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package jdk.jfr;

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Path;
import java.time.Duration;
import java.time.Instant;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

import jdk.jfr.internal.PlatformRecorder;
import jdk.jfr.internal.PlatformRecording;
import jdk.jfr.internal.Type;
import jdk.jfr.internal.Utils;
import jdk.jfr.internal.WriteableUserPath;

Provides means to configure, start, stop and dump recording data to disk.

The following example shows how configure, start, stop and dump recording data to disk.


  Configuration c = Configuration.getConfiguration("default");
  Recording r = new Recording(c);
  r.start();
  System.gc();
  Thread.sleep(5000);
  r.stop();
  r.copyTo(Files.createTempFile("my-recording", ".jfr"));

Since:9
/** * Provides means to configure, start, stop and dump recording data to disk. * <p> * The following example shows how configure, start, stop and dump recording data to disk. * * <pre> * <code> * Configuration c = Configuration.getConfiguration("default"); * Recording r = new Recording(c); * r.start(); * System.gc(); * Thread.sleep(5000); * r.stop(); * r.copyTo(Files.createTempFile("my-recording", ".jfr")); * </code> * </pre> * * @since 9 */
public final class Recording implements Closeable { private static class RecordingSettings extends EventSettings { private final Recording recording; private final String identifier; RecordingSettings(Recording r, String identifier) { this.recording = r; this.identifier = identifier; } RecordingSettings(Recording r, Class<? extends Event> eventClass) { Utils.ensureValidEventSubclass(eventClass); this.recording = r; this.identifier = String.valueOf(Type.getTypeId(eventClass)); } @Override public EventSettings with(String name, String value) { Objects.requireNonNull(value); recording.setSetting(identifier + "#" + name, value); return this; } @Override public Map<String, String> toMap() { return recording.getSettings(); } } private final PlatformRecording internal; public Recording(Map<String, String> settings) { PlatformRecorder r = FlightRecorder.getFlightRecorder().getInternal(); synchronized (r) { this.internal = r.newRecording(settings); this.internal.setRecording(this); if (internal.getRecording() != this) { throw new InternalError("Internal recording not properly setup"); } } }
Creates a recording without any settings.

A newly created recording is in the RecordingState.NEW state. To start the recording, invoke the start() method.

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)
  • SecurityException – If a security manager is used and FlightRecorderPermission "accessFlightRecorder" is not set.
/** * Creates a recording without any settings. * <p> * A newly created recording is in the {@link RecordingState#NEW} state. To start * the recording, invoke the {@link Recording#start()} method. * * @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 is used and * FlightRecorderPermission "accessFlightRecorder" is not set. */
public Recording() { this(new HashMap<String, String>()); }
Creates a recording with settings from a configuration.

The following example shows how create a recording that uses a predefined configuration.


Recording r = new Recording(Configuration.getConfiguration("default"));

The newly created recording is in the RecordingState.NEW state. To start the recording, invoke the start() method.
Params:
  • configuration – configuration that contains the settings to be use, not 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)
  • SecurityException – if a security manager is used and FlightRecorderPermission "accessFlightRecorder" is not set.
See Also:
/** * Creates a recording with settings from a configuration. * <p> * The following example shows how create a recording that uses a predefined configuration. * * <pre> * <code> * Recording r = new Recording(Configuration.getConfiguration("default")); * </code> * </pre> * * The newly created recording is in the {@link RecordingState#NEW} state. To * start the recording, invoke the {@link Recording#start()} method. * * @param configuration configuration that contains the settings to be use, 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 is used and * FlightRecorderPermission "accessFlightRecorder" is not set. * * @see Configuration */
public Recording(Configuration configuration) { this(configuration.getSettings()); }
Starts this recording.

It's recommended that the recording options and event settings are configured before calling this method. The benefits of doing so are a more consistent state when analyzing the recorded data, and improved performance because the configuration can be applied atomically.

After a successful invocation of this method, this recording is in the RUNNING state.

Throws:
/** * Starts this recording. * <p> * It's recommended that the recording options and event settings are configured * before calling this method. The benefits of doing so are a more consistent * state when analyzing the recorded data, and improved performance because the * configuration can be applied atomically. * <p> * After a successful invocation of this method, this recording is in the * {@code RUNNING} state. * * @throws IllegalStateException if recording is already started or is in the * {@code CLOSED} state */
public void start() { internal.start(); }
Starts this recording after a delay.

After a successful invocation of this method, this recording is in the DELAYED state.

Params:
  • delay – the time to wait before starting this recording, not null
Throws:
/** * Starts this recording after a delay. * <p> * After a successful invocation of this method, this recording is in the * {@code DELAYED} state. * * @param delay the time to wait before starting this recording, not * {@code null} * @throws IllegalStateException if the recording is not it the {@code NEW} state */
public void scheduleStart(Duration delay) { Objects.requireNonNull(delay); internal.scheduleStart(delay); }
Stops this recording.

When a recording is stopped it can't be restarted. If this recording has a destination, data is written to that destination and the recording is closed. After a recording is closed, the data is no longer available.

After a successful invocation of this method, this recording will be in the STOPPED state.

Throws:
  • IllegalStateException – if the recording is not started or is already stopped
  • SecurityException – if a security manager exists and the caller doesn't have FilePermission to write to the destination path
See Also:
Returns:true if recording is stopped, false otherwise
/** * Stops this recording. * <p> * When a recording is stopped it can't be restarted. If this * recording has a destination, data is written to that destination and * the recording is closed. After a recording is closed, the data is no longer * available. * <p> * After a successful invocation of this method, this recording will be * in the {@code STOPPED} state. * * @return {@code true} if recording is stopped, {@code false} otherwise * * @throws IllegalStateException if the recording is not started or is already stopped * * @throws SecurityException if a security manager exists and the caller * doesn't have {@code FilePermission} to write to the destination * path * * @see #setDestination(Path) * */
public boolean stop() { return internal.stop("Stopped by user"); }
Returns settings used by this recording.

Modifying the returned Map will not change the settings for this recording.

If no settings are set for this recording, an empty Map is returned.

Returns:recording settings, not null
/** * Returns settings used by this recording. * <p> * Modifying the returned {@code Map} will not change the settings for this recording. * <p> * If no settings are set for this recording, an empty {@code Map} is * returned. * * @return recording settings, not {@code null} */
public Map<String, String> getSettings() { return new HashMap<>(internal.getSettings()); }
Returns the current size of this recording in the disk repository, measured in bytes.

The size is updated when recording buffers are flushed. If the recording is not written to the disk repository the returned size is always 0.

Returns:amount of recorded data, measured in bytes, or 0 if the recording is not written to the disk repository
/** * Returns the current size of this recording in the disk repository, * measured in bytes. * <p> * The size is updated when recording buffers are flushed. If the recording is * not written to the disk repository the returned size is always {@code 0}. * * @return amount of recorded data, measured in bytes, or {@code 0} if the * recording is not written to the disk repository */
public long getSize() { return internal.getSize(); }
Returns the time when this recording was stopped.
Returns:the time, or null if this recording is not stopped
/** * Returns the time when this recording was stopped. * * @return the time, or {@code null} if this recording is not stopped */
public Instant getStopTime() { return internal.getStopTime(); }
Returns the time when this recording was started.
Returns:the the time, or null if this recording is not started
/** * Returns the time when this recording was started. * * @return the the time, or {@code null} if this recording is not started */
public Instant getStartTime() { return internal.getStartTime(); }
Returns the maximum size, measured in bytes, at which data is no longer kept in the disk repository.
Returns:maximum size in bytes, or 0 if no maximum size is set
/** * Returns the maximum size, measured in bytes, at which data is no longer kept in the disk repository. * * @return maximum size in bytes, or {@code 0} if no maximum size is set */
public long getMaxSize() { return internal.getMaxSize(); }
Returns the length of time that the data is kept in the disk repository before it is removed.
Returns:maximum length of time, or null if no maximum length of time has been set
/** * Returns the length of time that the data is kept in the disk repository * before it is removed. * * @return maximum length of time, or {@code null} if no maximum length of time * has been set */
public Duration getMaxAge() { return internal.getMaxAge(); }
Returns the name of this recording.

By default, the name is the same as the recording ID.

Returns:the recording name, not null
/** * Returns the name of this recording. * <p> * By default, the name is the same as the recording ID. * * @return the recording name, not {@code null} */
public String getName() { return internal.getName(); }
Replaces all settings for this recording.

The following example shows how to set event settings for a recording.

 Map<String, String> settings = new HashMap<>(); settings.putAll(EventSettings.enabled("jdk.CPUSample").withPeriod(Duration.ofSeconds(2)).toMap()); settings.putAll(EventSettings.enabled(MyEvent.class).withThreshold(Duration.ofSeconds(2)).withoutStackTrace().toMap()); settings.put("jdk.ExecutionSample#period", "10 ms"); recording.setSettings(settings); 
The following example shows how to merge settings.
 
    Map<String, String> settings = recording.getSettings();
    settings.putAll(additionalSettings);
    recording.setSettings(settings);
 
Params:
  • settings – the settings to set, not null
/** * Replaces all settings for this recording. * <p> * The following example shows how to set event settings for a recording. * * <pre> * <code> * Map{@literal <}String, String{@literal >} settings = new HashMap{@literal <}{@literal >}(); * settings.putAll(EventSettings.enabled("jdk.CPUSample").withPeriod(Duration.ofSeconds(2)).toMap()); * settings.putAll(EventSettings.enabled(MyEvent.class).withThreshold(Duration.ofSeconds(2)).withoutStackTrace().toMap()); * settings.put("jdk.ExecutionSample#period", "10 ms"); * recording.setSettings(settings); * </code> * </pre> * * The following example shows how to merge settings. * * <pre> * {@code * Map<String, String> settings = recording.getSettings(); * settings.putAll(additionalSettings); * recording.setSettings(settings); * } * </pre> * * @param settings the settings to set, not {@code null} */
public void setSettings(Map<String, String> settings) { Objects.requireNonNull(settings); Map<String, String> sanitized = Utils.sanitizeNullFreeStringMap(settings); internal.setSettings(sanitized); }
Returns the recording state that this recording is currently in.
See Also:
Returns:the recording state, not null
/** * Returns the recording state that this recording is currently in. * * @return the recording state, not {@code null} * * @see RecordingState */
public RecordingState getState() { return internal.getState(); }
Releases all data that is associated with this recording.

After a successful invocation of this method, this recording is in the CLOSED state.

/** * Releases all data that is associated with this recording. * <p> * After a successful invocation of this method, this recording is in the * {@code CLOSED} state. */
@Override public void close() { internal.close(); }
Returns a clone of this recording, with a new recording ID and name. Clones are useful for dumping data without stopping the recording. After a clone is created, the amount of data to copy is constrained with the setMaxAge(Duration) method and the setMaxSize(long)method.
Params:
  • stop – true if the newly created copy should be stopped immediately, false otherwise
Returns:the recording copy, not null
/** * Returns a clone of this recording, with a new recording ID and name. * * Clones are useful for dumping data without stopping the recording. After * a clone is created, the amount of data to copy is constrained * with the {@link #setMaxAge(Duration)} method and the {@link #setMaxSize(long)}method. * * @param stop {@code true} if the newly created copy should be stopped * immediately, {@code false} otherwise * @return the recording copy, not {@code null} */
public Recording copy(boolean stop) { return internal.newCopy(stop); }
Writes recording data to a file.

Recording must be started, but not necessarily stopped.

Params:
  • destination – the location where recording data is written, not null
Throws:
  • IOException – if the recording can't be copied to the specified location
  • SecurityException – if a security manager exists and the caller doesn't have FilePermission to write to the destination path
/** * Writes recording data to a file. * <p> * Recording must be started, but not necessarily stopped. * * @param destination the location where recording data is written, not * {@code null} * * @throws IOException if the recording can't be copied to the specified * location * * @throws SecurityException if a security manager exists and the caller doesn't * have {@code FilePermission} to write to the destination path */
public void dump(Path destination) throws IOException { Objects.requireNonNull(destination); internal.dump(new WriteableUserPath(destination)); }
Returns true if this recording uses the disk repository, false otherwise.

If no value is set, true is returned.

Returns:true if the recording uses the disk repository, false otherwise
/** * Returns {@code true} if this recording uses the disk repository, {@code false} otherwise. * <p> * If no value is set, {@code true} is returned. * * @return {@code true} if the recording uses the disk repository, {@code false} * otherwise */
public boolean isToDisk() { return internal.isToDisk(); }
Determines how much data is kept in the disk repository.

To control the amount of recording data that is stored on disk, the maximum amount of data to retain can be specified. When the maximum limit is exceeded, the Java Virtual Machine (JVM) removes the oldest chunk to make room for a more recent chunk.

If neither maximum limit or the maximum age is set, the size of the recording may grow indefinitely.

Params:
  • maxSize – the amount of data to retain, 0 if infinite
Throws:
/** * Determines how much data is kept in the disk repository. * <p> * To control the amount of recording data that is stored on disk, the maximum * amount of data to retain can be specified. When the maximum limit is * exceeded, the Java Virtual Machine (JVM) removes the oldest chunk to make * room for a more recent chunk. * <p> * If neither maximum limit or the maximum age is set, the size of the * recording may grow indefinitely. * * @param maxSize the amount of data to retain, {@code 0} if infinite * * @throws IllegalArgumentException if <code>maxSize</code> is negative * * @throws IllegalStateException if the recording is in {@code CLOSED} state */
public void setMaxSize(long maxSize) { if (maxSize < 0) { throw new IllegalArgumentException("Max size of recording can't be negative"); } internal.setMaxSize(maxSize); }
Determines how far back data is kept in the disk repository.

To control the amount of recording data stored on disk, the maximum length of time to retain the data can be specified. Data stored on disk that is older than the specified length of time is removed by the Java Virtual Machine (JVM).

If neither maximum limit or the maximum age is set, the size of the recording may grow indefinitely.

Params:
  • maxAge – the length of time that data is kept, or null if infinite
Throws:
/** * Determines how far back data is kept in the disk repository. * <p> * To control the amount of recording data stored on disk, the maximum length of * time to retain the data can be specified. Data stored on disk that is older * than the specified length of time is removed by the Java Virtual Machine (JVM). * <p> * If neither maximum limit or the maximum age is set, the size of the * recording may grow indefinitely. * * @param maxAge the length of time that data is kept, or {@code null} if infinite * * @throws IllegalArgumentException if <code>maxAge</code> is negative * * @throws IllegalStateException if the recording is in the {@code CLOSED} state */
public void setMaxAge(Duration maxAge) { if (maxAge != null && maxAge.isNegative()) { throw new IllegalArgumentException("Max age of recording can't be negative"); } internal.setMaxAge(maxAge); }
Sets a location where data is written on recording stop, or null if data is not to be dumped.

If a destination is set, this recording is automatically closed after data is successfully copied to the destination path.

If a destination is not set, Flight Recorder retains the recording data until this recording is closed. Use the dump(Path) method to manually write data to a file.

Params:
  • destination – the destination path, or null if recording should not be dumped at stop
Throws:
  • IllegalStateException – if recording is in the STOPPED or CLOSED state.
  • SecurityException – if a security manager exists and the caller doesn't have FilePermission to read, write, and delete the destination file
  • IOException – if the path is not writable
/** * Sets a location where data is written on recording stop, or * {@code null} if data is not to be dumped. * <p> * If a destination is set, this recording is automatically closed * after data is successfully copied to the destination path. * <p> * If a destination is <em>not</em> set, Flight Recorder retains the * recording data until this recording is closed. Use the {@link #dump(Path)} method to * manually write data to a file. * * @param destination the destination path, or {@code null} if recording should * not be dumped at stop * * @throws IllegalStateException if recording is in the {@code STOPPED} or * {@code CLOSED} state. * * @throws SecurityException if a security manager exists and the caller * doesn't have {@code FilePermission} to read, write, and delete the * {@code destination} file * * @throws IOException if the path is not writable */
public void setDestination(Path destination) throws IOException { internal.setDestination(destination != null ? new WriteableUserPath(destination) : null); }
Returns the destination file, where recording data is written when the recording stops, or null if no destination is set.
Returns:the destination file, or null if not set.
/** * Returns the destination file, where recording data is written when the * recording stops, or {@code null} if no destination is set. * * @return the destination file, or {@code null} if not set. */
public Path getDestination() { WriteableUserPath usp = internal.getDestination(); if (usp == null) { return null; } else { return usp.getPotentiallyMaliciousOriginal(); } }
Returns a unique ID for this recording.
Returns:the recording ID
/** * Returns a unique ID for this recording. * * @return the recording ID */
public long getId() { return internal.getId(); }
Sets a human-readable name (for example, "My Recording").
Params:
  • name – the recording name, not null
Throws:
/** * Sets a human-readable name (for example, {@code "My Recording"}). * * @param name the recording name, not {@code null} * * @throws IllegalStateException if the recording is in {@code CLOSED} state */
public void setName(String name) { Objects.requireNonNull(name); internal.setName(name); }
Sets whether this recording is dumped to disk when the JVM exits.
Params:
  • dumpOnExit – if this recording should be dumped when the JVM exits
/** * Sets whether this recording is dumped to disk when the JVM exits. * * @param dumpOnExit if this recording should be dumped when the JVM exits */
public void setDumpOnExit(boolean dumpOnExit) { internal.setDumpOnExit(dumpOnExit); }
Returns whether this recording is dumped to disk when the JVM exits.

If dump on exit is not set, false is returned.

Returns:true if the recording is dumped on exit, false otherwise.
/** * Returns whether this recording is dumped to disk when the JVM exits. * <p> * If dump on exit is not set, {@code false} is returned. * * @return {@code true} if the recording is dumped on exit, {@code false} * otherwise. */
public boolean getDumpOnExit() { return internal.getDumpOnExit(); }
Determines whether this recording is continuously flushed to the disk repository or data is constrained to what is available in memory buffers.
Params:
  • disk – true if this recording is written to disk, false if in-memory
/** * Determines whether this recording is continuously flushed to the disk * repository or data is constrained to what is available in memory buffers. * * @param disk {@code true} if this recording is written to disk, * {@code false} if in-memory * */
public void setToDisk(boolean disk) { internal.setToDisk(disk); }
Creates a data stream for a specified interval.

The stream may contain some data outside the specified range.

Params:
  • the – start start time for the stream, or null to get data from start time of the recording
  • the – end end time for the stream, or null to get data until the present time.
Throws:
Returns:an input stream, or null if no data is available in the interval.
/** * Creates a data stream for a specified interval. * <p> * The stream may contain some data outside the specified range. * * @param the start start time for the stream, or {@code null} to get data from * start time of the recording * * @param the end end time for the stream, or {@code null} to get data until the * present time. * * @return an input stream, or {@code null} if no data is available in the * interval. * * @throws IllegalArgumentException if {@code end} happens before * {@code start} * * @throws IOException if a stream can't be opened */
public InputStream getStream(Instant start, Instant end) throws IOException { if (start != null && end != null && end.isBefore(start)) { throw new IllegalArgumentException("End time of requested stream must not be before start time"); } return internal.open(start, end); }
Returns the specified duration for this recording, or null if no duration is set.

The duration can be set only when the recording is in the RecordingState.NEW state.

Returns:the desired duration of the recording, or null if no duration has been set.
/** * Returns the specified duration for this recording, or {@code null} if no * duration is set. * <p> * The duration can be set only when the recording is in the * {@link RecordingState#NEW} state. * * @return the desired duration of the recording, or {@code null} if no duration * has been set. */
public Duration getDuration() { return internal.getDuration(); }
Sets a duration for how long a recording runs before it stops.

By default, a recording has no duration (null).

Params:
  • duration – the duration, or null if no duration is set
Throws:
/** * Sets a duration for how long a recording runs before it stops. * <p> * By default, a recording has no duration ({@code null}). * * @param duration the duration, or {@code null} if no duration is set * * @throws IllegalStateException if recording is in the {@code STOPPED} or {@code CLOSED} state */
public void setDuration(Duration duration) { internal.setDuration(duration); }
Enables the event with the specified name.

If multiple events have the same name (for example, the same class is loaded in different class loaders), then all events that match the name are enabled. To enable a specific class, use the enable(Class<? extends Event>) method or a String representation of the event type ID.

Params:
  • name – the settings for the event, not null
See Also:
Returns:an event setting for further configuration, not null
/** * Enables the event with the specified name. * <p> * If multiple events have the same name (for example, the same class is loaded * in different class loaders), then all events that match the name are enabled. To * enable a specific class, use the {@link #enable(Class)} method or a {@code String} * representation of the event type ID. * * @param name the settings for the event, not {@code null} * * @return an event setting for further configuration, not {@code null} * * @see EventType */
public EventSettings enable(String name) { Objects.requireNonNull(name); RecordingSettings rs = new RecordingSettings(this, name); rs.with("enabled", "true"); return rs; }
Disables event with the specified name.

If multiple events with same name (for example, the same class is loaded in different class loaders), then all events that match the name is disabled. To disable a specific class, use the disable(Class<? extends Event>) method or a String representation of the event type ID.

Params:
  • name – the settings for the event, not null
Returns:an event setting for further configuration, not null
/** * Disables event with the specified name. * <p> * If multiple events with same name (for example, the same class is loaded * in different class loaders), then all events that match the * name is disabled. To disable a specific class, use the * {@link #disable(Class)} method or a {@code String} representation of the event * type ID. * * @param name the settings for the event, not {@code null} * * @return an event setting for further configuration, not {@code null} * */
public EventSettings disable(String name) { Objects.requireNonNull(name); RecordingSettings rs = new RecordingSettings(this, name); rs.with("enabled", "false"); return rs; }
Enables event.
Params:
  • eventClass – the event to enable, not null
Throws:
Returns:an event setting for further configuration, not null
/** * Enables event. * * @param eventClass the event to enable, not {@code null} * * @throws IllegalArgumentException if {@code eventClass} is an abstract * class or not a subclass of {@link Event} * * @return an event setting for further configuration, not {@code null} */
public EventSettings enable(Class<? extends Event> eventClass) { Objects.requireNonNull(eventClass); RecordingSettings rs = new RecordingSettings(this, eventClass); rs.with("enabled", "true"); return rs; }
Disables event.
Params:
  • eventClass – the event to enable, not null
Throws:
Returns:an event setting for further configuration, not null
/** * Disables event. * * @param eventClass the event to enable, not {@code null} * * @throws IllegalArgumentException if {@code eventClass} is an abstract * class or not a subclass of {@link Event} * * @return an event setting for further configuration, not {@code null} * */
public EventSettings disable(Class<? extends Event> eventClass) { Objects.requireNonNull(eventClass); RecordingSettings rs = new RecordingSettings(this, eventClass); rs.with("enabled", "false"); return rs; } // package private PlatformRecording getInternal() { return internal; } private void setSetting(String id, String value) { Objects.requireNonNull(id); Objects.requireNonNull(value); internal.setSetting(id, value); } }