code: function getKeys (memcached, cb) {
    var keyArray = []
    var keyLength = 0
  
    memcached.items().then(function (items) {
      items.forEach(function (item) {
        keyLength += item.data.number
  
        memcached.cachedump(item.slab_id, item.data.number).then(function (dataSet) {
          dataSet.forEach(function (data) {
            if (data.key) {
              memcached.get(data.key).then(function (val) {
                if (val) {
                  keyArray.push(data.key)
                }
  
                keyLength -= 1
  
                if (keyLength === 0) {
                  cb(null, keyArray)
                }
              })
            }
          })
        })
      })
    }).catch(function (err) {
      cb(err)
    })
  }
docs: from: http://blog.pointerstack.com/2012/08/nodejs-extract-keys-from-memcache-server.html