// GetBlock attempts to retrieve a particular block from peers, within timeout.
func (bs *BitSwap) GetBlock(k u.Key, timeout time.Duration) (
*blocks.Block, error) {
u.DOut("Bitswap GetBlock: '%s'\n", k.Pretty())
begin := time.Now()
tleft := timeout - time.Now().Sub(begin)
provs_ch := bs.routing.FindProvidersAsync(k, 20, timeout)
valchan := make(chan []byte)
after := time.After(tleft)
// TODO: when the data is received, shut down this for loop ASAP
go func() {
for p := range provs_ch {
go func(pr *peer.Peer) {
blk, err := bs.getBlock(k, pr, tleft)
if err != nil {
u.PErr("getBlock returned: %v\n", err)
return
}
select {
case valchan <- blk:
default:
}
}(p)
}
}()
select {
case blkdata := <-valchan:
close(valchan)
return blocks.NewBlock(blkdata)
case <-after:
return nil, u.ErrTimeout
}
}
// GetBlock retrieves a particular block from the service,
// Getting it from the datastore using the key (hash).
func (s *BlockService) GetBlock(k u.Key) (*blocks.Block, error) {
u.DOut("BlockService GetBlock: '%s'\n", k.Pretty())
dsk := ds.NewKey(string(k))
datai, err := s.Datastore.Get(dsk)
if err == nil {
u.DOut("Blockservice: Got data in datastore.\n")
bdata, ok := datai.([]byte)
if !ok {
return nil, fmt.Errorf("data associated with %s is not a []byte", k)
}
return &blocks.Block{
Multihash: mh.Multihash(k),
Data: bdata,
}, nil
} else if err == ds.ErrNotFound && s.Remote != nil {
u.DOut("Blockservice: Searching bitswap.\n")
blk, err := s.Remote.GetBlock(k, time.Second*5)
if err != nil {
return nil, err
}
return blk, nil
} else {
u.DOut("Blockservice GetBlock: Not found.\n")
return nil, u.ErrNotFound
}
}
func (bs *BitSwap) getBlock(k u.Key, p *peer.Peer, timeout time.Duration) ([]byte, error) {
u.DOut("[%s] getBlock '%s' from [%s]\n", bs.peer.ID.Pretty(), k.Pretty(), p.ID.Pretty())
message := newMessage()
message.AppendWanted(k)
after := time.After(timeout)
resp := bs.listener.Listen(string(k), 1, timeout)
bs.meschan.Outgoing <- message.ToSwarm(p)
select {
case resp_mes := <-resp:
return resp_mes.Data, nil
case <-after:
u.PErr("getBlock for '%s' timed out.\n", k.Pretty())
return nil, u.ErrTimeout
}
}