improvements on the new accesslog middleware

relative to: https://github.com/kataras/iris/issues/1601

middleware/accesslog/log.go

@@ -0,0 +1,94 @@
+package accesslog
+
+import (
+	"encoding/json"
+	"io"
+	"sync"
+	"time"
+
+	"github.com/kataras/iris/v12/context"
+	"github.com/kataras/iris/v12/core/memstore"
+)
+
+// Log represents the log data specifically for the accesslog middleware.
+type Log struct {
+	// The AccessLog instance this Log was created of.
+	Logger *AccessLog `json:"-"`
+
+	// The time the log is created.
+	Now time.Time `json:"-"`
+	// Timestamp the Now's unix timestamp (seconds).
+	Timestamp int64 `json:"timestamp"`
+
+	// Request-Response latency.
+	Latency time.Duration `json:"latency"`
+	// Init request's Method and Path.
+	Method string `json:"method"`
+	Path   string `json:"path"`
+	// Sorted URL Query arguments.
+	Query []memstore.StringEntry
+	// Dynamic path parameters.
+	PathParams []memstore.Entry
+	// Fields any data information useful to represent this Log.
+	Fields context.Map `json:"fields,omitempty"`
+
+	// The Request and Response raw bodies.
+	// If they are escaped (e.g. JSON),
+	// A third-party software can read it through:
+	// data, _ := strconv.Unquote(log.Request)
+	// err := json.Unmarshal([]byte(data), &customStruct)
+	Request  string `json:"request"`
+	Response string `json:"response"`
+
+	// A copy of the Request's Context when Async is true (safe to use concurrently),
+	// otherwise it's the current Context (not safe for concurrent access).
+	Ctx *context.Context `json:"-"`
+}
+
+// Formatter is responsible to print a Log to the accesslog's writer.
+type Formatter interface {
+	// Format should print the Log.
+	// Returns true on handle successfully,
+	// otherwise the log will be printed using the default formatter.
+	Format(log *Log) bool
+	// SetWriter should inject the accesslog's output.
+	SetOutput(dest io.Writer)
+}
+
+// JSON is a Formatter type for JSON logs.
+type JSON struct {
+	Prefix, Indent string
+	EscapeHTML     bool
+
+	enc *json.Encoder
+	mu  sync.Mutex
+}
+
+// SetOutput creates the json encoder writes to the "dest".
+// It's called automatically by the middleware when this Formatter is used.
+func (f *JSON) SetOutput(dest io.Writer) {
+	if dest == nil {
+		return
+	}
+
+	// All logs share the same accesslog's writer and it cannot change during serve-time.
+	enc := json.NewEncoder(dest)
+	enc.SetEscapeHTML(f.EscapeHTML)
+	enc.SetIndent(f.Prefix, f.Indent)
+	f.enc = enc
+}
+
+// Format prints the logs in JSON format.
+func (f *JSON) Format(log *Log) bool {
+	f.mu.Lock()
+	if f.enc == nil {
+		// If no custom writer is given then f.enc is nil,
+		// this code block should only be executed once.
+		// Also, the app's logger's writer cannot change during serve-time,
+		// so all logs share the same instance output.
+		f.SetOutput(log.Ctx.Application().Logger().Printer)
+	}
+	err := f.enc.Encode(log)
+	f.mu.Unlock()
+	return err == nil
+}