Update pos even if line is skipped

Signed-off-by: been.zino <been.zino@kakaocorp.com>

lib/fluent/plugin/in_tail.rb

@@ -566,7 +566,7 @@ def update_watcher(tail_watcher, pe, new_inode)
       if @follow_inodes && new_inode.nil?
         # nil inode means the file disappeared, so we only need to stop it.
         @tails.delete(tail_watcher.path)
-        # https://github.com/fluent/fluentd/pull/4237#issuecomment-1633358632 
+        # https://github.com/fluent/fluentd/pull/4237#issuecomment-1633358632
         # Because of this problem, log duplication can occur during `rotate_wait`.
         # Need to set `rotate_wait 0` for a workaround.
         # Duplication will occur if `refresh_watcher` is called during the `rotate_wait`.
@@ -1012,6 +1012,7 @@ def initialize(from_encoding, encoding, log, max_line_size=nil)
           @eol = "\n".encode(from_encoding).freeze
           @max_line_size = max_line_size
           @was_long_line = false
+          @has_skipped_line = false
           @log = log
         end
 
@@ -1047,6 +1048,7 @@ def convert(s)
 
         def read_lines(lines)
           idx = @buffer.index(@eol)
+          @has_skipped_line = false
 
           until idx.nil?
             # Using freeze and slice is faster than slice!
@@ -1064,6 +1066,7 @@ def read_lines(lines)
               @log.warn "received line length is longer than #{@max_line_size}"
               @log.debug("skipped line: ") { convert(rbuf).chomp }
               @was_long_line = false
+              @has_skipped_line = true
               next
             end
 
@@ -1077,12 +1080,17 @@ def read_lines(lines)
           if is_long_line
             @buffer.clear
             @was_long_line = true
+            @has_skipped_line = true
           end
         end
 
         def bytesize
           @buffer.bytesize
         end
+
+        def has_skipped_line?
+          @has_skipped_line
+        end
       end
 
       class IOHandler
@@ -1181,6 +1189,7 @@ def handle_notify
           with_io do |io|
             begin
               read_more = false
+              has_skipped_line = false
 
               if !io.nil? && @lines.empty?
                 begin
@@ -1195,6 +1204,7 @@ def handle_notify
 
                     n_lines_before_read = @lines.size
                     @fifo.read_lines(@lines)
+                    has_skipped_line = @fifo.has_skipped_line?
                     group_watcher&.update_lines_read(@path, @lines.size - n_lines_before_read)
 
                     group_watcher_limit = group_watcher&.limit_lines_reached?(@path)
@@ -1217,6 +1227,10 @@ def handle_notify
                 end
               end
 
+              if @lines.empty? && has_skipped_line
+                @watcher.pe.update_pos(io.pos - @fifo.bytesize)
+              end
+
               unless @lines.empty?
                 if @receive_lines.call(@lines, @watcher)
                   @watcher.pe.update_pos(io.pos - @fifo.bytesize)

test/plugin/in_tail/test_io_handler.rb

@@ -146,36 +146,34 @@ def create_watcher
       assert_equal 5, returned_lines[0].size
       assert_equal 3, returned_lines[1].size
     end
+  end
 
-    test 'call receive_lines some times when long line(more than 8192) and max_line_size is 4096' do
-      t = 'line' * (8192 / 8)
-      text = "#{t}\n" * 8
-      t = 'line' * 8
-      text += "#{t}\n" * 8
+  test 'does not call receive_lines when line_size exceeds max_line_size' do
+    t = 'x' * (8192)
+    text = "#{t}\n"
 
-      @file.write(text)
-      @file.close
+    max_line_size = 8192
 
-      update_pos = 0
+    @file.write(text)
+    @file.close
 
-      watcher = create_watcher
-      stub(watcher).pe do
-        pe = 'position_file'
-        stub(pe).read_pos {0}
-        stub(pe).update_pos { |val| update_pos = val }
-        pe
-      end
+    update_pos = 0
 
-      returned_lines = []
-      r = Fluent::Plugin::TailInput::TailWatcher::IOHandler.new(watcher, path: @file.path, read_lines_limit: 5, read_bytes_limit_per_second: -1, max_line_size: 4096, log: $log, open_on_every_update: false, metrics: @metrics) do |lines, _watcher|
-        returned_lines << lines.dup
-        true
-      end
+    watcher = create_watcher
+    stub(watcher).pe do
+      pe = 'position_file'
+      stub(pe).read_pos {0}
+      stub(pe).update_pos { |val| update_pos = val }
+      pe
+    end
 
-      r.on_notify
-      assert_equal text.bytesize, update_pos
-      assert_equal 1, returned_lines.size
-      assert_equal 8, returned_lines[0].size
+    returned_lines = []
+    r = Fluent::Plugin::TailInput::TailWatcher::IOHandler.new(watcher, path: @file.path, read_lines_limit: 1000, read_bytes_limit_per_second: -1, max_line_size: max_line_size, log: $log, open_on_every_update: false, metrics: @metrics) do |lines, _watcher|
+      returned_lines << lines.dup
+      true
     end
+
+    r.on_notify
+    assert_equal text.bytesize, update_pos
+    assert_equal 0, returned_lines.size
   end
-end