harness-drone/livelog/stream.go
2019-02-27 23:07:13 -08:00

84 lines
1.6 KiB
Go

// Copyright 2019 Drone.IO Inc. All rights reserved.
// Use of this source code is governed by the Drone Non-Commercial License
// that can be found in the LICENSE file.
// +build !oss
package livelog
import (
"context"
"sync"
"github.com/drone/drone/core"
)
// this is the amount of items that are stored in memory
// in the buffer. This should result in approximately 10kb
// of memory allocated per-stream and per-subscriber, not
// including any logdata stored in these structures.
const bufferSize = 5000
type stream struct {
sync.Mutex
hist []*core.Line
list map[*subscriber]struct{}
}
func newStream() *stream {
return &stream{
list: map[*subscriber]struct{}{},
}
}
func (s *stream) write(line *core.Line) error {
s.Lock()
s.hist = append(s.hist, line)
for l := range s.list {
l.publish(line)
}
// the history should not be unbounded. The history
// slice is capped and items are removed in a FIFO
// ordering when capacity is reached.
if size := len(s.hist); size >= bufferSize {
s.hist = s.hist[size-bufferSize:]
}
s.Unlock()
return nil
}
func (s *stream) subscribe(ctx context.Context) (<-chan *core.Line, <-chan error) {
sub := &subscriber{
handler: make(chan *core.Line, bufferSize),
closec: make(chan struct{}),
}
err := make(chan error)
s.Lock()
for _, line := range s.hist {
sub.publish(line)
}
s.list[sub] = struct{}{}
s.Unlock()
go func() {
defer close(err)
select {
case <-sub.closec:
case <-ctx.Done():
sub.close()
}
}()
return sub.handler, err
}
func (s *stream) close() error {
s.Lock()
defer s.Unlock()
for sub := range s.list {
delete(s.list, sub)
sub.close()
}
return nil
}