From 01012f282a8a7f9e9f1631c90c5522b75a8dd3f5 Mon Sep 17 00:00:00 2001
From: Glenn Kim <changkyu@ab180.co>
Date: Thu, 13 Jul 2023 11:38:17 +0900
Subject: [PATCH] Limit resolving concurrency (#4)

* early return when ResolveNow is already resolving in another goroutine

* fix broken test
---
 resolver.go    |  7 +++++--
 target_test.go | 39 ++++++++++++++++++++++++++-------------
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/resolver.go b/resolver.go
index f854523..1c1c5d1 100644
--- a/resolver.go
+++ b/resolver.go
@@ -32,8 +32,11 @@ type resolver struct {
 }
 
 func (c *resolver) ResolveNow(grpcresolver.ResolveNowOptions) {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
+	locked := c.mu.TryLock()
+	if !locked { // already resolving
+		return
+	}
+	defer c.mu.Unlock()
 
 	if c.isClosed {
 		return
diff --git a/target_test.go b/target_test.go
index c4e2bc2..21d53cc 100644
--- a/target_test.go
+++ b/target_test.go
@@ -1,6 +1,7 @@
 package cloudmap
 
 import (
+	"net/url"
 	"reflect"
 	"testing"
 
@@ -65,7 +66,9 @@ func Test_parseTarget(t *testing.T) {
 			name: "unexpected scheme",
 			args: args{
 				t: grpcresolver.Target{
-					Scheme: "https",
+					URL: url.URL{
+						Scheme: "https",
+					},
 				},
 			},
 			wantErr: true,
@@ -74,7 +77,9 @@ func Test_parseTarget(t *testing.T) {
 			name: "empty namespace",
 			args: args{
 				t: grpcresolver.Target{
-					Scheme: "https",
+					URL: url.URL{
+						Scheme: Scheme,
+					},
 				},
 			},
 			wantErr: true,
@@ -83,8 +88,10 @@ func Test_parseTarget(t *testing.T) {
 			name: "empty service",
 			args: args{
 				t: grpcresolver.Target{
-					Scheme:    Scheme,
-					Authority: "test-namespace",
+					URL: url.URL{
+						Scheme: Scheme,
+						Host:   "test-namespace",
+					},
 				},
 			},
 			wantErr: true,
@@ -93,9 +100,11 @@ func Test_parseTarget(t *testing.T) {
 			name: "normal",
 			args: args{
 				t: grpcresolver.Target{
-					Scheme:    Scheme,
-					Authority: "test-namespace",
-					Endpoint:  "test-service",
+					URL: url.URL{
+						Scheme: Scheme,
+						Host:   "test-namespace",
+						Path:   "test-service",
+					},
 				},
 			},
 			want: &target{
@@ -107,9 +116,11 @@ func Test_parseTarget(t *testing.T) {
 			name: "with slash",
 			args: args{
 				t: grpcresolver.Target{
-					Scheme:    Scheme,
-					Authority: "test-namespace",
-					Endpoint:  "test/service",
+					URL: url.URL{
+						Scheme: Scheme,
+						Host:   "test-namespace",
+						Path:   "test/service",
+					},
 				},
 			},
 			want: &target{
@@ -121,9 +132,11 @@ func Test_parseTarget(t *testing.T) {
 			name: "with whitespace",
 			args: args{
 				t: grpcresolver.Target{
-					Scheme:    Scheme,
-					Authority: "test-namespace",
-					Endpoint:  "test%20service",
+					URL: url.URL{
+						Scheme: Scheme,
+						Host:   "test-namespace",
+						Path:   "test%20service",
+					},
 				},
 			},
 			want: &target{