1package swift
2
3import (
4	"io"
5	"time"
6)
7
8// An io.ReadCloser which obeys an idle timeout
9type timeoutReader struct {
10	reader  io.ReadCloser
11	timeout time.Duration
12	cancel  func()
13}
14
15// Returns a wrapper around the reader which obeys an idle
16// timeout. The cancel function is called if the timeout happens
17func newTimeoutReader(reader io.ReadCloser, timeout time.Duration, cancel func()) *timeoutReader {
18	return &timeoutReader{
19		reader:  reader,
20		timeout: timeout,
21		cancel:  cancel,
22	}
23}
24
25// Read reads up to len(p) bytes into p
26//
27// Waits at most for timeout for the read to complete otherwise returns a timeout
28func (t *timeoutReader) Read(p []byte) (int, error) {
29	// FIXME limit the amount of data read in one chunk so as to not exceed the timeout?
30	// Do the read in the background
31	type result struct {
32		n   int
33		err error
34	}
35	done := make(chan result, 1)
36	go func() {
37		n, err := t.reader.Read(p)
38		done <- result{n, err}
39	}()
40	// Wait for the read or the timeout
41	timer := time.NewTimer(t.timeout)
42	defer timer.Stop()
43	select {
44	case r := <-done:
45		return r.n, r.err
46	case <-timer.C:
47		t.cancel()
48		return 0, TimeoutError
49	}
50	panic("unreachable") // for Go 1.0
51}
52
53// Close the channel
54func (t *timeoutReader) Close() error {
55	return t.reader.Close()
56}
57
58// Check it satisfies the interface
59var _ io.ReadCloser = &timeoutReader{}
60