Add cmd/log.go

cmd/log.go

@@ -0,0 +1,106 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"sync"
+	"time"
+)
+
+// Logging request.
+//
+
+// RequestLogger logs all incoming HTTP requests.
+type RequestLogger struct {
+	buf      map[logEntry]int
+	filename string
+	m        sync.Mutex
+
+	period    time.Duration
+	lastFlush time.Time
+}
+
+type logEntry struct {
+	Proto     string
+	IP        string
+	URI       string
+	UserAgent string
+}
+
+// NewRequestLogger returns a new RequestLogger for the specified log file.
+// Flush logging entries after period of time.
+func NewRequestLogger(filename string, period time.Duration) *RequestLogger {
+	return &RequestLogger{
+		buf:      map[logEntry]int{},
+		filename: filename,
+		m:        sync.Mutex{},
+		period:   period,
+	}
+}
+
+// Log logs information about a HTTP request.
+func (rl *RequestLogger) Log(r *http.Request) error {
+	le := logEntry{
+		Proto:     "http",
+		IP:        readUserIP(r),
+		URI:       r.RequestURI,
+		UserAgent: r.Header.Get("User-Agent"),
+	}
+
+	rl.m.Lock()
+	rl.buf[le]++
+	rl.m.Unlock()
+
+	if time.Since(rl.lastFlush) > rl.period {
+		return rl.flush()
+	}
+	return nil
+}
+
+// flush stores log data to disk, and flushes the buffer.
+func (rl *RequestLogger) flush() error {
+	rl.m.Lock()
+	defer rl.m.Unlock()
+
+	// It is possible, that while waiting the mutex,
+	// the buffer was already flushed.
+	if time.Since(rl.lastFlush) <= rl.period {
+		return nil
+	}
+
+	// Generate log output.
+	output := ""
+	for k, hitsNumber := range rl.buf {
+		output += fmt.Sprintf("%s %3d %s\n", time.Now().Format(time.RFC3339), hitsNumber, k.String())
+	}
+
+	// Open log file.
+	f, err := os.OpenFile(rl.filename, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	// Save output to log file.
+	_, err = f.Write([]byte(output))
+	if err != nil {
+		return err
+	}
+
+	// Flush buffer.
+	rl.buf = map[logEntry]int{}
+	rl.lastFlush = time.Now()
+
+	return nil
+}
+
+func (e *logEntry) String() string {
+	return fmt.Sprintf(
+		"%s %s %s %s",
+		e.Proto,
+		e.IP,
+		e.URI,
+		e.UserAgent,
+	)
+}