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140 lines
2.3 KiB
Go
140 lines
2.3 KiB
Go
// Package ring provides a simple ring buffer for storing local data
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package ring
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import (
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"sync"
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"time"
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"github.com/google/uuid"
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)
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// Buffer is ring buffer.
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type Buffer struct {
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size int
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sync.RWMutex
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vals []*Entry
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streams map[string]*Stream
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}
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// Entry is ring buffer data entry.
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type Entry struct {
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Value interface{}
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Timestamp time.Time
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}
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// Stream is used to stream the buffer.
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type Stream struct {
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// Id of the stream
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Id string
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// Buffered entries
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Entries chan *Entry
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// Stop channel
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Stop chan bool
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}
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// Put adds a new value to ring buffer.
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func (b *Buffer) Put(v interface{}) {
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b.Lock()
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defer b.Unlock()
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// append to values
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entry := &Entry{
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Value: v,
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Timestamp: time.Now(),
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}
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b.vals = append(b.vals, entry)
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// trim if bigger than size required
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if len(b.vals) > b.size {
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b.vals = b.vals[1:]
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}
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// send to every stream
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for _, stream := range b.streams {
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select {
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case <-stream.Stop:
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delete(b.streams, stream.Id)
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close(stream.Entries)
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case stream.Entries <- entry:
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}
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}
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}
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// Get returns the last n entries.
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func (b *Buffer) Get(n int) []*Entry {
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b.RLock()
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defer b.RUnlock()
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// reset any invalid values
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if n > len(b.vals) || n < 0 {
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n = len(b.vals)
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}
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// create a delta
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delta := len(b.vals) - n
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// return the delta set
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return b.vals[delta:]
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}
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// Return the entries since a specific time.
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func (b *Buffer) Since(t time.Time) []*Entry {
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b.RLock()
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defer b.RUnlock()
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// return all the values
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if t.IsZero() {
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return b.vals
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}
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// if its in the future return nothing
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if time.Since(t).Seconds() < 0.0 {
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return nil
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}
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for i, v := range b.vals {
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// find the starting point
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d := v.Timestamp.Sub(t)
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// return the values
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if d.Seconds() > 0.0 {
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return b.vals[i:]
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}
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}
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return nil
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}
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// Stream logs from the buffer
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// Close the channel when you want to stop.
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func (b *Buffer) Stream() (<-chan *Entry, chan bool) {
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b.Lock()
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defer b.Unlock()
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entries := make(chan *Entry, 128)
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id := uuid.New().String()
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stop := make(chan bool)
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b.streams[id] = &Stream{
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Id: id,
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Entries: entries,
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Stop: stop,
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}
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return entries, stop
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}
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// Size returns the size of the ring buffer.
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func (b *Buffer) Size() int {
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return b.size
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}
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// New returns a new buffer of the given size.
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func New(i int) *Buffer {
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return &Buffer{
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size: i,
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streams: make(map[string]*Stream),
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}
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}
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