in_tail: position_file: Define path based equalities on TargetInfo

In the previous Fluentd v1.11.x implementation uses patch based tailing
keys.
We wouldn't rewrite tailing mechanism entirely.
And also we're implicitly assuming path based equality for TargetInfo in tailing logic.
We should handle TargetInfo with path based equality instead of path and
inode based equality.

Signed-off-by: Hiroshi Hatake <hatake@calyptia.com>

lib/fluent/plugin/in_tail/position_file.rb

@@ -248,6 +248,20 @@ def read_inode
       end
     end
 
-    TargetInfo = Struct.new(:path, :ino)
+    TargetInfo = Struct.new(:path, :ino) do
+      def ==(other)
+        return false unless other.is_a?(TargetInfo)
+        self.path == other.path
+      end
+
+      def hash
+        self.path.hash
+      end
+
+      def eql?(other)
+        return false unless other.is_a?(TargetInfo)
+        self.path == other.path
+      end
+    end
   end
 end