Cache null values.

Author: Eric Koleda

src/Storage.js

@@ -40,25 +40,38 @@ function Storage_(prefix, properties, optCache) {
  */
 Storage_.CACHE_EXPIRATION_TIME_SECONDS = 21600; // 6 hours.
 
+/**
+ * The special value to use in the cache to indicate that there is no value.
+ * @type {string}
+ * @private
+ */
+Storage_.CACHE_NULL_VALUE = '__NULL__';
+
 /**
  * Gets a stored value.
  * @param {string} key The key.
  * @return {*} The stored value.
  */
 Storage_.prototype.getValue = function(key) {
- // Check memory.
- if (this.memory_[key]) {
- return this.memory_[key];
- }
-
  var prefixedKey = this.getPrefixedKey_(key);
  var jsonValue;
  var value;
 
+ // Check memory.
+ if (value = this.memory_[key]) {
+ if (value === Storage_.CACHE_NULL_VALUE) {
+ return null;
+ }
+ return value;
+ }
+
  // Check cache.
  if (this.cache_ && (jsonValue = this.cache_.get(prefixedKey))) {
  value = JSON.parse(jsonValue);
  this.memory_[key] = value;
+ if (value === Storage_.CACHE_NULL_VALUE) {
+ return null;
+ }
  return value;
  }
 
@@ -73,7 +86,13 @@ Storage_.prototype.getValue = function(key) {
  return value;
  }
 
- // Not found.
+ // Not found. Store a special null value in the memory and cache to reduce
+ // hits on the PropertiesService.
+ this.memory_[key] = Storage_.CACHE_NULL_VALUE;
+ if (this.cache_) {
+ this.cache_.put(prefixedKey, JSON.stringify(Storage_.CACHE_NULL_VALUE),
+ Storage_.CACHE_EXPIRATION_TIME_SECONDS);
+ }
  return null;
 };
 

test/test.js

@@ -91,6 +91,37 @@ describe('Service', function() {
  assert.equal(cache.counter, cacheStart);
  assert.equal(properties.counter, propertiesStart);
  });
+
+ it('should load null tokens from the cache',
+ function() {
+ var cache = new MockCache();
+ var properties = new MockProperties();
+ for (var i = 0; i < 10; ++i) {
+ var service = OAuth2.createService('test')
+ .setPropertyStore(properties)
+ .setCache(cache);
+ service.getToken();
+ }
+ assert.equal(properties.counter, 1);
+ });
+
+ it('should load null tokens from memory',
+ function() {
+ var cache = new MockCache();
+ var properties = new MockProperties();
+ var service = OAuth2.createService('test')
+ .setPropertyStore(properties)
+ .setCache(cache);
+
+ service.getToken();
+ var cacheStart = cache.counter;
+ var propertiesStart = properties.counter;
+ for (var i = 0; i < 10; ++i) {
+ service.getToken();
+ }
+ assert.equal(cache.counter, cacheStart);
+ assert.equal(properties.counter, propertiesStart);
+ });
  });
 
  describe('#saveToken_()', function() {