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get_job_progress_from_log_file()

Description

Scan a log file from the end and return the most recent line matching a pattern.

The file is read in fixed-size blocks starting from EOF and scanned backwards
line-by-line for the first line that matches the supplied regular expression
(by default, lines containing "[PROGRESS]").

On the first read pass, the function also captures the last non-empty line in
the file (closest to EOF), regardless of whether it matches the pattern.


or if the file could not be read
last_line: string|null The last non-empty line in the file, or null if unavailable

Parameters

ColumnTypeDefaultDescription
$path string "" Path to the log file to scan
$pattern string "/\[PROGRESS\]/i" Regular expression used to match progress lines
$block_size int Number of bytes to read per backward scan iteration
'rb';

Return

array found: string|null The most recent line matching $pattern, or null if none found

Location

include/job_functions.php lines 522 to 593

Definition

 
function get_job_progress_from_log_file(string $path = "", string $pattern = "/\[PROGRESS\]/i", int $block_size = 65536): array
{
    $fp = @fopen($path, 'rb');

    if (!$fp) {
        return ['found' => null, 'last_line' => null];
    }

    if (fseek($fp, 0, SEEK_END) === -1) {
        fclose($fp);
        return ['found' => null, 'last_line' => null];
    }

    $position  = ftell($fp);
    $carry     = '';
    $last_line  = null;
    $first_pass = true;

    while ($position > 0) {
        $read_size = ($position >= $block_size) ? $block_size : $position;
        $position -= $read_size;
        
        fseek($fp, $position);
        
        $chunk = fread($fp, $read_size);

        // Combine with carried partial line
        $buffer = $chunk . $carry;

        // Split into lines
        $lines = preg_split("/\r\n|\n|\r/", $buffer);

        // The first element may be incomplete (its beginning lies in an earlier block)
        $carry = array_shift($lines);

        if ($first_pass) {
            // Capture the last non-empty line (closest to EOF)
            for ($i = count($lines) - 1; $i >= 0; $i--) {
                if ($lines[$i] !== '') {
                    $last_line = $lines[$i];
                    break;
                }
            }
            $first_pass = false;
        }

        // Scan lines backward (from newest to oldest)
        for ($i = count($lines) - 1; $i >= 0; $i--) {
            $line = $lines[$i];
            if ($line === '') continue;
            if (@preg_match($pattern, $line)) {
                fclose($fp);
                return ['found' => $line, 'last_line' => $last_line];
            }
        }
    }

    // Handle the very first (oldest) line if any partial remains
    if ($carry !== '') {
        if ($last_line === null && $carry !== '') {
            $last_line = $carry;
        }
        if (@preg_match($pattern, $carry)) {
            fclose($fp);
            return ['found' => $carry, 'last_line' => $last_line];
        }
    }

    fclose($fp);
    return ['found' => null, 'last_line' => $last_line];

}

This article was last updated 16th January 2026 17:35 Europe/London time based on the source file dated 16th January 2026 14:45 Europe/London time.