.

internal/jsonlog/jsonlog.go

@@ -1,26 +1,23 @@
 package jsonlog
 
 import (
-"encoding/json"
-"io"
-"os"
-"runtime/debug"
-"sync"
-"time"
+	"encoding/json"
+	"io"
+	"os"
+	"runtime/debug"
+	"sync"
+	"time"
 )
-// Define a Level type to represent the severity level for a log entry.
+
 type Level int8
 
-// Initialize constants which represent a specific severity level. We use the iota
-// keyword as a shortcut to assign successive integer values to the constants.
 const (
-	LevelInfo Level = iota // Has the value 0.
-	LevelError // Has the value 1.
-	LevelFatal // Has the value 2.
-	LevelOff // Has the value 3.
+	LevelInfo Level = iota
+	LevelError
+	LevelFatal
+	LevelOff
 )
 
-// Return a human-friendly string for the severity level.
 func (l Level) String() string {
 	switch l {
 	case LevelInfo:
@@ -34,17 +31,12 @@ func (l Level) String() string {
 	}
 }
 
-// Define a custom Logger type. This holds the output destination that the log entries
-// will be written to, the minimum severity level that log entries will be written for,
-// plus a mutex for coordinating the writes.
 type Logger struct {
 	out      io.Writer
 	minLevel Level
 	mu       sync.Mutex
 }
 
-// Return a new Logger instance which writes log entries at or above a minimum severity
-// level to a specific output destination.
 func New(out io.Writer, minLevel Level) *Logger {
 	return &Logger{
 	out: out,
@@ -52,9 +44,6 @@ func New(out io.Writer, minLevel Level) *Logger {
 	}
 }
 
-// Declare some helper methods for writing log entries at the different levels. Notice
-// that these all accept a map as the second parameter which can contain any arbitrary
-// 'properties' that you want to appear in the log entry.
 func (l *Logger) PrintInfo(message string, properties map[string]string) {
 	l.print(LevelInfo, message, properties)
 }
@@ -65,18 +54,14 @@ func (l *Logger) PrintError(err error, properties map[string]string) {
 
 func (l *Logger) PrintFatal(err error, properties map[string]string) {
 	l.print(LevelFatal, err.Error(), properties)
-	os.Exit(1) // For entries at the FATAL level, we also terminate the application.
+	os.Exit(1)
 }
 
-// Print is an internal method for writing the log entry.
 func (l *Logger) print(level Level, message string, properties map[string]string) (int, error) {
-	// If the severity level of the log entry is below the minimum severity for the
-	// logger, then return with no further action.
 	if level < l.minLevel {
 		return 0, nil
 	}
 
-	// Declare an anonymous struct holding the data for the log entry.
 	aux := struct {
 		Level      string            `json:"level"`
 		Time       string            `json:"time"`
@@ -90,35 +75,23 @@ func (l *Logger) print(level Level, message string, properties map[string]string
 		Properties: properties,
 	}
 
-	// Include a stack trace for entries at the ERROR and FATAL levels.
 	if level >= LevelError {
 		aux.Trace = string(debug.Stack())
 	}
 
-	// Declare a line variable for holding the actual log entry text.
 	var line []byte
 
-	// Marshal the anonymous struct to JSON and store it in the line variable. If there
-	// was a problem creating the JSON, set the contents of the log entry to be that
-	// plain-text error message instead.
 	line, err := json.Marshal(aux)
 	if err != nil {
 		line = []byte(LevelError.String() + ": unable to marshal log message:" + err.Error())
 	}
 
-	// Lock the mutex so that no two writes to the output destination cannot happen
-	// concurrently. If we don't do this, it's possible that the text for two or more
-	// log entries will be intermingled in the output.
 	l.mu.Lock()
 	defer l.mu.Unlock()
 
-	// Write the log entry followed by a newline.
 	return l.out.Write(append(line, '\n'))
 }
 
-// We also implement a Write() method on our Logger type so that it satisfies the
-// io.Writer interface. This writes a log entry at the ERROR level with no additional
-// properties.
 func (l *Logger) Write(message []byte) (n int, err error) {
 	return l.print(LevelError, string(message), nil)
 }