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59 lines
1.2 KiB
59 lines
1.2 KiB
3 years ago
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package buffer
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import (
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"io"
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"math"
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"github.com/djherbis/buffer/wrapio"
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)
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type ring struct {
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BufferAt
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L int64
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*wrapio.WrapReader
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*wrapio.WrapWriter
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}
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// NewRing returns a Ring Buffer from a BufferAt.
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// It overwrites old data in the Buffer when needed (when its full).
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func NewRing(buffer BufferAt) Buffer {
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return &ring{
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BufferAt: buffer,
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WrapReader: wrapio.NewWrapReader(buffer, 0, buffer.Cap()),
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WrapWriter: wrapio.NewWrapWriter(buffer, 0, buffer.Cap()),
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}
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}
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func (buf *ring) Len() int64 {
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return buf.L
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}
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func (buf *ring) Cap() int64 {
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return math.MaxInt64
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}
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func (buf *ring) Read(p []byte) (n int, err error) {
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if buf.L == buf.BufferAt.Cap() {
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buf.WrapReader.Seek(buf.WrapWriter.Offset(), 0)
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}
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n, err = io.LimitReader(buf.WrapReader, buf.L).Read(p)
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buf.L -= int64(n)
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return n, err
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}
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func (buf *ring) Write(p []byte) (n int, err error) {
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n, err = buf.WrapWriter.Write(p)
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buf.L += int64(n)
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if buf.L > buf.BufferAt.Cap() {
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buf.L = buf.BufferAt.Cap()
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}
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return n, err
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}
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func (buf *ring) Reset() {
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buf.BufferAt.Reset()
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buf.L = 0
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buf.WrapReader = wrapio.NewWrapReader(buf.BufferAt, 0, buf.BufferAt.Cap())
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buf.WrapWriter = wrapio.NewWrapWriter(buf.BufferAt, 0, buf.BufferAt.Cap())
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}
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