Cache log messages

Author: tknie

logging.go

@@ -1,5 +1,5 @@
 /*
-* Copyright 2022-2023 Thorsten A. Knieling
+* Copyright 2022-2024 Thorsten A. Knieling
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -13,30 +13,65 @@ package log
 
 import (
 	"fmt"
+	"os"
 	"strings"
 	"time"
 )
 
+const maxBufferEntries = 100
+
+type errorLevel byte
+
+const (
+	fataL errorLevel = iota
+	errorL
+	infoL
+	debugL
+)
+
+type tempStoreElement struct {
+	level   errorLevel
+	message string
+}
+
+var tempStore = make([]tempStoreElement, 0)
+
 type nilLogger struct {
 }
 
 func lognil() *nilLogger {
 	return &nilLogger{}
 }
 
+func disableLog() {
+	Log = lognil()
+}
+
+func shrinkTempStore() {
+	if len(tempStore) > maxBufferEntries {
+		tempStore = tempStore[len(tempStore)-maxBufferEntries:]
+	}
+}
+
 func (*nilLogger) Debugf(format string, args ...interface{}) {
 }
 
 func (*nilLogger) Infof(format string, args ...interface{}) {
+	tempStore = append(tempStore, tempStoreElement{infoL, fmt.Sprintf(format, args...)})
+	shrinkTempStore()
 }
 
 func (*nilLogger) Errorf(format string, args ...interface{}) {
+	tempStore = append(tempStore, tempStoreElement{errorL, fmt.Sprintf(format, args...)})
+	shrinkTempStore()
 }
 
 func (*nilLogger) Fatal(args ...interface{}) {
 }
 
 func (*nilLogger) Fatalf(format string, args ...interface{}) {
+	tempStore = append(tempStore, tempStoreElement{fataL, fmt.Sprintf(format, args...)})
+	os.Exit(1)
 }
 
 // Log defines the log interface to manage other Log output frameworks
@@ -52,6 +87,24 @@ type LogI interface {
 var Log = LogI(lognil())
 var debug = false
 
+func InitLog(newLog LogI) {
+	Log = newLog
+	if len(tempStore) > 0 {
+		for _, t := range tempStore {
+			switch t.level {
+			case fataL:
+				Log.Fatalf(t.message)
+			case errorL:
+				Log.Errorf(t.message)
+			case infoL:
+				Log.Infof(t.message)
+			default:
+			}
+		}
+	}
+	tempStore = make([]tempStoreElement, 0)
+}
+
 func IsDebugLevel() bool {
 	return debug
 }

logging_test.go

@@ -1,5 +1,5 @@
 /*
-* Copyright 2022-2023 Thorsten A. Knieling
+* Copyright 2022-2024 Thorsten A. Knieling
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -80,7 +80,7 @@ func initLogLevelWithFile(fileName string, level zapcore.Level) (err error) {
 	defer logger.Sync()
 
 	sugar := logger.Sugar()
-	Log = sugar
+	InitLog(sugar)
 
 	sugar.Infof("AdabasGoApi logger initialization succeeded")
 	return nil
@@ -150,7 +150,7 @@ func TestLogrus(t *testing.T) {
 	}
 	log.SetOutput(f)
 	log.Infof("Init logrus")
-	Log = log
+	InitLog(log)
 	fmt.Println("Logging running")
 
 	flog, err := os.Open(os.TempDir() + "/" + fileName)
@@ -163,3 +163,48 @@ func TestLogrus(t *testing.T) {
 	}
 	assert.Regexp(t, "time=\"20..-..-..T..:..:..\" level=info msg=\"Init logrus\"\n", string(logInfo))
 }
+
+const testResult = `info:INFO: Pre-log information
+error:ERROR: Pre-log information
+debug:DEBUG: Post-log information
+info:INFO: Post-log information
+error:ERROR: Post-log information
+`
+
+type testLogger struct {
+	testLog string
+}
+
+var testLog = &testLogger{}
+
+func (t *testLogger) Debugf(format string, args ...interface{}) {
+	t.testLog += "debug:" + fmt.Sprintf(format+"\n", args...)
+}
+
+func (t *testLogger) Infof(format string, args ...interface{}) {
+	t.testLog += "info:" + fmt.Sprintf(format+"\n", args...)
+}
+
+func (t *testLogger) Errorf(format string, args ...interface{}) {
+	t.testLog += "error:" + fmt.Sprintf(format+"\n", args...)
+}
+
+func (t *testLogger) Fatal(args ...interface{}) {
+}
+
+func (t *testLogger) Fatalf(format string, args ...interface{}) {
+	t.testLog += "fatal:" + fmt.Sprintf(format+"\n", args...)
+	os.Exit(1)
+}
+
+func TestCache(t *testing.T) {
+	disableLog()
+	Log.Debugf("DEBUG: Pre-log information")
+	Log.Infof("INFO: Pre-log information")
+	Log.Errorf("ERROR: Pre-log information")
+	InitLog(testLog)
+	Log.Debugf("DEBUG: Post-log information")
+	Log.Infof("INFO: Post-log information")
+	Log.Errorf("ERROR: Post-log information")
+	assert.Equal(t, testResult, testLog.testLog)
+}