Prevent double delays and add some docs (#411)

* Fix a few linter warnings

* Prevent double delays and add some docs

I just noticed that reusing `delay` for the poll interval will cause an unintended double delay (first the delay is used as interval, and when a change happened delay is used to wait before building after the change).

Adding a dedicated `poll_interval` parameter allows people to prevent that and apply a more fine-grained configuration.

Also added the new params to the example toml file with some docs which I forgot to do in the initial PR.

air_example.toml

@@ -30,6 +30,10 @@ exclude_unchanged = true
 follow_symlink = true
 # This log file places in your tmp_dir.
 log = "air.log"
+# Poll files for changes instead of using fsnotify.
+poll = false
+# Poll interval (defaults to the minimum interval of 500ms).
+poll_interval = 500 # ms
 # It's not necessary to trigger build each time file changes if it's too frequent.
 delay = 0 # ms
 # Stop running old binary when build errors occur.

runner/config.go

@@ -48,6 +48,7 @@ type cfgBuild struct {
 	ExcludeUnchanged bool          `toml:"exclude_unchanged"`
 	FollowSymlink    bool          `toml:"follow_symlink"`
 	Poll             bool          `toml:"poll"`
+	PollInterval     int           `toml:"poll_interval"`
 	Delay            int           `toml:"delay"`
 	StopOnError      bool          `toml:"stop_on_error"`
 	SendInterrupt    bool          `toml:"send_interrupt"`

runner/engine.go

@@ -345,7 +345,6 @@ func (e *Engine) start() {
 			e.mainLog("%s has changed", e.config.rel(filename))
 		case <-firstRunCh:
 			// go down
-			break
 		}
 
 		// already build and run now
@@ -449,7 +448,6 @@ func (e *Engine) runBin() error {
 			close(e.canExit)
 		default:
 		}
-
 	}()
 
 	killFunc := func(cmd *exec.Cmd, stdout io.ReadCloser, stderr io.ReadCloser, killCh chan struct{}, processExit chan struct{}, wg *sync.WaitGroup) {

runner/engine_test.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"io/ioutil"
+	"log"
 	"net"
 	"os"
 	"os/exec"
@@ -508,10 +509,7 @@ func checkPortConnectionRefused(port int) bool {
 			_ = conn.Close()
 		}
 	}()
-	if errors.Is(err, syscall.ECONNREFUSED) {
-		return true
-	}
-	return false
+	return errors.Is(err, syscall.ECONNREFUSED)
 }
 
 func checkPortHaveBeenUsed(port int) bool {
@@ -572,6 +570,9 @@ func main() {
 		return err
 	}
 	_, err = file.WriteString(code)
+	if err != nil {
+		return err
+	}
 
 	// generate go mod file
 	mod := `module air.sample.com
@@ -604,6 +605,9 @@ func main() {
 		return err
 	}
 	_, err = file.WriteString(code)
+	if err != nil {
+		return err
+	}
 
 	// generate go mod file
 	mod := `module air.sample.com
@@ -639,6 +643,9 @@ func main() {
 		return err
 	}
 	_, err = file.WriteString(code)
+	if err != nil {
+		return err
+	}
 
 	// generate go mod file
 	mod := `module air.sample.com
@@ -688,12 +695,12 @@ func TestRebuildWhenRunCmdUsingDLV(t *testing.T) {
 	go func() {
 		file, err := os.OpenFile("main.go", os.O_APPEND|os.O_WRONLY, 0o644)
 		if err != nil {
-			t.Fatalf("Should not be fail: %s.", err)
+			log.Fatalf("Should not be fail: %s.", err)
 		}
 		defer file.Close()
 		_, err = file.WriteString("\n")
 		if err != nil {
-			t.Fatalf("Should not be fail: %s.", err)
+			log.Fatalf("Should not be fail: %s.", err)
 		}
 	}()
 	err = waitingPortConnectionRefused(t, port, time.Second*10)
@@ -895,11 +902,11 @@ include_ext = ["sh"]
 include_dir = ["nonexist"] # prevent default "." watch from taking effect
 include_file = ["main.sh"]
 `
-	if err := ioutil.WriteFile(dftTOML, []byte(config), 0644); err != nil {
+	if err := ioutil.WriteFile(dftTOML, []byte(config), 0o644); err != nil {
 		t.Fatal(err)
 	}
 
-	err := os.WriteFile("main.sh", []byte("#!/bin/sh\nprintf original > output"), 0755)
+	err := os.WriteFile("main.sh", []byte("#!/bin/sh\nprintf original > output"), 0o755)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -922,9 +929,9 @@ include_file = ["main.sh"]
 
 	t.Logf("start change main.sh")
 	go func() {
-		err := os.WriteFile("main.sh", []byte("#!/bin/sh\nprintf modified > output"), 0755)
+		err := os.WriteFile("main.sh", []byte("#!/bin/sh\nprintf modified > output"), 0o755)
 		if err != nil {
-			t.Fatalf("Error updating file: %s.", err)
+			log.Fatalf("Error updating file: %s.", err)
 		}
 	}()
 

runner/logger.go

@@ -53,7 +53,7 @@ func newLogFunc(colorname string, cfg cfgLog) logFunc {
 	return func(msg string, v ...interface{}) {
 		// There are some escape sequences to format color in terminal, so cannot
 		// just trim new line from right.
-		msg = strings.Replace(msg, "\n", "", -1)
+		msg = strings.ReplaceAll(msg, "\n", "")
 		msg = strings.TrimSpace(msg)
 		if len(msg) == 0 {
 			return

runner/watcher.go

@@ -12,9 +12,9 @@ func newWatcher(cfg *Config) (filenotify.FileWatcher, error) {
 	}
 
 	// Get the poll interval from the config.
-	interval := cfg.Build.Delay
+	interval := cfg.Build.PollInterval
 
-	// Configure a minimum poll interval of 500ms.
+	// Make sure the interval is at least 500ms.
 	if interval < 500 {
 		interval = 500
 	}