Esempio n. 1
0
// GetBlocks gets a list of blocks asynchronously and returns through
// the returned channel.
// NB: No guarantees are made about order.
func (s *BlockService) GetBlocks(ctx context.Context, ks []key.Key) <-chan *blocks.Block {
	out := make(chan *blocks.Block, 0)
	go func() {
		defer close(out)
		var misses []key.Key
		for _, k := range ks {
			hit, err := s.Blockstore.Get(k)
			if err != nil {
				misses = append(misses, k)
				continue
			}
			select {
			case out <- hit:
			case <-ctx.Done():
				return
			}
		}

		rblocks, err := s.Exchange.GetBlocks(ctx, misses)
		if err != nil {
			// blocks not found are ignored. this is an optimistic call.
			return
		}

		for b := range rblocks {
			select {
			case out <- b:
			case <-ctx.Done():
				return
			}
		}
	}()
	return out
}
Esempio n. 2
0
func (e *offlineExchange) GetBlocks(ctx context.Context, ks []key.Key) (<-chan *blocks.Block, error) {
	out := make(chan *blocks.Block, 0)
	go func() {
		defer close(out)
		var misses []key.Key
		for _, k := range ks {
			hit, err := e.bs.Get(k)
			if err != nil {
				misses = append(misses, k)
				// a long line of misses should abort when context is cancelled.
				select {
				// TODO case send misses down channel
				case <-ctx.Done():
					return
				default:
					continue
				}
			}
			select {
			case out <- hit:
			case <-ctx.Done():
				return
			}
		}
	}()
	return out, nil
}
Esempio n. 3
0
// WithContext constructs and returns a Process that respects
// given context. It is the equivalent of:
//
//   func ProcessWithContext(ctx context.Context) goprocess.Process {
//     p := goprocess.WithParent(goprocess.Background())
//     go func() {
//       <-ctx.Done()
//       p.Close()
//     }()
//     return p
//   }
//
func WithContext(ctx context.Context) goprocess.Process {
	if ctx == nil {
		panic("nil Context")
	}

	p := goprocess.WithParent(goprocess.Background())
	go func() {
		<-ctx.Done()
		p.Close()
	}()
	return p
}
Esempio n. 4
0
// AllKeysChan runs a query for keys from the blockstore.
// this is very simplistic, in the future, take dsq.Query as a param?
//
// AllKeysChan respects context
func (bs *blockstore) AllKeysChan(ctx context.Context) (<-chan key.Key, error) {

	// KeysOnly, because that would be _a lot_ of data.
	q := dsq.Query{KeysOnly: true}
	// datastore/namespace does *NOT* fix up Query.Prefix
	q.Prefix = BlockPrefix.String()
	res, err := bs.datastore.Query(q)
	if err != nil {
		return nil, err
	}

	// this function is here to compartmentalize
	get := func() (k key.Key, ok bool) {
		select {
		case <-ctx.Done():
			return k, false
		case e, more := <-res.Next():
			if !more {
				return k, false
			}
			if e.Error != nil {
				return k, false
			}

			// need to convert to key.Key using key.KeyFromDsKey.
			k = key.KeyFromDsKey(ds.NewKey(e.Key))

			// key must be a multihash. else ignore it.
			_, err := mh.Cast([]byte(k))
			if err != nil {
				return "", true
			}

			return k, true
		}
	}

	output := make(chan key.Key)
	go func() {
		defer func() {
			res.Process().Close() // ensure exit (signals early exit, too)
			close(output)
		}()

		for {
			k, ok := get()
			if !ok {
				return
			}
			if k == "" {
				continue
			}

			select {
			case <-ctx.Done():
				return
			case output <- k:
			}
		}
	}()

	return output, nil
}