Prevents event.sprintf from converting floats to sci notation

This allows sprintf to correctly print floats up to 15 decimal
places, which should be enough for most. Without this, very big
or very small floats will be converted to scientific notation.

closes #1670

lib/logstash/event.rb

@@ -48,6 +48,11 @@ class LogStash::Event
   TIMESTAMP_FAILURE_TAG = "_timestampparsefailure"
   TIMESTAMP_FAILURE_FIELD = "_@timestamp"
 
+  # Floats outside of these upper and lower bounds are forcibly converted
+  # to scientific notation by Float#to_s
+  MIN_FLOAT_BEFORE_SCI_NOT = 0.0001
+  MAX_FLOAT_BEFORE_SCI_NOT = 1000000000000000.0
+
   public
   def initialize(data = {})
     @logger = Cabin::Channel.get(LogStash)
@@ -192,7 +197,12 @@ class LogStash::Event
   # is an array (or hash?) should be. Join by comma? Something else?
   public
   def sprintf(format)
-    format = format.to_s
+    if format.is_a?(Float) and
+        (format < MIN_FLOAT_BEFORE_SCI_NOT or format >= MAX_FLOAT_BEFORE_SCI_NOT) then
+      format = ("%.15f" % format).sub(/0*$/,"")
+    else
+      format = format.to_s
+    end
     if format.index("%").nil?
       return format
     end

lib/logstash/outputs/statsd.rb

@@ -95,11 +95,11 @@ class LogStash::Outputs::Statsd < LogStash::Outputs::Base
     end
     @count.each do |metric, val|
       @client.count(build_stat(event.sprintf(metric), sender),
-                    event.sprintf(val).to_f, @sample_rate)
+                    event.sprintf(val), @sample_rate)
     end
     @timing.each do |metric, val|
       @client.timing(build_stat(event.sprintf(metric), sender),
-                     event.sprintf(val).to_f, @sample_rate)
+                     event.sprintf(val), @sample_rate)
     end
     @set.each do |metric, val|
       @client.set(build_stat(event.sprintf(metric), sender),
@@ -107,7 +107,7 @@ class LogStash::Outputs::Statsd < LogStash::Outputs::Base
     end
     @gauge.each do |metric, val|
       @client.gauge(build_stat(event.sprintf(metric), sender),
-                    event.sprintf(val).to_f, @sample_rate)
+                    event.sprintf(val), @sample_rate)
     end
   end # def receive
 

spec/outputs/statsd.rb

@@ -0,0 +1,86 @@
+require "test_utils"
+require "logstash/outputs/statsd"
+require "mocha/api"
+require "socket"
+
+describe LogStash::Outputs::Statsd do
+  extend LogStash::RSpec
+  port = 4399
+  udp_server = UDPSocket.new
+  udp_server.bind("127.0.0.1", port)
+
+  describe "send metric to statsd" do
+    config <<-CONFIG
+      input {
+        generator {
+          message => "valid"
+          count => 1
+        }
+      }
+
+      output {
+        statsd {
+          host => "localhost"
+          sender => "spec"
+          port => #{port}
+          count => [ "test.valid", "0.1" ]
+        }
+      }
+    CONFIG
+
+    agent do
+      metric, *data = udp_server.recvfrom(100)
+      insist { metric } == "logstash.spec.test.valid:0.1|c"
+    end
+  end
+
+  describe "output a very small float" do
+    config <<-CONFIG
+      input {
+        generator {
+          message => "valid"
+          count => 1
+        }
+      }
+
+      output {
+        statsd {
+          host => "localhost"
+          sender => "spec"
+          port => #{port}
+          count => [ "test.valid", 0.000001 ]
+        }
+      }
+    CONFIG
+
+    agent do
+      metric, *data = udp_server.recvfrom(100)
+      insist { metric } == "logstash.spec.test.valid:0.000001|c"
+    end
+  end
+
+  describe "output a very big float" do
+    config <<-CONFIG
+      input {
+        generator {
+          message => "valid"
+          count => 1
+        }
+      }
+
+      output {
+        statsd {
+          host => "localhost"
+          sender => "spec"
+          port => #{port}
+          count => [ "test.valid", 9999999999999.01 ]
+        }
+      }
+    CONFIG
+
+    agent do
+      metric, *data = udp_server.recvfrom(100)
+      insist { metric } == "logstash.spec.test.valid:9999999999999.01|c"
+    end
+  end
+end