feat(kv): Asyncify key-value

examples/key-value/README.md

@@ -11,7 +11,7 @@ spin up --build
 
 In another terminal window, you can interact with the Spin app:
 ```sh
-curl localhost:3000/hello
+curl localhost:3000
 ```
 
 You should receive the following output:

examples/key-value/main.go

@@ -34,10 +34,13 @@ func init() {
 			return
 		}
 
-		keys, err := store.GetKeys()
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
+		var keys []string
+		for key, err := range store.GetKeys() {
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+			keys = append(keys, key)
 		}
 
 		w.Header().Set("Content-Type", "application/json")

examples/key-value/spin.toml

@@ -7,7 +7,7 @@ name = "hello-kv"
 version = "1.0.0"
 
 [[trigger.http]]
-route = "/hello"
+route = "/..."
 component = "hello"
 
 [component.hello]

kv/kv.go

@@ -3,8 +3,9 @@ package kv
 
 import (
 	"fmt"
+	"iter"
 
-	keyvalue "github.com/spinframework/spin-go-sdk/v3/imports/fermyon_spin_2_0_0_key_value"
+	keyvalue "github.com/spinframework/spin-go-sdk/v3/imports/spin_key_value_3_0_0_key_value"
 )
 
 // Store represents a connection to a key-value store.
@@ -76,14 +77,35 @@ func (s *Store) Exists(key string) (bool, error) {
 	return result.Ok(), nil
 }
 
-// GetKeys returns all the keys from the store.
-func (s *Store) GetKeys() ([]string, error) {
-	result := s.store.GetKeys()
-	if result.IsErr() {
-		return nil, errorVariantToError(result.Err())
+// GetKeys returns an iterator over the keys in the store. Keys are yielded as
+// they arrive from the host, allowing the consumer to process them
+// concurrently with the underlying stream read.
+//
+// The iterator yields each key with a nil error. If the host reports an error
+// after the stream completes, a final pair of ("", err) is yielded. Stopping
+// the iteration early releases the underlying stream.
+func (s *Store) GetKeys() iter.Seq2[string, error] {
+	return func(yield func(string, error) bool) {
+		stream, future := s.store.GetKeys()
+		defer stream.Drop()
+
+		buf := make([]string, 64)
+		for {
+			n := stream.Read(buf)
+			for _, k := range buf[:n] {
+				if !yield(k, nil) {
+					return
+				}
+			}
+			if stream.WriterDropped() {
+				break
+			}
+		}
+
+		if result := future.Read(); result.IsErr() {
+			yield("", errorVariantToError(result.Err()))
+		}
 	}
-
-	return result.Ok(), nil
 }
 
 func errorVariantToError(code keyvalue.Error) error {

testdata/key-value/main.go

@@ -34,10 +34,13 @@ func init() {
 			return
 		}
 
-		keys, err := store.GetKeys()
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
+		var keys []string
+		for key, err := range store.GetKeys() {
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+			keys = append(keys, key)
 		}
 
 		w.Header().Set("Content-Type", "application/json")