<?php
//  Copyright (c) 2009 Facebook
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//

//
// This file contains various XHProf library (utility) functions.
// Do not add any display specific code here.
//

function xhprof_error($message) {
  error_log($message);
}

/*
 * The list of possible metrics collected as part of XHProf that
 * require inclusive/exclusive handling while reporting.
 *
 * @author Kannan
 */
function xhprof_get_possible_metrics() {
 static $possible_metrics =
   array("wt" => array("Wall", "microsecs", "walltime"),
         "ut" => array("User", "microsecs", "user cpu time"),
         "st" => array("Sys", "microsecs", "system cpu time"),
         "cpu" => array("Cpu", "microsecs", "cpu time"),
         "mu" => array("MUse", "bytes", "memory usage"),
         "pmu" => array("PMUse", "bytes", "peak memory usage"),
         "samples" => array("Samples", "samples", "cpu time"));
 return $possible_metrics;
}

/**
 * Initialize the metrics we'll display based on the information
 * in the raw data.
 *
 * @author Kannan
 */
function init_metrics($xhprof_data, $rep_symbol, $sort, $diff_report = false) {
  global $stats;
  global $pc_stats;
  global $metrics;
  global $diff_mode;
  global $sortable_columns;
  global $sort_col;
  global $display_calls;

  $diff_mode = $diff_report;

  if (!empty($sort)) {
    if (array_key_exists($sort, $sortable_columns)) {
      $sort_col = $sort;
    } else {
      print("Invalid Sort Key $sort specified in URL");
    }
  }

  // For C++ profiler runs, walltime attribute isn't present.
  // In that case, use "samples" as the default sort column.
  if (!isset($xhprof_data["main()"]["wt"])) {

    if ($sort_col == "wt") {
      $sort_col = "samples";
    }

    // C++ profiler data doesn't have call counts.
    // ideally we should check to see if "ct" metric
    // is present for "main()". But currently "ct"
    // metric is artificially set to 1. So, relying
    // on absence of "wt" metric instead.
    $display_calls = false;
  } else {
    $display_calls = true;
  }

  // parent/child report doesn't support exclusive times yet.
  // So, change sort hyperlinks to closest fit.
  if (!empty($rep_symbol)) {
    $sort_col = str_replace("excl_", "", $sort_col);
  }

  if ($display_calls) {
    $stats = array("fn", "ct", "Calls%");
  } else {
    $stats = array("fn");
  }

  $pc_stats = $stats;

  $possible_metrics = xhprof_get_possible_metrics($xhprof_data);
  foreach ($possible_metrics as $metric => $desc) {
    if (isset($xhprof_data["main()"][$metric])) {
      $metrics[] = $metric;
      // flat (top-level reports): we can compute
      // exclusive metrics reports as well.
      $stats[] = $metric;
      $stats[] = "I" . $desc[0] . "%";
      $stats[] = "excl_" . $metric;
      $stats[] = "E" . $desc[0] . "%";

      // parent/child report for a function: we can
      // only breakdown inclusive times correctly.
      $pc_stats[] = $metric;
      $pc_stats[] = "I" . $desc[0] . "%";
    }
  }
}

/*
 * Get the list of metrics present in $xhprof_data as an array.
 *
 * @author Kannan
 */
function xhprof_get_metrics($xhprof_data) {

  // get list of valid metrics
  $possible_metrics = xhprof_get_possible_metrics();

  // return those that are present in the raw data.
  // We'll just look at the root of the subtree for this.
  $metrics = array();
  foreach ($possible_metrics as $metric => $desc) {
    if (isset($xhprof_data["main()"][$metric])) {
      $metrics[] = $metric;
    }
  }

  return $metrics;
}

/**
 * Takes a parent/child function name encoded as
 * "a==>b" and returns array("a", "b").
 *
 * @author Kannan
 */
function xhprof_parse_parent_child($parent_child) {
  $ret = explode("==>", $parent_child);

  // Return if both parent and child are set
  if (isset($ret[1])) {
    return $ret;
  }

  return array(null, $ret[0]);
}

/**
 * Given parent & child function name, composes the key
 * in the format present in the raw data.
 *
 * @author Kannan
 */
function xhprof_build_parent_child_key($parent, $child) {
  if ($parent) {
    return $parent . "==>" . $child;
  } else {
    return $child;
  }
}


/**
 * Checks if XHProf raw data appears to be valid and not corrupted.
 *
 *  @param   int    $run_id        Run id of run to be pruned.
 *                                 [Used only for reporting errors.]
 *  @param   array  $raw_data      XHProf raw data to be pruned
 *                                 & validated.
 *
 *  @return  bool   true on success, false on failure
 *
 *  @author Kannan
 */
function xhprof_valid_run($run_id, $raw_data) {

  $main_info = $raw_data["main()"];
  if (empty($main_info)) {
    xhprof_error("XHProf: main() missing in raw data for Run ID: $run_id");
    return false;
  }

  // raw data should contain either wall time or samples information...
  if (isset($main_info["wt"])) {
    $metric = "wt";
  } else if (isset($main_info["samples"])) {
    $metric = "samples";
  } else {
    xhprof_error("XHProf: Wall Time information missing from Run ID: $run_id");
    return false;
  }

  foreach ($raw_data as $info) {
    $val = $info[$metric];

    // basic sanity checks...
    if ($val < 0) {
      xhprof_error("XHProf: $metric should not be negative: Run ID $run_id"
                   . serialize($info));
      return false;
    }
    if ($val > (86400000000)) {
      xhprof_error("XHProf: $metric > 1 day found in Run ID: $run_id "
                   . serialize($info));
      return false;
    }
  }
  return true;
}


/**
 * Return a trimmed version of the XHProf raw data. Note that the raw
 * data contains one entry for each unique parent/child function
 * combination.The trimmed version of raw data will only contain
 * entries where either the parent or child function is in the list
 * of $functions_to_keep.
 *
 * Note: Function main() is also always kept so that overall totals
 * can still be obtained from the trimmed version.
 *
 * @param  array  XHProf raw data
 * @param  array  array of function names
 *
 * @return array  Trimmed XHProf Report
 *
 * @author Kannan
 */
function xhprof_trim_run($raw_data, $functions_to_keep) {

  // convert list of functions to a hash with function as the key
  $function_map = array_fill_keys($functions_to_keep, 1);

  // always keep main() as well so that overall totals can still
  // be computed if need be.
  $function_map['main()'] = 1;

  $new_raw_data = array();
  foreach ($raw_data as $parent_child => $info) {
    list($parent, $child) = xhprof_parse_parent_child($parent_child);

    if (isset($function_map[$parent]) || isset($function_map[$child])) {
      $new_raw_data[$parent_child] = $info;
    }
  }

  return $new_raw_data;
}

/**
 * Takes raw XHProf data that was aggregated over "$num_runs" number
 * of runs averages/nomalizes the data. Essentially the various metrics
 * collected are divided by $num_runs.
 *
 * @author Kannan
 */
function xhprof_normalize_metrics($raw_data, $num_runs) {

  if (empty($raw_data) || ($num_runs == 0)) {
    return $raw_data;
  }

  $raw_data_total = array();

  if (isset($raw_data["==>main()"]) && isset($raw_data["main()"])) {
    xhprof_error("XHProf Error: both ==>main() and main() set in raw data...");
  }

  foreach ($raw_data as $parent_child => $info) {
    foreach ($info as $metric => $value) {
      $raw_data_total[$parent_child][$metric] = ($value / $num_runs);
    }
  }

  return $raw_data_total;
}


/**
 * Get raw data corresponding to specified array of runs
 * aggregated by certain weightage.
 *
 * Suppose you have run:5 corresponding to page1.php,
 *                  run:6 corresponding to page2.php,
 *             and  run:7 corresponding to page3.php
 *
 * and you want to accumulate these runs in a 2:4:1 ratio. You
 * can do so by calling:
 *
 *     xhprof_aggregate_runs(array(5, 6, 7), array(2, 4, 1));
 *
 * The above will return raw data for the runs aggregated
 * in 2:4:1 ratio.
 *
 *  @param object  $xhprof_runs_impl  An object that implements
 *                                    the iXHProfRuns interface
 *  @param  array  $runs            run ids of the XHProf runs..
 *  @param  array  $wts             integral (ideally) weights for $runs
 *  @param  string $source          source to fetch raw data for run from
 *  @param  bool   $use_script_name If true, a fake edge from main() to
 *                                  to __script::<scriptname> is introduced
 *                                  in the raw data so that after aggregations
 *                                  the script name is still preserved.
 *
 *  @return array  Return aggregated raw data
 *
 *  @author Kannan
 */
function xhprof_aggregate_runs($xhprof_runs_impl, $runs,
                               $wts, $source="phprof",
                               $use_script_name=false) {

  $raw_data_total = null;
  $raw_data       = null;
  $metrics        = array();

  $run_count = count($runs);
  $wts_count = count($wts);

  if (($run_count == 0) ||
      (($wts_count > 0) && ($run_count != $wts_count))) {
    return array('description' => 'Invalid input..',
                 'raw'  => null);
  }

  $bad_runs = array();
  foreach ($runs as $idx => $run_id) {

    $raw_data = $xhprof_runs_impl->get_run($run_id, $source, $description);

    // use the first run to derive what metrics to aggregate on.
    if ($idx == 0) {
      foreach ($raw_data["main()"] as $metric => $val) {
        if ($metric != "pmu") {
          // for now, just to keep data size small, skip "peak" memory usage
          // data while aggregating.
          // The "regular" memory usage data will still be tracked.
          if (isset($val)) {
            $metrics[] = $metric;
          }
        }
      }
    }

    if (!xhprof_valid_run($run_id, $raw_data)) {
      $bad_runs[] = $run_id;
      continue;
    }

    if ($use_script_name) {
      $page = $description;

      // create a fake function '__script::$page', and have and edge from
      // main() to '__script::$page'. We will also need edges to transfer
      // all edges originating from main() to now originate from
      // '__script::$page' to all function called from main().
      //
      // We also weight main() ever so slightly higher so that
      // it shows up above the new entry in reports sorted by
      // inclusive metrics or call counts.
      if ($page) {
        foreach ($raw_data["main()"] as $metric => $val) {
          $fake_edge[$metric] = $val;
          $new_main[$metric]  = $val + 0.00001;
        }
        $raw_data["main()"] = $new_main;
        $raw_data[xhprof_build_parent_child_key("main()",
                                                "__script::$page")]
          = $fake_edge;
      } else {
        $use_script_name = false;
      }
    }

    // if no weights specified, use 1 as the default weightage..
    $wt = ($wts_count == 0) ? 1 : $wts[$idx];

    // aggregate $raw_data into $raw_data_total with appropriate weight ($wt)
    foreach ($raw_data as $parent_child => $info) {
      if ($use_script_name) {
        // if this is an old edge originating from main(), it now
        // needs to be from '__script::$page'
        if (substr($parent_child, 0, 9) == "main()==>") {
          $child = substr($parent_child, 9);
          // ignore the newly added edge from main()
          if (substr($child, 0, 10) != "__script::") {
            $parent_child = xhprof_build_parent_child_key("__script::$page",
                                                          $child);
          }
        }
      }

      if (!isset($raw_data_total[$parent_child])) {
        foreach ($metrics as $metric) {
          $raw_data_total[$parent_child][$metric] = ($wt * $info[$metric]);
        }
      } else {
        foreach ($metrics as $metric) {
          $raw_data_total[$parent_child][$metric] += ($wt * $info[$metric]);
        }
      }
    }
  }

  $runs_string = implode(",", $runs);

  if (isset($wts)) {
    $wts_string  = "in the ratio (" . implode(":", $wts) . ")";
    $normalization_count = array_sum($wts);
  } else {
    $wts_string = "";
    $normalization_count = $run_count;
  }

  $run_count = $run_count - count($bad_runs);

  $data['description'] = "Aggregated Report for $run_count runs: ".
                         "$runs_string $wts_string\n";
  $data['raw'] = xhprof_normalize_metrics($raw_data_total,
                                          $normalization_count);
  $data['bad_runs'] = $bad_runs;

  return $data;
}


/**
 * Analyze hierarchical raw data, and compute per-function (flat)
 * inclusive and exclusive metrics.
 *
 * Also, store overall totals in the 2nd argument.
 *
 * @param  array $raw_data          XHProf format raw profiler data.
 * @param  array &$overall_totals   OUT argument for returning
 *                                  overall totals for various
 *                                  metrics.
 * @return array Returns a map from function name to its
 *               call count and inclusive & exclusive metrics
 *               (such as wall time, etc.).
 *
 * @author Kannan Muthukkaruppan
 */
function xhprof_compute_flat_info($raw_data, &$overall_totals) {

  global $display_calls;

  $metrics = xhprof_get_metrics($raw_data);

  $overall_totals = array("ct" => 0,
                           "wt" => 0,
                           "ut" => 0,
                           "st" => 0,
                           "cpu" => 0,
                           "mu" => 0,
                           "pmu" => 0,
                           "samples" => 0
                           );

  // compute inclusive times for each function
  $symbol_tab = xhprof_compute_inclusive_times($raw_data);

  /* total metric value is the metric value for "main()" */
  foreach ($metrics as $metric) {
    $overall_totals[$metric] = $symbol_tab["main()"][$metric];
  }

  /*
   * initialize exclusive (self) metric value to inclusive metric value
   * to start with.
   * In the same pass, also add up the total number of function calls.
   */
  foreach ($symbol_tab as $symbol => $info) {
    foreach ($metrics as $metric) {
      $symbol_tab[$symbol]["excl_" . $metric] = $symbol_tab[$symbol][$metric];
    }
    if ($display_calls) {
      /* keep track of total number of calls */
      $overall_totals["ct"] += $info["ct"];
    }
  }

  /* adjust exclusive times by deducting inclusive time of children */
  foreach ($raw_data as $parent_child => $info) {
    list($parent, $child) = xhprof_parse_parent_child($parent_child);

    if ($parent) {
      foreach ($metrics as $metric) {
        // make sure the parent exists hasn't been pruned.
        if (isset($symbol_tab[$parent])) {
          $symbol_tab[$parent]["excl_" . $metric] -= $info[$metric];
        }
      }
    }
  }

  return $symbol_tab;
}

/**
 * Hierarchical diff:
 * Compute and return difference of two call graphs: Run2 - Run1.
 *
 * @author Kannan
 */
function xhprof_compute_diff($xhprof_data1, $xhprof_data2) {
  global $display_calls;

  // use the second run to decide what metrics we will do the diff on
  $metrics = xhprof_get_metrics($xhprof_data2);

  $xhprof_delta = $xhprof_data2;

  foreach ($xhprof_data1 as $parent_child => $info) {

    if (!isset($xhprof_delta[$parent_child])) {

      // this pc combination was not present in run1;
      // initialize all values to zero.
      if ($display_calls) {
        $xhprof_delta[$parent_child] = array("ct" => 0);
      } else {
        $xhprof_delta[$parent_child] = array();
      }
      foreach ($metrics as $metric) {
        $xhprof_delta[$parent_child][$metric] = 0;
      }
    }

    if ($display_calls) {
      $xhprof_delta[$parent_child]["ct"] -= $info["ct"];
    }

    foreach ($metrics as $metric) {
      $xhprof_delta[$parent_child][$metric] -= $info[$metric];
    }
  }

  return $xhprof_delta;
}


/**
 * Compute inclusive metrics for function. This code was factored out
 * of xhprof_compute_flat_info().
 *
 * The raw data contains inclusive metrics of a function for each
 * unique parent function it is called from. The total inclusive metrics
 * for a function is therefore the sum of inclusive metrics for the
 * function across all parents.
 *
 * @return array  Returns a map of function name to total (across all parents)
 *                inclusive metrics for the function.
 *
 * @author Kannan
 */
function xhprof_compute_inclusive_times($raw_data) {
  global $display_calls;

  $metrics = xhprof_get_metrics($raw_data);

  $symbol_tab = array();

  /*
   * First compute inclusive time for each function and total
   * call count for each function across all parents the
   * function is called from.
   */
  foreach ($raw_data as $parent_child => $info) {

    list($parent, $child) = xhprof_parse_parent_child($parent_child);

    if ($parent == $child) {
      /*
       * XHProf PHP extension should never trigger this situation any more.
       * Recursion is handled in the XHProf PHP extension by giving nested
       * calls a unique recursion-depth appended name (for example, foo@1).
       */
      xhprof_error("Error in Raw Data: parent & child are both: $parent");
      return;
    }

    if (!isset($symbol_tab[$child])) {

      if ($display_calls) {
        $symbol_tab[$child] = array("ct" => $info["ct"]);
      } else {
        $symbol_tab[$child] = array();
      }
      foreach ($metrics as $metric) {
        $symbol_tab[$child][$metric] = $info[$metric];
      }
    } else {
      if ($display_calls) {
        /* increment call count for this child */
        $symbol_tab[$child]["ct"] += $info["ct"];
      }

      /* update inclusive times/metric for this child  */
      foreach ($metrics as $metric) {
        $symbol_tab[$child][$metric] += $info[$metric];
      }
    }
  }

  return $symbol_tab;
}


/*
 * Prunes XHProf raw data:
 *
 * Any node whose inclusive walltime accounts for less than $prune_percent
 * of total walltime is pruned. [It is possible that a child function isn't
 * pruned, but one or more of its parents get pruned. In such cases, when
 * viewing the child function's hierarchical information, the cost due to
 * the pruned parent(s) will be attributed to a special function/symbol
 * "__pruned__()".]
 *
 *  @param   array  $raw_data      XHProf raw data to be pruned & validated.
 *  @param   double $prune_percent Any edges that account for less than
 *                                 $prune_percent of time will be pruned
 *                                 from the raw data.
 *
 *  @return  array  Returns the pruned raw data.
 *
 *  @author Kannan
 */
function xhprof_prune_run($raw_data, $prune_percent) {

  $main_info = $raw_data["main()"];
  if (empty($main_info)) {
    xhprof_error("XHProf: main() missing in raw data");
    return false;
  }

  // raw data should contain either wall time or samples information...
  if (isset($main_info["wt"])) {
    $prune_metric = "wt";
  } else if (isset($main_info["samples"])) {
    $prune_metric = "samples";
  } else {
    xhprof_error("XHProf: for main() we must have either wt "
                 ."or samples attribute set");
    return false;
  }

  // determine the metrics present in the raw data..
  $metrics = array();
  foreach ($main_info as $metric => $val) {
    if (isset($val)) {
      $metrics[] = $metric;
    }
  }

  $prune_threshold = (($main_info[$prune_metric] * $prune_percent) / 100.0);

  init_metrics($raw_data, null, null, false);
  $flat_info = xhprof_compute_inclusive_times($raw_data);

  foreach ($raw_data as $parent_child => $info) {

    list($parent, $child) = xhprof_parse_parent_child($parent_child);

    // is this child's overall total from all parents less than threshold?
    if ($flat_info[$child][$prune_metric] < $prune_threshold) {
      unset($raw_data[$parent_child]); // prune the edge
    } else if ($parent &&
               ($parent != "__pruned__()") &&
               ($flat_info[$parent][$prune_metric] < $prune_threshold)) {

      // Parent's overall inclusive metric is less than a threshold.
      // All edges to the parent node will get nuked, and this child will
      // be a dangling child.
      // So instead change its parent to be a special function __pruned__().
      $pruned_edge = xhprof_build_parent_child_key("__pruned__()", $child);

      if (isset($raw_data[$pruned_edge])) {
        foreach ($metrics as $metric) {
          $raw_data[$pruned_edge][$metric]+=$raw_data[$parent_child][$metric];
        }
      } else {
        $raw_data[$pruned_edge] = $raw_data[$parent_child];
      }

      unset($raw_data[$parent_child]); // prune the edge
    }
  }

  return $raw_data;
}


/**
 * Set one key in an array and return the array
 *
 * @author Kannan
 */
function xhprof_array_set($arr, $k, $v) {
  $arr[$k] = $v;
  return $arr;
}

/**
 * Removes/unsets one key in an array and return the array
 *
 * @author Kannan
 */
function xhprof_array_unset($arr, $k) {
  unset($arr[$k]);
  return $arr;
}

/**
 * Type definitions for URL params
 */
define('XHPROF_STRING_PARAM', 1);
define('XHPROF_UINT_PARAM',   2);
define('XHPROF_FLOAT_PARAM',  3);
define('XHPROF_BOOL_PARAM',   4);


/**
 * Internal helper function used by various
 * xhprof_get_param* flavors for various
 * types of parameters.
 *
 * @param string   name of the URL query string param
 *
 * @author Kannan
 */
function xhprof_get_param_helper($param) {
  $val = null;
  if (isset($_GET[$param]))
    $val = $_GET[$param];
  else if (isset($_POST[$param])) {
    $val = $_POST[$param];
  }
  return $val;
}

/**
 * Extracts value for string param $param from query
 * string. If param is not specified, return the
 * $default value.
 *
 * @author Kannan
 */
function xhprof_get_string_param($param, $default = '') {
  $val = xhprof_get_param_helper($param);

  if ($val === null)
    return $default;

  return $val;
}

/**
 * Extracts value for unsigned integer param $param from
 * query string. If param is not specified, return the
 * $default value.
 *
 * If value is not a valid unsigned integer, logs error
 * and returns null.
 *
 * @author Kannan
 */
function xhprof_get_uint_param($param, $default = 0) {
  $val = xhprof_get_param_helper($param);

  if ($val === null)
    $val = $default;

  // trim leading/trailing whitespace
  $val = trim($val);

  // if it only contains digits, then ok..
  if (ctype_digit($val)) {
    return $val;
  }

  xhprof_error("$param is $val. It must be an unsigned integer.");
  return null;
}


/**
 * Extracts value for a float param $param from
 * query string. If param is not specified, return
 * the $default value.
 *
 * If value is not a valid unsigned integer, logs error
 * and returns null.
 *
 * @author Kannan
 */
function xhprof_get_float_param($param, $default = 0) {
  $val = xhprof_get_param_helper($param);

  if ($val === null)
    $val = $default;

  // trim leading/trailing whitespace
  $val = trim($val);

  // TBD: confirm the value is indeed a float.
  if (true) // for now..
    return (float)$val;

  xhprof_error("$param is $val. It must be a float.");
  return null;
}

/**
 * Extracts value for a boolean param $param from
 * query string. If param is not specified, return
 * the $default value.
 *
 * If value is not a valid unsigned integer, logs error
 * and returns null.
 *
 * @author Kannan
 */
function xhprof_get_bool_param($param, $default = false) {
  $val = xhprof_get_param_helper($param);

  if ($val === null)
    $val = $default;

  // trim leading/trailing whitespace
  $val = trim($val);

  switch (strtolower($val)) {
  case '0':
  case '1':
    $val = (bool)$val;
    break;
  case 'true':
  case 'on':
  case 'yes':
    $val = true;
    break;
  case 'false':
  case 'off':
  case 'no':
    $val = false;
    break;
  default:
    xhprof_error("$param is $val. It must be a valid boolean string.");
    return null;
  }

  return $val;

}

/**
 * Initialize params from URL query string. The function
 * creates globals variables for each of the params
 * and if the URL query string doesn't specify a particular
 * param initializes them with the corresponding default
 * value specified in the input.
 *
 * @params array $params An array whose keys are the names
 *                       of URL params who value needs to
 *                       be retrieved from the URL query
 *                       string. PHP globals are created
 *                       with these names. The value is
 *                       itself an array with 2-elems (the
 *                       param type, and its default value).
 *                       If a param is not specified in the
 *                       query string the default value is
 *                       used.
 * @author Kannan
 */
function xhprof_param_init($params) {
  /* Create variables specified in $params keys, init defaults */
  foreach ($params as $k => $v) {
    switch ($v[0]) {
    case XHPROF_STRING_PARAM:
      $p = xhprof_get_string_param($k, $v[1]);
      break;
    case XHPROF_UINT_PARAM:
      $p = xhprof_get_uint_param($k, $v[1]);
      break;
    case XHPROF_FLOAT_PARAM:
      $p = xhprof_get_float_param($k, $v[1]);
      break;
    case XHPROF_BOOL_PARAM:
      $p = xhprof_get_bool_param($k, $v[1]);
      break;
    default:
      xhprof_error("Invalid param type passed to xhprof_param_init: "
                   . $v[0]);
      exit();
    }

    // create a global variable using the parameter name.
    $GLOBALS[$k] = $p;
  }
}


/**
 * Given a partial query string $q return matching function names in
 * specified XHProf run. This is used for the type ahead function
 * selector.
 *
 * @author Kannan
 */
function xhprof_get_matching_functions($q, $xhprof_data) {

  $matches = array();

  foreach ($xhprof_data as $parent_child => $info) {
    list($parent, $child) = xhprof_parse_parent_child($parent_child);
    if (stripos($parent, $q) !== false) {
      $matches[$parent] = 1;
    }
    if (stripos($child, $q) !== false) {
      $matches[$child] = 1;
    }
  }

  $res = array_keys($matches);

  // sort it so the answers are in some reliable order...
  asort($res);

  return ($res);
}

