| protected readAdjacentChunk ( resource $fp, integer $head, integer $tail, integer $direction ) : array | ||
| $fp | resource | filepointer |
| $head | integer | position head of last chunk |
| $tail | integer | position tail of last chunk |
| $direction | integer | positive forward, negative backward |
| return | array | with entries: - $lines: changelog lines of readed chunk - $head: head of chunk - $tail: tail of chunk |
protected function readAdjacentChunk($fp, $head, $tail, $direction)
{
if (!$fp) {
return array(array(), $head, $tail);
}
if ($direction > 0) {
//read forward
$head = $tail;
$tail = $head + floor($this->chunk_size * (2 / 3));
$tail = $this->getNewlinepointer($fp, $tail);
} else {
//read backward
$tail = $head;
$head = max($tail - $this->chunk_size, 0);
while (true) {
$nl = $this->getNewlinepointer($fp, $head);
// was the chunk big enough? if not, take another bite
if ($nl > 0 && $tail <= $nl) {
$head = max($head - $this->chunk_size, 0);
} else {
$head = $nl;
break;
}
}
}
//load next chunck
$lines = $this->readChunk($fp, $head, $tail);
return array($lines, $head, $tail);
}