A client/server helper wrapper for endpoints in Go.

go/src/infra/gae/libs/ephelper/ephelper.go

Index: go/src/infra/gae/libs/ephelper/ephelper.go
diff --git a/go/src/infra/gae/libs/ephelper/ephelper.go b/go/src/infra/gae/libs/ephelper/ephelper.go
new file mode 100644
index 0000000000000000000000000000000000000000..1a16c638d2ace593c9fc5d96c31a506820604de4
--- /dev/null
+++ b/go/src/infra/gae/libs/ephelper/ephelper.go
@@ -0,0 +1,77 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package ephelper
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/GoogleCloudPlatform/go-endpoints/endpoints"
+)
+
+const errPrefix = "endpoints.Register: "
+
+var (
+	// ErrServerNil is returned if you pass a nil server to Register. Don't do
+	// that.
+	ErrServerNil = errors.New(errPrefix + "server is nil")
+
+	// ErrServiceNil is returned if you pass a nil service to Register. Don't do
+	// that.
+	ErrServiceNil = errors.New(errPrefix + "service is nil")
+)
+
+// MethodInfoMap is the common registry for an endpoints service. It's
+// used by infra/libs/endpoints_client to populate its API.
+type MethodInfoMap map[string]*endpoints.MethodInfo
+
+// Register adds an endpoints.RegisterService-compatible service object using
+// the MethodInfoMap to look up the MethodInfo objects by methodName. It is
+// intended to be called at init()-time of an app or client which relies on
+// these endpoints.
+//
+// service should be an instance of your service type (as if you were passing
+// it to "go-endpoints/endpoints".RegisterService).
+func Register(server *endpoints.Server, service interface{}, si *endpoints.ServiceInfo, mi MethodInfoMap) error {
+	if server == nil {
+		return ErrServerNil
+	}
+	if service == nil {
+		return ErrServiceNil
+	}
+	if si == nil {
+		si = &endpoints.ServiceInfo{Default: true}
+	}
+
+	api, err := server.RegisterService(service, si.Name, si.Version,
+		si.Description, si.Default)
+	if err != nil {
+		return err
+	}
+
+	for methodName, info := range mi {
+		method := api.MethodByName(methodName)
+		if method == nil {
+			return fmt.Errorf(
+				errPrefix+"no method %q (did you forget to export it?)", methodName)
+		}
+		curInfo := method.Info()
+		// These three are set automatically based on reflection, so only override
+		// them if the info object contains something new.
+		if info.Name == "" {
+			info.Name = curInfo.Name
+		}
+		if info.Path == "" {
+			info.Path = curInfo.Path
+		}
+		if info.HTTPMethod == "" {
+			info.HTTPMethod = curInfo.HTTPMethod
+		}
+		*curInfo = *info
+		mi[methodName] = curInfo // So that we can observe the merged result
+	}
+
+	return nil
+}