EagleCast

internal/buflog/buflog.go

@@ -0,0 +1,51 @@
+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()
+	defer bu.Unlock()
+
+	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)))
+
+	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
+}