org.graalvm.nativeimage.c.function.CFunction Maven / Gradle / Ivy
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package org.graalvm.nativeimage.c.function;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.graalvm.nativeimage.c.CContext;
import org.graalvm.nativeimage.c.constant.CEnum;
import org.graalvm.word.WordBase;
/**
* Denotes a {@code native} method that calls directly from Java to C, without following the JNI
* protocol. This means that there are no artificial additional parameters such as the JNI
* environment passed, and no marshaling or processing of arguments (such as creating handles for
* objects) is performed. If the method is non-static, the receiver will be ignored.
*
* Parameter types and return types must not be Java reference types, only
* {@linkplain Class#isPrimitive() primitive} Java types, {@linkplain WordBase word types} and
* {@link CEnum} types are allowed. The representation of passed primitive values matches exactly
* how they are specified in the Java language, for example, {@code int} as a 32-bit signed integer
* or {@code char} as a 16-bit unsigned integer. {@code boolean} is specified as a single byte that
* corresponds to {@code true} if non-zero, and to {@code false} if zero. If a Word value is passed
* that points to a Java object, no guarantees are taken regarding its integrity as a pointer.
*
* The class containing the annotated method must be annotated with {@link CContext}.
*
* @since 19.0
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface CFunction {
/**
* Describes the thread state transition performed when the C function is invoked.
*
* @since 19.0
*/
enum Transition {
/**
* The thread state is transitioned from Java to C, and the Java parts of the stack are made
* walkable. The C code can block and call back to Java.
*
* @since 19.0
*/
TO_NATIVE,
/**
* No prologue and epilogue is emitted. The C code must not block and must not call back to
* Java. Also, long running C code delays safepoints (and therefore garbage collection) of
* other threads until the call returns.
*
* @since 19.0
*/
NO_TRANSITION,
}
/**
* The symbol name to use to link this method. If no value is specified, the name of the method
* (without name mangling or a class name prefix) is used.
*
* @since 19.0
*/
String value() default "";
/**
* The Java-to-C thread transition code used when calling the function.
*
* @since 19.0
*/
Transition transition() default Transition.TO_NATIVE;
}