/**
* This function generates a 'Top' file from a sorted log file
* For each criterion (which index is $criterionIndex),
* it counts the occurrence of the values which index are $valueIndex
*
* @param $filename, name of the sorted log file
* @param $topFilename, name of the top file that will be generated
* @param $topNumber, number of the Top such as 'Top ($topNumber)' is generated
* @param $nbLogParam, number of log parameters per line
* @param $criterionIndex, the index of the criterion for the top (0: song_id, 1: usr_id, 2: country_code)
* @param $valueIndex, the index of the value that will be counted (0: song_id, 1: usr_id, 2: country_code)
*/
function generateTopFile($filename, $topFilename, $topNumber, $nbLogParam, $criterionIndex, $valueIndex)
{
global $red, $green, $blue, $noColor, $OK;
echo $blue . "*** Generating " . $topFilename . " ***" . $noColor . "\n";
// The sorted log file is opened
$fh = fopen($filename, 'r') or die($red . "Oops, couldn't open " . $filename . "!" . $noColor . "\n\n");
// The top file is created
$fp = fopen($topFilename, 'w') or die($red . "Oops, couldn't create a new file!" . $noColor . "\n\n");
$currentCriterionID = 0;
// ID of the criterion that is currently analyzed
$currentValueID = 0;
// ID of the value that is currently counted
$counter = 0;
// Counter for the values
// In order to keep the Top updated for each criterion, the data is stored in a MinHeap each time.
// The structure of this array is as the following: list($valueID, $counter) = $array;
// Thus, MyHeap class is used and sorted according to $counter, and then according to $valueID in case of equality
$VALUE_INDEX = 0;
$COUNTER_INDEX = 1;
$heap = new MyHeap($COUNTER_INDEX, $VALUE_INDEX);
echo "Reading and counting data... ";
// The first line is read
if (!feof($fh)) {
$line = trim(fgets($fh));
$row = explode('|', $line);
$currentCriterionID = $row[$criterionIndex];
$currentValueID = $row[$valueIndex];
$counter++;
} else {
// File shouldn't be empty at this point; if it is, something wrong must have happened meanwhile
exit($red . "Unexpected EOF reached... Script aborted!" . $noColor . "\n");
}
while (!feof($fh)) {
$line = trim(fgets($fh));
$row = explode('|', $line);
if (count($row) == $nbLogParam) {
// When next criterion is detected, the Top of the $currentCriterionID is written in the file
if ($currentCriterionID != $row[$criterionIndex]) {
// First, insert the last data of $currentCriterionID into the heap
$heap->insert(array($currentValueID, $counter));
if ($heap->count() > $topNumber) {
$heap->extract();
// Maximum length of the heap is equal to $topNumber
}
// Empty MinHeap and reverse it (with a stack) to get the Top in descending order
// Note: An array is used as a stack (instead of SplStack) for better performance
$stack = array();
while (!$heap->isEmpty()) {
$stack[] = $heap->extract();
}
// Write the Top of the $currentCriterionID (in our example: Top 50)
// Format: country|sng_id1:n1,sng_id2:n2,sng_id3:n3,...,sng_id50:n50
$data = array_pop($stack);
fwrite($fp, $currentCriterionID . "|" . $data[$VALUE_INDEX] . ":" . $data[$COUNTER_INDEX]);
while (!empty($stack)) {
$data = array_pop($stack);
fwrite($fp, "," . $data[$VALUE_INDEX] . ":" . $data[$COUNTER_INDEX]);
}
fwrite($fp, "\n");
unset($stack);
// Update $currentCriterionID, $currentValueID and $counter
$currentCriterionID = $row[$criterionIndex];
$currentValueID = $row[$valueIndex];
$counter = 1;
} elseif ($currentValueID != $row[$valueIndex]) {
// When next value is detected, insert the last data of $currentCriterionID into the heap
$heap->insert(array($currentValueID, $counter));
if ($heap->count() > $topNumber) {
$heap->extract();
//
}
// Then update $currentValueID and $counter
$currentValueID = $row[$valueIndex];
$counter = 1;
} else {
// Else, keep counting
$counter++;
}
} else {
// Data is expected to have ($nbLogParam) values;
// if not, it means that the end of this file has been reached
break;
}
}
// Repeat the process for the last Top
$heap->insert(array($currentValueID, $counter));
if ($heap->count() > $topNumber) {
$heap->extract();
}
$stack = array();
while (!$heap->isEmpty()) {
$stack[] = $heap->extract();
}
$data = array_pop($stack);
fwrite($fp, $currentCriterionID . "|" . $data[$VALUE_INDEX] . ":" . $data[$COUNTER_INDEX]);
while (!empty($stack)) {
$data = array_pop($stack);
fwrite($fp, "," . $data[$VALUE_INDEX] . ":" . $data[$COUNTER_INDEX]);
}
echo $OK . $blue . "*** DONE! ***" . $noColor . "\n";
unset($stack);
unset($heap);
fclose($fh);
fclose($fp);
}
