Profiler.java

package dev.hephaestus.atmosfera.util;

import org.apache.logging.log4j.Logger;

import java.util.Map;
import java.util.Stack;
import java.util.TreeMap;

public class Profiler {
  private static final Map<String, Long> TIMES = new TreeMap<>();
  private static final Map<String, Long> COUNTS = new TreeMap<>();
  private static final Stack<Section> STACK = new Stack<>();

  public static void push(String name) {
    STACK.push(new Section(name));
  }

  public static void pop(Logger logger) {
    STACK.pop().pop(logger);
  }

  public static void pop() {
    STACK.pop().pop();
  }

  public static void report(Logger logger) {
    logger.debug("Times per category:");

    for (Map.Entry<String, Long> entry : TIMES.entrySet()) {
      logger.debug("  {}: {}", entry.getKey(), ((double) entry.getValue()) / 1_000_000_000.0);
    }

    logger.debug("Average time per category:");

    for (Map.Entry<String, Long> entry : TIMES.entrySet()) {
      logger.debug("  {}: {}", entry.getKey(), (((double) entry.getValue()) / ((double) COUNTS.get(entry.getKey()))) / 1_000_000_000.0);
    }
  }

  private static class Section {
    private final String name;
    private final long timeStart;

    private Section(String name) {
      this.name = name;
      this.timeStart = System.nanoTime();
    }

    private void pop(Logger logger) {
      long time = System.nanoTime() - this.timeStart;
      Profiler.TIMES.compute(this.name, (key, val) -> (val == null ? 0 : val) + time);
      Profiler.COUNTS.compute(this.name, (key, val) -> (val == null ? 0 : val) + 1);

      if (logger != null) {
        logger.debug("{}: {}ns", this.name, time);
      }
    }

    private void pop() {
      this.pop(null);
    }
  }
}