Implement HTTP POST based RPC (#5840)

Added support for new RPC support using HTTP POST.  RPC's 
arguments and reply are Gob encoded and sent as HTTP 
request/response body.

This patch also removes Go RPC based implementation.

cmd/local-admin-client_test.go

@@ -0,0 +1,140 @@
+/*
+ * Minio Cloud Storage, (C) 2018 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"testing"
+	"time"
+)
+
+func TestLocalAdminClientSignalService(t *testing.T) {
+	testAdminCmdRunnerSignalService(t, &localAdminClient{})
+}
+
+func TestLocalAdminClientReInitFormat(t *testing.T) {
+	testAdminCmdRunnerReInitFormat(t, &localAdminClient{})
+}
+
+func TestLocalAdminClientListLocks(t *testing.T) {
+	testAdminCmdRunnerListLocks(t, &localAdminClient{})
+}
+
+func TestLocalAdminClientServerInfo(t *testing.T) {
+	testAdminCmdRunnerServerInfo(t, &localAdminClient{})
+}
+
+func TestLocalAdminClientGetConfig(t *testing.T) {
+	testAdminCmdRunnerGetConfig(t, &localAdminClient{})
+}
+
+func TestLocalAdminClientWriteTmpConfig(t *testing.T) {
+	testAdminCmdRunnerWriteTmpConfig(t, &localAdminClient{})
+}
+
+func TestLocalAdminClientCommitConfig(t *testing.T) {
+	testAdminCmdRunnerCommitConfig(t, &localAdminClient{})
+}
+
+func TestListLocksInfo(t *testing.T) {
+	// reset global variables to start afresh.
+	resetTestGlobals()
+	// Initialize minio server config.
+	rootPath, err := newTestConfig(globalMinioDefaultRegion)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(rootPath)
+
+	// Initializing new XL objectLayer.
+	objAPI, _, xlErr := initTestXLObjLayer()
+	if xlErr != nil {
+		t.Fatalf("failed to init object layer")
+	}
+	// Make objLayer available to all internal services via globalObjectAPI.
+	globalObjLayerMutex.Lock()
+	globalObjectAPI = objAPI
+	globalObjLayerMutex.Unlock()
+	// Set globalIsXL to indicate that the setup uses an erasure code backend.
+	// initialize NSLock.
+	isDistXL := false
+	initNSLock(isDistXL)
+
+	var nsMutex *nsLockMap
+
+	nsMutex = objAPI.(*xlSets).sets[0].nsMutex
+
+	// Acquire a few locks to populate lock instrumentation.
+	// Take 10 read locks on bucket1/prefix1/obj1
+	for i := 0; i < 10; i++ {
+		readLk := nsMutex.NewNSLock("bucket1", "prefix1/obj1")
+		if readLk.GetRLock(newDynamicTimeout(60*time.Second, time.Second)) != nil {
+			t.Errorf("Failed to get read lock on iteration %d", i)
+		}
+	}
+
+	// Take write locks on bucket1/prefix/obj{11..19}
+	for i := 0; i < 10; i++ {
+		wrLk := nsMutex.NewNSLock("bucket1", fmt.Sprintf("prefix1/obj%d", 10+i))
+		if wrLk.GetLock(newDynamicTimeout(60*time.Second, time.Second)) != nil {
+			t.Errorf("Failed to get write lock on iteration %d", i)
+		}
+	}
+
+	client := &localAdminClient{}
+
+	testCases := []struct {
+		bucket   string
+		prefix   string
+		duration time.Duration
+		numLocks int
+	}{
+		// Test 1 - Matches all the locks acquired above.
+		{
+			bucket:   "bucket1",
+			prefix:   "prefix1",
+			duration: time.Duration(0 * time.Second),
+			numLocks: 20,
+		},
+		// Test 2 - Bucket doesn't match.
+		{
+			bucket:   "bucket",
+			prefix:   "prefix1",
+			duration: time.Duration(0 * time.Second),
+			numLocks: 0,
+		},
+		// Test 3 - Prefix doesn't match.
+		{
+			bucket:   "bucket1",
+			prefix:   "prefix11",
+			duration: time.Duration(0 * time.Second),
+			numLocks: 0,
+		},
+	}
+
+	for i, test := range testCases {
+		actual, err := client.ListLocks(test.bucket, test.prefix, test.duration)
+		if err != nil {
+			t.Fatalf("unexpected error %v", err)
+		}
+		if len(actual) != test.numLocks {
+			t.Errorf("Test %d - Expected %d locks but observed %d locks",
+				i+1, test.numLocks, len(actual))
+		}
+	}
+}