Implementation.

.gitignore

@@ -1,3 +1,4 @@
+vendor/*/
 # Compiled Object files, Static and Dynamic libs (Shared Objects)
 *.o
 *.a

.travis.yml

@@ -0,0 +1,13 @@
+language: go
+
+go:
+  - 1.7
+script:
+  - go test -coverprofile=coverage.txt -covermode=atomic -coverpkg .
+
+before_install:
+  - go get -u github.com/kardianos/govendor
+  - govendor sync
+
+after_success:
+- bash <(curl -s https://codecov.io/bash)

README.md

@@ -1 +1,6 @@
-# reloader
+# Reloader
+[![Build Status](https://travis-ci.org/aandryashin/reloader.svg?branch=master)](https://travis-ci.org/aandryashin/reloader)
+[![Coverage](https://codecov.io/github/aandryashin/reloader/reloader.svg)](https://codecov.io/gh/aandryashin/reloader)
+[![Release](https://img.shields.io/github/release/aandryashin/reloader.svg)](https://github.com/aandryashin/reloader/releases/latest)
+
+Library for automatic reloading configuration files based on file system events.

reloader.go

@@ -0,0 +1,44 @@
+package reloader
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+func Watch(dir string, load func(), delay time.Duration) error {
+	return watch(fsnotify.NewWatcher, dir, load, delay)
+}
+
+func watch(fn func() (*fsnotify.Watcher, error), dir string, load func(), delay time.Duration) error {
+	watcher, err := fn()
+	if err != nil {
+		return fmt.Errorf("unable to initialize file system notifications: %v", err)
+	}
+	if err := watcher.Add(dir); err != nil {
+		return fmt.Errorf("unable to watch directory: %v", err)
+	}
+	go func() {
+		var cancel chan struct{}
+		for {
+			select {
+			case e := <-watcher.Events:
+				if e.Op != 0 {
+					if cancel != nil {
+						close(cancel)
+					}
+					cancel = make(chan struct{})
+					go func(cancel chan struct{}) {
+						select {
+						case <-time.After(delay):
+							load()
+						case <-cancel:
+						}
+					}(cancel)
+				}
+			}
+		}
+	}()
+	return nil
+}

reloader_test.go

@@ -0,0 +1,141 @@
+package reloader
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+func TestWatch(t *testing.T) {
+	dir, err := ioutil.TempDir("", "config")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(dir)
+	err = Watch(dir, func() {}, 1*time.Second)
+	if err != nil {
+		t.Errorf("uexpected error: %v\n", err)
+	}
+}
+
+func TestWatchUexistentDir(t *testing.T) {
+	dir, err := ioutil.TempDir("", "config")
+	if err != nil {
+		t.Fatal(err)
+	}
+	os.Remove(dir)
+	err = Watch(dir, func() {}, 1*time.Second)
+	if err == nil {
+		t.Error("uexpected success")
+	}
+}
+
+func TestNewWatcherError(t *testing.T) {
+	fn := func() (*fsnotify.Watcher, error) {
+		return nil, fmt.Errorf("error")
+	}
+	err := watch(fn, "", func() {}, 1*time.Second)
+	if err == nil {
+		t.Error("uexpected success")
+	}
+}
+
+func TestTimerShouldNotTrigger(t *testing.T) {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer watcher.Close()
+	fn := func() (*fsnotify.Watcher, error) {
+		return watcher, nil
+	}
+	dir, err := ioutil.TempDir("", "config")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(dir)
+	ch := make(chan bool)
+	watch(fn, dir, func() { ch <- true }, 200*time.Millisecond)
+	call := false
+	watcher.Events <- fsnotify.Event{Op: fsnotify.Create}
+	select {
+	case <-time.After(100 * time.Millisecond):
+	case call = <-ch:
+	}
+	if call {
+		t.Error("timer should not be triggered after 100ms")
+	}
+}
+
+func TestTimerShouldTrigger(t *testing.T) {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer watcher.Close()
+	fn := func() (*fsnotify.Watcher, error) {
+		return watcher, nil
+	}
+	dir, err := ioutil.TempDir("", "config")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(dir)
+	ch := make(chan bool)
+	watch(fn, dir, func() { ch <- true }, 100*time.Millisecond)
+	call := false
+	watcher.Events <- fsnotify.Event{Op: fsnotify.Create}
+	select {
+	case <-time.After(200 * time.Millisecond):
+	case call = <-ch:
+	}
+	if !call {
+		t.Error("timer should be triggered after 200ms")
+	}
+}
+
+func TestTimerShouldTriggerOnce(t *testing.T) {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer watcher.Close()
+	fn := func() (*fsnotify.Watcher, error) {
+		return watcher, nil
+	}
+	dir, err := ioutil.TempDir("", "config")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(dir)
+	ch := make(chan bool)
+	watch(fn, dir, func() { ch <- true }, 300*time.Millisecond)
+	call := false
+	watcher.Events <- fsnotify.Event{Op: fsnotify.Create}
+	select {
+	case <-time.After(200 * time.Millisecond):
+	case call = <-ch:
+	}
+	if call {
+		t.Error("timer should not be triggered after 200ms")
+	}
+	watcher.Events <- fsnotify.Event{Op: fsnotify.Create}
+	select {
+	case <-time.After(200 * time.Millisecond):
+	case call = <-ch:
+	}
+	if call {
+		t.Error("timer still should not be triggered after 400ms")
+	}
+	select {
+	case <-time.After(200 * time.Millisecond):
+	case call = <-ch:
+	}
+	if !call {
+		t.Error("timer should be triggered after 600ms")
+	}
+}

vendor/vendor.json

@@ -0,0 +1,19 @@
+{
+	"comment": "",
+	"ignore": "",
+	"package": [
+		{
+			"checksumSHA1": "74zwCNDSsh7NdJcEhgItnfU6d/E=",
+			"path": "github.com/fsnotify/fsnotify",
+			"revision": "fd9ec7deca8bf46ecd2a795baaacf2b3a9be1197",
+			"revisionTime": "2016-10-26T20:31:22Z"
+		},
+		{
+			"checksumSHA1": "yAfJ8xBj7cQuDtznpPwPt3UmJiE=",
+			"path": "golang.org/x/sys/unix",
+			"revision": "30237cf4eefd639b184d1f2cb77a581ea0be8947",
+			"revisionTime": "2016-11-19T15:29:01Z"
+		}
+	],
+	"rootPath": "github.com/aandryashin/reloader"
+}