logger.rb: fix extra log ratation

* lib/logger.rb (lock_shift_log): no need to rotate the log file
  if it has been rotated by another process.  based on the patch
  by no6v (Nobuhiro IMAI) in [ruby-core:58620].  [Bug #9133]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44203 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Sat Dec 14 14:42:53 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/logger.rb (lock_shift_log): no need to rotate the log file
+	  if it has been rotated by another process.  based on the patch
+	  by no6v (Nobuhiro IMAI) in [ruby-core:58620].  [Bug #9133]
+
 Sat Dec 14 13:01:45 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* proc.c (mnew_from_me): method by respond_to_missing? should be

lib/logger.rb

@@ -644,8 +644,7 @@ private
         begin
           File.open(@filename, File::WRONLY | File::APPEND) do |lock|
             lock.flock(File::LOCK_EX) # inter-process locking. will be unlocked at closing file
-            ino = lock.stat.ino
-            if ino == File.stat(@filename).ino
+            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)

test/logger/test_logger.rb

@@ -2,6 +2,7 @@
 require 'test/unit'
 require 'logger'
 require 'tempfile'
+require 'tmpdir'
 require_relative '../ruby/envutil'
 
 
@@ -542,6 +543,44 @@ class TestLogDevice < Test::Unit::TestCase
     end
   end
 
+  def test_shifting_size_not_rotate_too_much
+    d(@filename).__send__(:add_log_header, @tempfile)
+    header_size = @tempfile.size
+    message = "*" * 99 + "\n"
+    shift_size = header_size + message.size * 3 - 1
+    opt = {shift_age: 1, shift_size: shift_size}
+
+    Dir.mktmpdir do |tmpdir|
+      begin
+        log = File.join(tmpdir, "log")
+        logdev1 = d(log, opt)
+        logdev2 = d(log, opt)
+
+        assert_file.identical?(log, logdev1.dev)
+        assert_file.identical?(log, logdev2.dev)
+
+        3.times{logdev1.write(message)}
+        assert_file.identical?(log, logdev1.dev)
+        assert_file.identical?(log, logdev2.dev)
+
+        logdev1.write(message)
+        assert_file.identical?(log, logdev1.dev)
+        assert_file.identical?(log + ".0", logdev2.dev)
+
+        logdev2.write(message)
+        assert_file.identical?(log, logdev1.dev)
+        assert_file.identical?(log, logdev2.dev)
+
+        logdev1.write(message)
+        assert_file.identical?(log, logdev1.dev)
+        assert_file.identical?(log, logdev2.dev)
+      ensure
+        logdev1.close if logdev1
+        logdev2.close if logdev2
+      end
+    end
+  end
+
   private
 
   def run_children(n, args, src)