From c33378540aa9156fc1efd27dcc3c537f80104ef6 Mon Sep 17 00:00:00 2001
From: John Guo <john@johng.cn>
Date: Sat, 27 Nov 2021 01:33:53 +0800
Subject: [PATCH] add Available function for Adapter of package gcfg

---
 os/gcfg/gcfg.go              | 9 ++++++---
 os/gcfg/gcfg_adaper.go       | 7 +++++++
 os/gcfg/gcfg_adapter_file.go | 2 +-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/os/gcfg/gcfg.go b/os/gcfg/gcfg.go
index df038492a..f21bb8013 100644
--- a/os/gcfg/gcfg.go
+++ b/os/gcfg/gcfg.go
@@ -54,7 +54,10 @@ func NewWithAdapter(adapter Adapter) *Config {
 // exists in the configuration directory, it then sets it as the default configuration file. The
 // toml file type is the default configuration file type.
 func Instance(name ...string) *Config {
-	key := DefaultName
+	var (
+		ctx = context.TODO()
+		key = DefaultName
+	)
 	if len(name) > 0 && name[0] != "" {
 		key = name[0]
 	}
@@ -67,9 +70,9 @@ func Instance(name ...string) *Config {
 		// If it's not using default configuration or its configuration file is not available,
 		// it searches the possible configuration file according to the name and all supported
 		// file types.
-		if key != DefaultName || !adapter.Available() {
+		if key != DefaultName || !adapter.Available(ctx) {
 			for _, fileType := range supportedFileTypes {
-				if file := fmt.Sprintf(`%s.%s`, key, fileType); adapter.Available(file) {
+				if file := fmt.Sprintf(`%s.%s`, key, fileType); adapter.Available(ctx, file) {
 					adapter.SetFileName(file)
 					break
 				}
diff --git a/os/gcfg/gcfg_adaper.go b/os/gcfg/gcfg_adaper.go
index 3d37d3edd..4c354e62c 100644
--- a/os/gcfg/gcfg_adaper.go
+++ b/os/gcfg/gcfg_adaper.go
@@ -10,6 +10,13 @@ import "context"
 
 // Adapter is the interface for configuration retrieving.
 type Adapter interface {
+	// Available checks and returns the configuration service is available.
+	// The optional parameter `pattern` specifies certain configuration resource.
+	//
+	// It returns true if configuration file is present in default AdapterFile, or else false.
+	// Note that this function does not return error as it just does simply check for backend configuration service.
+	Available(ctx context.Context, pattern ...string) (ok bool)
+
 	// Get retrieves and returns value by specified `pattern`.
 	Get(ctx context.Context, pattern string) (value interface{}, err error)
 
diff --git a/os/gcfg/gcfg_adapter_file.go b/os/gcfg/gcfg_adapter_file.go
index f2a15f2ae..54c306b9f 100644
--- a/os/gcfg/gcfg_adapter_file.go
+++ b/os/gcfg/gcfg_adapter_file.go
@@ -175,7 +175,7 @@ func (c *AdapterFile) Dump() {
 }
 
 // Available checks and returns whether configuration of given `file` is available.
-func (c *AdapterFile) Available(fileName ...string) bool {
+func (c *AdapterFile) Available(ctx context.Context, fileName ...string) bool {
 	var (
 		usedFileName string
 	)