Added ability to add additional information to the logs via processors.

Added backtrace processor to include backtraces in the logs.
Added requestid processor to include a unique id per request in the logs.

library/Zend/Log/Logger.php

@@ -59,13 +59,27 @@ class Logger implements LoggerInterface
      */
     protected $writers;
 
+    /**
+     * Processors
+     *
+     * @var SplPriorityQueue
+     */
+    protected $processors;
+
     /**
      * Writer plugins
      *
      * @var WriterPluginManager
      */
     protected $writerPlugins;
 
+    /**
+     * Processor plugins
+     *
+     * @var ProcessorPluginManager
+     */
+    protected $processorPlugins;
+
     /**
      * Registered error handler
      *
@@ -89,6 +103,7 @@ class Logger implements LoggerInterface
     public function __construct()
     {
         $this->writers = new SplPriorityQueue();
+        $this->processors = new SplPriorityQueue();
     }
 
     /**
@@ -206,6 +221,90 @@ public function setWriters(SplPriorityQueue $writers)
         return $this;
     }
 
+
+    /**
+     * Get processor plugin manager
+     *
+     * @return ProcessorPluginManager
+     */
+    public function getProcessorPluginManager()
+    {
+        if (null === $this->processorPlugins) {
+            $this->setProcessorPluginManager(new ProcessorPluginManager());
+        }
+        return $this->processorPlugins;
+    }
+
+    /**
+     * Set processor plugin manager
+     *
+     * @param  string|ProcessorPluginManager $plugins
+     * @return Logger
+     * @throws Exception\InvalidArgumentException
+     */
+    public function setProcessorPluginManager($plugins)
+    {
+        if (is_string($plugins)) {
+            $plugins = new $plugins;
+        }
+        if (!$plugins instanceof ProcessorPluginManager) {
+            throw new Exception\InvalidArgumentException(sprintf(
+                    'processor plugin manager must extend %s\ProcessorPluginManager; received %s',
+                    __NAMESPACE__,
+                    is_object($plugins) ? get_class($plugins) : gettype($plugins)
+            ));
+        }
+
+        $this->processorPlugins = $plugins;
+        return $this;
+    }
+
+    /**
+     * Get processor instance
+     *
+     * @param string $name
+     * @param array|null $options
+     * @return Processor\ProcessorInterface
+     */
+    public function processorPlugin($name, array $options = null)
+    {
+        return $this->getProcessorPluginManager()->get($name, $options);
+    }
+
+    /**
+     * Add a processor to a logger
+     *
+     * @param  string|Processor\ProcessorInterface $processor
+     * @param  int $priority
+     * @param  array|null $options
+     * @return Logger
+     * @throws Exception\InvalidArgumentException
+     */
+    public function addProcessor($processor, $priority = 1, array $options = null)
+    {
+        if (is_string($processor)) {
+            $processor = $this->processorPlugin($processor, $options);
+        } elseif (!$processor instanceof Processor\ProcessorInterface) {
+            throw new Exception\InvalidArgumentException(sprintf(
+                    'Processor must implement Zend\Log\ProcessorInterface; received "%s"',
+                    is_object($processor) ? get_class($processor) : gettype($processor)
+            ));
+        }
+        $this->processors->insert($processor, $priority);
+
+        return $this;
+    }
+
+    /**
+     * Get processors
+     *
+     * @return SplPriorityQueue
+     */
+    public function getProcessors()
+    {
+        return $this->processors;
+    }
+
     /**
      * Add a message as a log entry
      *
@@ -250,14 +349,20 @@ public function log($priority, $message, $extra = array())
             $message = var_export($message, true);
         }
 
+        $event = array(
+            'timestamp'    => $timestamp,
+            'priority'     => (int) $priority,
+            'priorityName' => $this->priorities[$priority],
+            'message'      => (string) $message,
+            'extra'        => $extra
+        );
+
+        foreach($this->processors->toArray() as $processor) {
+            $event = $processor->process($event);
+        }
+
         foreach ($this->writers->toArray() as $writer) {
-            $writer->write(array(
-                'timestamp'    => $timestamp,
-                'priority'     => (int) $priority,
-                'priorityName' => $this->priorities[$priority],
-                'message'      => (string) $message,
-                'extra'        => $extra
-            ));
+            $writer->write($event);
         }
 
         return $this;

library/Zend/Log/Processor/Backtrace.php

@@ -0,0 +1,84 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+*
+* @link      http://github.com/zendframework/zf2 for the canonical source repository
+* @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
+* @license   http://framework.zend.com/license/new-bsd New BSD License
+* @package   Zend_Log
+*/
+
+namespace Zend\Log\Processor;
+
+/**
+ * @category   Zend
+ * @package    Zend_Log
+ * @subpackage Processor
+ */
+class Backtrace implements ProcessorInterface
+{
+    /**
+     * Maximum stack level of backtrace (PHP > 5.4.0)
+     * @var int
+     */
+    protected $traceLimit = 10;
+
+    /**
+     * Classes within this namespace in the stack are ignored
+     * @var string
+     */
+    protected $ignoredNamespace = 'Zend\\Log';
+
+    /**
+     * Adds the origin of the log() call to the event extras
+     *
+     * @param array $event event data
+     * @return array event data
+    */
+    public function process(array $event)
+    {
+      $trace = $this->getBacktrace();
+
+      array_shift($trace); // ignore $this->getBacktrace();
+      array_shift($trace); // ignore $this->process()
+
+      $i = 0;
+      while (isset($trace[$i]['class']) && false !== strpos($trace[$i]['class'], $this->ignoredNamespace)) {
+          $i++;
+      }
+
+      $origin = array(
+          'file' => isset($trace[$i-1]['file']) ? $trace[$i-1]['file'] : null,
+          'line' => isset($trace[$i-1]['line']) ? $trace[$i-1]['line'] : null,
+          'class' => isset($trace[$i]['class']) ? $trace[$i]['class'] : null,
+          'function' => isset($trace[$i]['function']) ? $trace[$i]['function'] : null,
+      );
+
+      if(!isset($event['extra'])) {
+          $event['extra'] = $origin;
+      } else {
+          $event['extra'] = array_merge($origin, $event['extra']);
+      }
+
+      return $event;
+    }
+
+    /**
+     * Provide backtrace as slim as posible
+     *
+     * @return  array:
+     */
+    protected function getBacktrace()
+    {
+        if (version_compare(PHP_VERSION, '5.4.0') >= 0) {
+            return debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, $this->traceLimit);
+        }
+
+        if (version_compare(PHP_VERSION, '5.3.6') >= 0) {
+            return debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
+        }
+
+        return debug_backtrace();
+    }
+
+}

library/Zend/Log/Processor/ProcessorInterface.php

@@ -0,0 +1,27 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @link      http://github.com/zendframework/zf2 for the canonical source repository
+ * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   http://framework.zend.com/license/new-bsd New BSD License
+ * @package   Zend_Log
+ */
+
+namespace Zend\Log\Processor;
+
+/**
+ * @category   Zend
+ * @package    Zend_Log
+ */
+interface ProcessorInterface
+{
+    /**
+     * Processes a log message before it is given to the writers
+     *
+     * @param  array $event
+     * @return WriterInterface
+     */
+    public function process(array $event);
+
+}

library/Zend/Log/Processor/RequestId.php

@@ -0,0 +1,61 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+*
+* @link      http://github.com/zendframework/zf2 for the canonical source repository
+* @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
+* @license   http://framework.zend.com/license/new-bsd New BSD License
+* @package   Zend_Log
+*/
+
+namespace Zend\Log\Processor;
+
+/**
+ * @category   Zend
+ * @package    Zend_Log
+ * @subpackage Processor
+ */
+class RequestId implements ProcessorInterface
+{
+
+    /**
+     * Adds a identfier for the request to the log.
+     * This enables to filter the log for messages belonging to a specific request
+     *
+     * @param array $event event data
+     * @return array event data
+     */
+    public function process(array $event)
+    {
+        if(!isset($event['extra'])) {
+            $event['extra'] = array();
+        }
+
+        $event['extra']['requestId'] = $this->getIdentifier();
+        return $event;
+    }
+
+    /**
+     * Provide unique identifier for a request
+     *
+     * @return  array:
+     */
+    protected function getIdentifier()
+    {
+        $requestTime = (version_compare(PHP_VERSION, '5.4.0') >= 0) ? $_SERVER['REQUEST_TIME_FLOAT'] : $_SERVER['REQUEST_TIME'];
+        $remoteAddr = $this->isCli() ? 'local' : $_SERVER['REMOTE_ADDR'];
+
+        return md5($requestTime . $remoteAddr);
+    }
+
+    /**
+     * Check if PHP is run from command line
+     *
+     * @return boolean true if php is run from command line
+     */
+    protected function isCli()
+    {
+        return php_sapi_name() == 'cli' && empty($_SERVER['REMOTE_ADDR']);
+    }
+
+}

library/Zend/Log/ProcessorPluginManager.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @link      http://github.com/zendframework/zf2 for the canonical source repository
+ * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   http://framework.zend.com/license/new-bsd New BSD License
+ * @package   Zend_Log
+ */
+
+namespace Zend\Log;
+
+use Zend\ServiceManager\AbstractPluginManager;
+
+/**
+ * @category   Zend
+ * @package    Zend_Log
+ */
+class ProcessorPluginManager extends AbstractPluginManager
+{
+    /**
+     * Default set of writers
+     *
+     * @var array
+     */
+    protected $invokableClasses = array(
+        'backtrace' => 'Zend\Log\Processor\Backtrace',
+        'requestid' => 'Zend\Log\Processor\RequestId',
+    );
+
+    /**
+     * Allow many writers of the same type
+     *
+     * @var bool
+     */
+    protected $shareByDefault = false;
+
+    /**
+     * Validate the plugin
+     *
+     * Checks that the processor loaded is an instance of Processor\ProcessorInterface.
+     *
+     * @param  mixed $plugin
+     * @return void
+     * @throws Exception\InvalidArgumentException if invalid
+     */
+    public function validatePlugin($plugin)
+    {
+        if ($plugin instanceof Processor\ProcessorInterface) {
+            // we're okay
+            return;
+        }
+
+        throw new Exception\InvalidArgumentException(sprintf(
+            'Plugin of type %s is invalid; must implement %s\Processor\ProcessorInterface',
+            (is_object($plugin) ? get_class($plugin) : gettype($plugin)),
+            __NAMESPACE__
+        ));
+    }
+}