log: Allow eggos implementations to programatically set log levels (#96)

When running applications on environments where there is no environment, calls to os.Setenv to set a loglevel have inconsistent results. Similarly, setting this environment variable before the first log event, and thus making that call moot, is racy.

Instead, then, export log levels, drop the potential stutter in log.LogLvl to log.Level, and allow implementations/ callers of this package to set a log level accordingly, while maintaining the default behaviour

log/log.go

@@ -4,13 +4,22 @@ import (
 	"bytes"
 	"fmt"
 	"os"
-	"sync"
 
 	"github.com/icexin/eggos/console"
 	"github.com/icexin/eggos/drivers/uart"
 	"github.com/icexin/eggos/kernel/sys"
 )
 
+type LogLevel int8
+
+const (
+	LoglvlDebug LogLevel = iota
+	LoglvlInfo
+	LoglvlWarn
+	LoglvlError
+	LoglvlNone
+)
+
 const (
 	loglvlEnv      = "EGGOS_LOGLVL"
 	loglvlEnvDebug = "debug"
@@ -19,39 +28,43 @@ const (
 	loglvlEnvError = "error"
 	loglvlEnvNone  = "none"
 
-	loglvlDebug = iota
-	loglvlInfo
-	loglvlWarn
-	loglvlError
-	loglvlNone
-
-	defaultLoglvl = loglvlError
+	defaultLoglvl = LoglvlError
 )
 
 var (
-	loglvl     int
-	loglvlonce sync.Once
+	Level LogLevel
+
+	ErrInvalidLogLevel = fmt.Errorf("invalid log level")
 )
 
-func setLoglvl() {
+func init() {
 	lvl := os.Getenv("EGGOS_LOGLVL")
 	switch lvl {
 	case loglvlEnvDebug:
-		loglvl = loglvlDebug
+		Level = LoglvlDebug
 	case loglvlEnvInfo:
-		loglvl = loglvlInfo
+		Level = LoglvlInfo
 	case loglvlEnvWarn:
-		loglvl = loglvlWarn
+		Level = LoglvlWarn
 	case loglvlEnvError:
-		loglvl = loglvlError
+		Level = LoglvlError
 	default:
-		loglvl = defaultLoglvl
+		Level = defaultLoglvl
 	}
 }
 
-func logf(lvl int, fmtstr string, args ...interface{}) {
-	loglvlonce.Do(setLoglvl)
-	if lvl < loglvl {
+func SetLevel(l LogLevel) error {
+	if l < LoglvlDebug || l > LoglvlNone {
+		return ErrInvalidLogLevel
+	}
+
+	Level = l
+
+	return nil
+}
+
+func logf(lvl LogLevel, fmtstr string, args ...interface{}) {
+	if lvl < Level {
 		return
 	}
 
@@ -62,19 +75,19 @@ func logf(lvl int, fmtstr string, args ...interface{}) {
 }
 
 func Debugf(fmtstr string, args ...interface{}) {
-	logf(loglvlDebug, fmtstr, args...)
+	logf(LoglvlDebug, fmtstr, args...)
 }
 
 func Infof(fmtstr string, args ...interface{}) {
-	logf(loglvlInfo, fmtstr, args...)
+	logf(LoglvlInfo, fmtstr, args...)
 }
 
 func Warnf(fmtstr string, args ...interface{}) {
-	logf(loglvlWarn, fmtstr, args...)
+	logf(LoglvlWarn, fmtstr, args...)
 }
 
 func Errorf(fmtstr string, args ...interface{}) {
-	logf(loglvlError, fmtstr, args...)
+	logf(LoglvlError, fmtstr, args...)
 }
 
 //go:nosplit

log/log_test.go

@@ -0,0 +1,48 @@
+package log_test
+
+import (
+	"testing"
+
+	"github.com/icexin/eggos/log"
+)
+
+func ExampleSetLogLevel() {
+	// Set the log level to Debug
+	log.Level = log.LoglvlDebug
+}
+
+func TestLog_SetLevel(t *testing.T) {
+	for _, test := range []struct {
+		name        string
+		l           log.LogLevel
+		expectError bool
+	}{
+		// These two cases require users to do something pretty explcitly
+		// wrong to hit, but they're worth catching
+		{"log level is too low", log.LogLevel(-1), true},
+		{"log level is too high", log.LogLevel(6), true},
+
+		// Included log levels
+		{"log.LoglvlDebug is valid", log.LoglvlDebug, false},
+		{"log.LoglvlInfo is valid", log.LoglvlInfo, false},
+		{"log.LoglvlWarn is valid", log.LoglvlWarn, false},
+		{"log.LoglvlError is valid", log.LoglvlError, false},
+		{"log.LoglvlNone is valid", log.LoglvlNone, false},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			err := log.SetLevel(test.l)
+
+			if err == nil && test.expectError {
+				t.Error("expected error, received none")
+			} else if err != nil && !test.expectError {
+				t.Errorf("unexpected error: %#v", err)
+			}
+
+			if !test.expectError {
+				if log.Level != test.l {
+					t.Errorf("log.Level should be %#v, received %#v", log.Level, test.l)
+				}
+			}
+		})
+	}
+}