hphp/tools/perf-lib.php

   1 <?php
   2 // Copyright 2004-present Facebook. All Rights Reserved.
   3
   4 function starts_with($str, $prefix) {
   5   return strncmp($str, $prefix, strlen($prefix)) === 0;
   6 }
   7
   8 # If $func looks like a mangled C++ symbol, attempt to demangle it, stripping
   9 # off any trailing junk first.
  10 function filter_func(string $func): string {
  11   static $cache = Map {};
  12
  13   if (strncmp($func, '_Z', 2) === 0) {
  14     if (preg_match('/^(.+)\.isra\.\d+$/', $func, $matches) === 1) {
  15       $func = $matches[1];
  16     }
  17     if (!isset($cache[$func])) {
  18       $cache[$func] = trim(shell_exec("echo '$func' | c++filt"));
  19     }
  20     $func = $cache[$func];
  21   }
  22
  23   return $func;
  24 }
  25
  26 # Read perf samples from the given file stream into a Vector of stack traces.
  27 # The stream should contain the output of "perf script -f comm,ip,sym".
  28 function read_perf_samples($file, $desired_binary_prefix = 'hhvmworker') {
  29   $samples = Vector {};
  30   $skip_sample = false;
  31   $stack = null;
  32   $binary = null;
  33
  34   while ($line = fgets($file)) {
  35     $line = trim($line);
  36
  37     if ($line === '') {
  38       if ($stack) {
  39         $samples[] = $stack;
  40         $stack = null;
  41       }
  42       $skip_sample = false;
  43       continue;
  44     }
  45     if ($skip_sample) {
  46       continue;
  47     }
  48
  49     if (preg_match('/^[a-f0-9]+ (.+)$/', $line, $matches) === 1) {
  50       if (!$stack) $stack = Vector {};
  51       $stack[] = filter_func($matches[1]);
  52     } else {
  53       if ($stack !== null) throw new Exception("Unexpected line $line");
  54       $binary = $line;
  55       $skip_sample = !starts_with($binary, $desired_binary_prefix);
  56     }
  57   }
  58
  59   if ($stack) $samples[] = $stack;
  60   return $samples;
  61 }