Add 404 exclusion via a NotFoundActivationStrategy, fixes #5

To configure use:

monolog:
    handlers:
        main:
            type:         fingers_crossed
            action_level: error
            handler:      nested
            excluded_404s:
                - ^/foo/

Author: Seldaek

DependencyInjection/Configuration.php

@@ -58,6 +58,7 @@
  * - fingers_crossed:
  *   - handler: the wrapped handler's name
  *   - [action_level|activation_strategy]: minimum level or service id to activate the handler, defaults to WARNING
+ *   - [excluded_404s]: if set, the strategy will be changed to one that excludes 404s coming from URLs matching any of those patterns
  *   - [buffer_size]: defaults to 0 (unlimited)
  *   - [stop_buffering]: bool to disable buffering once the handler has been activated, defaults to true
  *   - [bubble]: bool, defaults to true
@@ -205,6 +206,10 @@ public function getConfigTreeBuilder()
                             ->scalarNode('action_level')->defaultValue('WARNING')->end() // fingers_crossed
                             ->scalarNode('activation_strategy')->defaultNull()->end() // fingers_crossed
                             ->booleanNode('stop_buffering')->defaultTrue()->end()// fingers_crossed
+                            ->arrayNode('excluded_404s') // fingers_crossed
+                                ->canBeUnset()
+                                ->prototype('scalar')->end()
+                            ->end()
                             ->scalarNode('buffer_size')->defaultValue(0)->end() // fingers_crossed and buffer
                             ->scalarNode('handler')->end() // fingers_crossed and buffer
                             ->scalarNode('url')->end() // cube
@@ -391,6 +396,10 @@ public function getConfigTreeBuilder()
                             ->ifTrue(function($v) { return ('fingers_crossed' === $v['type'] || 'buffer' === $v['type']) && 1 !== count($v['handler']); })
                             ->thenInvalid('The handler has to be specified to use a FingersCrossedHandler or BufferHandler')
                         ->end()
+                        ->validate()
+                            ->ifTrue(function($v) { return 'fingers_crossed' === $v['type'] && !empty($v['excluded_404s']) && !empty($v['activation_strategy']); })
+                            ->thenInvalid('You can not use excluded_404s together with a custom activation_strategy in a FingersCrossedHandler')
+                        ->end()
                         ->validate()
                             ->ifTrue(function($v) { return 'swift_mailer' === $v['type'] && empty($v['email_prototype']) && (empty($v['from_email']) || empty($v['to_email']) || empty($v['subject'])); })
                             ->thenInvalid('The sender, recipient and subject or an email prototype have to be specified to use a SwiftMailerHandler')

DependencyInjection/MonologExtension.php

@@ -17,6 +17,7 @@
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Reference;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpKernel\Kernel;
 
 /**
@@ -192,6 +193,11 @@ private function buildHandler(ContainerBuilder $container, $name, array $handler
 
             if (isset($handler['activation_strategy'])) {
                 $activation = new Reference($handler['activation_strategy']);
+            } elseif (!empty($handler['excluded_404s'])) {
+                $activationDef = new Definition('%monolog.activation_strategy.not_found.class%', array($handler['excluded_404s'], $handler['action_level']));
+                $activationDef->addMethodCall('setRequest', array(new Reference('request', ContainerInterface::NULL_ON_INVALID_REFERENCE, false)));
+                $container->setDefinition($handlerId.'.not_found_strategy', $activationDef);
+                $activation = new Reference($handlerId.'.not_found_strategy');
             } else {
                 $activation = $handler['action_level'];
             }

NotFoundActivationStrategy.php

@@ -0,0 +1,58 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\MonologBundle;
+
+use Monolog\Handler\FingersCrossed\ErrorLevelActivationStrategy;
+use Symfony\Component\HttpKernel\Exception\HttpException;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Activation strategy that ignores 404s for certain URLs
+ *
+ * Configure with:
+ *
+ *   monolog:
+ *       handlers:
+ *           main:
+ *               type:         fingers_crossed
+ *               action_level: error
+ *               handler:      nested
+ *               excluded_404s:
+ *                   - ^/foo/
+ *
+ * @author Jordi Boggiano <j.boggiano@seld.be>
+ */
+class NotFoundActivationStrategy extends ErrorLevelActivationStrategy
+{
+    private $blacklist;
+    private $request;
+
+    public function __construct(array $excludedUrls, $actionLevel)
+    {
+        parent::__construct($actionLevel);
+        $this->blacklist = '{('.implode('|', $excludedUrls).')}i';
+    }
+
+    public function isHandlerActivated(array $record)
+    {
+        if (parent::isHandlerActivated($record) && $this->request && isset($record['context']['exception']) && $record['context']['exception'] instanceof HttpException && $record['context']['exception']->getStatusCode() == 404) {
+            return !preg_match($this->blacklist, $this->request->getPathInfo());
+        }
+
+        return false;
+    }
+
+    public function setRequest(Request $req = null)
+    {
+        $this->request = $req;
+    }
+}

Resources/config/monolog.xml

@@ -29,6 +29,7 @@
         <parameter key="monolog.handler.cube.class">Monolog\Handler\CubeHandler</parameter>
         <parameter key="monolog.handler.amqp.class">Monolog\Handler\AmqpHandler</parameter>
         <parameter key="monolog.handler.error_log.class">Monolog\Handler\ErrorLogHandler</parameter>
+        <parameter key="monolog.activation_strategy.not_found.class">Symfony\Bundle\MonologBundle\NotFoundActivationStrategy</parameter>
 
         <parameter key="monolog.handler.fingers_crossed.class">Monolog\Handler\FingersCrossedHandler</parameter>
         <parameter key="monolog.handler.fingers_crossed.error_level_activation_strategy.class">Monolog\Handler\FingersCrossed\ErrorLevelActivationStrategy</parameter>