Paginated metrics

Gemfile

@@ -24,5 +24,6 @@ gem "dotenv"
 group :development do
   gem "foreman"
   gem "pry"
-  gem "rack-test"
+  # 0.6.2 on rubygems is too old, lacks things like 'env'
+  gem "rack-test", :github => "brynary/rack-test", :ref => "8cdb86e1d7"
 end

Gemfile.lock

@@ -1,3 +1,11 @@
+GIT
+  remote: git://github.com/brynary/rack-test.git
+  revision: 8cdb86e1d710194ce45f439915707db7fb2b27e5
+  ref: 8cdb86e1d7
+  specs:
+    rack-test (0.6.2)
+      rack (>= 1.0)
+
 GEM
   remote: http://rubygems.org/
   specs:
@@ -54,8 +62,6 @@ GEM
     rack-protection (1.5.2)
       rack
     rack-ssl-enforcer (0.2.6)
-    rack-test (0.6.2)
-      rack (>= 1.0)
     rake (10.1.1)
     redis (3.0.6)
     rest-client (1.6.7)
@@ -117,7 +123,7 @@ DEPENDENCIES
   pry
   rack-canonical-host
   rack-ssl-enforcer
-  rack-test
+  rack-test!
   rake
   rest-client
   rspec

lib/descartes/public/js/list-metrics.js

@@ -37,22 +37,30 @@ var addMetricsToolbar = function(metric) {
     html('<a class="axis left selected" title="Left axis" href="#">1</a><a class="axis right" title="Right axis" href="#">2</a>');
 };
 
-// Grab configuration blob and construct our graph urls
-var renderGraphs = function() {
-  // Load index.json at first load and cache as myLoadedMetrics
-  // Use cached myLoadedMetrics for infinite scrolling
-  if (myLoadedMetrics.length > 0) {
-    // Use cached myLoadedMetrics
-    renderSparklines();
-  } else {
-    // Load index.json and cache in myLoadedMetrics
+// Load a page of metrics from backend
+var loadMetricsPage = function(page) {
     return $.ajax({
       accepts: {'json': 'application/json'},
       cache: false,
       dataType: 'json',
       error: function(xhr, textStatus, errorThrown) { console.log(errorThrown); },
-      url: '/metrics/'
-    }).done(function(d) {
+      // Load first page by default
+      url: '/metrics/',
+      data: {limit: myMetricsPerPage, page: page}
+    });
+}
+
+
+// Render current page of graphs, querying 1st page if none stored
+var renderGraphs = function() {
+  // loaded metrics non-empty? just render 'em
+  if (myLoadedMetrics.length > 0) {
+    // Use cached myLoadedMetrics
+    renderSparklines();
+  // empty? grab 1st page.
+  } else {
+    $('div.loading').removeClass('hidden');
+    return loadMetricsPage(1).done(function(d) {
       if (d.length === 0) {
         console.log('No metrics found');
       } else {
@@ -67,15 +75,18 @@ var renderSparklines = function() {
   // Show our loading div
   $('div.loading').removeClass('hidden');
 
-  if (myMatchedMetrics.length === 0) {
-    myMatchedMetrics = myLoadedMetrics;
+  // Use loaded-from-beginning metric cache by default;
+  // but if search results seem to exist, use those instead.
+  var myLocalMetrics = myLoadedMetrics;
+  if (myMatchedMetrics.length != 0) {
+    myLocalMetrics = myMatchedMetrics;
   }
 
   for (var target = ((myPageIndex - 1) * myMetricsPerPage); target < (myPageIndex * myMetricsPerPage); target += 1) {
     // Only run if we have an actual target, ignore end of page undefs
-    if (myMatchedMetrics[target] !== undefined) {
+    if (myLocalMetrics[target] !== undefined) {
       // unique identifier so we can track each metric to its DOM element
-      hash = CryptoJS.SHA256(myMatchedMetrics[target]).toString(CryptoJS.enc.Hex);
+      hash = CryptoJS.SHA256(myLocalMetrics[target]).toString(CryptoJS.enc.Hex);
       $('div.metrics').append('<div class="default" id="' + hash + '"></div>');
       $.ajax({
         accepts: {'json': 'application/json'},
@@ -91,8 +102,8 @@ var renderSparklines = function() {
         dataType: 'json',
         error: function(xhr, textStatus, errorThrown) { console.log(errorThrown); },
         hash: hash,
-        target: myMatchedMetrics[target],
-        url: graphiteUrl + '/render?target=' + myMatchedMetrics[target] + '&from=-' + myInterval + '&format=json'
+        target: myLocalMetrics[target],
+        url: graphiteUrl + '/render?target=' + myLocalMetrics[target] + '&from=-' + myInterval + '&format=json'
       }).done(function(output) {
         if (output.length === 1) {
           var data = [];
@@ -134,7 +145,7 @@ var renderSparklines = function() {
     }
   }
   // Disable infinite scrolling
-  if (myPageIndex * myMetricsPerPage > myMatchedMetrics.length) {
+  if (myPageIndex * myMetricsPerPage > myLocalMetrics.length) {
     myPageIndex = 0;
   }
 };
@@ -242,8 +253,16 @@ var scrollNextPage = function() {
       if (!this.lastCall || (delta > threshold)) {
         this.lastCall = now;
         myPageIndex += 1;
-        console.log("loading more metrics, myPageIndex is now " + myPageIndex);
-        renderGraphs();
+        // Actually load more metrics
+        loadMetricsPage(myPageIndex).done(function(d) {
+            if (d.length != 0) {
+                myLoadedMetrics = myLoadedMetrics.concat(d);
+            }
+            // Ensure the new metrics get rendered (basically just passes
+            // through to renderSparklines). Do this inside the callback or
+            // things don't line up right.
+            renderGraphs();
+        });
       } else {
         console.log("throttling");
       }

lib/descartes/routes/metrics.rb

@@ -3,9 +3,22 @@ class Web < Sinatra::Base
 
     get '/metrics/?' do
       if request.xhr?
+        # No params -> just return everything.
+        metrics = if %w(page limit).map {|x| params.include?(x)}.none?
+          Metric.all
+        # Params -> paginate, depending.
+        else
+          page = (params['page'] || 1).to_i
+          size = (params['limit'] || 50).to_i
+          start = (page - 1) * size
+          end_ = start + size
+          Metric.all[start...end_]
+        end
+
+        # Response
         content_type "application/json"
         status 200
-        Metric.all.to_json
+        metrics.to_json
       else
         haml :'metrics/index', :locals => { :title => "Descartes - Metrics List", :cache_age => MetricCacheStatus.first.updated_at.to_s }
       end
@@ -22,4 +35,4 @@ class Web < Sinatra::Base
     end
 
   end
-end
+end

spec/web_spec.rb

@@ -1,7 +1,28 @@
+require 'rspec'
 require 'rack/test'
 require 'spec_helper'
 
 require './lib/descartes/web'
+require './lib/descartes/models/metrics'
+
+
+# Meh?
+class Metric
+  def self.paths=(paths)
+    @@paths = paths
+  end
+end
+
+# Don't see a way to do this natively in Rack. 'response.json' idea stolen
+# from python-requests lib.
+module Rack
+  class Response
+    def json
+      JSON.parse(body)
+    end
+  end
+end
+
 
 describe Descartes::Web do
   include Rack::Test::Methods
@@ -10,5 +31,45 @@ def app
     Descartes::Web
   end
 
-  it 'should have some tests'
+  it 'should have more tests'
+
+  describe '/metrics/' do
+    context 'json' do
+      before :each do
+        # Be an API request.
+        env 'HTTP_X_DESCARTES_API_TOKEN', ENV['API_TOKEN']
+        header 'Accept', 'application/json'
+        # Fake metric paths
+        Metric.paths = 1.upto(100).to_a
+      end
+
+      def assert_array(size, start=nil, end_=nil)
+        expect(last_response.ok?).to be_true # Fail fast
+        result = last_response.json
+        expect(result.size).to eq(size)
+        expect(result.first).to(eq(start)) unless start.nil?
+        expect(result.last).to(eq(end_)) unless end_.nil?
+      end
+
+      it 'without page/limit params, loads entire cache' do
+        get '/metrics/', :_ => 12345 # ape real webapp behavior
+        assert_array 100
+      end
+
+      it 'loads specific pages when requested via :page' do
+        get '/metrics/', :page => 1
+        assert_array 50, 1, 50
+      end
+
+      it 'changes page size optionally via :limit' do
+        get '/metrics/', :page => 2, :limit => 25
+        assert_array 25, 26, 50
+      end
+
+      it 'assumes page 1 when :limit given & no :page' do
+        get '/metrics/', :limit => 25
+        assert_array 25, 1, 25
+      end
+    end
+  end
 end