[ruby/logger] split logger classes/modules into separate files

f10ce9fff2

lib/logger/log_device.rb

@@ -0,0 +1,197 @@
+require 'logger/period'
+
+class Logger
+  # Device used for logging messages.
+  class LogDevice
+    include Period
+
+    attr_reader :dev
+    attr_reader :filename
+    include MonitorMixin
+
+    def initialize(log = nil, shift_age: nil, shift_size: nil, shift_period_suffix: nil)
+      @dev = @filename = @shift_age = @shift_size = @shift_period_suffix = nil
+      mon_initialize
+      set_dev(log)
+      if @filename
+        @shift_age = shift_age || 7
+        @shift_size = shift_size || 1048576
+        @shift_period_suffix = shift_period_suffix || '%Y%m%d'
+
+        unless @shift_age.is_a?(Integer)
+          base_time = @dev.respond_to?(:stat) ? @dev.stat.mtime : Time.now
+          @next_rotate_time = next_rotate_time(base_time, @shift_age)
+        end
+      end
+    end
+
+    def write(message)
+      begin
+        synchronize do
+          if @shift_age and @dev.respond_to?(:stat)
+            begin
+              check_shift_log
+            rescue
+              warn("log shifting failed. #{$!}")
+            end
+          end
+          begin
+            @dev.write(message)
+          rescue
+            warn("log writing failed. #{$!}")
+          end
+        end
+      rescue Exception => ignored
+        warn("log writing failed. #{ignored}")
+      end
+    end
+
+    def close
+      begin
+        synchronize do
+          @dev.close rescue nil
+        end
+      rescue Exception
+        @dev.close rescue nil
+      end
+    end
+
+    def reopen(log = nil)
+      # reopen the same filename if no argument, do nothing for IO
+      log ||= @filename if @filename
+      if log
+        synchronize do
+          if @filename and @dev
+            @dev.close rescue nil # close only file opened by Logger
+            @filename = nil
+          end
+          set_dev(log)
+        end
+      end
+      self
+    end
+
+  private
+
+    def set_dev(log)
+      if log.respond_to?(:write) and log.respond_to?(:close)
+        @dev = log
+      else
+        @dev = open_logfile(log)
+        @dev.sync = true
+        @filename = log
+      end
+    end
+
+    def open_logfile(filename)
+      begin
+        File.open(filename, (File::WRONLY | File::APPEND))
+      rescue Errno::ENOENT
+        create_logfile(filename)
+      end
+    end
+
+    def create_logfile(filename)
+      begin
+        logdev = File.open(filename, (File::WRONLY | File::APPEND | File::CREAT | File::EXCL))
+        logdev.flock(File::LOCK_EX)
+        logdev.sync = true
+        add_log_header(logdev)
+        logdev.flock(File::LOCK_UN)
+      rescue Errno::EEXIST
+        # file is created by another process
+        logdev = open_logfile(filename)
+        logdev.sync = true
+      end
+      logdev
+    end
+
+    def add_log_header(file)
+      file.write(
+        "# Logfile created on %s by %s\n" % [Time.now.to_s, Logger::ProgName]
+      ) if file.size == 0
+    end
+
+    def check_shift_log
+      if @shift_age.is_a?(Integer)
+        # Note: always returns false if '0'.
+        if @filename && (@shift_age > 0) && (@dev.stat.size > @shift_size)
+          lock_shift_log { shift_log_age }
+        end
+      else
+        now = Time.now
+        if now >= @next_rotate_time
+          @next_rotate_time = next_rotate_time(now, @shift_age)
+          lock_shift_log { shift_log_period(previous_period_end(now, @shift_age)) }
+        end
+      end
+    end
+
+    if /mswin|mingw/ =~ RUBY_PLATFORM
+      def lock_shift_log
+        yield
+      end
+    else
+      def lock_shift_log
+        retry_limit = 8
+        retry_sleep = 0.1
+        begin
+          File.open(@filename, File::WRONLY | File::APPEND) do |lock|
+            lock.flock(File::LOCK_EX) # inter-process locking. will be unlocked at closing file
+            if File.identical?(@filename, lock) and File.identical?(lock, @dev)
+              yield # log shifting
+            else
+              # log shifted by another process (i-node before locking and i-node after locking are different)
+              @dev.close rescue nil
+              @dev = open_logfile(@filename)
+              @dev.sync = true
+            end
+          end
+        rescue Errno::ENOENT
+          # @filename file would not exist right after #rename and before #create_logfile
+          if retry_limit <= 0
+            warn("log rotation inter-process lock failed. #{$!}")
+          else
+            sleep retry_sleep
+            retry_limit -= 1
+            retry_sleep *= 2
+            retry
+          end
+        end
+      rescue
+        warn("log rotation inter-process lock failed. #{$!}")
+      end
+    end
+
+    def shift_log_age
+      (@shift_age-3).downto(0) do |i|
+        if FileTest.exist?("#{@filename}.#{i}")
+          File.rename("#{@filename}.#{i}", "#{@filename}.#{i+1}")
+        end
+      end
+      @dev.close rescue nil
+      File.rename("#{@filename}", "#{@filename}.0")
+      @dev = create_logfile(@filename)
+      return true
+    end
+
+    def shift_log_period(period_end)
+      suffix = period_end.strftime(@shift_period_suffix)
+      age_file = "#{@filename}.#{suffix}"
+      if FileTest.exist?(age_file)
+        # try to avoid filename crash caused by Timestamp change.
+        idx = 0
+        # .99 can be overridden; avoid too much file search with 'loop do'
+        while idx < 100
+          idx += 1
+          age_file = "#{@filename}.#{suffix}.#{idx}"
+          break unless FileTest.exist?(age_file)
+        end
+      end
+      @dev.close rescue nil
+      File.rename("#{@filename}", age_file)
+      @dev = create_logfile(@filename)
+      return true
+    end
+  end
+end