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package com.oracle.svm.core.stack;

import org.graalvm.nativeimage.c.function.CodePointer;
import org.graalvm.word.Pointer;

import com.oracle.svm.core.annotate.Uninterruptible;
import com.oracle.svm.core.code.CodeInfo;
import com.oracle.svm.core.code.CodeInfoAccess;
import com.oracle.svm.core.deopt.DeoptimizedFrame;


Given access to a thread stack frame, perform some computation on it. This is a more generic version of StackFrameVisitor that allows an arbitrary object to be passed through. 
/**
 * Given access to a thread stack frame, perform some computation on it. This is a more generic
 * version of {@link StackFrameVisitor} that allows an arbitrary object to be passed through.
 */
public abstract class ParameterizedStackFrameVisitor<T> {

    
Called for each frame that is visited. Note that unless this method is annotated with Uninterruptible or executing within a safepoint, the frame on the stack could be deoptimized at any safepoint check. Nevertheless, the passed codeInfo remains valid for accessing information about the code at the (possibly outdated) instruction pointer (this is ensured by the caller). 
Params:
  • sp – The stack pointer of the frame being visited.
  • ip – The instruction pointer of the frame being visited.
  • codeInfo – Information on the code at the IP, for use with CodeInfoAccess.
  • deoptimizedFrame – The information about a deoptimized frame, or null if the frame is not deoptimized.
  • data – An arbitrary data value passed through the stack walker.
Returns:true if visiting should continue, false otherwise.
/**
     * Called for each frame that is visited. Note that unless this method is annotated with
     * {@link Uninterruptible} or executing within a safepoint, the frame on the stack could be
     * deoptimized at any safepoint check. Nevertheless, the passed codeInfo remains valid for
     * accessing information about the code at the (possibly outdated) instruction pointer (this is
     * ensured by the caller).
     *
     * @param sp The stack pointer of the frame being visited.
     * @param ip The instruction pointer of the frame being visited.
     * @param codeInfo Information on the code at the IP, for use with {@link CodeInfoAccess}.
     * @param deoptimizedFrame The information about a deoptimized frame, or {@code null} if the
     *            frame is not deoptimized.
     * @param data An arbitrary data value passed through the stack walker.
     * @return true if visiting should continue, false otherwise.
     */
    protected abstract boolean visitFrame(Pointer sp, CodePointer ip, CodeInfo codeInfo, DeoptimizedFrame deoptimizedFrame, T data);

    
Called when no frame metadata can be found for a frame. That usually means that the VM is in an inconsistent state. The default implementation therefore aborts VM execution with a fatal error. Stack walking for diagnostic purposes can override this method to just report a message. 
Params:
  • sp – The stack pointer of the frame being visited.
  • ip – The instruction pointer of the frame being visited.
  • deoptimizedFrame – The information about a deoptimized frame, or null if the frame is not deoptimized.
  • data – An arbitrary data value passed through the stack walker.
Returns:The value returned to the caller of stack walking. Note that walking of the thread is
        always aborted, regardless of the return value.
/**
     * Called when no {@link CodeInfo frame metadata} can be found for a frame. That usually means
     * that the VM is in an inconsistent state. The default implementation therefore aborts VM
     * execution with a fatal error. Stack walking for diagnostic purposes can override this method
     * to just report a message.
     *
     * @param sp The stack pointer of the frame being visited.
     * @param ip The instruction pointer of the frame being visited.
     * @param deoptimizedFrame The information about a deoptimized frame, or {@code null} if the
     *            frame is not deoptimized.
     * @param data An arbitrary data value passed through the stack walker.
     * @return The value returned to the caller of stack walking. Note that walking of the thread is
     *         always aborted, regardless of the return value.
     */
    protected abstract boolean unknownFrame(Pointer sp, CodePointer ip, DeoptimizedFrame deoptimizedFrame, T data);
}