Add encode for Line Protocol

lib/linr.rb

@@ -1,5 +1,6 @@
 require "linr/version"
 require "linr/data"
+require "linr/encoder"
 require "linr/connection"
 
 # A simple UDP client for InfluxDB

lib/linr/connection/udp.rb

@@ -1,5 +1,9 @@
 module Linr
   module Connection
+    # Connects to a InfluxDB UDP port
+    # @see https://influxdb.com/docs/v0.9/write_protocols/udp.html
+    # @example
+    #   UDP.new("localhost", 8089).send("series a=0.51")
     class UDP
       # Use non-custom flags
       SEND_FLAGS = 0
@@ -12,7 +16,9 @@ def initialize(host, port)
         @socket.connect(host, port)
       end
 
-      # Send arbitrary data ober the UDP connection
+      # Send data over the UDP connection. Should be encoded using the Line
+      # Protocol.
+      # @see Encoder::Line
       # @param data [String]
       def send(data)
         @socket.send(data, SEND_FLAGS)

lib/linr/encoder.rb

@@ -0,0 +1 @@
+require "linr/encoder/line"

lib/linr/encoder/line.rb

@@ -0,0 +1,81 @@
+module Linr
+  module Encoder
+    # Encodes data entry into the InfluxDB line format.
+    # @see https://influxdb.com/docs/v0.9/write_protocols/write_syntax.html
+    # @example Encode a data series
+    #   Line.new.dump(Data.new(measurement: "series", fields: { a: 0.5 }))
+    class Line
+      # Encodes data into the line syntax
+      # @param data [Data]
+      # @return [String]
+      def dump(data)
+        [
+          dump_measurement(data.measurement),
+          dump_tags(data.tags),
+          dump_fields(data.fields),
+          dump_timestamp(data.timestamp)
+        ].compact.join
+      end
+
+      private
+
+      def dump_measurement(measurement)
+        escape_key(measurement)
+      end
+
+      def dump_tags(tags)
+        dump_collection(tags, ",") do |key, value|
+          "#{escape_key(key)}=#{escape_value(value)}"
+        end
+      end
+
+      def dump_fields(fields)
+        dump_collection(fields) do |key, value|
+          "#{escape_key(key)}=#{encode_field_value(value)}"
+        end
+      end
+
+      def dump_timestamp(timestamp)
+        " #{timestamp}" if timestamp
+      end
+
+      def dump_collection(data, prefix = " ", &block)
+        return unless data && !data.empty?
+        prefix + data.map(&block).join(",")
+      end
+
+      def encode_field_value(value)
+        case value
+        when Numeric
+          encode_numberic(value)
+        when TrueClass, FalseClass
+          value.to_s
+        else
+          escape_qoute(escape_value(value))
+        end
+      end
+
+      def encode_numberic(value)
+        "#{value}i" if value.is_a?(Fixnum)
+        value
+      end
+
+      def escape_value(input)
+        input.to_s
+          .gsub(/\s/, '\ ')
+          .gsub(",", '\,')
+          .gsub('"', '\"')
+      end
+
+      def escape_qoute(input)
+        %("#{input}")
+      end
+
+      def escape_key(input)
+        input.to_s
+          .gsub(/\s/, '\ ')
+          .gsub(",", '\,')
+      end
+    end
+  end
+end

spec/encoder/line_spec.rb

@@ -0,0 +1,71 @@
+require "spec_helper"
+
+describe ::Linr::Encoder::Line do
+  subject      { ::Linr::Encoder::Line.new }
+  let(:data)   { ::Linr::Data.new(source)  }
+  let(:output) { subject.dump(data) }
+
+  describe "whitespace" do
+    let(:source) do
+      {
+        measurement: "A test measurement",
+        fields: { "some long field" => 5 },
+        tags: { "some tag" => "with whitespace" },
+        timestamp: 123_456_789
+      }
+    end
+
+    it "escapes" do
+      expected =  'A\ test\ measurement'
+      expected << ',some\ tag=with\ whitespace'
+      expected << ' some\ long\ field=5'
+      expected << " 123456789"
+      output.must_equal expected
+    end
+  end
+
+  describe "commas" do
+    let(:source) do
+      {
+        measurement: "A,test,measurement",
+        fields: { "some,long,field" => 5 },
+        tags: { "some,tag" => "with,comma" },
+        timestamp: 123_456_789
+      }
+    end
+
+    it "escapes" do
+      expected =  'A\,test\,measurement'
+      expected << ',some\,tag=with\,comma'
+      expected << ' some\,long\,field=5'
+      expected << " 123456789"
+      output.must_equal expected
+    end
+  end
+
+  describe "minimum data" do
+    let(:source) do
+      {
+        measurement: "series",
+        fields: { "field" => 0.51 }
+      }
+    end
+
+    it "dumps" do
+      output.must_equal "series field=0.51"
+    end
+  end
+
+  describe "complex data types" do
+    let(:source) do
+      {
+        measurement: "series",
+        fields: { A: true, B: false, C: 'A"B' }
+      }
+    end
+
+    it "dumps" do
+      output.must_equal 'series A=true,B=false,C="A\"B"'
+    end
+  end
+end