refactor(remote/pinning): Ls to take results channel instead of ret…

…urning one (#738)

CHANGELOG.md

@@ -72,6 +72,7 @@ The following emojis are used to highlight certain changes:
 - `routing/http/client`: creating delegated routing client with `New` now defaults to querying delegated routing server with `DefaultProtocolFilter`  ([IPIP-484](https://github.com/ipfs/specs/pull/484)) [#689](https://github.com/ipfs/boxo/pull/689)
 - `bitswap/client`: Wait at lease one broadcast interval before resending wants to a peer. Check for peers to rebroadcast to more often than one broadcast interval.
 - No longer using `github.com/jbenet/goprocess` to avoid requiring in dependents. [#710](https://github.com/ipfs/boxo/pull/710)
+- `pinning/remote/client`: Refactor remote pinning `Ls` to take results channel instead of returning one. The previous `Ls` behavior is implemented by the GoLs function, which creates the channels, starts the goroutine that calls Ls, and returns the channels to the caller [#738](https://github.com/ipfs/boxo/pull/738)
 
 ### Removed
 

pinning/remote/client/client.go

@@ -137,77 +137,90 @@ func (pinLsOpts) LsMeta(meta map[string]string) LsOption {
 
 type pinResults = openapi.PinResults
 
-func (c *Client) Ls(ctx context.Context, opts ...LsOption) (chan PinStatusGetter, chan error) {
-	res := make(chan PinStatusGetter, 1)
-	errs := make(chan error, 1)
-
+// Ls writes pin statuses to the PinStatusGetter channel. The channel is
+// closed when there are no more pins. If an error occurs or ctx is canceled,
+// then the channel is closed and an error is returned.
+//
+// Example:
+//
+//	res := make(chan PinStatusGetter, 1)
+//	lsErr := make(chan error, 1)
+//	go func() {
+//		lsErr <- c.Ls(ctx, res, opts...)
+//	}()
+//	for r := range res {
+//		processPin(r)
+//	}
+//	return <-lsErr
+func (c *Client) Ls(ctx context.Context, res chan<- PinStatusGetter, opts ...LsOption) (err error) {
 	settings := new(lsSettings)
 	for _, o := range opts {
-		if err := o(settings); err != nil {
+		if err = o(settings); err != nil {
 			close(res)
-			errs <- err
-			close(errs)
-			return res, errs
+			return err
 		}
 	}
 
-	go func() {
-		defer func() {
-			if r := recover(); r != nil {
-				var err error
-				switch x := r.(type) {
-				case string:
-					err = fmt.Errorf("unexpected error while listing remote pins: %s", x)
-				case error:
-					err = fmt.Errorf("unexpected error while listing remote pins: %w", x)
-				default:
-					err = errors.New("unknown panic while listing remote pins")
-				}
-				errs <- err
-			}
-			close(errs)
-			close(res)
-		}()
-
-		for {
-			pinRes, err := c.lsInternal(ctx, settings)
-			if err != nil {
-				errs <- err
-				return
+	defer func() {
+		if r := recover(); r != nil {
+			switch x := r.(type) {
+			case string:
+				err = fmt.Errorf("unexpected error while listing remote pins: %s", x)
+			case error:
+				err = fmt.Errorf("unexpected error while listing remote pins: %w", x)
+			default:
+				err = errors.New("unknown panic while listing remote pins")
 			}
+		}
+		close(res)
+	}()
 
-			results := pinRes.GetResults()
-			for _, r := range results {
-				select {
-				case res <- &pinStatusObject{r}:
-				case <-ctx.Done():
-					errs <- ctx.Err()
-					return
-				}
-			}
+	for {
+		pinRes, err := c.lsInternal(ctx, settings)
+		if err != nil {
+			return err
+		}
 
-			batchSize := len(results)
-			if int(pinRes.Count) == batchSize {
-				// no more batches
-				return
+		results := pinRes.GetResults()
+		for _, r := range results {
+			select {
+			case res <- &pinStatusObject{r}:
+			case <-ctx.Done():
+				return ctx.Err()
 			}
+		}
 
-			// Better DX/UX for cases like https://github.com/application-research/estuary/issues/124
-			if batchSize == 0 && int(pinRes.Count) != 0 {
-				errs <- fmt.Errorf("invalid pinning service response: PinResults.count=%d but no PinResults.results", int(pinRes.Count))
-				return
-			}
+		batchSize := len(results)
+		if int(pinRes.Count) == batchSize {
+			// no more batches
+			return nil
+		}
 
-			oldestResult := results[batchSize-1]
-			settings.before = &oldestResult.Created
+		// Better DX/UX for cases like https://github.com/application-research/estuary/issues/124
+		if batchSize == 0 && int(pinRes.Count) != 0 {
+			return fmt.Errorf("invalid pinning service response: PinResults.count=%d but no PinResults.results", int(pinRes.Count))
 		}
+
+		oldestResult := results[batchSize-1]
+		settings.before = &oldestResult.Created
+	}
+}
+
+// GoLs creates the results and error channels, starts the goroutine that calls
+// Ls, and returns the channels to the caller.
+func (c *Client) GoLs(ctx context.Context, opts ...LsOption) (<-chan PinStatusGetter, <-chan error) {
+	res := make(chan PinStatusGetter)
+	errs := make(chan error, 1)
+
+	go func() {
+		errs <- c.Ls(ctx, res, opts...)
 	}()
 
 	return res, errs
 }
 
 func (c *Client) LsSync(ctx context.Context, opts ...LsOption) ([]PinStatusGetter, error) {
-	resCh, errCh := c.Ls(ctx, opts...)
+	resCh, errCh := c.GoLs(ctx, opts...)
 
 	var res []PinStatusGetter
 	for r := range resCh {
@@ -219,8 +232,6 @@ func (c *Client) LsSync(ctx context.Context, opts ...LsOption) ([]PinStatusGette
 
 // Manual version of Ls that returns a single batch of results and int with total count
 func (c *Client) LsBatchSync(ctx context.Context, opts ...LsOption) ([]PinStatusGetter, int, error) {
-	var res []PinStatusGetter
-
 	settings := new(lsSettings)
 	for _, o := range opts {
 		if err := o(settings); err != nil {
@@ -233,9 +244,13 @@ func (c *Client) LsBatchSync(ctx context.Context, opts ...LsOption) ([]PinStatus
 		return nil, 0, err
 	}
 
+	var res []PinStatusGetter
 	results := pinRes.GetResults()
-	for _, r := range results {
-		res = append(res, &pinStatusObject{r})
+	if len(results) != 0 {
+		res = make([]PinStatusGetter, len(results))
+		for i, r := range results {
+			res[i] = &pinStatusObject{r}
+		}
 	}
 
 	return res, int(pinRes.Count), nil
@@ -274,8 +289,7 @@ func (c *Client) lsInternal(ctx context.Context, settings *lsSettings) (pinResul
 	// TODO: Ignoring HTTP Response OK?
 	results, httpresp, err := getter.Execute()
 	if err != nil {
-		err := httperr(httpresp, err)
-		return pinResults{}, err
+		return pinResults{}, httperr(httpresp, err)
 	}
 
 	return results, nil