Commit 4de263a9 authored by Łukasz Magiera's avatar Łukasz Magiera Committed by Steven Allen

add a streaming CID set

used in https://github.com/ipfs/go-ipfs/pull/4804
parent 99995a30
package cid package cid
import (
"context"
)
// Set is a implementation of a set of Cids, that is, a structure // Set is a implementation of a set of Cids, that is, a structure
// to which holds a single copy of every Cids that is added to it. // to which holds a single copy of every Cids that is added to it.
type Set struct { type Set struct {
...@@ -65,3 +69,34 @@ func (s *Set) ForEach(f func(c *Cid) error) error { ...@@ -65,3 +69,34 @@ func (s *Set) ForEach(f func(c *Cid) error) error {
} }
return nil return nil
} }
// StreamingSet is an extension of Set which allows to implement back-pressure
// for the Visit function
type StreamingSet struct {
Set *Set
New chan *Cid
}
// NewStreamingSet initializes and returns new Set.
func NewStreamingSet() *StreamingSet {
return &StreamingSet{
Set: NewSet(),
New: make(chan *Cid),
}
}
// Visitor creates new visitor which adds a Cids to the set and emits them to
// the set.New channel
func (s *StreamingSet) Visitor(ctx context.Context) func(c *Cid) bool {
return func(c *Cid) bool {
if s.Set.Visit(c) {
select {
case s.New <- c:
case <-ctx.Done():
}
return true
}
return false
}
}
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