Module jdk.jfr

Package jdk.jfr

Annotation Interface 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 TransactionId {
}

@Severity(80)
@Label("Transaction Blocked")
class TransactionBlocked extends Event {
    @TransactionId
    @Label("Transaction")
    long transactionId1;

    @TransactionId
    @Label("Transaction Blocker")
    long transactionId2;
}

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

Since:

9