static Map onEnter()

in feline/src/main/java/com/spotify/feline/FelineTransformer.java [83:122]
21 lines of code
3 McCabe index (conditional complexity)

    static Map<String, Object> onEnter(
        @Advice.This() final Object thisObject,
        @Advice.Origin("#t") final String typeName,
        @Advice.Origin("#m") final String methodName,
        @Advice.Origin("#s") final String methodSig) {
      final Future<?> future = (Future<?>) thisObject;

      boolean state = FelineRuntime.BLOCKED_THREADS.contains(Thread.currentThread().getId());

      if (state) {
        // Already inside a blocking operation, fast-exit
        // and keep state as true (i.e. do nothing)
        return Collections.emptyMap();
      }

      if (future.isDone()) {
        // This method call is not actually blocking, so fast-exit
        // and keep state as false (i.e. do nothing)
        return Collections.emptyMap();
      }

      final String methodCall = typeName + "." + methodName + methodSig;
      FelineRuntime.accept(methodCall);

      // Set state to true as to ignore any nested blocked calls, e.g. where one Future delegates
      // to another.
      // The state must be set after consumers are invoked above. Consumers can throw exceptions,
      // in which case we
      // must not have modified the state first as it would not be reset in onExit().
      FelineRuntime.BLOCKED_THREADS.add(Thread.currentThread().getId());

      // Can't use custom classes here, since they won't be visible to classes in standard library
      // such as Future.

      final Map<String, Object> data = new HashMap<>(2);
      data.put("method", methodCall);
      data.put("startTimeNanos", System.nanoTime());

      return data;
    }