content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.cassandra.simulator.asm;
  
  import org.objectweb.asm.MethodVisitor;
  import org.objectweb.asm.Opcodes;
  import org.objectweb.asm.tree.InsnNode;
  import org.objectweb.asm.tree.LabelNode;
  import org.objectweb.asm.tree.LdcInsnNode;
  import org.objectweb.asm.tree.MethodInsnNode;
  import org.objectweb.asm.tree.MethodNode;
  
  /**
   * Generate a new static method in the class with a randomly generated constant chance of triggering the nemesis.
   * Generate also the invocation of this method at the relevant point(s).
   *
   * A static method with no parameters or return values is created, so that only the method invocation instruction is
   * needed in the original method, simplifying the transformation.
   */
  class NemesisGenerator extends MethodNode
  {
      private final ChanceSupplier chanceSupplier;
  
      private final String className;
      private String baseName;
      private int methodsCounter = 0; // avoid nemesis method name clashes when weaving two or more methods with same name
      private int withinMethodCounter = 0;
      private final LdcInsnNode ldc = new LdcInsnNode(null);
  
      NemesisGenerator(int api, String className, ChanceSupplier chanceSupplier)
      {
          super(api, Opcodes.ACC_STATIC | Opcodes.ACC_SYNTHETIC | Opcodes.ACC_PRIVATE, null, "()V", "", null);
          this.chanceSupplier = chanceSupplier;
          this.className = className;
          this.maxLocals = 0;
          this.maxStack = 1;
          instructions.add(new LabelNode());
          instructions.add(ldc);
          instructions.add(new MethodInsnNode(Opcodes.INVOKESTATIC, "org/apache/cassandra/simulator/systems/InterceptorOfSystemMethods$Global", "nemesis", "(F)V", false));
          instructions.add(new LabelNode());
          instructions.add(new InsnNode(Opcodes.RETURN));
      }
  
      void newMethod(String name)
      {
          this.baseName = name.replaceAll("[<>]", "") + '$' + (methodsCounter++) + '$';
          this.withinMethodCounter = 0;
      }
  
      void generateAndCall(TransformationKind kind, ClassTransformer writeDefinitionTo, MethodVisitor writeInvocationTo)
      {
          this.name = baseName + '$' + (withinMethodCounter++) + "$nemesis";
          ldc.cst = chanceSupplier.get();
          writeDefinitionTo.writeSyntheticMethod(kind, this);
          writeInvocationTo.visitMethodInsn(Opcodes.INVOKESTATIC, className, name, "()V", false);
      }
  }
  