1 files changed, 93 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/logger.rb b/activesupport/lib/active_support/logger.rb
new file mode 100644
index 0000000000..b8555c887b
--- /dev/null
+++ b/activesupport/lib/active_support/logger.rb
@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+require "active_support/logger_silence"
+require "active_support/logger_thread_safe_level"
+require "logger"
+
+module ActiveSupport
+  class Logger < ::Logger
+    include LoggerSilence
+
+    # Returns true if the logger destination matches one of the sources
+    #
+    #   logger = Logger.new(STDOUT)
+    #   ActiveSupport::Logger.logger_outputs_to?(logger, STDOUT)
+    #   # => true
+    def self.logger_outputs_to?(logger, *sources)
+      logdev = logger.instance_variable_get("@logdev")
+      logger_source = logdev.dev if logdev.respond_to?(:dev)
+      sources.any? { |source| source == logger_source }
+    end
+
+    # Broadcasts logs to multiple loggers.
+    def self.broadcast(logger) # :nodoc:
+      Module.new do
+        define_method(:add) do |*args, &block|
+          logger.add(*args, &block)
+          super(*args, &block)
+        end
+
+        define_method(:<<) do |x|
+          logger << x
+          super(x)
+        end
+
+        define_method(:close) do
+          logger.close
+          super()
+        end
+
+        define_method(:progname=) do |name|
+          logger.progname = name
+          super(name)
+        end
+
+        define_method(:formatter=) do |formatter|
+          logger.formatter = formatter
+          super(formatter)
+        end
+
+        define_method(:level=) do |level|
+          logger.level = level
+          super(level)
+        end
+
+        define_method(:local_level=) do |level|
+          logger.local_level = level if logger.respond_to?(:local_level=)
+          super(level) if respond_to?(:local_level=)
+        end
+
+        define_method(:silence) do |level = Logger::ERROR, &block|
+          if logger.respond_to?(:silence)
+            logger.silence(level) do
+              if defined?(super)
+                super(level, &block)
+              else
+                block.call(self)
+              end
+            end
+          else
+            if defined?(super)
+              super(level, &block)
+            else
+              block.call(self)
+            end
+          end
+        end
+      end
+    end
+
+    def initialize(*args)
+      super
+      @formatter = SimpleFormatter.new
+    end
+
+    # Simple formatter which only displays the message.
+    class SimpleFormatter < ::Logger::Formatter
+      # This method is invoked when a log event occurs
+      def call(severity, timestamp, progname, msg)
+        "#{String === msg ? msg : msg.inspect}\n"
+      end
+    end
+  end
+end