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// Called when a breakpoint is hit.
void JNICALL BreakpointCallback(jvmtiEnv *jvmti_env, JNIEnv *jni, jthread thread, jmethodID method, jlocation location) {
  // Get hold of the parameter. In this example, we just get the first parameter.
  // Which parameter is first depends on whether this is a static or instance method. 
  // For instance methods, the first parameter is a synthetic parameter representing
  // the current instance of the class. So here, we get the first "real" parameter.
  int parameterPos = 1;
  
  jobject the_parameter;
  assert(JVMTI_ERROR_NONE == (*jvmti_env)->GetLocalObject(jvmti_env, thread, 0, parameterPos, &the_parameter));

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void JNICALL ClassPrepareCallback(jvmtiEnv *jvmti_env, JNIEnv *jni, jthread thread, jclass klass) {
  // Avoid re-entrancy, and return early if we already attached.
  if (in_prepare || attached) {
    return;
  }
  
  in_prepare = true;

  jclass clazz = (*jni)->FindClass(jni, classConfig->name);
  // In case we don't find the class, don't throw an exception

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JNIEXPORT jint JNICALL 
Agent_OnLoad(JavaVM *vm, char *options, void *reserved) {
  char *option = strtok(options, ",");
  // ...
  // Load the config file using options from `option`. Also parse out an option for
  // a log file to write to.
  // .. 
  
  fprintf(stderr, "mlogagent: Loaded agent\n");

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someMethod: /foo
  trace: <- someMethod <- run <- main
someMethod: /bar
  trace: <- someMethod <- run <- main

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# This is the class I care about
- frodo/Test
    # And this is a method I want to log with its super ugly JVM signature
    - someMethod(Lfrodo/Test$RealFile;)Ljava/lang/String;
        # Please show me an abbreviated stack trace for each call
        - showTrace: true
        # And use the getPath() method to convert the parameter to a String
        - displayMethod: getPath

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package frodo;

public class Example {
  public static void main(String[] args) {
    new Test().run();
  }

  public void run() {
    System.out.println(someMethod(new RealFile("/foo")));
    System.out.println(someMethod(new RealFile("/bar")));

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public void doSomethingInteresting(Thingy t) {
  if (Config.shoudLogInterestingThings()) {
    LOG.info("doSomethingInteresting(%s)", t);
  }

  // Actually do something interesting
}

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type RecordIndex = i32;
type ContentIndex = i32;
type Bytes = Vec<u8>;

/// IJ has the notion of "enumerations" which are basically fast bimaps between a value of
/// arbitrary type and an integer, and support automatically adding new values which
/// get an auto-incremented integer value.
type Enumeration<A> = BiMap<A, i32>;

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for (IjProjectElement dep : moduleDeps.keySet()) {
  if (dep instanceof IjLibrary) {
    referencedLibraries.add((IjLibrary) dep);
  }
}

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moduleDeps.keySet().stream()
    .filter(dep -> dep instanceof IjLibrary)
    .map(library -> (IjLibrary) library)
    .forEach(referencedLibraries::add);