prysm-pulse/io/logs/stream.go

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package logs
import (
"io"
lru "github.com/hashicorp/golang-lru"
"github.com/prysmaticlabs/prysm/async/event"
2021-09-14 23:11:25 +00:00
lruwrpr "github.com/prysmaticlabs/prysm/cache/lru"
"github.com/prysmaticlabs/prysm/crypto/rand"
)
const (
// The number of log entries to keep in memory.
logCacheSize = 20
)
var (
// Compile time interface checks.
_ = io.Writer(&StreamServer{})
_ = Streamer(&StreamServer{})
)
// Streamer defines a struct which can retrieve and stream process logs.
type Streamer interface {
GetLastFewLogs() [][]byte
LogsFeed() *event.Feed
}
// StreamServer defines a a websocket server which can receive events from
// a feed and write them to open websocket connections.
type StreamServer struct {
feed *event.Feed
cache *lru.Cache
}
// NewStreamServer initializes a new stream server capable of
// streaming log events.
func NewStreamServer() *StreamServer {
ss := &StreamServer{
feed: new(event.Feed),
cache: lruwrpr.New(logCacheSize),
}
addLogWriter(ss)
return ss
}
// GetLastFewLogs returns the last few entries of logs stored in an LRU cache.
func (ss *StreamServer) GetLastFewLogs() [][]byte {
messages := make([][]byte, 0)
for _, k := range ss.cache.Keys() {
d, ok := ss.cache.Get(k)
if ok {
messages = append(messages, d.([]byte))
}
}
return messages
}
// LogsFeed returns a feed callers can subscribe to to receive logs via a channel.
func (ss *StreamServer) LogsFeed() *event.Feed {
return ss.feed
}
// Write a binary message and send over the event feed.
func (ss *StreamServer) Write(p []byte) (n int, err error) {
ss.feed.Send(p)
ss.cache.Add(rand.NewGenerator().Uint64(), p)
return len(p), nil
}