Optional Cache Value Compression

lib/index.js

@@ -6,7 +6,8 @@
 
 var mongodb = require('mongodb')
   , Promise = require('./promise')
-  , noop = function () {};
+  , noop = function () {}
+  , zlib = require('zlib');
 
 /**
  * Export `MongoStore`.
@@ -29,6 +30,7 @@ function MongoStore(options, bucket) {
   this.coll = options.collection || bucket._name || 'cacheman';
   this.collection = null;
   this.connected = false;
+  this.compression = options.compression || false;
 
   var store = this
     , db = options.db || 'cache'
@@ -82,6 +84,10 @@ MongoStore.prototype.get = function get(key, fn) {
         return fn(null, null);
       }
       try {
+        if(data.compressed){
+          return decompressDataValue(data.value, fn);
+        }
+
         fn(null, data.value);
       } catch (err) {
         fn(err);
@@ -124,11 +130,13 @@ MongoStore.prototype.set = function set(key, val, ttl, fn) {
     fn(err);
   }
 
-  store.conn.then(function then(err, db){
-    db.collection(store.coll).update(query, data, options, function update(err, data) {
-      if (err) return fn(err);
-      if (!data) return fn(null, null);
-      fn(null, val);
+  compressDataValue(store, data, function(err, data){
+    store.conn.then(function then(err, db){
+      db.collection(store.coll).update(query, data, options, function update(err, data) {
+        if (err) return fn(err);
+        if (!data) return fn(null, null);
+        fn(null, val);
+      });
     });
   });
 };
@@ -170,3 +178,31 @@ MongoStore.prototype.clear = function clear(key, fn) {
     db.collection(store.coll).remove({}, { safe: true }, fn);
   });
 };
+
+/**
+ * Non-exported Helpers
+ */
+
+var compressDataValue = function(opts, data, callback){
+  // Compression option turned off
+  if(!opts.compression) return callback(null, data);
+
+  // Data is not of a "compressable" type (currently only Buffer)
+  if(!Buffer.isBuffer(data.value)) return callback(null, data);
+
+  zlib.gzip(data.value, function(err, compressedvalue){
+    // If compression was successful, then use the compressed data.
+    // Otherwise, save the original data.
+    if(!err) {
+      data.value = compressedvalue;
+      data.compressed = true;
+    }
+
+    callback(err, data);
+  });
+};
+
+var decompressDataValue = function(value, callback){
+  var v = (value.buffer && Buffer.isBuffer(value.buffer)) ? value.buffer : value;
+  zlib.gunzip(v, callback);
+};

test/test.js

@@ -1,4 +1,6 @@
 var assert = require('assert')
+  , fs = require('fs')
+  , crypto = require('crypto')
   , Cache = require('../')
   , cache;
 
@@ -117,4 +119,57 @@ describe('cacheman-mongo', function () {
     });
   });
 
+});
+
+describe('cacheman-mongo compression', function () {
+
+  before(function(done){
+    cache = new Cache({ compression: true }, {});
+    done();
+  });
+
+  after(function(done){
+    cache.clear('test');
+    done();
+  });
+
+  it('should store compressable item compressed', function (done) {
+    var value = Date.now().toString();
+
+    cache.set('test1', new Buffer(value), function (err) {
+      if (err) return done(err);
+      cache.get('test1', function (err, data) {
+        if (err) return done(err);
+        assert.equal(data.toString(), value);
+        done();
+      });
+    });
+  });
+
+  it('should store non-compressable item normally', function (done) {
+    var value = Date.now().toString();
+
+    cache.set('test1', value, function (err) {
+      if (err) return done(err);
+      cache.get('test1', function (err, data) {
+        if (err) return done(err);
+        assert.equal(data, value);
+        done();
+      });
+    });
+  });
+
+  it('should store large compressable item compressed', function (done) {
+    var value = fs.readFileSync('./test/large.bin'), // A file larger than the 16mb MongoDB document size limit
+        md5 = function(d){ return crypto.createHash('md5').update(d).digest('hex'); };
+
+    cache.set('test1', value, function (err) {
+      if (err) return done(err);
+      cache.get('test1', function (err, data) {
+        if (err) return done(err);
+        assert.equal(md5(data), md5(value));
+        done();
+      });
+    });
+  });
 });