Rewrite the memcached client

* Update syntax to ES6
* Use `memcached` instead of `memcache`
* Fix restrictions where expirations weren't pushed forward on GET
* Fix a bug where we were unnecessarily bumping expirations on key search

Closes #201

README.md

@@ -156,9 +156,9 @@ All of which are optional except `type` with very logical default values.
 
 ### Memcached
 
-To use memcached storage you must install the `memcache` package via npm
+To use memcache storage you must install the `memcached` package via npm
 
-`npm install memcache`
+`npm install memcached`
 
 Once you've done that, your config section should look like:
 

config.js

@@ -33,10 +33,9 @@
   },
 
   "storage": {
-    "type": "redis",
-    "host": "0.0.0.0",
-    "port": 6379,
-    "db": 2,
+    "type": "memcached",
+    "host": "127.0.0.1",
+    "port": 11211,
     "expire": 2592000
   },
 

lib/document_handler.js

@@ -123,7 +123,7 @@ DocumentHandler.prototype.chooseKey = function(callback) {
     } else {
       callback(key);
     }
-  });
+  }, true); // Don't bump expirations when key searching
 };
 
 DocumentHandler.prototype.acceptableKey = function() {

lib/document_stores/memcached.js

@@ -1,45 +1,52 @@
-var memcached = require('memcache');
-var winston = require('winston');
+const memcached = require('memcached');
+const winston = require('winston');
+
+class MemcachedDocumentStore {
 
   // Create a new store with options
-var MemcachedDocumentStore = function(options) {
+  constructor(options) {
     this.expire = options.expire;
-  if (!MemcachedDocumentStore.client) {
-    MemcachedDocumentStore.connect(options);
+
+    const host = options.host || '127.0.0.1';
+    const port = options.port || 11211;
+    const url = `${host}:${port}`;
+    this.connect(url);
   }
-};
 
   // Create a connection
-MemcachedDocumentStore.connect = function(options) {
-  var host = options.host || '127.0.0.1';
-  var port = options.port || 11211;
-  this.client = new memcached.Client(port, host);
-  this.client.connect();
-  this.client.on('connect', function() {
-    winston.info('connected to memcached on ' + host + ':' + port);
+  connect(url) {
+    this.client = new memcached(url);
+
+    winston.info(`connecting to memcached on ${url}`);
+
+    this.client.on('failure', function(error) {
+      winston.info('error connecting to memcached', {error});
     });
-  this.client.on('error', function(e) {
-    winston.info('error connecting to memcached', { error: e });
-  });
-};
+  }
 
   // Save file in a key
-MemcachedDocumentStore.prototype.set =
-function(key, data, callback, skipExpire) {
-  MemcachedDocumentStore.client.set(key, data, function(err) {
-    err ? callback(false) : callback(true);
-  }, skipExpire ? 0 : this.expire);
-};
+  set(key, data, callback, skipExpire) {
+    this.client.set(key, data, skipExpire ? 0 : this.expire, (error) => {
+      callback(!error);
+    });
+  }
 
   // Get a file from a key
-MemcachedDocumentStore.prototype.get = function(key, callback, skipExpire) {
-  var _this = this;
-  MemcachedDocumentStore.client.get(key, function(err, reply) {
-    callback(err ? false : reply);
-    if (_this.expire && !skipExpire) {
-      winston.warn('store does not currently push forward expirations on GET');
+  get(key, callback, skipExpire) {
+    this.client.get(key, (error, data) => {
+      callback(error ? false : data);
+
+      // Update the key so that the expiration is pushed forward
+      if (!skipExpire) {
+        this.set(key, data, (updateSucceeded) => {
+          if (!updateSucceeded) {
+            winston.error('failed to update expiration on GET', {key});
+          }
+        }, skipExpire);
       }
     });
-};
+  }
+
+}
 
 module.exports = MemcachedDocumentStore;