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README.md

stubbles/log

Provides support for writing log data which are business related. For a more technical approach to logging check PSR-3 compliant packages.

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Installation

stubbles/log is distributed as Composer package. To install it as a dependency of your package use the following command:

composer require "stubbles/log": "^6.0"

Requirements

stubbles/log requires at least PHP 7.0.

Usage

In your class where you want to write logs simply create a dependency to stubbles\log\Logger and use this instance to write log data:

namespace example;
use stubbles\log\Logger;
class ExampleClass
{
    private $logger;

    /**
     * @param  Logger  $logger
     */
    public function __construct(Logger $logger)
    {
        $this->logger = $logger;
    }

    public function doSomething()
    {
        // maybe some code here that does something
        $this->logger->createLogEntry('myapp')
                ->addData('foo', 'bar', 'baz')
                ->log();
        // maybe some code afterwards that does something
    }
}

In the doSomething() method we use the logger instance to create a log entry, and to add data to it. We can do this in one call, or we can add as many calls to addData() as required. After we finished adding all data we want to log we call the log() method which will take care of the actual logging process.

The string passed to createLogEntry() is the target where the log entry should end. What this means in practice depends on the log appender added to the logger. For instance, the file log appender will use the target to create a log file with this name, in this case myapp.log.

Delayed logging

Sometimes you want to log data, but not all of the data required to create the basic log entry is already available. This is where delayed logging comes into play. Instead of calling log() you simple call logDelayed():

namespace example;
use stubbles\log\Logger;
class ExampleClass
{
    private $logger;

    /**
     * @param  Logger  $logger
     */
    public function __construct(Logger $logger)
    {
        $this->logger = $logger;
    }

    public function doSomething()
    {
        // maybe some code here that does something
        $this->logger->createLogEntry('myapp')
                ->addData('foo', 'bar', 'baz')
                ->logDelayed();
        // maybe some code afterwards that does something
    }
}

This will cause a delay in logging the data, it will be logged latest when PHP process is shutdown, so if you are in a web environment this is most likely at the end of the request. Now all data of the prefilled log entry may be updated by the log entry factory used.

Log entry factories

Purpose

When new log data is created, you don't want to care about standard log data in all places where data should be logged. Log entry factories take care of creating log entries which are prefilled with data. This can be a timestamp, a session id or any other data you want to have in all log entries. Specific log data creation then only has to care about adding the specific log data.

Create log entries with a timestamp

Most common use case for log data is that the first field contains a timestamp of when this specific log data was created. For this the stubbles\log\entryfactory\TimedLogEntryFactory creates log entries which have the current timestamp in format Y-m-d H:i:s as their first field.

Create non-prefilled log entries

Sometimes it is necessary to create non prefilled log entries which after writing the log data contain the business log data only, e.g. in test cases. That's when the stubbles\log\entryfactory\EmptyLogEntryFactory can be used.

Custom log entry factories

In case the provided log entry factories don't fulfil your needs you can create your own log entry factory. For this you have to extend the stubbles\log\entryfactory\LogEntryFactory class which consists of two methods:

public function create($target, Logger $logger)
public function recreate(LogEntry $logEntry, Logger $logger)

The create() method should create new instances of stubbles\log\LogEntry. Both parameters need to be passed to the stubbles\log\LogEntry constructor. After creation, your implementation can add any log data it wants to have in all log entries. After pre filling the created log entry instance must be returned.

The recreate() is called for all log entries which are logged delayed. This is useful in case during the initial creation of the log entry not all data was available - now all data in the log entry can be replaced with the most likely now available data. In case your implementation does not have such a use case it must not implement this method, the base class already has a basic implementation which simply returns the given LogEntry instance.

Log appenders

Purpose

The stubbles\log\Logger class itself does not know how the log data is stored. Storing the log data is the task of a stubbles\log\appender\LogAppender. A log appender takes log data and writes it to the target. The target can be a file, a database or anything else suited for log data. As a concrete example stubbles/log offers a stubbles\log\appender\FileLogAppender which writes the log data into a logfile on the hard disk.

File log appender

The file log appender takes the log data and writes it into log files. It is the default appender used by stubbles/log if no other appender is specified and the log binding module (see below) is used without any alterations.

It writes the log files to a specific directory. For the default configuration this means the directory which is specified with the binding constant stubbles.log.path. In case the directory does not exist it is created beforehand. Newly created directories have the permission 0700. If you want a different permission you need to specify a constant binding named stubbles.log.filemode with the permission value.

The name of the log file will consist of the log entry target with the current date in the format YYYY-MM-DD and the file ending .log appended. So suppose today would be February 4 2012 and you create the following log data:

$logger->create('example')->addData('foo','bar')->log();

This will create a log file example-2012-02-04.log which has at least the content foo|bar.

Memory log appender

The memory log appender can be used to test classes which create log data. Instead of writing the log entries to a file or a database it simply keeps them in memory so they can be retrieved later on to perform assertions on the written log data. Suppose we have the following class:

namespace example;
use stubbles\log\Logger;
class ExampleClass
{
    private $logger;

    /**
     * @param  Logger  $logger
     */
    public function __construct(Logger $logger)
    {
        $this->logger = $logger;
    }

    public function doSomething()
    {
        ...
        $this->logger->createLogEntry('myapp')
                ->addData('foo', 'bar', 'baz')
                ->log();
        ...
    }
}

How can we make sure the correct log data is created, e.g. in a test? The answer to this is really simple - use the memory log appender:

public function testLogging()
{
    $logger = new Logger(new EmptyLogEntryFactory());
    $memoryLogAppender = new MemoryLogAppender();
    $logger->addLogAppender($memoryLogAppender);
    $exampleClasss = new ExampleClass($logger);
    $exampleClass->doSomething();

    $this->assertEquals(1, $memoryLogAppender->countLogEntries('myapp'));
    $this->assertEquals(
            ['foo', 'bar', 'baz'],
            $memoryLogAppender->getLogEntryData('myapp', 0)
    );
}

The memory log appender provides three methods to check for the logged data:

countLogEntries($target)

Returns the amount of log entries created for the given target.

getLogEntryData($target, $position)

Returns the logged data for the given target as an array. The position denotes the order in which log entries for this target were written. If there are two entries for the target myapp the first can be found at position 0 and the second at position 1.

getLogEntries($target)

Returns a list of all stubbles\log\LogEntry instances for the given target.

Custom log appenders

Other log appenders may be created by implementing the stubbles\log\appender\LogAppender interface. This interface consists of two methods:

    append(LogEntry $logEntry);
    finalize();

While append(LogEntry $logEntry) takes the log entry the log appender can do with it whatever it wants. The finalize() method is called when the PHP process ends, which means the end of the request in a web environment. The purpose of the finalize() method is to do anything necessary to persist the log entries which could not be done before.

A log appender can be added to a concrete stubbles\log\Logger instance via the addLogAppender() method:

$myLogAppender = new MyLogAppender('/path/to/dir');
$logger->addLogAppender($myLogAppender);

Integration with a Stubbles App from stubbles/ioc

Simply add the stubbles\log\ioc\Logfiles binding module to the list of bindings returned by your application class:

namespace example;
use stubbles\App;
class MyApplication extends App
{
    /**
     * returns a list of binding modules used to wire the object graph
     *
     * @return  array
     */
    public static function __bindings()
    {
        return [
                new Logfiles(),
                new StuffRequiredForExampleApplicationBindingModule()
        ];
    }

    // application methods here
}

The log binding module provides three ways to further configure how logs should be created:

  • createEntriesWith($logEntryFactory) accepts a class name or instance for a log entry factory to be used instead of the default. When not changed, the stubbles\log\entryfactory\TimedLogEntryFactory is used by default.
  • loggerProvidedBy($loggerProvider) changes the default logger instance provider to the class or instance given.
  • writeTo($logPath) can be used if you want complete freedom to name the log path. You can use this method to bind the stubbles.log.path constant to any path you like, /var/log/yourapp for example.