Module jdk.jfr
Package jdk.jfr

# Annotation Type MetadataDefinition

    @Retention(RUNTIME)
    @Target(TYPE)
    public @interface MetadataDefinition

Meta annotation for defining new types of event metadata.

In the following example, a transaction event is defined with two user-defined annotations, `@Severity` and `@TransactionId`.

    @MetadataDefinition
    @Label("Severity")
    @Description("Value between 0 and 100 that indicates severity. 100 is most severe.")
    @Retention(RetentionPolicy.RUNTIME)
    @Target({ ElementType.TYPE })
     public @interface @Severity {
       int value() default 50;
     }

    @MetadataDefinition
    @Label("Transaction Id")
    @Relational
    @Retention(RetentionPolicy.RUNTIME)
    @Target({ ElementType.FIELD })
     public @interface @Severity {
     }

    @Severity(80)
    @Label("Transaction Blocked");
     class TransactionBlocked extends Event {
      @TransactionId
      @Label("Transaction");
       long transactionId;

      @TransactionId
      @Label("Transaction Blocker");
       long transactionId;
     }

Adding `@MetadataDefinition` to the declaration of `@Severity` and `@TransactionId` ensures the information is saved by Flight Recorder.

Since:
  9