fix: cutting out read_from_io from Input class

- To change the way to extract data after IO.select, override Input#read_from_io method
- When using binary encoded packed data containing "\n" in the data with input plugin using msgpack, an error occurred
- With the previous implementation, the input plugin depended on `io.readline(chomp: true)` when extracting data after IO.select, so the input plugin needed to send a string containing a newline
- By cutting out read_from_io method, each plugin can extend the way data is extracted

lib/fusuma/plugin/inputs/input.rb

@@ -25,19 +25,22 @@ def self.select(inputs)
 
           input = inputs.find { |i| i.io == io }
 
-          begin
-            # NOTE: io.readline is blocking method
-            # each input plugin must write line to pipe (include `\n`)
-            line = io.readline(chomp: true)
-          rescue EOFError => e
-            MultiLogger.error "#{input.class.name}: #{e}"
-            MultiLogger.error "Shutdown fusuma process..."
-            Process.kill("TERM", Process.pid)
-          rescue => e
-            MultiLogger.error "#{input.class.name}: #{e}"
-            exit 1
-          end
-          input.create_event(record: line)
+          input.create_event(record: input.read_from_io)
+        end
+
+        # @return [String, Record]
+        # IO#readline is blocking method
+        # so input plugin must write line to pipe (include `\n`)
+        # or, override read_from_io and implement your own read method
+        def read_from_io
+          io.readline(chomp: true)
+        rescue EOFError => e
+          MultiLogger.error "#{self.class.name}: #{e}"
+          MultiLogger.error "Shutdown fusuma process..."
+          Process.kill("TERM", Process.pid)
+        rescue => e
+          MultiLogger.error "#{self.class.name}: #{e}"
+          exit 1
         end
 
         # @return [Integer]

spec/fusuma/plugin/inputs/input_spec.rb

@@ -66,6 +66,11 @@ def io
           it { is_expected.to be_a IO }
         end
 
+        describe "#read_from_io" do
+          subject { dummy_input.read_from_io }
+          it { is_expected.to eq "hoge" }
+        end
+
         describe "#config_params" do
           subject { dummy_input.config_params(:dummy) }
           it { is_expected.to eq("dummy") }