Cache: Implementing redis cache on common services

app/config/cache.js

@@ -0,0 +1,37 @@
+var redis = require('redis');
+
+// create a new redis client and connect to our local redis instance
+var client = redis.createClient({
+  host: 'redis'
+});
+
+// if an error occurs, print it to the console
+client.on('error', function (err) {
+  console.log("Error " + err);
+});
+
+client.flushdb( function (err, succeeded) {
+    console.log(succeeded); // will be true if successfull
+});
+
+function cacheFilter(key) {
+  return function(key, req, res, next) {
+    client.get(key, function(error, result) {
+        if (result) {
+          console.log('>> source - cache');
+          res.json(JSON.parse(result));
+        } else {
+          next();
+        }
+      });
+  }.bind(null, key);
+}
+
+function cache(key, value) {
+  // Cache last 10 hours
+  client.set(key, JSON.stringify(value), 'EX', 36000);
+}
+
+module.exports = {
+  cacheFilter, cache
+};

app/routes/attendance.js

@@ -1,6 +1,7 @@
 var express = require('express');
 var router = express.Router();
 var models  = require('../models');
+var cache = require('../config/cache');
 
 /* Path: /legislature/LXIII/attendance => attendance.js
   /api/legislature/LXIII/attendance/avg
@@ -10,21 +11,22 @@ var models  = require('../models');
 */
 
 /* /api/legislature/LXIII/attendance */
-router.get('/', function(req, res, next) {
-  let queryString =
-    'select * from attendance_list order by entries desc';
+router.get('/', cache.cacheFilter('LXIII-attendance'), function(req, res, next) {
+    let queryString =
+      'select * from attendance_list order by entries desc';
 
-  models.sequelize
-  .query(queryString, {
-    type: models.sequelize.QueryTypes.SELECT
-  })
-  .then(function(result) {
-    res.json(result);
+    models.sequelize
+    .query(queryString, {
+      type: models.sequelize.QueryTypes.SELECT
+    })
+    .then(function(result) {
+      cache.cache('LXIII-attendance', result);
+      res.json(result);
+    });
   });
-});
 
 /* /api/legislature/LXIII/attendance/avg */
-router.get('/avg', function(req, res, next) {
+router.get('/avg', cache.cacheFilter('LXIII-attendance-avg'), function(req, res, next) {
   let queryString =
     'select avg(quantity) as average, max(quantity) as max, min(quantity) as min from seat_attendance';
 
@@ -33,12 +35,13 @@ router.get('/avg', function(req, res, next) {
     type: models.sequelize.QueryTypes.SELECT
   })
   .then(function(result) {
+    cache.cache('LXIII-attendance-avg', result[0]);
     res.json(result[0]);
   });
 });
 
 /* /api/legislature/LXIII/attendance/frequency */
-router.get('/frequency', function(req, res, next) {
+router.get('/frequency', cache.cacheFilter('LXIII-attendance-frequency'), function(req, res, next) {
   let queryString =
     'select st2.quantity, st2.frequency, @running_total := @running_total + st2.frequency AS cumulative_frequency from attendance_frequency st2 join (select @running_total := 0) r'
 
@@ -47,12 +50,13 @@ router.get('/frequency', function(req, res, next) {
     type: models.sequelize.QueryTypes.SELECT
   })
   .then(function(result) {
+    cache.cache('LXIII-attendance-frequency', result);
     res.json(result);
   });
 });
 
 /* /api/legislature/LXIII/attendance/by_party */
-router.get('/by_party', function(req, res, next) {
+router.get('/by_party', cache.cacheFilter('LXIII-attendance-by-party'), function(req, res, next) {
   let queryString =
     'select party, round(avg(quantity), 2) as average, max(quantity) as max, min(quantity) as min, round(avg(quantity) + stddev(quantity)/2, 2) as max_std, round(avg(quantity) - stddev(quantity)/2,2) as min_std, count(1) as deputies from seat_attendance group by party order by average';
 
@@ -61,12 +65,13 @@ router.get('/by_party', function(req, res, next) {
     type: models.sequelize.QueryTypes.SELECT
   })
   .then(function(result) {
+    cache.cache('LXIII-attendance-by-party', result);
     res.json(result);
   });
 });
 
 /* /api/legislature/LXIII/attendance/by_state */
-router.get('/by_state', function(req, res, next) {
+router.get('/by_state', cache.cacheFilter('LXIII-attendance-by-state'), function(req, res, next) {
   let queryString =
     'select state, round(avg(entries), 2) as average, max(entries) as max, min(entries) as min, round(avg(entries) + stddev(entries)/2, 2) as max_std, round(avg(entries) - stddev(entries)/2,2) as min_std, count(1) as deputies from attendance_list group by state order by average';
 
@@ -75,12 +80,13 @@ router.get('/by_state', function(req, res, next) {
     type: models.sequelize.QueryTypes.SELECT
   })
   .then(function(result) {
+    cache.cache('LXIII-attendance-by-state', result);
     res.json(result);
   });
 });
 
 /* /api/legislature/LXIII/attendance/by_deputy_type */
-router.get('/by_deputy_type', function(req, res, next) {
+router.get('/by_deputy_type', cache.cacheFilter('LXIII-attendance-by-deputy-type'), function(req, res, next) {
   let queryString =
     'select type, party, avg(quantity) as average, count(1) as deputies from seat_attendance group by type, party order by party, type';
 
@@ -89,6 +95,7 @@ router.get('/by_deputy_type', function(req, res, next) {
     type: models.sequelize.QueryTypes.SELECT
   })
   .then(function(result) {
+    cache.cache('LXIII-attendance-by-deputy-type', result);
     res.json(result);
   });
 });