bump:(github.com/armon/circbuf):bbbad097214e2918d8543d5201d12bfd7bca254d

vendor/github.com/armon/circbuf/circbuf.go

@@ -0,0 +1,92 @@
+package circbuf
+
+import (
+	"fmt"
+)
+
+// Buffer implements a circular buffer. It is a fixed size,
+// and new writes overwrite older data, such that for a buffer
+// of size N, for any amount of writes, only the last N bytes
+// are retained.
+type Buffer struct {
+	data        []byte
+	size        int64
+	writeCursor int64
+	written     int64
+}
+
+// NewBuffer creates a new buffer of a given size. The size
+// must be greater than 0.
+func NewBuffer(size int64) (*Buffer, error) {
+	if size <= 0 {
+		return nil, fmt.Errorf("Size must be positive")
+	}
+
+	b := &Buffer{
+		size: size,
+		data: make([]byte, size),
+	}
+	return b, nil
+}
+
+// Write writes up to len(buf) bytes to the internal ring,
+// overriding older data if necessary.
+func (b *Buffer) Write(buf []byte) (int, error) {
+	// Account for total bytes written
+	n := len(buf)
+	b.written += int64(n)
+
+	// If the buffer is larger than ours, then we only care
+	// about the last size bytes anyways
+	if int64(n) > b.size {
+		buf = buf[int64(n)-b.size:]
+	}
+
+	// Copy in place
+	remain := b.size - b.writeCursor
+	copy(b.data[b.writeCursor:], buf)
+	if int64(len(buf)) > remain {
+		copy(b.data, buf[remain:])
+	}
+
+	// Update location of the cursor
+	b.writeCursor = ((b.writeCursor + int64(len(buf))) % b.size)
+	return n, nil
+}
+
+// Size returns the size of the buffer
+func (b *Buffer) Size() int64 {
+	return b.size
+}
+
+// TotalWritten provides the total number of bytes written
+func (b *Buffer) TotalWritten() int64 {
+	return b.written
+}
+
+// Bytes provides a slice of the bytes written. This
+// slice should not be written to.
+func (b *Buffer) Bytes() []byte {
+	switch {
+	case b.written >= b.size && b.writeCursor == 0:
+		return b.data
+	case b.written > b.size:
+		out := make([]byte, b.size)
+		copy(out, b.data[b.writeCursor:])
+		copy(out[b.size-b.writeCursor:], b.data[:b.writeCursor])
+		return out
+	default:
+		return b.data[:b.writeCursor]
+	}
+}
+
+// Reset resets the buffer so it has no content.
+func (b *Buffer) Reset() {
+	b.writeCursor = 0
+	b.written = 0
+}
+
+// String returns the contents of the buffer as a string
+func (b *Buffer) String() string {
+	return string(b.Bytes())
+}