Merge pull request #168 from fastly/dgryski/httpcache-swr-wait

fsthttp: ensure swr goroutines have completed before exiting

Author: dgryski

fsthttp/handle.go

@@ -37,6 +37,8 @@ func Serve(h Handler) {
 
 	h.ServeHTTP(ctx, clientResponseWriter, clientRequest)
 	clientResponseWriter.Close()
+	// wait for any stale-while-revalidate goroutines to complete.
+	guestCacheSWRPending.Wait()
 }
 
 // ServeFunc is sugar for Serve(HandlerFunc(f)).

fsthttp/request.go

@@ -10,6 +10,7 @@ import (
 	"io"
 	"net/url"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/fastly/compute-sdk-go/internal/abi/fastly"
@@ -489,6 +490,8 @@ func pendingToABIResponse(ctx context.Context, errc chan error, abiPending *fast
 	}
 }
 
+var guestCacheSWRPending sync.WaitGroup
+
 func (req *Request) sendWithGuestCache(ctx context.Context, backend string) (*Response, error) {
 	// use guest cache
 
@@ -550,7 +553,9 @@ func (req *Request) sendWithGuestCache(ctx context.Context, backend string) (*Re
 			}
 
 			// Wait for the pending respond, then call any after-end hooks
+			guestCacheSWRPending.Add(1)
 			go func(p *pendingBackendRequestForCaching, h *fastly.HTTPCacheHandle) {
+				defer guestCacheSWRPending.Done()
 				candidate, err := newCandidateFromPendingBackendCaching(p)
 				if err != nil {
 					// nowhere to log error

internal/abi/fastly/httpcache_guest.go

@@ -334,7 +334,7 @@ func HTTPCacheTransactionInsert(h *HTTPCacheHandle, resp *HTTPResponse, opts *HT
 		return nil, err
 	}
 
-	return &HTTPBody{h: body}, nil
+	return &HTTPBody{h: body, closable: true}, nil
 }
 
 // witx: