Sorted-Set based implementation

redis-timeseries-sorted-set.rb

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+require 'base64'
+
+class RedisTimeSeries
+    def initialize(prefix,timestep,redis)
+        @prefix = prefix
+        @timestep = timestep
+        @redis = redis
+    end
+
+    def normalize_time(t)
+        t = t.to_i
+        t - (t % @timestep)
+    end
+
+    def getkey(t)
+        "ts:#{@prefix}:#{normalize_time t}"
+    end
+
+    def add(data,timestamp=nil,marshal=true)
+        timestamp ||= Time.now.to_f
+        data = marshal ? Marshal.dump(data) : data
+        @redis.zadd(getkey(timestamp), timestamp, data)
+    end
+
+    def fetch_range(begin_time,end_time,marshal=true)
+      begin_time = begin_time.to_f
+      end_time = end_time.to_f
+      result = (0..((end_time - begin_time) / @timestep)).collect do |i|
+        key = getkey(begin_time + (i*@timestep))
+
+        r = @redis.zrangebyscore(key, begin_time.to_f,end_time.to_f)
+        marshal ? r.collect{|elem| Marshal.load(elem) } : r
+      end
+      result.flatten
+    end
+
+    def fetch_timestep(time, marshal=true)
+        t = time.to_f
+        r = @redis.zrangebyscore(getkey(time), t, t)
+        marshal ? r.collect{|elem| Marshal.load(elem) } : r
+    end
+end

sorted-set-example.rb

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+require 'rubygems'
+require 'redis'
+require './redis-timeseries-sorted-set'
+
+# To show the lib implementation here we use a timestep of just one second.
+# Then we sample every 0.1 seconds, producing on average 10 samples per key.
+# This way we should how multi-key range queries are working.
+ts = RedisTimeSeries.new("test",1,Redis.new)
+
+now = Time.now.to_f
+puts "Adding data points: "
+(0..300).each{|i|
+    print "#{i} "
+    STDOUT.flush
+    time = (now+(i/10.0))
+    ts.add({:time => time, :data => i.to_s}, time)
+}
+puts ""
+
+# Get the second in the middle of our sampling.
+begin_time = now+1
+end_time = now+2
+puts "\nGet range from #{begin_time} to #{end_time}"
+
+ts.fetch_range(begin_time,end_time).each{|record|
+    puts "Record time #{record[:time]}, data #{record[:data]}"
+}
+
+# Show API to get a single timestep
+puts "\nGet a single timestep near #{begin_time}"
+ts.fetch_timestep(begin_time).each{|record|
+    puts "Record time #{record[:time]}, data #{record[:data]}"
+}