add handy script to summarize multiple json files

json_to_csv.php

@@ -0,0 +1,120 @@
+<?hh
+
+newtype Sample = shape(
+  'framework' => string,
+  'runtime' => string,
+  'rps' => float,
+);
+
+newtype Row = shape(
+  'framework' => string,
+  'runtime' => string,
+  'rps_samples' => Vector<float>,
+  'rps_mean' => ?float,
+  'rps_sd' => ?float,
+);
+
+function load_file(string $file): Vector<Sample> {
+  $json = file_get_contents($file);
+  $data = json_decode($json, /* as associative array = */ true);
+
+  $results = Vector {};
+  foreach ($data as $framework => $framework_data) {
+    $results->addAll(load_framework($framework, $framework_data));
+  }
+
+  return $results;
+}
+
+function load_framework(string $framework, $data): Vector<Sample> {
+  $results = Vector {};
+  foreach ($data as $runtime => $runtime_data) {
+    $results[] = load_run($framework, $runtime, $runtime_data['Combined']);
+  }
+  return $results;
+}
+
+function load_run(string $framework, string $runtime, $data): Sample {
+  return shape(
+    'framework' => $framework,
+    'runtime' => $runtime,
+    'rps' => $data['Siege RPS'],
+  );
+}
+
+function load_files(Vector<string> $files): Vector<Row> {
+  $rows_by_key = Map {};
+  foreach ($files as $file) {
+    $samples = load_file($file);
+    foreach ($samples as $sample) {
+      $key = $sample['framework']."\0".$sample['runtime'];
+      if (!$rows_by_key->containsKey($key)) {
+        $rows_by_key[$key] = shape(
+          'framework' => $sample['framework'],
+          'runtime' => $sample['runtime'],
+          'rps_samples' => Vector { },
+          'rps_mean' => null,
+          'rps_sd' => null,
+        );
+      }
+      $rows_by_key[$key]['rps_samples'][] = $sample['rps'];
+    }
+  }
+
+  foreach ($rows_by_key as $key => $row) {
+    $samples = $row['rps_samples'];
+    $count = count($samples);
+
+    // toArray(): https://github.com/facebook/hhvm/issues/5454
+    $mean = (float) array_sum($samples->toArray()) / $count;
+    $variance = array_sum(
+      $samples->map($x ==> pow($mean - $x, 2))->toArray()
+    ) / $count;
+    $sd = sqrt($variance);
+
+    $row['rps_mean'] = $mean;
+    $row['rps_sd'] =  $sd;
+
+    $rows_by_key[$key] = $row;
+  }
+
+  return $rows_by_key->values();
+}
+
+function dump_csv(Vector<Row> $rows): void {
+  $header = Vector {
+    'Framework',
+    'Runtime',
+    'Mean RPS',
+    'RPS Standard Deviation',
+  };
+
+  $max_sample_count = max($rows->map($row ==> count($row['rps_samples'])));
+  for ($i = 1; $i <= $max_sample_count; ++$i) {
+    $header[] = 'Sample '.$i.' RPS';
+  }
+
+  fputcsv(STDOUT, $header);
+  foreach ($rows as $row) {
+    $out = Vector {
+      $row['framework'],
+      $row['runtime'],
+      $row['rps_mean'],
+      $row['rps_sd'],
+    };
+    $out->addAll($row['rps_samples']);
+    fputcsv(STDOUT, $out);
+  }
+}
+
+function main(Vector<string> $argv) {
+  $files = clone $argv;
+  $files->removeKey(0);
+  if ($files->isEmpty()) {
+    fprintf(STDERR, "Usage: %s results.json [results2.json ...]\n", $argv[0]);
+    exit(1);
+  }
+  dump_csv(load_files($files));
+}
+
+main(new Vector($argv));