Allows setting empty buffer vis SharedData API (#401)

Signed-off-by: Takeshi Yoneda <[email protected]>

e2e/e2e_test.go

@@ -307,7 +307,7 @@ func Test_properties(t *testing.T) {
 func Test_shared_data(t *testing.T) {
 	stdErr, kill := startEnvoy(t, 8001)
 	defer kill()
-	var count int = 10000000
+	var count int
 	require.Eventually(t, func() bool {
 		res, err := http.Get("http://localhost:18000")
 		if err != nil {
@@ -318,11 +318,12 @@ func Test_shared_data(t *testing.T) {
 			return false
 		}
 		count++
-		return count == 10000010
+		return count == 10
 	}, 10*time.Second, 100*time.Millisecond, "Endpoint not healthy.")
 	require.Eventually(t, func() bool {
 		return checkMessage(stdErr.String(), []string{fmt.Sprintf("shared value: %d", count)})
 	}, 10*time.Second, 100*time.Millisecond, stdErr.String())
+	fmt.Println(stdErr.String())
 }
 
 func Test_shared_queue(t *testing.T) {

examples/shared_data/main.go

@@ -23,8 +23,7 @@ import (
 )
 
 const (
-	sharedDataKey                 = "shared_data_key"
-	sharedDataInitialValue uint64 = 10000000
+	sharedDataKey = "shared_data_key"
 )
 
 func main() {
@@ -48,8 +47,7 @@ type (
 
 // Override types.VMContext.
 func (*vmContext) OnVMStart(vmConfigurationSize int) types.OnVMStartStatus {
-	initialValueBuf := make([]byte, 8)
-	binary.LittleEndian.PutUint64(initialValueBuf, sharedDataInitialValue)
+	initialValueBuf := make([]byte, 0) // Empty data to indicate that the data is not initialized.
 	if err := proxywasm.SetSharedData(sharedDataKey, initialValueBuf, 0); err != nil {
 		proxywasm.LogWarnf("error setting shared data on OnVMStart: %v", err)
 	}
@@ -81,18 +79,24 @@ func (ctx *httpContext) OnHttpRequestHeaders(numHeaders int, endOfStream bool) t
 }
 
 func (ctx *httpContext) incrementData() (uint64, error) {
-	value, cas, err := proxywasm.GetSharedData(sharedDataKey)
+	data, cas, err := proxywasm.GetSharedData(sharedDataKey)
 	if err != nil {
 		proxywasm.LogWarnf("error getting shared data on OnHttpRequestHeaders: %v", err)
 		return 0, err
 	}
 
+	var nextValue uint64
+	if len(data) > 0 {
+		nextValue = binary.LittleEndian.Uint64(data) + 1
+	} else {
+		nextValue = 1
+	}
+
 	buf := make([]byte, 8)
-	ret := binary.LittleEndian.Uint64(value) + 1
-	binary.LittleEndian.PutUint64(buf, ret)
+	binary.LittleEndian.PutUint64(buf, nextValue)
 	if err := proxywasm.SetSharedData(sharedDataKey, buf, cas); err != nil {
 		proxywasm.LogWarnf("error setting shared data on OnHttpRequestHeaders: %v", err)
 		return 0, err
 	}
-	return ret, err
+	return nextValue, err
 }

examples/shared_data/main_test.go

@@ -30,7 +30,7 @@ func TestData(t *testing.T) {
 
 		// Check Envoy logs.
 		logs := host.GetInfoLogs()
-		require.Contains(t, logs, "shared value: 10000001")
+		require.Contains(t, logs, "shared value: 1")
 
 		// Call OnHttpRequestHeaders again.
 		action = host.CallOnRequestHeaders(contextID, nil, false)
@@ -40,7 +40,7 @@ func TestData(t *testing.T) {
 
 		// Check Envoy logs.
 		logs = host.GetInfoLogs()
-		require.Contains(t, logs, "shared value: 10000003")
+		require.Contains(t, logs, "shared value: 3")
 	})
 }
 

proxywasm/hostcall.go

@@ -526,8 +526,11 @@ func GetSharedData(key string) (value []byte, cas uint32, err error) {
 // Another VM may have already incremented the value, and the value you
 // see is already different from the one stored when you call this function.
 func SetSharedData(key string, data []byte, cas uint32) error {
-	st := internal.ProxySetSharedData(internal.StringBytePtr(key),
-		len(key), &data[0], len(data), cas)
+	var dataPtr *byte
+	if len(data) > 0 { // Empty data is allowed to set, so we need this check.
+		dataPtr = &data[0]
+	}
+	st := internal.ProxySetSharedData(internal.StringBytePtr(key), len(key), dataPtr, len(data), cas)
 	return internal.StatusToError(st)
 }
 

proxywasm/proxytest/root.go

@@ -158,7 +158,9 @@ func (r *rootHostEmulator) ProxyGetSharedData(keyData *byte, keySize int,
 	}
 
 	*returnValueSize = len(value.data)
-	*returnValueData = &value.data[0]
+	if len(value.data) > 0 {
+		*returnValueData = &value.data[0]
+	}
 	*returnCas = value.cas
 	return internal.StatusOK
 }