add test case, found some issue and fixed them.

lib/logstash/filters/sort.rb

@@ -31,7 +31,7 @@ require "logstash/namespace"
 class LogStash::Filters::Sort < LogStash::Filters::Base
 
   config_name "sort"
-  plugin_status "experimental"
+  milestone 3
 
   config :sortSize, :validate => :number, :default => 1000
   config :sortInterval, :validate => :string, :default => "1m"
@@ -64,20 +64,23 @@ class LogStash::Filters::Sort < LogStash::Filters::Base
       return
     end
 
-    # if the event is sorted, a "sorted" tag will be marked.
-    if (!event.tags.include?"sorted")
+    # if the event is sorted, a "sorted" tag will be marked, so for those unsorted event, cancel them first.
+    if event.tags.nil? || !event.tags.include?("sorted")
       event.cancel
     else
       return
     end
 
     @mutex.synchronize{
+      @sortingArray.push(event.clone)
+
       if (@sortingArray.length == @sortSize)
         sort
       end
 
       if (@sortingDone)
         while sortedEvent = @sortingArray.pop
+          sortedEvent.tags = Array.new if sortedEvent.tags.nil?
           sortedEvent.tags << "sorted"
           filter_matched(sortedEvent)
           yield sortedEvent
@@ -85,8 +88,6 @@ class LogStash::Filters::Sort < LogStash::Filters::Base
         # reset sortingDone flag
         @sortingDone = false
       end
-
-      @sortingArray.push(event.clone)
     }
   end # def filter
 

spec/filters/sort.rb

@@ -0,0 +1,117 @@
+require "test_utils"
+require "logstash/filters/sort"
+
+describe LogStash::Filters::Sort do
+  extend LogStash::RSpec
+
+  describe "sort when sortSize is full" do
+    config <<-CONFIG
+      filter {
+        sort {
+          sortSize => 2
+        }
+      }
+    CONFIG
+
+    events = [
+      {
+        "@timestamp" => Time.iso8601("2013-01-02T00:00:00.000Z"),
+        "message" => "later message"
+      },
+      {
+        "@timestamp" => Time.iso8601("2013-01-01T00:00:00.000Z"),
+        "message" => "earlier message"
+      }
+    ]
+
+    sample(events) do
+      insist { subject }.is_a? Array
+      insist { subject.length } == 2
+      subject.each_with_index do |s,i|
+        if i == 0 # first one should be the earlier message
+          insist { s["message"] } == "earlier message"
+        end
+        if i == 1 # second one should be the later message
+          insist { s["message"]} == "later message"
+        end
+      end
+    end
+  end
+
+  describe "sort by desc" do
+    config <<-CONFIG
+      filter {
+        sort {
+          sortSize => 3
+          sortBy => "desc"
+        }
+      }
+    CONFIG
+
+    events = [
+      {
+        "@timestamp" => Time.iso8601("2013-01-03T00:00:00.000Z"),
+        "message" => "third message"
+      },
+      {
+        "@timestamp" => Time.iso8601("2013-01-01T00:00:00.000Z"),
+        "message" => "first message"
+      },
+      {
+        "@timestamp" => Time.iso8601("2013-01-02T00:00:00.000Z"),
+        "message" => "second message"
+      }
+    ]
+
+    sample(events) do
+      insist { subject }.is_a? Array
+      insist { subject.length } == 3
+      subject.each_with_index do |s,i|
+        if i == 0 # first one should be the third message
+          insist { s["message"] } == "third message"
+        end
+        if i == 1 # second one should be the second message
+          insist { s["message"]} == "second message"
+        end
+        if i == 2 # third one should be the third message
+          insist { s["message"]} == "first message"
+        end
+      end
+    end
+  end
+
+  # describe "sort when sort interval reached" do
+  #   config <<-CONFIG
+  #     filter {
+  #       sort {
+  #         sortInterval => "1s"
+  #       }
+  #     }
+  #   CONFIG
+
+  #   events = [
+  #     {
+  #       "@timestamp" => Time.iso8601("2013-01-02T00:00:00.000Z"),
+  #       "message" => "later message"
+  #     },
+  #     {
+  #       "@timestamp" => Time.iso8601("2013-01-01T00:00:00.000Z"),
+  #       "message" => "earlier message"
+  #     }
+  #   ]
+
+  #   sample(events) do
+  #     sleep(2)
+  #     insist { subject }.is_a? Array
+  #     insist { subject.length } == 2
+  #     subject.each_with_index do |s,i|
+  #       if i == 0 # first one should be the earlier message
+  #         insist { s["message"] } == "earlier message"
+  #       end
+  #       if i == 1 # second one should be the later message
+  #         insist { s["message"]} == "later message"
+  #       end
+  #     end
+  #   end
+  # end
+end