add pmtiles serialization/deserialization benchmark [onthegomap#98]

planetiler-benchmarks/src/main/java/com/onthegomap/planetiler/benchmarks/BenchmarkPmtiles.java

@@ -0,0 +1,45 @@
+package com.onthegomap.planetiler.benchmarks;
+
+import static io.prometheus.client.Collector.NANOSECONDS_PER_SECOND;
+
+import com.carrotsearch.hppc.ObjectArrayList;
+import com.onthegomap.planetiler.pmtiles.Pmtiles;
+import com.onthegomap.planetiler.stats.Timer;
+import com.onthegomap.planetiler.util.Format;
+import java.io.IOException;
+import java.util.Random;
+
+public class BenchmarkPmtiles {
+
+  public static void main(String[] args) throws IOException {
+
+    long num = 40_000_000;
+
+    var random = new Random(0);
+
+    for (int i = 0; i < 3; i++) {
+
+      var entries = new ObjectArrayList<Pmtiles.Entry>();
+
+      long offset = 0;
+      for (int j = 0; j < num; j++) {
+        int len = random.nextInt(200, 64000);
+        entries.add(new Pmtiles.Entry(j, offset, len, 1));
+        offset += len;
+      }
+
+      var timer = Timer.start();
+
+      var result = Pmtiles.deserializeDirectory(Pmtiles.serializeDirectory(entries, 0, entries.size()));
+      assert (result.size() == entries.size());
+
+      System.err.println(
+        num + " entries took " +
+          Format.defaultInstance().duration(timer.stop().elapsed().wall()) + " (" +
+          Format.defaultInstance()
+            .numeric(num * 1d / (timer.stop().elapsed().wall().toNanos() / NANOSECONDS_PER_SECOND)) +
+          "/s)"
+      );
+    }
+  }
+}