diff --git a/core/authorize.php b/core/authorize.php
index 2ddd7d6..e8ba8b5 100644
--- a/core/authorize.php
+++ b/core/authorize.php
@@ -148,7 +148,7 @@ function authorize_access_allowed() {
 }
 else {
   drupal_add_http_header('Status', '403 Forbidden');
-  watchdog('access denied', 'authorize.php', NULL, WATCHDOG_WARNING);
+  watchdog('access denied', 'authorize.php', array(), WATCHDOG_WARNING);
   $page_title = t('Access denied');
   $output = t('You are not allowed to access this page.');
 }
diff --git a/core/core.services.yml b/core/core.services.yml
index 1d4d172..5071aa6 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -141,6 +141,15 @@ services:
     tags:
       - { name: needs_destruction }
     arguments: ['@database']
+  logger.factory:
+    class: Drupal\Core\Logger\LoggerChannelFactory
+    calls:
+      - [setContainer, ['@service_container']]
+  logger.channel.default:
+    class: Drupal\Core\Logger\LoggerChannel
+    factory_method: get
+    factory_service: logger.factory
+    arguments: ['system']
   settings:
     class: Drupal\Component\Utility\Settings
     factory_class: Drupal\Component\Utility\Settings
@@ -246,7 +255,7 @@ services:
     arguments: ['@service_container']
   controller_resolver:
     class: Drupal\Core\Controller\ControllerResolver
-    arguments: ['@service_container']
+    arguments: ['@service_container', '@logger.channel.default']
   title_resolver:
     class: Drupal\Core\Controller\TitleResolver
     arguments: ['@controller_resolver', '@string_translation']
@@ -317,7 +326,7 @@ services:
       - [setFinalMatcher, ['@router.matcher.final_matcher']]
   url_generator:
     class: Drupal\Core\Routing\UrlGenerator
-    arguments: ['@router.route_provider', '@path_processor_manager', '@route_processor_manager', '@config.factory', '@settings']
+    arguments: ['@router.route_provider', '@path_processor_manager', '@route_processor_manager', '@config.factory', '@settings', '@logger.channel.default']
     calls:
       - [setRequest, ['@?request']]
       - [setContext, ['@?router.request_context']]
diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index cbe749d..93110bb 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -1168,58 +1168,18 @@ function watchdog_exception($type, Exception $exception, $message = NULL, $varia
  * @param $link
  *   A link to associate with the message.
  *
+ * @deprecated in Drupal 8.x-dev, will be removed before Drupal 8.0.
+ *   Use \Drupal::logger($channel)->log($severity, $message, $context), or any
+ *   of the shortcut methods of \Psr\Log\LoggerTrait.
+ *
  * @see watchdog_severity_levels()
  * @see hook_watchdog()
  */
-function watchdog($type, $message, array $variables = NULL, $severity = WATCHDOG_NOTICE, $link = NULL) {
-  global $user, $base_root;
-
-  static $in_error_state = FALSE;
-
-  // It is possible that the error handling will itself trigger an error. In that case, we could
-  // end up in an infinite loop. To avoid that, we implement a simple static semaphore.
-  if (!$in_error_state && \Drupal::hasService('module_handler')) {
-    $in_error_state = TRUE;
-
-    // The user object may not exist in all conditions, so 0 is substituted if needed.
-    $user_uid = isset($user) ? $user->id() : 0;
-
-    // Prepare the fields to be logged
-    $log_entry = array(
-      'type'        => $type,
-      'message'     => $message,
-      'variables'   => $variables,
-      'severity'    => $severity,
-      'link'        => $link,
-      'user'        => $user,
-      'uid'         => $user_uid,
-      'request_uri' => '',
-      'referer'     => '',
-      'ip'          => '',
-      // Request time isn't accurate for long processes, use time() instead.
-      'timestamp'   => time(),
-    );
-
-    try {
-      $request = \Drupal::request();
-      $log_entry['request_uri'] = $request->getUri();
-      $log_entry['referer'] = $request->headers->get('Referer', '');
-      $log_entry['ip'] = $request->getClientIP();
-    }
-    catch (DependencyInjectionRuntimeException $e) {
-      // We are not in a request context.
-    }
-
-    // Call the logging hooks to log/process the message
-    foreach (\Drupal::moduleHandler()->getImplementations('watchdog') as $module) {
-      $function = $module . '_watchdog';
-      $function($log_entry);
-    }
-
-    // It is critical that the semaphore is only cleared here, in the parent
-    // watchdog() call (not outside the loop), to prevent recursive execution.
-    $in_error_state = FALSE;
+function watchdog($type, $message, array $variables = array(), $severity = WATCHDOG_NOTICE, $link = NULL) {
+  if ($link) {
+    $variables['link'] = $link;
   }
+  \Drupal::service('logger.factory')->get($type)->log($severity, $message, $variables);
 }
 
 /**
diff --git a/core/lib/Drupal.php b/core/lib/Drupal.php
index e1ae91a..c12e923 100644
--- a/core/lib/Drupal.php
+++ b/core/lib/Drupal.php
@@ -612,4 +612,18 @@ public static function formBuilder() {
     return static::$container->get('form_builder');
   }
 
+  /**
+   * Returns a channel logger object.
+   *
+   * @param string $channel
+   *   The name of the channel. Can be any string, but the general practice is
+   *   to use the name of the subsystem calling this.
+   *
+   * @return \Drupal\Core\Logger\LoggerChannelInterface
+   *   The logger for this channel.
+   */
+  public static function logger($channel) {
+    return static::$container->get('logger.factory')->get($channel);
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Controller/ControllerResolver.php b/core/lib/Drupal/Core/Controller/ControllerResolver.php
index 7928c36..2ce142b 100644
--- a/core/lib/Drupal/Core/Controller/ControllerResolver.php
+++ b/core/lib/Drupal/Core/Controller/ControllerResolver.php
@@ -7,9 +7,9 @@
 
 namespace Drupal\Core\Controller;
 
+use Psr\Log\LoggerInterface;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Controller\ControllerResolver as BaseControllerResolver;
-use Symfony\Component\HttpKernel\Log\LoggerInterface;
 use Symfony\Component\DependencyInjection\ContainerAwareInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
@@ -49,7 +49,7 @@ class ControllerResolver extends BaseControllerResolver implements ControllerRes
    *
    * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
    *   A ContainerInterface instance.
-   * @param \Symfony\Component\HttpKernel\Log\LoggerInterface $logger
+   * @param \Psr\Log\LoggerInterface $logger
    *   (optional) A LoggerInterface instance.
    */
   public function __construct(ContainerInterface $container, LoggerInterface $logger = NULL) {
diff --git a/core/lib/Drupal/Core/Controller/ExceptionController.php b/core/lib/Drupal/Core/Controller/ExceptionController.php
index d79567c..926d65f 100644
--- a/core/lib/Drupal/Core/Controller/ExceptionController.php
+++ b/core/lib/Drupal/Core/Controller/ExceptionController.php
@@ -136,7 +136,7 @@ public function on405Html(FlattenException $exception, Request $request) {
    */
   public function on403Html(FlattenException $exception, Request $request) {
     $system_path = $request->attributes->get('_system_path');
-    watchdog('access denied', $system_path, NULL, WATCHDOG_WARNING);
+    watchdog('access denied', $system_path, array(), WATCHDOG_WARNING);
 
     $system_config = $this->container->get('config.factory')->get('system.site');
     $path = $this->container->get('path.alias_manager')->getSystemPath($system_config->get('page.403'));
@@ -200,7 +200,7 @@ public function on403Html(FlattenException $exception, Request $request) {
    *   A response object.
    */
   public function on404Html(FlattenException $exception, Request $request) {
-    watchdog('page not found', String::checkPlain($request->attributes->get('_system_path')), NULL, WATCHDOG_WARNING);
+    watchdog('page not found', String::checkPlain($request->attributes->get('_system_path')), array(), WATCHDOG_WARNING);
 
     // Check for and return a fast 404 page if configured.
     $config = \Drupal::config('system.performance');
diff --git a/core/lib/Drupal/Core/CoreServiceProvider.php b/core/lib/Drupal/Core/CoreServiceProvider.php
index 184c767..e5b4e3e 100644
--- a/core/lib/Drupal/Core/CoreServiceProvider.php
+++ b/core/lib/Drupal/Core/CoreServiceProvider.php
@@ -15,6 +15,7 @@
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\DependencyInjection\Compiler\ModifyServiceDefinitionsPass;
 use Drupal\Core\DependencyInjection\Compiler\RegisterKernelListenersPass;
+use Drupal\Core\DependencyInjection\Compiler\RegisterLoggersPass;
 use Drupal\Core\DependencyInjection\Compiler\RegisterAccessChecksPass;
 use Drupal\Core\DependencyInjection\Compiler\RegisterPathProcessorsPass;
 use Drupal\Core\DependencyInjection\Compiler\RegisterRouteProcessorsPass;
@@ -77,6 +78,8 @@ public function register(ContainerBuilder $container) {
     $container->addCompilerPass(new CacheContextsPass());
     // Add the compiler pass for appending string translators.
     $container->addCompilerPass(new RegisterStringTranslatorsPass());
+    // Add a compiler pass for registering logging services.
+    $container->addCompilerPass(new RegisterLoggersPass());
     // Add the compiler pass that will process the tagged breadcrumb builder
     // services.
     $container->addCompilerPass(new RegisterBreadcrumbBuilderPass());
diff --git a/core/lib/Drupal/Core/DependencyInjection/Compiler/RegisterLoggersPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/RegisterLoggersPass.php
new file mode 100644
index 0000000..80723c6
--- /dev/null
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/RegisterLoggersPass.php
@@ -0,0 +1,33 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\DependencyInjection\Compiler\RegisterLoggersPass.
+ */
+
+namespace Drupal\Core\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * Registers loggers to the logger factory.
+ */
+class RegisterLoggersPass implements CompilerPassInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function process(ContainerBuilder $container) {
+    $factory = $container->getDefinition('logger.factory');
+    // Loop through all available logger services (eg dblog, syslog) and add
+    // them to the factory.
+    foreach ($container->findTaggedServiceIds('logger') as $id => $attributes) {
+      $priority = isset($attributes[0]['priority']) ? $attributes[0]['priority'] : 0;
+      $factory->addMethodCall('addLogger', array(new Reference($id), $priority));
+    }
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Form/FormBuilder.php b/core/lib/Drupal/Core/Form/FormBuilder.php
index 424b464..4b8fd4b 100644
--- a/core/lib/Drupal/Core/Form/FormBuilder.php
+++ b/core/lib/Drupal/Core/Form/FormBuilder.php
@@ -1736,7 +1736,7 @@ protected function drupalInstallationAttempted() {
   /**
    * Wraps watchdog().
    */
-  protected function watchdog($type, $message, array $variables = NULL, $severity = WATCHDOG_NOTICE, $link = NULL) {
+  protected function watchdog($type, $message, array $variables = array(), $severity = WATCHDOG_NOTICE, $link = NULL) {
     watchdog($type, $message, $variables, $severity, $link);
   }
 
diff --git a/core/lib/Drupal/Core/Logger/LogMessageParserTrait.php b/core/lib/Drupal/Core/Logger/LogMessageParserTrait.php
new file mode 100644
index 0000000..309f1e1
--- /dev/null
+++ b/core/lib/Drupal/Core/Logger/LogMessageParserTrait.php
@@ -0,0 +1,62 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Logger\LogMessageParserTrait.
+ */
+
+namespace Drupal\Core\Logger;
+
+/**
+ * Defines a trait for parsing log messages and their placeholders.
+ */
+trait LogMessageParserTrait {
+
+  /**
+   * Parses and transforms message and its placeholders to a common format.
+   *
+   * For a value to be considered as a placeholder should be in the following
+   * formats:
+   *   - PSR3 format:
+   *     @see https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-3-logger-interface.md#12-message
+   *   - Drupal specific string placeholder format:
+   *     @see \Drupal\Component\Utility\String::format()
+   *
+   * Values in PSR3 format will be transformed to String::format() format.
+   *
+   * @param string $message
+   *   The message that contains the placeholders.
+   *   If the message is in PSR3 style, it will be transformed to
+   *   \Drupal\Component\Utility\String::format() style.
+   * @param array $context
+   *   An array that may or may not contain placeholder variables.
+   *   $context['variables'] will contain the transformed variables.
+   */
+  protected function parseMessagePlaceholders(&$message, array &$context) {
+    $variables = array();
+    $has_psr3 = FALSE;
+    if (($start = strpos($message, '{')) !== FALSE && strpos($message, '}') > $start) {
+      $has_psr3 = TRUE;
+      // Transform PSR3 style messages containing placeholders to
+      // \Drupal\Component\Utility\String::format() style.
+      $message = preg_replace('/\{(.*)\}/U', '@$1', $message);
+    }
+    foreach ($context as $key => $variable) {
+      // PSR3 style placeholders.
+      if ($has_psr3) {
+        // Keys are not prefixed with anything according to PSR3 specs.
+        // If the message is "User {username} created" the variable key will be
+        // just "username".
+        if (strpos($message, '@' . $key) !== FALSE) {
+          $key = '@' . $key;
+        }
+      }
+      if (!empty($key) && ($key[0] === '@' || $key[0] === '%' || $key[0] === '!')) {
+        // The key is now in \Drupal\Component\Utility\String::format() style.
+        $variables[$key] = $variable;
+      }
+    }
+    $context['variables'] = $variables;
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Logger/LoggerChannel.php b/core/lib/Drupal/Core/Logger/LoggerChannel.php
new file mode 100644
index 0000000..3cc64e7
--- /dev/null
+++ b/core/lib/Drupal/Core/Logger/LoggerChannel.php
@@ -0,0 +1,157 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Logger\LoggerChannel.
+ */
+
+namespace Drupal\Core\Logger;
+
+use Drupal\Core\Session\AccountInterface;
+use Psr\Log\LoggerInterface;
+use Psr\Log\LoggerTrait;
+use Psr\Log\LogLevel;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Defines a logger channel that most implementations will use.
+ */
+class LoggerChannel implements LoggerChannelInterface {
+  use LoggerTrait;
+
+  /**
+   * The name of the channel of this logger instance.
+   */
+  protected $channel;
+
+  /**
+   * Map of PSR Log constants to Watchdog log constants.
+   *
+   * This only exists for BC.
+   * @todo Remove once watchdog() is removed.
+   *
+   * @var array
+   */
+  protected $levelTranslation = array(
+    LogLevel::EMERGENCY => WATCHDOG_EMERGENCY,
+    LogLevel::ALERT => WATCHDOG_ALERT,
+    LogLevel::CRITICAL => WATCHDOG_CRITICAL,
+    LogLevel::ERROR => WATCHDOG_ERROR,
+    LogLevel::WARNING => WATCHDOG_WARNING,
+    LogLevel::NOTICE => WATCHDOG_NOTICE,
+    LogLevel::INFO => WATCHDOG_INFO,
+    LogLevel::DEBUG => WATCHDOG_DEBUG,
+  );
+
+  /**
+   * An array of arrays of \Psr\Log\LoggerInterface keyed by priority.
+   *
+   * @var array
+   */
+  protected $loggers = array();
+
+  /**
+   * The request object.
+   *
+   * @var \Symfony\Component\HttpFoundation\Request
+   */
+  protected $request;
+
+  /**
+   * The current user object.
+   *
+   * @var \Drupal\Core\Session\AccountInterface
+   */
+  protected $currentUser;
+
+  /**
+   * Constructs a LoggerChannel object
+   *
+   * @param string $channel
+   *   The channel name for this instance.
+   */
+  public function __construct($channel) {
+    $this->channel = $channel;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function log($level, $message, array $context = array()) {
+    // Merge in defaults.
+    $context += array(
+      'channel' => $this->channel,
+      'link' => '',
+      'user' => NULL,
+      'uid' => 0,
+      'request_uri' => '',
+      'referer' => '',
+      'ip' => '',
+      'timestamp' => time(),
+    );
+    if ($this->currentUser) {
+      $context['user'] = $this->currentUser;
+      $context['uid'] = $this->currentUser->id();
+    }
+    // Some context values are only available when in a request context.
+    if ($this->request) {
+      $context['request_uri'] = $this->request->getUri();
+      $context['referer'] = $this->request->headers->get('Referer', '');
+      $context['ip'] = $this->request->getClientIP();
+    }
+
+    if (is_string($level)) {
+      // Convert to integer equivalent for BC.
+      $level = $this->levelTranslation[$level];
+    }
+    // Call all available loggers.
+    foreach ($this->sortLoggers() as $logger) {
+      $logger->log($level, $message, $context);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setRequest(Request $request = NULL) {
+    $this->request = $request;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setCurrentUser(AccountInterface $current_user = NULL) {
+    $this->currentUser = $current_user;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setLoggers(array $loggers) {
+    $this->loggers = $loggers;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function addLogger(LoggerInterface $logger, $priority = 0) {
+    $this->loggers[$priority][] = $logger;
+  }
+
+  /**
+   * Sorts loggers according to priority.
+   *
+   * @return array
+   *   An array of sorted loggers by priority.
+   */
+  protected function sortLoggers() {
+    $sorted = array();
+    krsort($this->loggers);
+
+    foreach ($this->loggers as $loggers) {
+      $sorted = array_merge($sorted, $loggers);
+    }
+    return $sorted;
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Logger/LoggerChannelFactory.php b/core/lib/Drupal/Core/Logger/LoggerChannelFactory.php
new file mode 100644
index 0000000..58c01ba
--- /dev/null
+++ b/core/lib/Drupal/Core/Logger/LoggerChannelFactory.php
@@ -0,0 +1,69 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Logger\LoggerChannelFactory.
+ */
+
+namespace Drupal\Core\Logger;
+
+use Psr\Log\LoggerInterface;
+use Symfony\Component\DependencyInjection\ContainerAware;
+use Symfony\Component\DependencyInjection\Exception\RuntimeException;
+
+/**
+ * Defines a factory for logging channels.
+ */
+class LoggerChannelFactory extends ContainerAware implements LoggerChannelFactoryInterface {
+
+  /**
+   * Array of all instantiated logger channels keyed by channel name.
+   *
+   * @var Drupal\Core\Logger\LoggerChannelInterface[]
+   */
+  protected $channels = array();
+
+  /**
+   * An array of arrays of \Psr\Log\LoggerInterface keyed by priority.
+   *
+   * @var array
+   */
+  protected $loggers = array();
+
+  /**
+   * {@inheritdoc}
+   */
+  public function get($channel) {
+    if (!isset($this->channels[$channel])) {
+      $instance = new LoggerChannel($channel);
+
+      // If the request is available, set it with the current user to the channel.
+      try {
+        $instance->setRequest($this->container->get('request'));
+        $instance->setCurrentUser($this->container->get('current_user'));
+      }
+      catch (RuntimeException $e) {
+        // We are not in a request context.
+      }
+
+      // Pass the loggers to the channel.
+      $instance->setLoggers($this->loggers);
+      $this->channels[$channel] = $instance;
+    }
+
+    return $this->channels[$channel];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function addLogger(LoggerInterface $logger, $priority = 0) {
+    // Store it so we can pass it to potential new logger instances.
+    $this->loggers[$priority][] = $logger;
+    // Add the logger to already instantiated channels.
+    foreach ($this->channels as $channel) {
+      $channel->addLogger($logger, $priority);
+    }
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Logger/LoggerChannelFactoryInterface.php b/core/lib/Drupal/Core/Logger/LoggerChannelFactoryInterface.php
new file mode 100644
index 0000000..67d178c
--- /dev/null
+++ b/core/lib/Drupal/Core/Logger/LoggerChannelFactoryInterface.php
@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Logger\LoggerChannelFactoryInterface.
+ */
+
+namespace Drupal\Core\Logger;
+
+use Psr\Log\LoggerInterface;
+
+/**
+ * Logger channel factory interface.
+ */
+interface LoggerChannelFactoryInterface {
+
+  /**
+   * Retrieves the registered logger for the requested channel.
+   *
+   * @return \Drupal\Core\Logger\LoggerChannelInterface
+   *   The registered logger for this channel.
+   */
+  public function get($channel);
+
+  /**
+   * Adds a logger.
+   *
+   * Here is were all services tagged as 'logger' are being retrieved and then
+   * passed to the channels after instantiation.
+   *
+   * @param \Psr\Log\LoggerInterface $logger
+   *   The PSR-3 logger to add.
+   * @param int $priority
+   *   The priority of the logger being added.
+   *
+   * @see \Drupal\Core\DependencyInjection\Compiler\RegisterLoggersPass
+   */
+  public function addLogger(LoggerInterface $logger, $priority = 0);
+
+}
diff --git a/core/lib/Drupal/Core/Logger/LoggerChannelInterface.php b/core/lib/Drupal/Core/Logger/LoggerChannelInterface.php
new file mode 100644
index 0000000..15d9741
--- /dev/null
+++ b/core/lib/Drupal/Core/Logger/LoggerChannelInterface.php
@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Logger\LoggerChannelInterface.
+ */
+
+namespace Drupal\Core\Logger;
+
+use Drupal\Core\Session\AccountInterface;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Logger channel interface.
+ */
+interface LoggerChannelInterface extends LoggerInterface {
+
+  /**
+   * Sets the request.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request|null $request
+   *   The current request object.
+   */
+  public function setRequest(Request $request = NULL);
+
+  /**
+   * Sets the current user.
+   *
+   * @param \Drupal\Core\Session\AccountInterface|null $current_user
+   *   The current user object.
+   */
+  public function setCurrentUser(AccountInterface $current_user = NULL);
+
+  /**
+   * Sets the loggers for this channel.
+   *
+   * @param array $loggers
+   *   An array of arrays of \Psr\Log\LoggerInterface keyed by priority.
+   */
+  public function setLoggers(array $loggers);
+
+  /**
+   * Adds a logger.
+   *
+   * @param \Psr\Log\LoggerInterface $logger
+   *   The PSR-3 logger to add.
+   * @param int $priority
+   *   The priority of the logger being added.
+   */
+  public function addLogger(LoggerInterface $logger, $priority = 0);
+
+}
diff --git a/core/lib/Drupal/Core/Routing/UrlGenerator.php b/core/lib/Drupal/Core/Routing/UrlGenerator.php
index 2402708..9f368ea 100644
--- a/core/lib/Drupal/Core/Routing/UrlGenerator.php
+++ b/core/lib/Drupal/Core/Routing/UrlGenerator.php
@@ -7,8 +7,8 @@
 
 namespace Drupal\Core\Routing;
 
+use Psr\Log\LoggerInterface;
 use Symfony\Component\HttpFoundation\Request;
-use Symfony\Component\HttpKernel\Log\LoggerInterface;
 
 use Symfony\Component\Routing\Route as SymfonyRoute;
 use Symfony\Component\Routing\Exception\RouteNotFoundException;
@@ -88,7 +88,7 @@ class UrlGenerator extends ProviderBasedGenerator implements UrlGeneratorInterfa
    *    The config factory.
    * @param \Drupal\Component\Utility\Settings $settings
    *    The read only settings.
-   * @param \Symfony\Component\HttpKernel\Log\LoggerInterface $logger
+   * @param \Psr\Log\LoggerInterface $logger
    *   An optional logger for recording errors.
    */
   public function __construct(RouteProviderInterface $provider, OutboundPathProcessorInterface $path_processor, OutboundRouteProcessorInterface $route_processor, ConfigFactoryInterface $config, Settings $settings, LoggerInterface $logger = NULL) {
diff --git a/core/modules/dblog/dblog.module b/core/modules/dblog/dblog.module
index 5052a8a..637385d 100644
--- a/core/modules/dblog/dblog.module
+++ b/core/modules/dblog/dblog.module
@@ -11,8 +11,6 @@
  * @see watchdog()
  */
 
-use Drupal\Core\Database\Database;
-
 /**
  * Implements hook_help().
  */
@@ -126,31 +124,6 @@ function _dblog_get_message_types() {
 }
 
 /**
- * Implements hook_watchdog().
- *
- * Note: Some values may be truncated to meet database column size restrictions.
- */
-function dblog_watchdog(array $log_entry) {
-  // Remove any backtraces since they may contain an unserializable variable.
-  unset($log_entry['variables']['backtrace']);
-
-  Database::getConnection('default', 'default')->insert('watchdog')
-    ->fields(array(
-      'uid' => $log_entry['uid'],
-      'type' => substr($log_entry['type'], 0, 64),
-      'message' => $log_entry['message'],
-      'variables' => serialize($log_entry['variables']),
-      'severity' => $log_entry['severity'],
-      'link' => substr($log_entry['link'], 0, 255),
-      'location' => $log_entry['request_uri'],
-      'referer' => $log_entry['referer'],
-      'hostname' => substr($log_entry['ip'], 0, 128),
-      'timestamp' => $log_entry['timestamp'],
-    ))
-    ->execute();
-}
-
-/**
  * Implements hook_form_FORM_ID_alter() for system_logging_settings().
  */
 function dblog_form_system_logging_settings_alter(&$form, $form_state) {
diff --git a/core/modules/dblog/dblog.services.yml b/core/modules/dblog/dblog.services.yml
new file mode 100644
index 0000000..c07cb32
--- /dev/null
+++ b/core/modules/dblog/dblog.services.yml
@@ -0,0 +1,6 @@
+services:
+  logger.dblog:
+    class: Drupal\dblog\Logger\DbLog
+    arguments: ['@database']
+    tags:
+      - { name: logger }
diff --git a/core/modules/dblog/lib/Drupal/dblog/Logger/DbLog.php b/core/modules/dblog/lib/Drupal/dblog/Logger/DbLog.php
new file mode 100644
index 0000000..80d7136
--- /dev/null
+++ b/core/modules/dblog/lib/Drupal/dblog/Logger/DbLog.php
@@ -0,0 +1,67 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\dblog\Logger\DbLog.
+ */
+
+namespace Drupal\dblog\Logger;
+
+use Drupal\Core\Database\Connection;
+use Drupal\Core\Logger\LogMessageParserTrait;
+use Psr\Log\LoggerInterface;
+use Psr\Log\LoggerTrait;
+
+/**
+ * Logs events in the watchdog database table.
+ */
+class DbLog implements LoggerInterface {
+  use LoggerTrait;
+  use LogMessageParserTrait;
+
+  /**
+   * The database connection object.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $database;
+
+  /**
+   * Constructs a DbLog object.
+   *
+   * @param \Drupal\Core\Database\Connection $database
+   *   The database connection object.
+   */
+  public function __construct(Connection $database) {
+    $this->database = $database;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function log($level, $message, array $context = array()) {
+    // Remove any backtraces since they may contain an unserializable variable.
+    unset($context['backtrace']);
+
+    // Convert PSR3-style messages to String::format() style, so they can be
+    // translated too in runtime.
+    $this->parseMessagePlaceholders($message, $context);
+
+    $this->database
+      ->insert('watchdog')
+      ->fields(array(
+        'uid' => $context['uid'],
+        'type' => substr($context['channel'], 0, 64),
+        'message' => $message,
+        'variables' => serialize($context['variables']),
+        'severity' => $level,
+        'link' => substr($context['link'], 0, 255),
+        'location' => $context['request_uri'],
+        'referer' => $context['referer'],
+        'hostname' => substr($context['ip'], 0, 128),
+        'timestamp' => $context['timestamp'],
+      ))
+      ->execute();
+  }
+
+}
diff --git a/core/modules/dblog/lib/Drupal/dblog/Tests/DbLogTest.php b/core/modules/dblog/lib/Drupal/dblog/Tests/DbLogTest.php
index 24add00..dd4a575 100644
--- a/core/modules/dblog/lib/Drupal/dblog/Tests/DbLogTest.php
+++ b/core/modules/dblog/lib/Drupal/dblog/Tests/DbLogTest.php
@@ -129,7 +129,7 @@ private function generateLogEntries($count, $type = 'custom', $severity = WATCHD
 
     // Prepare the fields to be logged
     $log = array(
-      'type'        => $type,
+      'channel'     => $type,
       'message'     => 'Log entry added to test the dblog row limit.',
       'variables'   => array(),
       'severity'    => $severity,
@@ -144,7 +144,7 @@ private function generateLogEntries($count, $type = 'custom', $severity = WATCHD
     $message = 'Log entry added to test the dblog row limit. Entry #';
     for ($i = 0; $i < $count; $i++) {
       $log['message'] = $message . $i;
-      dblog_watchdog($log);
+      $this->container->get('logger.dblog')->log($severity, $log['message'], $log);
     }
   }
 
@@ -412,7 +412,7 @@ protected function testDBLogAddAndClear() {
     // Get a count of how many watchdog entries already exist.
     $count = db_query('SELECT COUNT(*) FROM {watchdog}')->fetchField();
     $log = array(
-      'type'        => 'custom',
+      'channel'     => 'system',
       'message'     => 'Log entry added to test the doClearTest clear down.',
       'variables'   => array(),
       'severity'    => WATCHDOG_NOTICE,
@@ -425,7 +425,7 @@ protected function testDBLogAddAndClear() {
       'timestamp'   => REQUEST_TIME,
     );
     // Add a watchdog entry.
-    dblog_watchdog($log);
+    $this->container->get('logger.dblog')->log($log['severity'], $log['message'], $log);
     // Make sure the table count has actually been incremented.
     $this->assertEqual($count + 1, db_query('SELECT COUNT(*) FROM {watchdog}')->fetchField(), format_string('dblog_watchdog() added an entry to the dblog :count', array(':count' => $count)));
     // Login the admin user.
@@ -530,7 +530,7 @@ protected function getLogEntries() {
       foreach ($table->tbody->tr as $row) {
         $entries[] = array(
           'severity' => $this->getSeverityConstant($row['class']),
-          'type' => $this->asText($row->td[1]),
+          'channel' => $this->asText($row->td[1]),
           'message' => $this->asText($row->td[3]),
           'user' => $this->asText($row->td[4]),
         );
@@ -553,7 +553,7 @@ protected function getTypeCount(array $types) {
     $count = array_fill(0, count($types), 0);
     foreach ($entries as $entry) {
       foreach ($types as $key => $type) {
-        if ($entry['type'] == $type['type'] && $entry['severity'] == $type['severity']) {
+        if ($entry['channel'] == $type['type'] && $entry['severity'] == $type['severity']) {
           $count[$key]++;
           break;
         }
diff --git a/core/modules/filter/lib/Drupal/filter/Tests/FilterSettingsTest.php b/core/modules/filter/lib/Drupal/filter/Tests/FilterSettingsTest.php
index a11db5d..f37d48b 100644
--- a/core/modules/filter/lib/Drupal/filter/Tests/FilterSettingsTest.php
+++ b/core/modules/filter/lib/Drupal/filter/Tests/FilterSettingsTest.php
@@ -34,13 +34,11 @@ public static function getInfo() {
    */
   function testFilterDefaults() {
     $filter_info = $this->container->get('plugin.manager.filter')->getDefinitions();
-    $filters = array_fill_keys(array_keys($filter_info), array());
 
     // Create text format using filter default settings.
     $filter_defaults_format = entity_create('filter_format', array(
       'format' => 'filter_defaults',
       'name' => 'Filter defaults',
-      'filters' => $filters,
     ));
     $filter_defaults_format->save();
 
diff --git a/core/modules/rest/lib/Drupal/rest/Tests/DBLogTest.php b/core/modules/rest/lib/Drupal/rest/Tests/DBLogTest.php
index 53e5ed7..0bebb19 100644
--- a/core/modules/rest/lib/Drupal/rest/Tests/DBLogTest.php
+++ b/core/modules/rest/lib/Drupal/rest/Tests/DBLogTest.php
@@ -41,9 +41,9 @@ public function setUp() {
    */
   public function testWatchdog() {
     // Write a log message to the DB.
-    watchdog('rest_test', 'Test message');
+    watchdog('rest', 'Test message');
     // Get the ID of the written message.
-    $id = db_query_range("SELECT wid FROM {watchdog} WHERE type = :type ORDER BY wid DESC", 0, 1, array(':type' => 'rest_test'))
+    $id = db_query_range("SELECT wid FROM {watchdog} WHERE type = :type ORDER BY wid DESC", 0, 1, array(':type' => 'rest'))
       ->fetchField();
 
     // Create a user account that has the required permissions to read
@@ -56,7 +56,7 @@ public function testWatchdog() {
     $this->assertHeader('content-type', $this->defaultMimeType);
     $log = Json::decode($response);
     $this->assertEqual($log['wid'], $id, 'Log ID is correct.');
-    $this->assertEqual($log['type'], 'rest_test', 'Type of log message is correct.');
+    $this->assertEqual($log['type'], 'rest', 'Type of log message is correct.');
     $this->assertEqual($log['message'], 'Test message', 'Log message text is correct.');
 
     // Request an unknown log entry.
diff --git a/core/modules/syslog/lib/Drupal/syslog/Logger/SysLog.php b/core/modules/syslog/lib/Drupal/syslog/Logger/SysLog.php
new file mode 100644
index 0000000..17dd040
--- /dev/null
+++ b/core/modules/syslog/lib/Drupal/syslog/Logger/SysLog.php
@@ -0,0 +1,86 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\syslog\Logger\SysLog.
+ */
+
+namespace Drupal\syslog\Logger;
+
+use Drupal\Core\Config\ConfigFactory;
+use Drupal\Core\Logger\LogMessageParserTrait;
+use Psr\Log\LoggerInterface;
+use Psr\Log\LoggerTrait;
+
+/**
+ * Redirects logging messages to syslog.
+ */
+class SysLog implements LoggerInterface {
+  use LoggerTrait;
+  use LogMessageParserTrait;
+
+  /**
+   * A configuration object containin syslog settings.
+   *
+   * @var \Drupal\Core\Config\Config
+   */
+  protected $config;
+
+  /**
+   * Stores whether there is a system logger connection opened or not.
+   *
+   * @var bool
+   */
+  protected $connectionOpened = FALSE;
+
+  /**
+   * Constructs a SysLog object.
+   *
+   * @param \Drupal\Core\Config\ConfigFactory $config_factory
+   *   The configuration factory object.
+   */
+  public function __construct(ConfigFactory $config_factory) {
+    $this->config = $config_factory->get('syslog.settings');
+  }
+
+  /**
+   * Opens a connection to the system logger.
+   */
+  protected function openConnection() {
+    if (!$this->connectionOpened) {
+      $facility = $this->config->get('facility');
+      if ($facility === '') {
+        $facility = defined('LOG_LOCAL0') ? LOG_LOCAL0 : LOG_USER;
+      }
+      $this->connectionOpened = openlog($this->config->get('identity'), LOG_NDELAY, $facility);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function log($level, $message, array $context = array()) {
+    global $base_url;
+
+    // Ensure we have a connection available.
+    $this->openConnection();
+
+    // Populate the $context['variables'] with the message placeholders.
+    $this->parseMessagePlaceholders($message, $context);
+
+    $entry = strtr($this->config->get('format'), array(
+      '!base_url' => $base_url,
+      '!timestamp' => $context['timestamp'],
+      '!type' => $context['channel'],
+      '!ip' => $context['ip'],
+      '!request_uri' => $context['request_uri'],
+      '!referer' => $context['referer'],
+      '!uid' => $context['uid'],
+      '!link' => strip_tags($context['link']),
+      '!message' => strip_tags(empty($context['variables']) ? $message : strtr($message, $context['variables'])),
+    ));
+
+    syslog($level, $entry);
+  }
+
+}
diff --git a/core/modules/syslog/syslog.module b/core/modules/syslog/syslog.module
index a93ee93..ef282d1 100644
--- a/core/modules/syslog/syslog.module
+++ b/core/modules/syslog/syslog.module
@@ -87,36 +87,3 @@ function syslog_facility_list() {
     LOG_LOCAL7 => 'LOG_LOCAL7',
   );
 }
-
-/**
- * Implements hook_watchdog().
- */
-function syslog_watchdog(array $log_entry) {
-  global $base_url;
-
-  $log_init = &drupal_static(__FUNCTION__, FALSE);
-  $config = \Drupal::config('syslog.settings');
-
-  if (!$log_init) {
-    $log_init = TRUE;
-    $facility = $config->get('facility');
-    if ($facility === '') {
-      $facility = defined('LOG_LOCAL0') ? LOG_LOCAL0 : LOG_USER;
-    }
-    openlog($config->get('identity'), LOG_NDELAY, $facility);
-  }
-
-  $message = strtr($config->get('format'), array(
-    '!base_url'    => $base_url,
-    '!timestamp'   => $log_entry['timestamp'],
-    '!type'        => $log_entry['type'],
-    '!ip'          => $log_entry['ip'],
-    '!request_uri' => $log_entry['request_uri'],
-    '!referer'     => $log_entry['referer'],
-    '!uid'         => $log_entry['uid'],
-    '!link'        => strip_tags($log_entry['link']),
-    '!message'     => strip_tags(!isset($log_entry['variables']) ? $log_entry['message'] : strtr($log_entry['message'], $log_entry['variables'])),
-  ));
-
-  syslog($log_entry['severity'], $message);
-}
diff --git a/core/modules/syslog/syslog.services.yml b/core/modules/syslog/syslog.services.yml
new file mode 100644
index 0000000..98f6041
--- /dev/null
+++ b/core/modules/syslog/syslog.services.yml
@@ -0,0 +1,6 @@
+services:
+  logger.syslog:
+    class: Drupal\syslog\Logger\SysLog
+    arguments: ['@config.factory']
+    tags:
+      - { name: logger }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityApiInfoTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityApiInfoTest.php
index 93fd554..1849f25 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityApiInfoTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityApiInfoTest.php
@@ -48,9 +48,9 @@ function testEntityInfoChanges() {
   /**
    * Tests entity info cache after enabling a module with a dependency on an entity providing module.
    *
-   * @see entity_cache_test_watchdog()
+   * @see entity_cache_test_modules_enabled()
    */
-  function testEntityInfoCacheWatchdog() {
+  function testEntityInfoCacheModulesEnabled() {
     \Drupal::moduleHandler()->install(array('entity_cache_test'));
     $entity_type = \Drupal::state()->get('entity_cache_test');
     $this->assertEqual($entity_type->getLabel(), 'Entity Cache Test', 'Entity info label is correct.');
diff --git a/core/modules/system/lib/Drupal/system/Tests/Pager/PagerTest.php b/core/modules/system/lib/Drupal/system/Tests/Pager/PagerTest.php
index dc8ead4..845aa28 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Pager/PagerTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Pager/PagerTest.php
@@ -36,7 +36,7 @@ function setUp() {
 
     // Insert 300 log messages.
     for ($i = 0; $i < 300; $i++) {
-      watchdog('pager_test', $this->randomString(), NULL, WATCHDOG_DEBUG);
+      watchdog('pager_test', $this->randomString(), array(), WATCHDOG_DEBUG);
     }
 
     $this->admin_user = $this->drupalCreateUser(array(
diff --git a/core/modules/system/system.api.php b/core/modules/system/system.api.php
index 8083f89..7189524 100644
--- a/core/modules/system/system.api.php
+++ b/core/modules/system/system.api.php
@@ -1230,94 +1230,6 @@ function hook_template_preprocess_default_variables_alter(&$variables) {
 }
 
 /**
- * Log an event message.
- *
- * This hook allows modules to route log events to custom destinations, such as
- * SMS, Email, pager, syslog, ...etc.
- *
- * @param array $log_entry
- *   An associative array containing the following keys:
- *   - type: The type of message for this entry.
- *   - user: The user object for the user who was logged in when the event
- *     happened.
- *   - uid: The user ID for the user who was logged in when the event happened.
- *   - request_uri: The request URI for the page the event happened in.
- *   - referer: The page that referred the user to the page where the event
- *     occurred.
- *   - ip: The IP address where the request for the page came from.
- *   - timestamp: The UNIX timestamp of the date/time the event occurred.
- *   - severity: The severity of the message; one of the following values as
- *     defined in @link http://www.faqs.org/rfcs/rfc3164.html RFC 3164: @endlink
- *     - WATCHDOG_EMERGENCY: Emergency, system is unusable.
- *     - WATCHDOG_ALERT: Alert, action must be taken immediately.
- *     - WATCHDOG_CRITICAL: Critical conditions.
- *     - WATCHDOG_ERROR: Error conditions.
- *     - WATCHDOG_WARNING: Warning conditions.
- *     - WATCHDOG_NOTICE: Normal but significant conditions.
- *     - WATCHDOG_INFO: Informational messages.
- *     - WATCHDOG_DEBUG: Debug-level messages.
- *   - link: An optional link provided by the module that called the watchdog()
- *     function.
- *   - message: The text of the message to be logged. Variables in the message
- *     are indicated by using placeholder strings alongside the variables
- *     argument to declare the value of the placeholders. See t() for
- *     documentation on how the message and variable parameters interact.
- *   - variables: An array of variables to be inserted into the message on
- *     display. Will be NULL or missing if a message is already translated or if
- *     the message is not possible to translate.
- */
-function hook_watchdog(array $log_entry) {
-  global $base_url;
-  $language_interface = \Drupal::languageManager()->getCurrentLanguage();
-
-  $severity_list = array(
-    WATCHDOG_EMERGENCY     => t('Emergency'),
-    WATCHDOG_ALERT     => t('Alert'),
-    WATCHDOG_CRITICAL     => t('Critical'),
-    WATCHDOG_ERROR       => t('Error'),
-    WATCHDOG_WARNING   => t('Warning'),
-    WATCHDOG_NOTICE    => t('Notice'),
-    WATCHDOG_INFO      => t('Info'),
-    WATCHDOG_DEBUG     => t('Debug'),
-  );
-
-  $to = 'someone@example.com';
-  $params = array();
-  $params['subject'] = t('[@site_name] @severity_desc: Alert from your web site', array(
-    '@site_name' => \Drupal::config('system.site')->get('name'),
-    '@severity_desc' => $severity_list[$log_entry['severity']],
-  ));
-
-  $params['message']  = "\nSite:         @base_url";
-  $params['message'] .= "\nSeverity:     (@severity) @severity_desc";
-  $params['message'] .= "\nTimestamp:    @timestamp";
-  $params['message'] .= "\nType:         @type";
-  $params['message'] .= "\nIP Address:   @ip";
-  $params['message'] .= "\nRequest URI:  @request_uri";
-  $params['message'] .= "\nReferrer URI: @referer_uri";
-  $params['message'] .= "\nUser:         (@uid) @name";
-  $params['message'] .= "\nLink:         @link";
-  $params['message'] .= "\nMessage:      \n\n@message";
-
-  $params['message'] = t($params['message'], array(
-    '@base_url'      => $base_url,
-    '@severity'      => $log_entry['severity'],
-    '@severity_desc' => $severity_list[$log_entry['severity']],
-    '@timestamp'     => format_date($log_entry['timestamp']),
-    '@type'          => $log_entry['type'],
-    '@ip'            => $log_entry['ip'],
-    '@request_uri'   => $log_entry['request_uri'],
-    '@referer_uri'   => $log_entry['referer'],
-    '@uid'           => $log_entry['uid'],
-    '@name'          => $log_entry['user']->name,
-    '@link'          => strip_tags($log_entry['link']),
-    '@message'       => strip_tags($log_entry['message']),
-  ));
-
-  drupal_mail('emaillog', 'entry', $to, $language_interface->id, $params);
-}
-
-/**
  * Prepare a message based on parameters; called from drupal_mail().
  *
  * Note that hook_mail(), unlike hook_mail_alter(), is only called on the
diff --git a/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module b/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module
index 9b28815..f91afde 100644
--- a/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module
+++ b/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module
@@ -6,7 +6,7 @@
  */
 
 /**
- * Implements hook_watchdog().
+ * Implements hook_modules_installed().
  *
  * This hook is called during \Drupal\Core\Extension\ModuleHandler::install()
  * and since this hook implementation is invoked, we have to expect that this
@@ -14,13 +14,11 @@
  * expect to be able to retrieve the entity information that has been registered
  * by the required dependency module.
  *
- * @see EnableDisableTestCase::testEntityCache()
+ * @see EntityApiInfoTest::testEntityInfoCacheModulesEnabled()
  */
-function entity_cache_test_watchdog($log_entry) {
-  if ($log_entry['type'] == 'system' && $log_entry['message'] == '%module module installed.') {
-    $info = \Drupal::entityManager()->getDefinition('entity_cache_test');
-    // Store the information in a system variable to analyze it later in the
-    // test case.
-    \Drupal::state()->set('entity_cache_test', $info);
-  }
+function entity_cache_test_modules_installed($modules_enabled) {
+  $info = \Drupal::entityManager()->getDefinition('entity_cache_test');
+  // Store the information in a system variable to analyze it later in the
+  // test case.
+  \Drupal::state()->set('entity_cache_test', $info);
 }
diff --git a/core/tests/Drupal/Tests/Core/EventSubscriber/SpecialAttributesRouteSubscriberTest.php b/core/tests/Drupal/Tests/Core/EventSubscriber/SpecialAttributesRouteSubscriberTest.php
index 0bb5006..65ba07d 100644
--- a/core/tests/Drupal/Tests/Core/EventSubscriber/SpecialAttributesRouteSubscriberTest.php
+++ b/core/tests/Drupal/Tests/Core/EventSubscriber/SpecialAttributesRouteSubscriberTest.php
@@ -118,7 +118,7 @@ public function testOnRouteBuildingInvalidVariables(Route $route) {
 
 namespace {
   if (!function_exists('watchdog')) {
-    function watchdog($type, $message, array $args = NULL) {
+    function watchdog($type, $message, array $args = array()) {
     }
   }
   if (!function_exists('drupal_set_message')) {
diff --git a/core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php b/core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php
index a1d2ff9..d070209 100644
--- a/core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php
+++ b/core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php
@@ -752,6 +752,7 @@ public static function create(ContainerInterface $container) {
 namespace {
   function test_form_id_custom_submit(array &$form, array &$form_state) {
   }
+  // @todo Remove once watchdog() is removed.
   if (!defined('WATCHDOG_ERROR')) {
     define('WATCHDOG_ERROR', 3);
   }
diff --git a/core/tests/Drupal/Tests/Core/Form/FormTestBase.php b/core/tests/Drupal/Tests/Core/Form/FormTestBase.php
index 44059c4..7cf98b7 100644
--- a/core/tests/Drupal/Tests/Core/Form/FormTestBase.php
+++ b/core/tests/Drupal/Tests/Core/Form/FormTestBase.php
@@ -297,7 +297,7 @@ protected function drupalSetMessage($message = NULL, $type = 'status', $repeat =
   /**
    * {@inheritdoc}
    */
-  protected function watchdog($type, $message, array $variables = NULL, $severity = WATCHDOG_NOTICE, $link = NULL) {
+  protected function watchdog($type, $message, array $variables = array(), $severity = WATCHDOG_NOTICE, $link = NULL) {
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTraitTest.php b/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTraitTest.php
new file mode 100644
index 0000000..a7b81cf
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTraitTest.php
@@ -0,0 +1,95 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Logger\LogMessageParserTraitTest
+ */
+
+namespace Drupal\Tests\Core\Logger;
+
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Tests the log message parser trait.
+ *
+ * @see \Drupal\Core\Logger\LogMessageParserTrait
+ * @coversDefaultClass \Drupal\Core\Logger\LogMessageParserTrait
+ *
+ * @group Drupal
+ * @group Logger
+ */
+class LogMessageParserTraitTest extends UnitTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Log message parser',
+      'description' => 'Unit tests for the log message parser trait.',
+      'group' => 'Logger',
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    $this->logger = $this->getObjectForTrait('Drupal\Core\Logger\LogMessageParserTrait');
+  }
+
+  /**
+   * Test for LogMessageParserTrait::parseMessagePlaceholders()
+   *
+   * @param array $value
+   *   An array containing:
+   *    - message: A string that contains a message with placeholders.
+   *    - context: An array with placeholder values.
+   * @param array $expected
+   *   An array with the expected values after the test has run.
+   *    - message: The expected parsed message.
+   *    - context: The expected values of the placeholders.
+   *
+   * @dataProvider providerTestParseMessagePlaceholders
+   * @covers ::parseMessagePlaceholders
+   */
+  public function testParseMessagePlaceholders(array $value, array $expected) {
+    $class = new \ReflectionClass($this->logger);
+    $method = $class->getMethod('parseMessagePlaceholders');
+    $method->setAccessible(TRUE);
+    $method->invokeArgs($this->logger, array(&$value['message'], &$value['context']));
+    $this->assertEquals($expected['message'], $value['message']);
+    $this->assertEquals($expected['context'], $value['context']['variables']);
+  }
+
+  /**
+   * Data provider for testParseMessagePlaceholders().
+   */
+  public function providerTestParseMessagePlaceholders() {
+    return array(
+      // PSR3 only message.
+      array(
+        array('message' => 'User {username} created', 'context' => array('username' => 'Dries')),
+        array('message' => 'User @username created', 'context' => array('@username' => 'Dries')),
+      ),
+      // PSR3 style mixed in a format_string style message.
+      array(
+        array('message' => 'User {username} created @time', 'context' => array('username' => 'Dries', '@time' => 'now')),
+        array('message' => 'User @username created @time', 'context' => array('@username' => 'Dries', '@time' => 'now')),
+      ),
+      // format_string style message only.
+      array(
+        array('message' => 'User @username created', 'context' => array('@username' => 'Dries')),
+        array('message' => 'User @username created', 'context' => array('@username' => 'Dries')),
+      ),
+      // Messsage without placeholders but wildcard characters.
+      array(
+        array('message' => 'User W-\\};~{&! created @', 'context' => array('' => '')),
+        array('message' => 'User W-\\};~{&! created @', 'context' => array()),
+      ),
+      // Messsage with double PSR3 style messages.
+      array(
+        array('message' => 'Test {with} two {encapsuled} strings', 'context' => array('with' => 'together', 'encapsuled' => 'awesome')),
+        array('message' => 'Test @with two @encapsuled strings', 'context' => array('@with' => 'together', '@encapsuled' => 'awesome')),
+      ),
+    );
+  }
+
+}
diff --git a/core/tests/Drupal/Tests/Core/Logger/LoggerChannelFactoryTest.php b/core/tests/Drupal/Tests/Core/Logger/LoggerChannelFactoryTest.php
new file mode 100644
index 0000000..23f2ef6
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Logger/LoggerChannelFactoryTest.php
@@ -0,0 +1,63 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Logger\LoggerChannelFactoryTest
+ */
+
+namespace Drupal\Tests\Logger;
+
+use Drupal\Core\Logger\LoggerChannelFactory;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\HttpFoundation\Request;
+
+// @todo Remove once watchdog() is removed.
+if (!defined('WATCHDOG_EMERGENCY')) {
+  define('WATCHDOG_EMERGENCY', 0);
+  define('WATCHDOG_ALERT', 1);
+  define('WATCHDOG_CRITICAL', 2);
+  define('WATCHDOG_WARNING', 4);
+  define('WATCHDOG_NOTICE', 5);
+  define('WATCHDOG_INFO', 6);
+  define('WATCHDOG_DEBUG', 7);
+}
+// WATCHDOG_ERROR is also defined in FormBuilderTest, so check independently.
+if (!defined('WATCHDOG_ERROR')) {
+  define('WATCHDOG_ERROR', 3);
+}
+
+/**
+ * Tests the logger channel factory.
+ *
+ * @see \Drupal\Core\Logger\LoggerChannelFactory
+ * @coversDefaultClass \Drupal\Core\Logger\LoggerChannelFactory
+ *
+ * @group Drupal
+ * @group Logger
+ */
+class LoggerChannelFactoryTest extends UnitTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Logger channel factory',
+      'description' => 'Unit tests for the logger channel factory object.',
+      'group' => 'Logger',
+    );
+  }
+
+  /**
+   * Test for LoggerChannelFactory::get()
+   *
+   * @covers ::get
+   */
+  public function testGet() {
+    $factory = new LoggerChannelFactory();
+    $factory->setContainer($this->getMock('Symfony\Component\DependencyInjection\ContainerInterface'));
+
+    // Ensure that when called with the same argument, always the same instance
+    // will be returned.
+    $this->assertEquals($factory->get('test'), $factory->get('test'));
+  }
+
+}
diff --git a/core/tests/Drupal/Tests/Core/Logger/LoggerChannelTest.php b/core/tests/Drupal/Tests/Core/Logger/LoggerChannelTest.php
new file mode 100644
index 0000000..817f935
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Logger/LoggerChannelTest.php
@@ -0,0 +1,155 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Logger\LoggerChannelTest
+ */
+
+namespace Drupal\Tests\Logger;
+
+use Drupal\Core\Logger\LoggerChannel;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\HttpFoundation\Request;
+
+// @todo Remove once watchdog() is removed.
+if (!defined('WATCHDOG_EMERGENCY')) {
+  define('WATCHDOG_EMERGENCY', 0);
+  define('WATCHDOG_ALERT', 1);
+  define('WATCHDOG_CRITICAL', 2);
+  define('WATCHDOG_WARNING', 4);
+  define('WATCHDOG_NOTICE', 5);
+  define('WATCHDOG_INFO', 6);
+  define('WATCHDOG_DEBUG', 7);
+}
+// WATCHDOG_ERROR is also defined in FormBuilderTest, so check independently.
+if (!defined('WATCHDOG_ERROR')) {
+  define('WATCHDOG_ERROR', 3);
+}
+
+/**
+ * Tests the logger channel.
+ *
+ * @see \Drupal\Core\Logger\LoggerChannel
+ * @coversDefaultClass \Drupal\Core\Logger\LoggerChannel
+ *
+ * @group Drupal
+ * @group Logger
+ */
+class LoggerChannelTest extends UnitTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Logger channel',
+      'description' => 'Unit tests for the logger channel object.',
+      'group' => 'Logger',
+    );
+  }
+
+  /**
+   * Test for LoggerChannel::log()
+   *
+   * @param callable $expected
+   *   An anonymous function to use with $this->callback() of the logger mock.
+   *   The function should check the $context array for expected values.
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   Will be passed to the channel under test if present.
+   * @param \Drupal\Core\Session\AccountInterface $current_user
+   *   Will be passed to the channel under test if present.
+   *
+   * @dataProvider providerTestLog
+   * @covers ::log
+   * @covers ::setCurrentUser
+   * @covers ::setRequest
+   */
+  public function testLog(callable $expected, Request $request = NULL, AccountInterface $current_user = NULL) {
+    $channel = new LoggerChannel('test');
+    $message = $this->randomName();
+    $logger = $this->getMock('Psr\Log\LoggerInterface');
+    $logger->expects($this->once())
+      ->method('log')
+      ->with($this->anything(), $message, $this->callback($expected));
+    $channel->addLogger($logger);
+    if ($request) {
+      $channel->setRequest($request);
+    }
+    if ($current_user) {
+      $channel->setCurrentUser($current_user);
+    }
+    $channel->log(rand(0, 7), $message);
+  }
+
+  /**
+   * Test for LoggerChannel::addLoggers()
+   *
+   * @covers ::addLogger
+   * @covers ::sortLoggers
+   */
+  public function testSortLoggers() {
+    $channel = new LoggerChannel($this->randomName());
+    $index_order = '';
+    for ($i = 0; $i < 4; $i++) {
+      $logger = $this->getMock('Psr\Log\LoggerInterface');
+      $logger->expects($this->once())
+        ->method('log')
+        ->will($this->returnCallback(function () use ($i, &$index_order) {
+          // Append the $i to the index order, so that we know the order that
+          // loggers got called with.
+          $index_order .= $i;
+        }));
+      $channel->addLogger($logger, $i);
+    }
+
+    $channel->log(rand(0, 7), $this->randomName());
+    // Ensure that the logger added in the end fired first.
+    $this->assertEquals($index_order, '3210');
+  }
+
+  /**
+   * Data provider for self::testLog().
+   */
+  public function providerTestLog() {
+    $account_mock = $this->getMock('Drupal\Core\Session\AccountInterface');
+    $account_mock->expects($this->exactly(2))
+      ->method('id')
+      ->will($this->returnValue(1));
+
+    $request_mock = $this->getMock('Symfony\Component\HttpFoundation\Request');
+    $request_mock->expects($this->exactly(2))
+      ->method('getClientIp')
+      ->will($this->returnValue('127.0.0.1'));
+    $request_mock->headers = $this->getMock('Symfony\Component\HttpFoundation\ParameterBag');
+
+    // No request or account.
+    $cases [] = array(
+      function ($context) {
+        return $context['channel'] == 'test' && empty($contex['uid']) && empty($context['ip']);
+      },
+    );
+    // With account but not request.
+    $cases [] = array(
+      function ($context) {
+        return $context['uid'] === 1 && empty($context['ip']);
+      },
+      NULL,
+      $account_mock,
+    );
+    // With request but not account.
+    $cases [] = array(
+      function ($context) {
+        return $context['ip'] === '127.0.0.1' && empty($contex['uid']);
+      },
+      $request_mock,
+    );
+    // Both request and account.
+    $cases [] = array(
+      function ($context) {
+        return $context['ip'] === '127.0.0.1' && $context['uid'] === 1;
+      },
+      $request_mock,
+      $account_mock,
+    );
+    return $cases;
+  }
+
+}
diff --git a/core/update.php b/core/update.php
index cd94972..5ab001b 100644
--- a/core/update.php
+++ b/core/update.php
@@ -230,7 +230,7 @@ function update_info_page() {
 function update_access_denied_page() {
   drupal_add_http_header('Status', '403 Forbidden');
   header(\Drupal::request()->server->get('SERVER_PROTOCOL') . ' 403 Forbidden');
-  watchdog('access denied', 'update.php', NULL, WATCHDOG_WARNING);
+  watchdog('access denied', 'update.php', array(), WATCHDOG_WARNING);
   $output = '<p>Access denied. You are not authorized to access this page. Log in using either an account with the <em>administer software updates</em> permission or the site maintenance account (the account you created during installation). If you cannot log in, you will have to edit <code>settings.php</code> to bypass this access check. To do this:</p>
 <ol>
  <li>With a text editor find the settings.php file on your system. From the main Drupal directory that you installed all the files into, go to <code>sites/your_site_name</code> if such directory exists, or else to <code>sites/default</code> which applies otherwise.</li>
