// Copyright 2009 Google Inc. All Rights Reserved.

package com.google.monitoring.runtime.instrumentation;

import org.objectweb.asm.ClassAdapter;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.commons.LocalVariablesSorter;
import org.objectweb.asm.commons.JSRInlinerAdapter;

/**
 * Instruments bytecodes that allocate heap memory to call a recording hook.
 * A <code>ClassAdapter</code> that processes methods with a
 * <code>AllocationMethodAdapter</code> to instrument heap allocations.
 *
 * @author jeremymanson@google.com (Jeremy Manson)
 * @author fischman@google.com (Ami Fischman) (Original Author)
 */
class AllocationClassAdapter extends ClassAdapter {
  private final String recorderClass;
  private final String recorderMethod;

  public AllocationClassAdapter(ClassVisitor cv, String recorderClass,
      String recorderMethod) {
    super(cv);
    this.recorderClass = recorderClass;
    this.recorderMethod = recorderMethod;
  }

  /**
   * For each method in the class being instrumented, <code>visitMethod</code>
   * is called and the returned MethodVisitor is used to visit the method.
   * Note that a new MethodVisitor is constructed for each method.
   */
  @Override
  public MethodVisitor visitMethod(int access, String base, String desc,
      String signature, String[] exceptions) {
    MethodVisitor mv =
      cv.visitMethod(access, base, desc, signature, exceptions);

    if (mv != null) {
      // We need to compute stackmaps (see
      // AllocationInstrumenter#instrument).  This can't really be
      // done for old bytecode that contains JSR and RET instructions.
      // So, we remove JSRs and RETs.
      JSRInlinerAdapter jsria = new JSRInlinerAdapter(
          mv, access, base, desc, signature, exceptions);
      AllocationMethodAdapter aimv =
        new AllocationMethodAdapter(jsria, recorderClass, recorderMethod);
      LocalVariablesSorter lvs = new LocalVariablesSorter(access, desc, aimv);
      aimv.lvs = lvs;
      mv = lvs;
    }
    return mv;
  }
}
