listmonk/internal/buflog/buflog.go

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package buflog
import (
"bytes"
"strings"
"sync"
)
// BufLog implements a simple log buffer that can be supplied to a std
// log instance. It stores logs up to N lines.
type BufLog struct {
maxLines int
buf *bytes.Buffer
lines []string
sync.RWMutex
}
// New returns a new log buffer that stores up to maxLines lines.
func New(maxLines int) *BufLog {
return &BufLog{
maxLines: maxLines,
buf: &bytes.Buffer{},
lines: make([]string, 0, maxLines),
}
}
// Write writes a log item to the buffer maintaining maxLines capacity
// using LIFO.
func (bu *BufLog) Write(b []byte) (n int, err error) {
bu.Lock()
if len(bu.lines) >= bu.maxLines {
bu.lines[0] = ""
bu.lines = bu.lines[1:len(bu.lines)]
}
bu.lines = append(bu.lines, strings.TrimSpace(string(b)))
bu.Unlock()
return len(b), nil
}
// Lines returns the log lines.
func (bu *BufLog) Lines() []string {
bu.RLock()
defer bu.RUnlock()
out := make([]string, len(bu.lines))
copy(out[:], bu.lines[:])
return out
}