woodpecker/server/logging/log.go

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package logging
import (
"context"
"io"
"sync"
)
// TODO (bradrydzewski) writing to subscribers is currently a blocking
// operation and does not protect against slow clients from locking
// the stream. This should be resolved.
// TODO (bradrydzewski) implement a mux.Info to fetch information and
// statistics for the multiplexier. Streams, subscribers, etc
// mux.Info()
// TODO (bradrydzewski) refactor code to place publisher and subscriber
// operations in separate files with more encapsulated logic.
// sub.push()
// sub.join()
// sub.start()... event loop
type subscriber struct {
handler Handler
}
type stream struct {
sync.Mutex
path string
list []*Entry
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subs map[*subscriber]struct{}
done chan struct{}
}
type log struct {
sync.Mutex
streams map[string]*stream
}
// New returns a new logger.
func New() Log {
return &log{
streams: map[string]*stream{},
}
}
func (l *log) Open(c context.Context, path string) error {
l.Lock()
_, ok := l.streams[path]
if !ok {
l.streams[path] = &stream{
path: path,
subs: make(map[*subscriber]struct{}),
done: make(chan struct{}),
}
}
l.Unlock()
return nil
}
func (l *log) Write(c context.Context, path string, entry *Entry) error {
l.Lock()
s, ok := l.streams[path]
l.Unlock()
if !ok {
return ErrNotFound
}
s.Lock()
s.list = append(s.list, entry)
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for sub := range s.subs {
go sub.handler(entry)
}
s.Unlock()
return nil
}
func (l *log) Tail(c context.Context, path string, handler Handler) error {
l.Lock()
s, ok := l.streams[path]
l.Unlock()
if !ok {
return ErrNotFound
}
sub := &subscriber{
handler: handler,
}
s.Lock()
if len(s.list) != 0 {
sub.handler(s.list...)
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}
s.subs[sub] = struct{}{}
s.Unlock()
select {
case <-c.Done():
case <-s.done:
}
s.Lock()
delete(s.subs, sub)
s.Unlock()
return nil
}
func (l *log) Close(c context.Context, path string) error {
l.Lock()
s, ok := l.streams[path]
l.Unlock()
if !ok {
return ErrNotFound
}
s.Lock()
close(s.done)
s.Unlock()
l.Lock()
delete(l.streams, path)
l.Unlock()
return nil
}
func (l *log) Snapshot(c context.Context, path string, w io.Writer) error {
l.Lock()
s, ok := l.streams[path]
l.Unlock()
if !ok {
return ErrNotFound
}
s.Lock()
defer s.Unlock()
for _, entry := range s.list {
if _, err := w.Write(entry.Data); err != nil {
return err
}
if _, err := w.Write(cr); err != nil {
return err
}
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}
return nil
}
var cr = []byte{'\n'}