rapide: make the client code cleaner with happy left

rapide/clientdriven.go

@@ -47,12 +47,8 @@ func (d *download) startClientDrivenWorker(impl ClientDrivenDownloader, start *n
 
 // err must be called while holding w.mu.
 func (w *clientDrivenWorker) err(err error) {
- if err == io.EOF {
- w.dl.workerFinished()
- } else {
- *w.outErr = err
- w.dl.workerErrored()
- }
+ *w.outErr = err
+ w.dl.workerErrored()
 
  toCancel := make([]cid.Cid, w.len)
  for i, p := 0, w.head; p != nil; i, p = i+1, p.children {
@@ -99,67 +95,76 @@ func (s *snake) callback(data []byte, err error) {
 
  if err != nil {
  // TODO: handle ErrNotFound
- goto Errr
+ s.update()
+ w.err(err)
+ return
  }
 
  n.mu.Lock()
- if n.state == todo {
- var block blocks.Block
- block, err = blocks.NewBlockWithCid(data, n.cid)
- if err != nil {
- goto Errr
- }
- err = n.expand(w.dl, block)
- n.mu.Lock()
- if err != nil {
- goto Errr
- }
+ if n.state != todo {
+ // duplicated block
+ s.update()
+ return
+ }
 
- newBlocksWanted := uint(len(n.childrens))
- if remainingSpace := targetParallelBlockDownloads - w.len; newBlocksWanted > remainingSpace {
- newBlocksWanted = remainingSpace
- }
- w.len += newBlocksWanted
- if newBlocksWanted != 0 {
- downloads := make([]CidCallbackPair, newBlocksWanted)
- // TODO: select blocks randomly within the children
- left, right := s.dup()
- for i := range downloads {
- child := n.childrens[i]
- child.mu.Lock()
- child.workers++
- child.mu.Unlock()
- ns := &snake{
- worker: s.worker,
- node: child,
- parent: left,
- level: s.level + 1,
- }
- left.children, left = ns, ns
- downloads[i] = CidCallbackPair{child.cid, ns.callback}
+ var block blocks.Block
+ block, err = blocks.NewBlockWithCid(data, n.cid)
+ if err != nil {
+ s.update()
+ w.err(err)
+ }
+ err = n.expand(w.dl, block)
+ eof := err == io.EOF
+ n.mu.Lock()
+ if err != nil && !eof {
+ s.update()
+ w.err(err)
+ return
+ }
+
+ newBlocksWanted := uint(len(n.childrens))
+ if remainingSpace := targetParallelBlockDownloads - w.len; newBlocksWanted > remainingSpace {
+ newBlocksWanted = remainingSpace
+ }
+ w.len += newBlocksWanted
+ if newBlocksWanted != 0 {
+ downloads := make([]CidCallbackPair, newBlocksWanted)
+ // TODO: select blocks randomly within the children
+ left, right := s.dup()
+ for i := range downloads {
+ child := n.childrens[i]
+ child.mu.Lock()
+ child.workers++
+ child.mu.Unlock()
+ ns := &snake{
+ worker: s.worker,
+ node: child,
+ parent: left,
+ level: s.level + 1,
  }
- left.children, right.parent = right, left
- s.update()
- // TODO: if we havn't found enough blocks to download, try in other nodes of the snake or try backtracking from the head.
- s.worker.impl.Download(downloads...)
- } else {
- s.update()
- }
- select {
- case w.dl.out <- blocks.Is(block):
- case <-w.dl.ctx.Done():
- err = w.dl.ctx.Err()
- goto Errr
+ left.children, left = ns, ns
+ downloads[i] = CidCallbackPair{child.cid, ns.callback}
  }
+ left.children, right.parent = right, left
+ s.update()
+ // TODO: if we havn't found enough blocks to download, try in other nodes of the snake or try backtracking from the head.
+ s.worker.impl.Download(downloads...)
+ } else {
+ s.update()
+ }
+
+ dl := w.dl
+ ctx := dl.ctx
+ select {
+ case dl.out <- blocks.Is(block):
+ case <-ctx.Done():
+ w.err(ctx.Err())
  return
  }
- // duplicated block
- s.update()
- return
 
-Errr:
- s.update()
- w.err(err)
+ if eof {
+  dl.finish()
+ }
 }
 
 // update checks if this node should be removed from the snake and do so if needed. It will update the metric if needed.