Use circular buffer for zap logs

internal/util/logging/logging.go

@@ -31,11 +31,18 @@ func Setup(level zapcore.Level) {
 		log.Fatal(err)
 	}
 
-	SetupWithLogger(logger)
+	logram := NewLogRAM()
+
+	logger = logger.WithOptions(zap.Hooks(func(entry zapcore.Entry) error {
+		logram.append(entry)
+		return nil
+	}))
+
+	setupWithLogger(logger)
 }
 
-// SetupWithLogger initializes logging with a given logger and its level.
-func SetupWithLogger(logger *zap.Logger) {
+// setupWithLogger initializes logging with a given logger and its level.
+func setupWithLogger(logger *zap.Logger) {
 	zap.ReplaceGlobals(logger)
 
 	if _, err := zap.RedirectStdLogAt(logger, zap.InfoLevel); err != nil {

internal/util/logging/logram.go

@@ -0,0 +1,77 @@
+// Copyright 2021 FerretDB Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logging
+
+import (
+	"sync"
+	"time"
+
+	"go.uber.org/zap/zapcore"
+)
+
+type record struct {
+	Level      zapcore.Level
+	Time       time.Time
+	LoggerName string
+	Message    string
+	Stack      string
+}
+
+// logRAM structure storage of log records in memory.
+type logRAM struct {
+	counter int64
+	log     [1024]*record
+	mu      sync.RWMutex
+}
+
+// NewLogRAM is creating entries log in memory.
+func NewLogRAM() *logRAM {
+	return &logRAM{
+		mu: sync.RWMutex{},
+	}
+}
+
+// append adding entry in logram.
+func (l *logRAM) append(entry zapcore.Entry) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	rec := &record{
+		Level:      entry.Level,
+		Time:       entry.Time,
+		LoggerName: entry.LoggerName,
+		Message:    entry.Message,
+		Stack:      entry.Stack,
+	}
+
+	l.log[l.counter] = rec
+	l.counter = (l.counter + 1) % 1024
+}
+
+func (l *logRAM) getLogRAM() (entrys []zapcore.Entry) {
+	for _, r := range l.log {
+		if r != nil {
+			e := zapcore.Entry{
+				Level:      r.Level,
+				Time:       r.Time,
+				LoggerName: r.LoggerName,
+				Message:    r.Message,
+				Stack:      r.Stack,
+			}
+			entrys = append(entrys, e)
+		}
+	}
+	return
+}