factor out recording func, add unit tests (#12585)

Signed-off-by: FFMMM <FFMMM@users.noreply.github.com>

agent/rpc/middleware/interceptors.go

@@ -19,6 +19,7 @@ import (
 // Really what we are measuring here is a "cluster operation". The term we have
 // used for this historically is "RPC", so we continue to use that here.
 const RPCTypeInternal = "internal"
+const RPCTypeNetRPC = "net/rpc"
 
 var metricRPCRequest = []string{"rpc", "server", "call"}
 var requestLogName = "rpc.server.request"
@@ -32,10 +33,11 @@ var NewRPCCounters = []prometheus.CounterDefinition{
 
 type RequestRecorder struct {
 	Logger       hclog.Logger
+	recorderFunc func(key []string, start time.Time, labels []metrics.Label)
 }
 
 func NewRequestRecorder(logger hclog.Logger) *RequestRecorder {
-	return &RequestRecorder{Logger: logger}
+	return &RequestRecorder{Logger: logger, recorderFunc: metrics.MeasureSinceWithLabels}
 }
 
 func (r *RequestRecorder) Record(requestName string, rpcType string, start time.Time, request interface{}, respErrored bool) {
@@ -50,9 +52,8 @@ func (r *RequestRecorder) Record(requestName string, rpcType string, start time.
 		{Name: "rpc_type", Value: rpcType},
 	}
 
-	// TODO(rpc-metrics-improv): consider using Telemetry API call here
-	// It'd be neat if we could actually pass the elapsed observed above
-	metrics.MeasureSinceWithLabels(metricRPCRequest, start, labels)
+	// TODO(FFMMM): it'd be neat if we could actually pass the elapsed observed above
+	r.recorderFunc(metricRPCRequest, start, labels)
 
 	r.Logger.Debug(requestLogName,
 		"method", requestName,
@@ -75,11 +76,6 @@ func GetNetRPCInterceptor(recorder *RequestRecorder) rpc.ServerServiceCallInterc
 
 		err := handler()
 
-		responseErr := false
-		if err != nil {
-			responseErr = true
-		}
-
-		recorder.Record(reqServiceMethod, "net/rpc", reqStart, argv.Interface(), responseErr)
+		recorder.Record(reqServiceMethod, RPCTypeNetRPC, reqStart, argv.Interface(), err != nil)
 	}
 }

agent/rpc/middleware/interceptors_test.go

@@ -0,0 +1,126 @@
+package middleware
+
+import (
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/armon/go-metrics"
+	"github.com/hashicorp/go-hclog"
+	"github.com/stretchr/testify/require"
+)
+
+// obs holds all the things we want to assert on that we recorded correctly in our tests.
+type obs struct {
+	key    []string
+	start  time.Time
+	labels []metrics.Label
+}
+
+// recorderStore acts as an in-mem mock storage for all the RequestRecorder.Record() recorderFunc calls.
+type recorderStore struct {
+	lock  sync.Mutex
+	store map[string]obs
+}
+
+func (rs *recorderStore) put(key []string, o obs) {
+	rs.lock.Lock()
+	defer rs.lock.Unlock()
+
+	actualKey := strings.Join(append(key, o.labels[0].Value), "")
+	rs.store[actualKey] = o
+}
+
+func (rs *recorderStore) get(key []string) obs {
+	rs.lock.Lock()
+	defer rs.lock.Unlock()
+
+	actualKey := strings.Join(key, "")
+	return rs.store[actualKey]
+}
+
+var store = recorderStore{store: make(map[string]obs)}
+var simpleRecorderFunc = func(key []string, start time.Time, labels []metrics.Label) {
+	o := obs{key: key, start: start, labels: labels}
+
+	store.put(key, o)
+}
+
+type readRequest struct{}
+type writeRequest struct{}
+
+func (rr readRequest) IsRead() bool {
+	return true
+}
+
+func (wr writeRequest) IsRead() bool {
+	return false
+}
+
+// TestRequestRecorder_SimpleOK tests that the RequestRecorder can record a simple request.
+func TestRequestRecorder_SimpleOK(t *testing.T) {
+	r := RequestRecorder{
+		Logger:       hclog.NewInterceptLogger(&hclog.LoggerOptions{}),
+		recorderFunc: simpleRecorderFunc,
+	}
+
+	start := time.Now()
+	r.Record("A.B", RPCTypeInternal, start, struct{}{}, false)
+
+	expectedLabels := []metrics.Label{
+		{Name: "method", Value: "A.B"},
+		{Name: "errored", Value: "false"},
+		{Name: "request_type", Value: "write"},
+		{Name: "rpc_type", Value: RPCTypeInternal},
+	}
+
+	o := store.get(append(metricRPCRequest, expectedLabels[0].Value))
+	require.Equal(t, o.key, metricRPCRequest)
+	require.Equal(t, o.start, start)
+	require.Equal(t, o.labels, expectedLabels)
+}
+
+// TestRequestRecorder_ReadRequest tests that RequestRecorder can record a read request AND a responseErrored arg.
+func TestRequestRecorder_ReadRequest(t *testing.T) {
+	r := RequestRecorder{
+		Logger:       hclog.NewInterceptLogger(&hclog.LoggerOptions{}),
+		recorderFunc: simpleRecorderFunc,
+	}
+
+	start := time.Now()
+
+	r.Record("B.A", RPCTypeNetRPC, start, readRequest{}, true)
+
+	expectedLabels := []metrics.Label{
+		{Name: "method", Value: "B.A"},
+		{Name: "errored", Value: "true"},
+		{Name: "request_type", Value: "read"},
+		{Name: "rpc_type", Value: RPCTypeNetRPC},
+	}
+
+	o := store.get(append(metricRPCRequest, expectedLabels[0].Value))
+	require.Equal(t, o.labels, expectedLabels)
+}
+
+// TestRequestRecorder_WriteRequest tests that RequestRecorder can record a write request.
+func TestRequestRecorder_WriteRequest(t *testing.T) {
+	r := RequestRecorder{
+		Logger:       hclog.NewInterceptLogger(&hclog.LoggerOptions{}),
+		recorderFunc: simpleRecorderFunc,
+	}
+
+	start := time.Now()
+
+	r.Record("B.C", RPCTypeNetRPC, start, writeRequest{}, true)
+
+	expectedLabels := []metrics.Label{
+		{Name: "method", Value: "B.C"},
+		{Name: "errored", Value: "true"},
+		{Name: "request_type", Value: "write"},
+		{Name: "rpc_type", Value: RPCTypeNetRPC},
+	}
+
+	o := store.get(append(metricRPCRequest, expectedLabels[0].Value))
+	require.Equal(t, o.labels, expectedLabels)
+}