Reduce unnecessary usage of LockService.

Author: Eric Koleda

src/Service.js

@@ -376,26 +376,33 @@ Service_.prototype.handleCallback = function(callbackRequest) {
  *     otherwise.
  */
 Service_.prototype.hasAccess = function() {
-  return this.lockable_(function() {
-    var token = this.getToken();
-    if (!token || this.isExpired_(token)) {
-      try {
-        if (token && this.canRefresh_(token)) {
-          this.refresh();
-        } else if (this.privateKey_) {
-          this.exchangeJwt_();
-        } else if (this.grantType_) {
-          this.exchangeGrant_();
-        } else {
+  var token = this.getToken();
+  if (!token || this.isExpired_(token)) {
+    return this.lockable_(function() {
+      // Get the token again, bypassing the local memory cache.
+      token = this.getToken(true);
+      // Check to see if the token is still missing or expired, as another
+      // execution may have refreshed it while we were waiting for the lock.
+      if (!token || this.isExpired_(token)) {
+        try {
+          if (token && this.canRefresh_(token)) {
+            this.refresh();
+          } else if (this.privateKey_) {
+            this.exchangeJwt_();
+          } else if (this.grantType_) {
+            this.exchangeGrant_();
+          } else {
+            return false;
+          }
+        } catch (e) {
+          this.lastError_ = e;
           return false;
         }
-      } catch (e) {
-        this.lastError_ = e;
-        return false;
       }
-    }
-    return true;
-  });
+      return true;
+    });
+  }
+  return true;
 };
 
 /**
@@ -579,10 +586,12 @@ Service_.prototype.saveToken_ = function(token) {
 
 /**
  * Gets the token from the service's property store or cache.
+ * @param {boolean} optSkipMemory Whether to bypass the local memory cache when
+ *     fetching the token (the default is false).
  * @return {Object} The token, or null if no token was found.
  */
-Service_.prototype.getToken = function() {
-  return this.getStorage().getValue(null);
+Service_.prototype.getToken = function(optSkipMemory) {
+  return this.getStorage().getValue(null, optSkipMemory);
 };
 
 /**

src/Storage.js

@@ -43,12 +43,16 @@ Storage_.CACHE_EXPIRATION_TIME_SECONDS = 21600; // 6 hours.
 /**
  * Gets a stored value.
  * @param {string} key The key.
+ * @param {boolean} optSkipMemory Whether to bypass the local memory cache when
+ *     fetching the value (the default is false).
  * @return {*} The stored value.
  */
-Storage_.prototype.getValue = function(key) {
-  // Check memory.
-  if (this.memory_[key]) {
-    return this.memory_[key];
+Storage_.prototype.getValue = function(key, optSkipMemory) {
+  if (!optSkipMemory) {
+    // Check memory.
+    if (this.memory_[key]) {
+      return this.memory_[key];
+    }
   }
 
   var prefixedKey = this.getPrefixedKey_(key);

test/mocks/lock.js

@@ -12,6 +12,7 @@ var waitingFibers = [];
 var MockLock = function() {
   this.hasLock_ = false;
   this.id = Math.random();
+  this.counter = 0;
 };
 
 MockLock.prototype.waitLock = function(timeoutInMillis) {
@@ -20,6 +21,7 @@ MockLock.prototype.waitLock = function(timeoutInMillis) {
     if (!locked || this.hasLock_) {
       locked = true;
       this.hasLock_ = true;
+      this.counter++;
       return;
     } else {
       waitingFibers.push(Fiber.current);

test/test.js

@@ -176,6 +176,27 @@ describe('Service', function() {
         done();
       });
     });
+
+    it('should not acquire a lock when the token is not expired', function() {
+      var token = {
+        granted_time: (new Date()).getTime(),
+        expires_in: 1000,
+        access_token: 'foo',
+        refresh_token: 'bar'
+      };
+      var lock = new MockLock();
+      var properties = new MockProperties({
+        'oauth2.test': JSON.stringify(token)
+      });
+      var service = OAuth2.createService('test')
+          .setClientId('abc')
+          .setClientSecret('def')
+          .setTokenUrl('http://www.example.com')
+          .setPropertyStore(properties)
+          .setLock(lock);
+      service.hasAccess();
+      assert.equal(lock.counter, 0);
+    });
   });
 
   describe('#refresh()', function() {