re: Better Manage the Stats Set

README.md

@@ -42,6 +42,7 @@ $ redmon -h
 Usage: /Users/sean/codez/steelThread/redmon/vendor/ruby/1.9.1/bin/redmon (options)
     -a, --address ADDRESS            The thin bind address for the app (default: 0.0.0.0)
     -n, --namespace NAMESPACE        The root Redis namespace (default: redmon)
+    -l, --lifespan MINUTES           Lifespan(in minutes) for polled data (default: 30)
     -i, --interval SECS              Poll interval in secs for the worker (default: 10)
     -p, --port PORT                  The thin bind port for the app (default: 4567)
     -r, --redis URL                  The Redis url for monitor (default: redis://127.0.0.1:6379)

bin/redmon

@@ -46,6 +46,13 @@ class RedmonCLI
     :description => 'Poll interval in secs for the worker (default: 10)',
     :proc        => to_i
 
+  option :data_lifespan,
+      :short       => '-l MINUTES',
+      :long        => '--lifespan MINUTES',
+      :default     => 30,
+      :description => 'Lifespan(in minutes) for polled data (default: 30)',
+      :proc        => to_i
+
   option :app,
     :on          => :tail,
     :long        => '--no-app',

lib/redmon.rb

@@ -10,6 +10,7 @@ def run(opts={})
   rescue Exception => e
     unless e.is_a?(SystemExit)
       log "!!! Redmon has shit the bed, restarting... #{e.message}"
+      e.backtrace.each { |line| log line }
       sleep(1)
       run(opts)
     end

lib/redmon/config.rb

@@ -15,6 +15,7 @@ class Config
       :worker        => true,
       :web_interface => ['0.0.0.0', 4567],
       :poll_interval => 10,
+      :data_lifespan => 30,
       :secure        => false
     }
 

lib/redmon/helpers.rb

@@ -10,6 +10,10 @@ def poll_interval
       Redmon.config.poll_interval * 1000
     end
 
+    def num_samples_to_request
+      (Redmon.config.data_lifespan * 60) / Redmon.config.poll_interval
+    end
+
     def count
       -(params[:count] ? params[:count].to_i : 1)
     end

lib/redmon/public/redmon.js

@@ -3,13 +3,13 @@ var Redmon = (function() {
     , events = $({});
 
   /**
-   * Loads the last 100 events and starts the periodic polling for new events.
+   * Loads the last numSamples events and starts the periodic polling for new events.
    */
   function init(opts) {
     config = opts;
     toolbar.init();
     cli.init();
-    requestData(100, function(data) {
+    requestData(config.numSamples, function(data) {
       renderDashboard(data);
       poll();
     });

lib/redmon/views/app.haml

@@ -167,6 +167,7 @@
   $(document).ready(function() {
     Redmon.init({
       pollInterval : #{poll_interval},
+      numSamples   : #{num_samples_to_request},
       cliPrompt    : '#{prompt}',
       absoluteUrl  : '#{absolute_url}'
     });

lib/redmon/worker.rb

@@ -3,13 +3,22 @@ class Worker
     include Redmon::Redis
 
     def run!
-      EM::PeriodicTimer.new(interval) {record_stats}
+      EM::PeriodicTimer.new(interval) {
+        record_stats
+        cleanup_old_stats
+      }
     end
 
     def record_stats
       redis.zadd stats_key, *stats
     end
 
+    def cleanup_old_stats
+      # When indexing from the end of a sorted set, we start at -1, so we need to add 1 here or we'll be keeping one
+      # fewer samples than expected
+      redis.zremrangebyscore stats_key,  '-inf', '(' + oldest_data_to_keep.to_s
+    end
+
     def stats
       stats = redis.info.merge! \
         :dbsize  => redis.dbsize,
@@ -37,5 +46,14 @@ def interval
       Redmon.config.poll_interval
     end
 
+    def data_lifespan
+      Redmon.config.data_lifespan
+    end
+
+    def oldest_data_to_keep
+      lifespan_seconds = data_lifespan * 60
+      oldest_time_to_keep = Time.now - lifespan_seconds
+      oldest_time_to_keep.to_i * 1000
+    end
   end
 end

spec/helpers_spec.rb

@@ -1,4 +1,7 @@
 require 'spec_helper'
+require 'redmon/helpers'
+
+include Redmon::Helpers
 
 describe "Helpers" do
 
@@ -83,4 +86,13 @@ def em_redis
     end
   end
 
+  describe "#num_samples_to_request" do
+    it "should return the number of samples to request based on poll interval and data lifespan" do
+      Redmon.config.stub(:data_lifespan).and_return(31)
+      Redmon.config.stub(:poll_interval).and_return(10)
+
+      num_samples_to_request.should == (31 * 60) / 10
+    end
+  end
+
 end

spec/worker_spec.rb

@@ -2,7 +2,7 @@
 
 describe "worker" do
 
-  before(:all) do
+  before(:each) do
     @worker = Redmon::Worker.new
   end
 
@@ -24,6 +24,14 @@ def mock_timer
     end
   end
 
+  describe "#cleanup_old_stats" do
+    it "should remove old stats entries from a redis sorted set" do
+      redis = mock_redis
+      redis.should_receive(:zremrangebyscore).with(Redmon::Redis.stats_key, '-inf', '(' + @worker.oldest_data_to_keep.to_s)
+      @worker.cleanup_old_stats
+    end
+  end
+
   describe "#stats" do
     it "should fetch info, dbsize and slowlog from redis" do
       pending
@@ -59,4 +67,19 @@ def mock_timer
     end
   end
 
+  describe "#data_lifespan" do
+    it "should return the data lifspan" do
+      @worker.data_lifespan.should == Redmon.config.data_lifespan
+    end
+  end
+
+  describe "#oldest_data_to_keep" do
+    it "should return the oldest data timestamp that should be kept" do
+      Time.stub(:now).and_return(Time.at(1366044862))
+      @worker.stub(:data_lifespan).and_return(30)
+
+      @worker.oldest_data_to_keep.should == 1366043062000
+    end
+  end
+
 end