Simple logger class to:

• Keep track of log entries.
• Keep track of timings with time() and timeEnd() methods, Javascript style.
• Optionally write log entries in real-time to file or to screen.
• Optionally dump the log to file in one go at any time.

Log entries can be added with any of the following methods:

• debug( $message, $title = '' ) > a diagnostic message intended for the developer
• info( $message, $title = '' ) > an informational message intended for the user
• warning( $message, $title = '' ) > a warning that something might go wrong
• error( $message, $title = '' ) > explain why the program is going to crash

The $title argument is optional; if present, it will be prepended to the message: "$title => $message".

The following code:

Logger::$log_level = 'debug';
Logger::debug( "variable x is false" );
Logger::info( "program started" );
Logger::warning( "variable not set, something bad might happen" );
Logger::error( "file not found, exiting" );

will print to STDOUT the following lines:

$> 2021-07-21T11:11:03+02:00 [DEBUG] : variable x is false
$> 2021-07-21T11:11:03+02:00 [INFO] : program started
$> 2021-07-21T11:11:03+02:00 [WARNING] : variable not set, something bad might happen
$> 2021-07-21T11:11:03+02:00 [ERROR] : file not found, exiting

You can keep track of elapsed time by using the time() and timeEnd() function.

Logger::time();
sleep(1);
Logger::timeEnd();

will print:

$> 2022-04-19T17:26:26+00:00 [DEBUG] : Elapsed time => 1.003163 seconds

If you need to time different processes at the same time, you can use named timers.

For example:

Logger::time('outer timer');
sleep(1);
Logger::time('inner timer');
sleep(1);
Logger::timeEnd('inner timer');
Logger::timeEnd('outer timer');

will print:

$> 2022-04-19T17:32:15+00:00 [DEBUG] : Elapsed time for 'inner timer' => 1.002268 seconds
$> 2022-04-19T17:32:15+00:00 [DEBUG] : Elapsed time for 'outer timer' => 2.006117 seconds

To customize the logger, you can either:

• extend the class and override the static properties or
• set the static properties at runtime.

In the following examples, we adopt the second approach.

By default, the logger will assume it runs in production and, therefore, will print only error-level messages.

Specify your desired log level in the following way:

Logger::$log_level = 'error'; // Show only errors
Logger::$log_level = 'warning'; // Show warnings and errors
Logger::$log_level = 'info'; // Show info messages, warnings and errors
Logger::$log_level = 'debug'; // Show debug messages, info messages, warnings and errors

To also write to file, set:

Logger::$write_log = true;

To customize the log file path:

Logger::$log_dir = 'logs';
Logger::$log_file_name = 'my-log';
Logger::$log_file_extension = 'log';

To overwrite the log file at every run of the script:

Logger::$log_file_append = false;

To prevent printing to STDOUT:

Logger::$print_log = false;

The class uses the static methods and internal flags (e.g. $logger_ready) to keep its state. We do this to make the class work straight away, without any previous configuration or the need to instantiate it. This however can create race conditions if you are executing parallel code. Please let us know if this is a problem for you, if we receive enough feedback, we will switch to a more class-like approach.

Feel free to fork the repository and make a pull request!

Before sending the request, please make sure your code passes all the tests:

composer run test