apostrophe/lib/cache.js

Apostrophe is a user-friendly content management system. This core module of Apostrophe provides rich content editing and essential facilities to integrate Apostrophe into your Express project. Apostrophe also includes simple facilities for storing your r

var _ = require('lodash');

 /**
 * cache
 * @augments Augments the apos object with methods supporting caching.
 */

module.exports = function(self) {
  // getCache('cachename') returns an object on which you may call .get and .set to get
  // and store values in the cache. If you call getCache('pollywobbles'), your get and set
  // methods will only interact with data stored in the pollywobbles cache. You may also
  // call .clear on a cache. All three methods require a callback.
  //
  // The default implementation is a single MongoDB collection but this can be swapped out
  // by overriding the getCache method.
  //
  // Note that the .set method takes an optional lifetime in seconds for the cached data.
  // If no lifetime is specified the data is cached forever.

  self.getCache = function(name) {
    if (!self._caches) {
      self._caches = {};
    }
    if (!self._caches[name]) {
      self._caches[name] = self.constructCache(name);
    }
    return self._caches[name];
  };

  self.constructCache = function(name) {
    return {
      get: function(key, callback) {
        return self._cache.findOne({
          name: name,
          key: key
        }, function(err, item) {
          if (err) {
            return callback(err);
          }
          if (!item) {
            return callback(null);
          }
          // MongoDB's expireAfterSeconds mechanism isn't instantaneous, so we
          // should still enforce this at get() time
          if (item.expires && (item.expires < (new Date()))) {
            return callback(null);
          }
          return callback(null, item.value);
        });
      },
      // Cache lifetime is optional
      set: function(key, value, lifetime, callback) {
        if (!callback) {
          callback = lifetime;
          lifetime = 0;
        }
        var action = {};
        var set = {
          name: name,
          key: key,
          value: value
        };
        action.$set = set;
        var unset = {};
        if (lifetime) {
          set.expires = new Date(new Date().getTime() + lifetime * 1000);
        } else {
          unset.expires = 1;
          action.$unset = unset;
        }
        return self._cache.update(
          {
            name: name,
            key: key
          },
          action,
          {
            upsert: true
          }, callback);
      },
      clear: function(callback) {
        return self._cache.remove({
          name: name
        }, callback);
      }
    };
  };
};