95 lines
2.1 KiB
Go
95 lines
2.1 KiB
Go
package io
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import (
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"bytes"
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"io"
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)
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// RingBuffer struct satisfies io.ReadWrite interface.
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//
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// ReadBuffer is a revolving buffer data structure, which can be used to store snapshots of data in a
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// revolving window.
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type RingBuffer struct {
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slice []byte
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start int
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end int
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size int
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}
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// NewRingBuffer method takes in a byte slice as an input and returns a RingBuffer.
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func NewRingBuffer(slice []byte) *RingBuffer {
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ringBuf := RingBuffer{
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slice: slice,
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}
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return &ringBuf
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}
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// Write method inserts the elements in a byte slice, and returns the number of bytes written along with any error.
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func (r *RingBuffer) Write(p []byte) (int, error) {
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for _, b := range p {
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// check if end points to invalid index, we need to circle back
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if r.end == len(r.slice) {
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r.end = 0
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}
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// check if start points to invalid index, we need to circle back
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if r.start == len(r.slice) {
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r.start = 0
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}
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// if ring buffer is filled, increment the start index
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if r.size == len(r.slice) {
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r.size--
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r.start++
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}
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r.slice[r.end] = b
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r.end++
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r.size++
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}
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return len(p), nil
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}
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// Read copies the data on the ring buffer into the byte slice provided to the method.
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// Returns the read count along with any error encountered while reading.
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func (r *RingBuffer) Read(p []byte) (int, error) {
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// readCount keeps track of the number of bytes read
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var readCount int
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for j := 0; j < len(p); j++ {
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// if ring buffer is empty or completely read
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// return EOF error.
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if r.size == 0 {
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return readCount, io.EOF
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}
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if r.start == len(r.slice) {
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r.start = 0
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}
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p[j] = r.slice[r.start]
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readCount++
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// increment the start pointer for ring buffer
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r.start++
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// decrement the size of ring buffer
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r.size--
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}
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return readCount, nil
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}
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// Len returns the number of unread bytes in the buffer.
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func (r *RingBuffer) Len() int {
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return r.size
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}
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// Bytes returns a copy of the RingBuffer's bytes.
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func (r RingBuffer) Bytes() []byte {
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var b bytes.Buffer
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io.Copy(&b, &r)
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return b.Bytes()
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}
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// Reset resets the ring buffer.
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func (r *RingBuffer) Reset() {
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*r = RingBuffer{
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slice: r.slice,
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}
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}
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