      * This method is also be invoked when a listener is added to an already
  40      * initialized Flight Recorder.
  41      * <p>
  42      * This method allows clients to implement their own initialization mechanism
  43      * that is executed before a {@code FlightRecorder} instance is returned by
  44      * {@code FlightRecorder#getFlightRecorder()}.
  45      *
  46      * @implNote This method should return as soon as possible, to avoid blocking
  47      *           initialization of Flight Recorder. To avoid deadlocks or unexpected
  48      *           behavior, this method should not call
  49      *           {@link FlightRecorder#getFlightRecorder()} or start new recordings.
  50      *
  51      * @implSpec The default implementation of this method is empty.
  52      *
  53      * @param recorder Flight Recorder instance, not {@code null}
  54      *
  55      * @see FlightRecorder#addListener(FlightRecorderListener)
  56      */
  57     default void recorderInitialized(FlightRecorder recorder) {
  58     }
  59 
  60     /**
  61      * Receives notification when the state of a recording changes.
  62      * <p>
  63      * Callback is invoked when a recording reaches the {@code RUNNING},
  64      * {@code STOPPED} and {@code CLOSED} state.
  65      *
  66      * @implNote The implementation of this method should return as soon as possible
  67      *           to avoid blocking normal operation of Flight Recorder.
  68      *
  69      * @implSpec The default implementation of this method is empty.
  70      *
  71      * @param recording the recording where the state change occurred, not
  72      *        {@code null}
  73      *
  74      * @see FlightRecorder#addListener(FlightRecorderListener)
  75      * @see RecordingState
  76      *
  77      */
  78     default void recordingStateChanged(Recording recording) {
  79     }
  80 }