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package org.jruby.runtime.ivars;

import org.jruby.RubyBasicObject;
import org.jruby.RubyClass;
import org.jruby.util.ArraySupport;

import java.lang.invoke.VarHandle;

/**
 * A variable accessor that uses a stamped volatile int and Unsafe methods to
 * ensure thread-friendly table updating.
 */
public class StampedVariableAccessor extends VariableAccessor {
    /**
     * Construct a new StampedVariableAccessor for the given "real" class,
     * variable name, variable index, and class ID.
     * 
     * @param realClass the "real" class
     * @param name the variable's name
     * @param index the variable's index
     * @param classId the class's ID
     */
    public StampedVariableAccessor(RubyClass realClass, String name, int index, int classId) {
        super(realClass, name, index, classId);
    }

    public StampedVariableAccessor cloneFor(RubyClass newRealClass) {
        return new StampedVariableAccessor(newRealClass, name, index, classId);
    }

    /**
     * Set this variable into the given object using Unsafe to ensure
     * safe updating of the variable table.
     * 
     * @param object the object into which to set this variable
     * @param value the variable's value
     */
    public void set(Object object, Object value) {
        ((RubyBasicObject)object).ensureInstanceVariablesSettable();
        AtomicVariableTable.setVariableAtomic((RubyBasicObject)object, realClass, true, index, value);
    }
    
    /**
     * Set the given variable index into the specified object. The "real" class
     * and index are pass in to provide functional access. This version checks
     * if self has been frozen before proceeding to set the variable.
     * 
     * @param self the object into which to set the variable
     * @param realClass the "real" class for the object
     * @param index the index of the variable
     * @param value the variable's value
     */
    public static void setVariableChecked(RubyBasicObject self, RubyClass realClass, int index, Object value) {
        self.ensureInstanceVariablesSettable();
        AtomicVariableTable.setVariableAtomic(self, realClass, true, index, value);
    }
}
