Logger - PHP

Mainly written for fun, but this is a configurable Logger written in PHP that supports multiple handlers, including Writers (File, SQL, Apache's Error Log, Echo), configurable Formatting. various logging levels (FATAL, ERROR, WARN, INFO, DEBUG, TRACE). Also useful functions like isDebug/TraceEnabled(), to check before building large strings to debug/trace(). While each logger instance can have a unique name, there isn't any parent/child hierarchy attributed to them.

Note: Now on GitHub

<?php
/**
 * PHP Logger
 * @author Kenny Cason
 * @site www.kennycason.com
 */
class Logger {

	/**
	 * static Logger for convenient quick use of logger
	 */
	public static function getStaticLogger($resource, $config=array()) {
		$logger = new Logger();
		$logger->resource = $resource;
		Logger::configure($logger, $config);
		return $logger;
	}

	/**
	 * singleton instances of a Logger indexed by a unique resource
	 */
	private static $loggerInstances = array();

	/*
	 * log levels, int value
	*/

	const FATAL         = 6;
	const ERROR         = 5;
	const WARN          = 4;
	const INFO          = 3;
	const DEBUG         = 2;
	const TRACE         = 1;

	/*
	 * log levels, string values
	*/
	private static $LOG_LEVELS = array( Logger::TRACE => "TRACE",
			Logger::DEBUG => "DEBUG",
			Logger::INFO => "INFO",
			Logger::WARN => "WARN",
			Logger::ERROR => "ERROR",
			Logger::FATAL => "FATAL");

	public $handlers = array();

	public $logLevel = Logger::INFO;   // default logging level is info

	/*
	 * formatting - move to LogFormatter Class later
	*/
	public $resource = ""; // a unique identifier for this logger (i.e. a class name, or script name)


	/**
	 * using singleton pattern return a logger instance
	 * @param string $resource
	 * @param array configuration
	 * @return Logger instance
	 */
	public static function getLogger($resource, $config=array()) {
		if (!isset(self::$loggerInstances[$resource])) {
			self::$loggerInstances[$resource] = new Logger();
		}
		Logger::$loggerInstances[$resource]->resource = $resource;
		Logger::configure(Logger::$loggerInstances[$resource],$config);
		return Logger::$loggerInstances[$resource];
	}

	private static function configure(Logger $logger, $config=array()) {
		if (isset($config['logLevel'])) {
			$logger->logLevel = $config['logLevel'];
		}
		if (isset($config['handlers']) && is_array($config['handlers'])) {
			$logger->clearHandlers();
			$logger->handlers = $config['handlers'];
		}
		if (isset($config['handler']) && !is_array($config['handler'])) {
			$logger->clearHandlers();
			$logger->addHandler($config['handler']);
		}

		if(empty($logger->handlers)) {
			$logger->addHandler(new LogFileHandler()); // create a default LogFileHandler
		}
	}

	public function setLevel($level=Logger::ERROR) {
		if($level >= Logger::TRACE && $level <= Logger::FATAL) {
			$this->logLevel = $level;
		} else {
			$this->logLevel = Logger::INFO;
		}
	}

	/**
	 * return the current log level
	 * @return string
	 */
	public function getLevel() {
		return  Logger::$LOG_LEVELS[$this->logLevel];
	}

	/**
	 * set the log mode. (i.e.log to LOG_TYPE_FILE / LOG_TYPE_SQL / LOG_TYPE_ERROR_LOG
	 * @param int
	 */
	public function setLogMode($logMode) {
		$this->logMode = $logMode;
	}

	/**
	 * get lhe log mode
	 * @return int
	 */
	public function getLogMode() {
		return $this->logMode;
	}


	/**
	 * get all handlers
	 */
	public function getHandlers() {
		return $this->handlers;
	}

	/**
	 * add a handler
	 * @param ILogHandler $handler
	 */
	public function addHandler(ILogHandler $handler) {
		$this->handlers[] = $handler;
	}

	/**
	 * clear all handlers
	 */
	public function clearHandlers() {
		$this->handlers = array();
	}

	/**
	 * determine if the logger level is at least DEBUG level
	 * @return bool
	 */
	public function isDebugEnabled() {
		if($this->getLevel() <= Logger::DEBUG) {
			return true;
		}
		return false;
	}

	/**
	 * determine if the logger level is at least TRACE level
	 * @return bool
	 */
	public function isTraceEnabled() {
		if($this->getLevel() <= Logger::TRACE) {
			return true;
		}
		return false;
	}

	/**
	 * log at trace level
	 * @param string $msg
	 * @param object $obj (optional)
	 */
	public function trace($msg, $obj=null) {
		if($this->logLevel <= Logger::TRACE) {
			$this->log(Logger::TRACE, $msg, $obj);
		}
	}

	/**
	 * log at debug level
	 * @param string $msg
	 * @param object $obj (optional)
	 */
	public function debug($msg, $obj=null) {
		if($this->logLevel <= Logger::DEBUG) {
			$this->log(Logger::DEBUG, $msg, $obj);
		}
	}

	/**
	 * log at info level
	 * @param string $msg
	 * @param object $obj (optional)
	 */
	public function info($msg, $obj=null) {
		if($this->logLevel <= Logger::INFO) {
			$this->log(Logger::INFO, $msg, $obj);
		}
	}

	/**
	 * log at warn level
	 * @param string $msg
	 * @param object $obj (optional)
	 */
	public function warn($msg, $obj=null) {
		if($this->logLevel <= Logger::WARN) {
			$this->log(Logger::WARN, $msg, $obj);
		}
	}

	/**
	 * log at error level
	 * @param string $msg
	 * @param object $obj (optional)
	 */
	public function error($msg, $obj=null) {
		if($this->logLevel <= Logger::ERROR) {
			$this->log(Logger::ERROR, $msg, $obj);
		}
	}

	/**
	 * log at catastrophic level
	 * @param string $msg
	 * @param object $obj (optional)
	 */
	public function fatal($msg, $obj=null) {
		if($this->logLevel <= Logger::FATAL) {
			$this->log(Logger::FATAL, $msg, $obj);
		}
	}

	/**
	 * private helper
	 * @param int $logLevel
	 * @param string $msg
	 */
	public function log($logLevel, $msg, $obj=null) {
		$record = new LogRecord();
		$record->setLevel(Logger::$LOG_LEVELS[$logLevel]);
		$record->setMessage($msg);
		$record->setResource($this->resource);
		$record->setObject($obj);
		foreach($this->handlers as $handler) {
			$handler->publish($record);
		}
	}

	/**
	 * private constructor init using getLogger()
	 */
	private function __construct() {
	}

	/**
	 *  Prevent users to clone the instance
	 */
	public function __clone() {
		$this->log('Clone is not allowed.');
	}

}

/**
 * This class encapsulates the Record to be logged
 */
class LogRecord {

	private $resource;

	private $level;

	private $msg;

	private $obj; // optional object to log along with $msg

	private $time;

	public function __construct() {
		$this->time = time();
	}

	public function setResource($resource) {
		$this->resource = $resource;
	}

	public function setLevel($level) {
		$this->level = $level;
	}

	public function setMessage($msg) {
		$this->msg = $msg;
	}

	public function setObject($obj) {
		$this->obj = $obj;
	}

	public function setTime($time) {
		$this->time = $time;
	}

	public function getResource() {
		return $this->resource;
	}

	public function getLevel() {
		return $this->level;
	}

	public function getMessage() {
		return $this->msg;
	}

	public function getObject() {
		return $this->obj;
	}

	public function getTime($format=null) {
		if($format == null) {
			return $this->time;
		}
		return date($format, $this->time);
	}

}

/**
 * LogHandler interface
 */
interface ILogHandler {

	public function publish(LogRecord $record);

	public function setFormatter(ILogFormatter $formatter);

	public function getFormatter();

}

/**
 * contains common functionality between log handlers
 */
abstract class AbstractLogHandler implements ILogHandler {

	protected $formatter;

	public function __construct() {
		$this->formatter = new LogDefaultFormatter();
	}

	public function setFormatter(ILogFormatter $formatter) {
		$this->formatter = $formatter;
	}

	public function getFormatter() {
		return $this->formatter;
	}

}

/**
 * Outputs to a LogFile
 */
class LogFileHandler extends AbstractLogHandler {

	private $logFileName = "/tmp/output.log";

	public function __construct($logFileName="") {
		parent::__construct();
		if($logFileName != "") {
			$this->logFileName = $logFileName;
		}
	}

	public function publish(LogRecord $record) {
		$log_msg = $this->formatter->format($record);

		$logFile = fopen($this->logFileName, 'a');
		if (!$logFile) {
			return array('status' => 'failure', 'msg' => 'Error Opening Log File');
		}
		fwrite($logFile, $log_msg);
		fclose($logFile);
	}

	/**
	 * set the log file name to append to
	 * @param string
	 */
	public function setLogFileName($logFileName) {
		$this->logFileName = $logFileName;
	}

	public function getLogFileName() {
		return $this->logFileName;
	}

}

/**
 * Echo out the Log
 */
class LogConsoleHandler extends AbstractLogHandler {

	public function __construct() {
		parent::__construct();
	}

	public function publish(LogRecord $record) {
		echo $this->formatter->format($record);
	}

}

/**
 * Log via error_log()
 */
class LogApacheErrorLogHandler extends AbstractLogHandler {

	public function __construct() {
		parent::__construct();
	}

	public function publish(LogRecord $record) {
		error_log($this->formatter->format($record));
	}

}

/**
 * Logs to SQL DataBase
 */
class LogSQLHandler extends AbstractLogHandler {

	private $db = null; // mysqli instance

	public function __construct($db) {
		$this->db = $db;
	}

	public function publish(LogRecord $record) {
		$sql = "INSERT INTO `log` (log_level, date, resource, msg) VALUES ('{$record->getLevel()}','{$record->getTime()}', ?, ?);";
		$statement = $this->db->prepare($sql);
		$statement->bind_param("ss", $record->getResource(), $record->getMessage());
		if (!$statement->execute()) {
			return array('status' => 'failure', 'msg' => 'SQL Error');
		}
		$statement->close();
	}

	public function setDB(mysqli $db) {
		$this->db = $mysqli;
	}

	public function getDB() {
		return $this->db;
	}

	public static function init() {
		$sql = "CREATE TABLE `log` (
		`id` BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
		`log_level` VARCHAR( 16 ) NOT NULL,
		`date` DATETIME NOT NULL,
		`resource` VARCHAR( 128 ) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
		`msg` VARCHAR( 1024 ) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL
		) ENGINE = MYISAM;";
		$this->db->query($sql);
	}

}








/**
 * Interface for formatting log messages
 */
interface ILogFormatter {

	public function format(LogRecord $record);

}

/**
 * concrete implementation of a Log Formatter that is formattable
 * %L - Log Level
 * %T - Time of logging
 * %R - Resource of the logger
 * %M - The Message
 * %O - The Object
 */
class LogFormatter implements ILogFormatter {

	private $format = null;

	private $dateFormat = "Y-m-d H:i:s";

	public function __construct($format="%L [%T] %R %M %O") {
		$this->format = $format;
	}

	/**
	 * return a formatted string
	 * @param LogRecord $record
	 */
	public function format(LogRecord $record) {
		$formatted_record = $this->format;
		$formatted_record = str_replace("%L",$record->getLevel(),$formatted_record);
		$formatted_record = str_replace("%T",$record->getTime($this->dateFormat),$formatted_record);
		$formatted_record = str_replace("%R",$record->getResource(),$formatted_record);
		$formatted_record = str_replace("%M",$record->getMessage(),$formatted_record);
		$formatted_record = str_replace("%O",$record->getObject(),$formatted_record);
		return $formatted_record;
	}

	public function setDateFormat($dateFormat) {
		$this->dateFormat = $dateFormat;
	}

}

/**
 * Default log formatter, format is immutable, but should suffice for most cases
 */
class LogDefaultFormatter implements ILogFormatter {

	private $dateFormat = "Y-m-d H:i:s";

	public function __construct() {
	}

	public function format(LogRecord $record) {
		return "{$record->getLevel()}\t[{$record->getTime($this->dateFormat)}]\t{$record->getResource()}\t{$record->getMessage()}\t".print_r($record->getObject(),1)."\n";
	}

}

?>

A simple Demo

<?php

require_once("DBConfig.php"); // <-- DB stuff only really needed if you want to use the SQL writer.
require_once("Logger.php");

$db = new mysqli($DB_HOST, $DB_USER, $DB_PASSWORD, $DB_DATABASE,$DB_PORT);
$db->set_charset("utf8");
// check connection
if (mysqli_connect_errno()) {
    printf("DB Connection failed: %s\n", mysqli_connect_error());
    exit();
}

/*
 * out of class example
 */
//$logger = Logger::getLogger(__FILE__);
//$logger->addHandler(new LogConsoleHandler());
//$logger->addHandler(new LogFileHandler("/tmp/output.log"));
//$logger->addHandler(new LogSQLHandler($db));


/*
 * in class example
 */

$foo = new Foo($db);
$foo->bar();

class Foo {

    private $logger;

    public function __construct($db) {
        /*
         * A simple Logger with default Formatter and a Default LogFileHandler (prints out to /tmp/output.log
         */
        $this->logger = Logger::getLogger(__CLASS__, array("logLevel" => Logger::TRACE));

        /**
         * add a custom Formatter
         */
        $this->logger->clearHandlers(); // this clears the default handler (i may make this happen invisibly later)
        $fh = new LogFileHandler("/tmp/output.log");
        $fh->setFormatter(new LogFormatter("%L --- %R --- (%T) --- %M %O\n"));
        $this->logger->addHandler($fh);

     //   $this->logger = Logger::getLogger(__CLASS__, array("logLevel" => Logger::TRACE,
     //       "handlers" => array(new LogFileHandler("/tmp/output3.log"), new LogSQLHandler($db), new LogConsoleHandler(), new LogErrorLogHandler())
    //        ));

        print_r($this->logger);
    }

    public function bar() {

        $this->logger->trace("A Trace Statement (Level INFO)");
        $this->logger->debug("A Debug Statement (Level INFO)");
        $this->logger->info("An Info level msg (Level INFO)");
        $this->logger->warn("A Warning Occured (Level INFO)");
        $this->logger->error("An Error Occured (Level INFO)");
        $this->logger->fatal("A Fatal Error occured (Level INFO)");

        $this->logger->setLevel(Logger::TRACE);
        $this->logger->trace("A Trace Statement (Level TRACE)");
        $this->logger->debug("A Debug Statement (Level TRACE)");
        $this->logger->info("An Info level msg (Level TRACE)", $this);
        $this->logger->warn("A Warning Occured (Level TRACE)");
        $this->logger->error("An Error Occured (Level TRACE)");
        $this->logger->fatal("A Fatal Error occured (Level TRACE)");

        $this->logger->setLevel(Logger::FATAL);
        $this->logger->trace("A Trace Statement (Level FATAL)");
        $this->logger->debug("A Debug Statement (Level FATAL)");
        $this->logger->info("An Info level msg (Level FATAL)");
        $this->logger->warn("A Warning Occured (Level FATAL)", $this);
        $this->logger->error("An Error Occured (Level FATAL)");
        $this->logger->fatal("A Fatal Error occured (Level FATAL)");

        if($this->logger->isDebugEnabled()) {
            $this->logger->debug("First Debug Statement (shouldn't be printed)");
        }
        $this->logger->setLevel(Logger::DEBUG);
        if($this->logger->isDebugEnabled()) {
            $this->logger->debug("Second Debug Statement (should be printed)");
        }
        if($this->logger->isTraceEnabled()) {
            $this->logger->trace("First Trace Statement (shouldn't be printed)");
        }
        $this->logger->setLevel(Logger::TRACE);
        if($this->logger->isTraceEnabled()) {
            $this->logger->trace("Second Trace Statement (should be printed)");
        }
    }

    public function __toString() {
        return "ASFASDFASDF";
    }
}


echo "<br/>Test Complete<br/>";