use Event#from_json when possible

cosmetic reindent

refactor for the array return value of from_json

wrong paramter

refactor to support testing from_json and legacy parser

refactor to support testing from_json and legacy parser - take2

lib/logstash/codecs/json_lines.rb

@@ -36,26 +36,34 @@ def register
     @converter.logger = @logger
   end
 
-  def decode(data)
+  def decode(data, &block)
     @buffer.extract(data).each do |line|
-      yield guard(@converter.convert(line))
+      parse(@converter.convert(line), &block)
     end
-  end # def decode
+  end
 
   def encode(event)
     # Tack on a @delimiter for now because previously most of logstash's JSON
     # outputs emitted one per line, and whitespace is OK in json.
     @on_event.call(event, "#{event.to_json}#{@delimiter}")
-  end # def encode
+  end
 
   private
 
-  def guard(data)
-    begin
-      LogStash::Event.new(LogStash::Json.load(data))
-    rescue LogStash::Json::ParserError => e
-      LogStash::Event.new("message" => data, "tags" => ["_jsonparsefailure"])
-    end
+  # from_json_parse uses the Event#from_json method to deserialize and directly produce events
+  def from_json_parse(json, &block)
+    LogStash::Event.from_json(json).each { |event| yield event }
+  rescue LogStash::Json::ParserError
+    yield LogStash::Event.new("message" => json, "tags" => ["_jsonparsefailure"])
   end
 
+  # legacy_parse uses the LogStash::Json class to deserialize json
+  def legacy_parse(json, &block)
+    yield LogStash::Event.new(LogStash::Json.load(json))
+  rescue LogStash::Json::ParserError
+    yield LogStash::Event.new("message" => json, "tags" => ["_jsonparsefailure"])
+  end
+
+  alias_method :parse, LogStash::Event.respond_to?(:from_json) ? :from_json_parse : :legacy_parse
+
 end # class LogStash::Codecs::JSONLines

spec/codecs/json_lines_spec.rb

@@ -6,9 +6,10 @@
 require "insist"
 
 describe LogStash::Codecs::JSONLines do
-  subject do
-    next LogStash::Codecs::JSONLines.new
-  end
+
+  let(:codec_options) { {} }
+
+  shared_examples :codec do
 
   context "#decode" do
     it "should return an event from json data" do
@@ -37,9 +38,7 @@
     context "when using custom delimiter" do
       let(:delimiter) { "|" }
       let(:line) { "{\"hey\":1}|{\"hey\":2}|{\"hey\":3}|" }
-      subject do
-        next LogStash::Codecs::JSONLines.new("delimiter" => delimiter)
-      end
+      let(:codec_options) { { "delimiter" => delimiter } }
 
       it "should decode multiple lines separated by the delimiter" do
         result = []
@@ -122,9 +121,7 @@
 
     context "when using custom delimiter" do
       let(:delimiter) { "|" }
-      subject do
-        next LogStash::Codecs::JSONLines.new("delimiter" => delimiter)
-      end
+      let(:codec_options) { { "delimiter" => delimiter } }
 
       it "should decode multiple lines separated by the delimiter" do
         subject.on_event do |e, d|
@@ -170,4 +167,35 @@
       expect(collector.last['field']).to eq('value2')
     end
   end
+
+  end
+
+  context "forcing legacy parsing" do
+    it_behaves_like :codec do
+      subject do
+        # register method is called in the constructor
+        LogStash::Codecs::JSONLines.new(codec_options)
+      end
+
+      before(:each) do
+        # stub codec parse method to force use of the legacy parser.
+        # this is very implementation specific but I am not sure how
+        # this can be tested otherwise.
+        allow(subject).to receive(:parse) do |line, &block|
+          subject.send(:legacy_parse, line, &block)
+        end
+      end
+    end
+  end
+
+  context "default parser choice" do
+    # here we cannot force the use of the Event#from_json since if this test is run in the
+    # legacy context (no Java Event) it will fail but if in the new context, it will be picked up.
+    it_behaves_like :codec do
+      subject do
+        # register method is called in the constructor
+        LogStash::Codecs::JSONLines.new(codec_options)
+      end
+    end
+  end
 end