config: minor changes to split config and watcher files

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

file.go

@@ -2,7 +2,6 @@ package file
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -16,7 +15,6 @@ import (
 
 var (
 	DefaultStructTag = "file"
-	ErrPathNotExist  = errors.New("path is not exist")
 )
 
 type fileConfig struct {
@@ -33,20 +31,16 @@ func (c *fileConfig) Init(opts ...config.Option) error {
 		o(&c.opts)
 	}
 
-	path := ""
-
 	if c.opts.Context != nil {
 		if v, ok := c.opts.Context.Value(pathKey{}).(string); ok {
-			path = v
+			c.path = v
 		}
 	}
 
-	if path == "" {
+	if c.path == "" {
-		return ErrPathNotExist
+		return fmt.Errorf("file path not exists: %v", c.path)
 	}
 
-	c.path = path
-
 	return nil
 }
 
@@ -59,7 +53,7 @@ func (c *fileConfig) Load(ctx context.Context, opts ...config.LoadOption) error
 
 	fp, err := os.OpenFile(c.path, os.O_RDONLY, os.FileMode(0400))
 	if err != nil && !c.opts.AllowFail {
-		return fmt.Errorf("failed to open: %s, error: %w", c.path, ErrPathNotExist)
+		return fmt.Errorf("failed to open: %s, error: %w", c.path, err)
 	} else if err == nil {
 		defer fp.Close()
 		var buf []byte
@@ -109,7 +103,7 @@ func (c *fileConfig) Save(ctx context.Context, opts ...config.SaveOption) error
 		if err != nil && c.opts.AllowFail {
 			return nil
 		} else if err != nil && !c.opts.AllowFail {
-			return fmt.Errorf("failed to open: %s, error: %w", c.path, ErrPathNotExist)
+			return fmt.Errorf("failed to open: %s, error: %w", c.path, err)
 		}
 
 		if _, werr := fp.Write(buf); werr == nil {
@@ -140,6 +134,21 @@ func (c *fileConfig) Name() string {
 	return c.opts.Name
 }
 
+func (c *fileConfig) Watch(ctx context.Context, opts ...config.WatchOption) (config.Watcher, error) {
+	w := &fileWatcher{
+		path:  c.path,
+		opts:  c.opts,
+		wopts: config.NewWatchOptions(opts...),
+		done:  make(chan struct{}),
+		vchan: make(chan map[string]interface{}),
+		echan: make(chan error),
+	}
+
+	go w.run()
+
+	return w, nil
+}
+
 func NewConfig(opts ...config.Option) config.Config {
 	options := config.NewOptions(opts...)
 	if len(options.StructTag) == 0 {

go.mod

@@ -4,5 +4,5 @@ go 1.16
 
 require (
 	github.com/imdario/mergo v0.3.12
-	github.com/unistack-org/micro/v3 v3.4.0
+	github.com/unistack-org/micro/v3 v3.5.9
 )

go.sum

@@ -1,12 +1,12 @@
-github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
 github.com/ef-ds/deque v1.0.4/go.mod h1:gXDnTC3yqvBcHbq2lcExjtAcVrOnJCbMcZXmuj8Z4tg=
-github.com/google/uuid v1.2.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/golang-jwt/jwt v3.2.2+incompatible/go.mod h1:8pz2t5EyA70fFQQSrl6XZXzqecmYZeUEB8OUGHkxJ+I=
+github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/imdario/mergo v0.3.12 h1:b6R2BslTbIEToALKP7LxUvijTsNI9TAe80pLWN2g/HU=
 github.com/imdario/mergo v0.3.12/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
 github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/silas/dag v0.0.0-20210121180416-41cf55125c34/go.mod h1:7RTUFBdIRC9nZ7/3RyRNH1bdqIShrDejd1YbLwgPS+I=
-github.com/unistack-org/micro/v3 v3.4.0 h1:z9F3lgAb2j4cZ1ib5qBj66JPYUAzR4sNIJqUDjVwyVQ=
+github.com/unistack-org/micro/v3 v3.5.9 h1:9iIxGZ56bVME7E9hqKIHeSHXkn69M9KFyJfaUzi7B9k=
-github.com/unistack-org/micro/v3 v3.4.0/go.mod h1:LXmPfbJnJNvL0kQs8HfnkV3Wya2Wb+C7keVq++RCZnk=
+github.com/unistack-org/micro/v3 v3.5.9/go.mod h1:zQnZPEy842kQNcyjmVys6tdMjty4PHdyUUKYm1wrg1s=
 golang.org/x/net v0.0.0-20210510120150-4163338589ed/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

watcher.go

@@ -0,0 +1,103 @@
+package file
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"reflect"
+
+	"github.com/unistack-org/micro/v3/codec"
+	"github.com/unistack-org/micro/v3/config"
+	"github.com/unistack-org/micro/v3/util/jitter"
+	rutil "github.com/unistack-org/micro/v3/util/reflect"
+)
+
+type fileWatcher struct {
+	path  string
+	opts  config.Options
+	wopts config.WatchOptions
+	done  chan struct{}
+	vchan chan map[string]interface{}
+	echan chan error
+}
+
+func (w *fileWatcher) run() {
+	ticker := jitter.NewTicker(w.wopts.MinInterval, w.wopts.MaxInterval)
+	defer ticker.Stop()
+
+	src := w.opts.Struct
+	if w.wopts.Struct != nil {
+		src = w.wopts.Struct
+	}
+
+	for {
+		select {
+		case <-w.done:
+			return
+		case <-ticker.C:
+			dst, err := rutil.Zero(src)
+			if err == nil {
+				var fp *os.File
+				if fp, err = os.OpenFile(w.path, os.O_RDONLY, os.FileMode(0400)); err != nil {
+					w.echan <- fmt.Errorf("failed to open: %s, error: %w", w.path, err)
+					return
+				}
+				var buf []byte
+				buf, err = ioutil.ReadAll(io.LimitReader(fp, int64(codec.DefaultMaxMsgSize)))
+				if err == nil {
+					err = w.opts.Codec.Unmarshal(buf, dst)
+				}
+				if err != nil {
+					_ = fp.Close()
+					w.echan <- err
+					return
+				}
+				err = fp.Close()
+			}
+			if err != nil {
+				w.echan <- err
+				return
+			}
+			srcmp, err := rutil.StructFieldsMap(src)
+			if err != nil {
+				w.echan <- err
+				return
+			}
+			dstmp, err := rutil.StructFieldsMap(dst)
+			if err != nil {
+				w.echan <- err
+				return
+			}
+			for sk, sv := range srcmp {
+				if reflect.DeepEqual(dstmp[sk], sv) {
+					delete(dstmp, sk)
+				}
+			}
+			if len(dstmp) > 0 {
+				w.vchan <- dstmp
+				src = dst
+			}
+		}
+	}
+}
+
+func (w *fileWatcher) Next() (map[string]interface{}, error) {
+	select {
+	case <-w.done:
+		break
+	case err := <-w.echan:
+		return nil, err
+	case v, ok := <-w.vchan:
+		if !ok {
+			break
+		}
+		return v, nil
+	}
+	return nil, config.ErrWatcherStopped
+}
+
+func (w *fileWatcher) Stop() error {
+	close(w.done)
+	return nil
+}