Fix data race of racingio Reader and Writer

Author: fbiville

neo4j/internal/racingio/reader.go

@@ -52,15 +52,9 @@ func (rr *racingReader) race(ctx context.Context, bytes []byte, readFn func(io.R
 		return 0, wrapRaceError(err)
 	}
 	resultChan := make(chan *ioResult, 1)
-	defer close(resultChan)
 	go func() {
+		defer close(resultChan)
 		n, err := readFn(rr.reader, bytes)
-		defer func() {
-			// When the read operation completes, the outer function may have returned already.
-			// In that situation, the channel will have been closed and the result emission will crash.
-			// Let's just swallow the panic that may happen and ignore it
-			_ = recover()
-		}()
 		resultChan <- &ioResult{
 			n:   n,
 			err: err,

neo4j/internal/racingio/reader_test.go

@@ -85,10 +85,10 @@ func TestRacingReader(outer *testing.T) {
 		})
 
 		outer.Run(fmt.Sprintf(`[%s] completes before read occurs`, testCase.qualifier), func(t *testing.T) {
-			reader := &slowFailingReader{sleep: 2 * time.Minute}
+			reader := &slowFailingReader{sleep: 50 * time.Millisecond}
 			racingReader := rio.NewRacingReader(reader)
 			result := make([]byte, 2)
-			ctx, cancelFunc := context.WithTimeout(context.Background(), 200*time.Millisecond)
+			ctx, cancelFunc := context.WithTimeout(context.Background(), 10*time.Millisecond)
 			defer cancelFunc()
 
 			n, err := testCase.readOperation(racingReader)(ctx, result)
@@ -102,7 +102,7 @@ func TestRacingReader(outer *testing.T) {
 		})
 
 		outer.Run("connection read times out after 1 successful read", func(t *testing.T) {
-			timeout := 400 * time.Millisecond
+			timeout := 100 * time.Millisecond
 			server, client := net.Pipe()
 			defer closePipe(t, server, client)
 			go func() {

testkit/unittests.py

@@ -21,3 +21,5 @@ def run(args):
 
     run(cmd + ["./neo4j"])
     run(cmd + ["./neo4j/internal/..."])
+    # Repeat racing tests
+    run(cmd + ["-race", "-count", "50", "./neo4j/internal/racingio"])