/usr/share/gocode/src/github.com/armon/circbuf/circbuf.go is in golang-github-armon-circbuf-dev 0.0~git20150827.0.bbbad09-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 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())
}
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