Cache proto objects (#2755)

Author: kolodny

packages/common-grpc/src/service.js

@@ -31,6 +31,12 @@ var Service = require('@google-cloud/common').Service;
 var through = require('through2');
 var util = require('@google-cloud/common').util;
 
+/**
+ * @const {object} - A cache of proto objects.
+ * @private
+ */
+var protoObjectCache = {};
+
 /**
  * @const {object} - A map of protobuf codes to HTTP status codes.
  * @private
@@ -752,13 +758,22 @@ GrpcService.prototype.loadProtoFile_ = function(protoConfig, config) {
     };
   }
 
-  var services = grpc.load({
-    root: config.protosDir,
-    file: protoConfig.path
-  }, 'proto', grpcOpts);
+  var protoObjectCacheKey = [
+    config.protosDir,
+    protoConfig.path,
+    protoConfig.service
+  ].join('$');
+
+  if (!protoObjectCache[protoObjectCacheKey]) {
+    var services = grpc.load({
+      root: config.protosDir,
+      file: protoConfig.path
+    }, 'proto', grpcOpts);
+    var service = dotProp.get(services.google, protoConfig.service);
+    protoObjectCache[protoObjectCacheKey] = service;
+  }
 
-  var service = dotProp.get(services.google, protoConfig.service);
-  return service;
+  return protoObjectCache[protoObjectCacheKey];
 };
 
 /**

packages/common-grpc/test/service.js

@@ -1780,6 +1780,29 @@ describe('GrpcService', function() {
       assert.strictEqual(service, fakeServices.google.FakeService);
     });
 
+    it('should cache the expensive proto object creation', function() {
+      var protoConfig = {
+        path: '/root/dir/path',
+        service: 'FakeService'
+      };
+
+      var mainConfig = {
+        service: 'OtherFakeService',
+        apiVersion: 'v2'
+      };
+
+      var gprcLoadCalled = 0;
+      grpcLoadOverride = function() {
+        gprcLoadCalled++;
+        return fakeServices;
+      };
+
+      var service1 = grpcService.loadProtoFile_(protoConfig, mainConfig);
+      var service2 = grpcService.loadProtoFile_(protoConfig, mainConfig);
+      assert.strictEqual(service1, service2);
+      assert.strictEqual(gprcLoadCalled, 1);
+    });
+
     it('should return the services object if invalid version', function() {
       var fakeProtoConfig = {
         path: '/root/dir/path',