func (px *standard) sendRequest(ctx context.Context, m *dhtpb.Message, remote peer.ID) (*dhtpb.Message, error) {
e := log.EventBegin(ctx, "sendRoutingRequest", px.Host.ID(), remote, logging.Pair("request", m))
defer e.Done()
if err := px.Host.Connect(ctx, peer.PeerInfo{ID: remote}); err != nil {
e.SetError(err)
return nil, err
}
s, err := px.Host.NewStream(ProtocolSNR, remote)
if err != nil {
e.SetError(err)
return nil, err
}
defer s.Close()
r := ggio.NewDelimitedReader(s, inet.MessageSizeMax)
w := ggio.NewDelimitedWriter(s)
if err = w.WriteMsg(m); err != nil {
e.SetError(err)
return nil, err
}
response := &dhtpb.Message{}
if err = r.ReadMsg(response); err != nil {
e.SetError(err)
return nil, err
}
// need ctx expiration?
if response == nil {
err := errors.New("no response to request")
e.SetError(err)
return nil, err
}
e.Append(logging.Pair("response", response))
e.Append(logging.Pair("uuid", logging.Uuid("foo")))
return response, nil
}
// GetBlock attempts to retrieve a particular block from peers within the
// deadline enforced by the context.
func (bs *Bitswap) GetBlock(parent context.Context, k key.Key) (*blocks.Block, error) {
// Any async work initiated by this function must end when this function
// returns. To ensure this, derive a new context. Note that it is okay to
// listen on parent in this scope, but NOT okay to pass |parent| to
// functions called by this one. Otherwise those functions won't return
// when this context's cancel func is executed. This is difficult to
// enforce. May this comment keep you safe.
ctx, cancelFunc := context.WithCancel(parent)
ctx = logging.ContextWithLoggable(ctx, logging.Uuid("GetBlockRequest"))
log.Event(ctx, "Bitswap.GetBlockRequest.Start", &k)
defer log.Event(ctx, "Bitswap.GetBlockRequest.End", &k)
defer func() {
cancelFunc()
}()
promise, err := bs.GetBlocks(ctx, []key.Key{k})
if err != nil {
return nil, err
}
select {
case block, ok := <-promise:
if !ok {
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
return nil, errors.New("promise channel was closed")
}
}
return block, nil
case <-parent.Done():
return nil, parent.Err()
}
}