93 lines
2.3 KiB
Go
93 lines
2.3 KiB
Go
|
// Package stream provides a way to read and write to a synchronous buffered pipe, with multiple reader support.
|
||
|
|
package stream
|
||
|
|
|
||
|
|
import (
|
||
|
|
"errors"
|
||
|
|
"sync"
|
||
|
|
)
|
||
|
|
|
||
|
|
// ErrRemoving is returned when requesting a Reader on a Stream which is being Removed.
|
||
|
|
var ErrRemoving = errors.New("cannot open a new reader while removing file")
|
||
|
|
|
||
|
|
// Stream is used to concurrently Write and Read from a File.
|
||
|
|
type Stream struct {
|
||
|
|
grp sync.WaitGroup
|
||
|
|
b *broadcaster
|
||
|
|
file File
|
||
|
|
fs FileSystem
|
||
|
|
removing chan struct{}
|
||
|
|
}
|
||
|
|
|
||
|
|
// New creates a new Stream from the StdFileSystem with Name "name".
|
||
|
|
func New(name string) (*Stream, error) {
|
||
|
|
return NewStream(name, StdFileSystem)
|
||
|
|
}
|
||
|
|
|
||
|
|
// NewStream creates a new Stream with Name "name" in FileSystem fs.
|
||
|
|
func NewStream(name string, fs FileSystem) (*Stream, error) {
|
||
|
|
f, err := fs.Create(name)
|
||
|
|
sf := &Stream{
|
||
|
|
file: f,
|
||
|
|
fs: fs,
|
||
|
|
b: newBroadcaster(),
|
||
|
|
removing: make(chan struct{}),
|
||
|
|
}
|
||
|
|
sf.inc()
|
||
|
|
return sf, err
|
||
|
|
}
|
||
|
|
|
||
|
|
// Name returns the name of the underlying File in the FileSystem.
|
||
|
|
func (s *Stream) Name() string { return s.file.Name() }
|
||
|
|
|
||
|
|
// Write writes p to the Stream. It's concurrent safe to be called with Stream's other methods.
|
||
|
|
func (s *Stream) Write(p []byte) (int, error) {
|
||
|
|
defer s.b.Broadcast()
|
||
|
|
s.b.Lock()
|
||
|
|
defer s.b.Unlock()
|
||
|
|
return s.file.Write(p)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Close will close the active stream. This will cause Readers to return EOF once they have
|
||
|
|
// read the entire stream.
|
||
|
|
func (s *Stream) Close() error {
|
||
|
|
defer s.dec()
|
||
|
|
defer s.b.Close()
|
||
|
|
s.b.Lock()
|
||
|
|
defer s.b.Unlock()
|
||
|
|
return s.file.Close()
|
||
|
|
}
|
||
|
|
|
||
|
|
// Remove will block until the Stream and all its Readers have been Closed,
|
||
|
|
// at which point it will delete the underlying file. NextReader() will return
|
||
|
|
// ErrRemoving if called after Remove.
|
||
|
|
func (s *Stream) Remove() error {
|
||
|
|
close(s.removing)
|
||
|
|
s.grp.Wait()
|
||
|
|
return s.fs.Remove(s.file.Name())
|
||
|
|
}
|
||
|
|
|
||
|
|
// NextReader will return a concurrent-safe Reader for this stream. Each Reader will
|
||
|
|
// see a complete and independent view of the stream, and can Read will the stream
|
||
|
|
// is written to.
|
||
|
|
func (s *Stream) NextReader() (*Reader, error) {
|
||
|
|
s.inc()
|
||
|
|
|
||
|
|
select {
|
||
|
|
case <-s.removing:
|
||
|
|
s.dec()
|
||
|
|
return nil, ErrRemoving
|
||
|
|
default:
|
||
|
|
}
|
||
|
|
|
||
|
|
file, err := s.fs.Open(s.file.Name())
|
||
|
|
if err != nil {
|
||
|
|
s.dec()
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
|
||
|
|
return &Reader{file: file, s: s}, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func (s *Stream) inc() { s.grp.Add(1) }
|
||
|
|
func (s *Stream) dec() { s.grp.Done() }
|