From 3e767ca5c8357c430f246433cdf2f89008e74554 Mon Sep 17 00:00:00 2001
From: lanzafame <adrianlanzafame92@gmail.com>
Date: Wed, 21 Oct 2020 18:10:27 +1000
Subject: [PATCH] wrap api in metrics proxy

---
 cmd/lotus/rpc.go   |  3 ++-
 metrics/metrics.go | 19 ++++++++++++++
 metrics/proxy.go   | 65 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 metrics/proxy.go

diff --git a/cmd/lotus/rpc.go b/cmd/lotus/rpc.go
index 9718deb3a..28af47ad7 100644
--- a/cmd/lotus/rpc.go
+++ b/cmd/lotus/rpc.go
@@ -22,6 +22,7 @@ import (
 
 	"github.com/filecoin-project/lotus/api"
 	"github.com/filecoin-project/lotus/api/apistruct"
+	"github.com/filecoin-project/lotus/metrics"
 	"github.com/filecoin-project/lotus/node"
 	"github.com/filecoin-project/lotus/node/impl"
 )
@@ -30,7 +31,7 @@ var log = logging.Logger("main")
 
 func serveRPC(a api.FullNode, stop node.StopFunc, addr multiaddr.Multiaddr, shutdownCh <-chan struct{}) error {
 	rpcServer := jsonrpc.NewServer()
-	rpcServer.Register("Filecoin", apistruct.PermissionedFullAPI(a))
+	rpcServer.Register("Filecoin", apistruct.PermissionedFullAPI(metrics.MetricedFullAPI(a)))
 
 	ah := &auth.Handler{
 		Verify: a.AuthVerify,
diff --git a/metrics/metrics.go b/metrics/metrics.go
index 5dd865263..8de6afc1e 100644
--- a/metrics/metrics.go
+++ b/metrics/metrics.go
@@ -1,6 +1,7 @@
 package metrics
 
 import (
+	"context"
 	"time"
 
 	"go.opencensus.io/stats"
@@ -24,6 +25,8 @@ var (
 	MessageTo, _    = tag.NewKey("message_to")
 	MessageNonce, _ = tag.NewKey("message_nonce")
 	ReceivedFrom, _ = tag.NewKey("received_from")
+	Endpoint, _     = tag.NewKey("endpoint")
+	APIInterface, _ = tag.NewKey("api") // to distinguish between gateway api and full node api endpoint calls
 )
 
 // Measures
@@ -49,6 +52,7 @@ var (
 	PubsubRecvRPC                       = stats.Int64("pubsub/recv_rpc", "Counter for total received RPCs", stats.UnitDimensionless)
 	PubsubSendRPC                       = stats.Int64("pubsub/send_rpc", "Counter for total sent RPCs", stats.UnitDimensionless)
 	PubsubDropRPC                       = stats.Int64("pubsub/drop_rpc", "Counter for total dropped RPCs", stats.UnitDimensionless)
+	APIRequestDuration                  = stats.Float64("api/request_duration_ms", "Duration of API requests", stats.UnitMilliseconds)
 )
 
 var (
@@ -137,6 +141,11 @@ var (
 		Measure:     PubsubDropRPC,
 		Aggregation: view.Count(),
 	}
+	APIRequestDurationView = &view.View{
+		Measure:     APIRequestDuration,
+		Aggregation: defaultMillisecondsDistribution,
+		TagKeys:     []tag.Key{APIInterface, Endpoint},
+	}
 )
 
 // DefaultViews is an array of OpenCensus views for metric gathering purposes
@@ -161,6 +170,7 @@ var DefaultViews = append([]*view.View{
 	PubsubRecvRPCView,
 	PubsubSendRPCView,
 	PubsubDropRPCView,
+	APIRequestDurationView,
 },
 	rpcmetrics.DefaultViews...)
 
@@ -168,3 +178,12 @@ var DefaultViews = append([]*view.View{
 func SinceInMilliseconds(startTime time.Time) float64 {
 	return float64(time.Since(startTime).Nanoseconds()) / 1e6
 }
+
+// Timer is a function stopwatch, calling it starts the timer,
+// calling the returned function will record the duration.
+func Timer(ctx context.Context, m *stats.Float64Measure) func() {
+	start := time.Now()
+	return func() {
+		stats.Record(ctx, m.M(SinceInMilliseconds(start)))
+	}
+}
\ No newline at end of file
diff --git a/metrics/proxy.go b/metrics/proxy.go
new file mode 100644
index 000000000..cafcaad89
--- /dev/null
+++ b/metrics/proxy.go
@@ -0,0 +1,65 @@
+package metrics
+
+import (
+	"context"
+	"reflect"
+
+	"go.opencensus.io/tag"
+
+	"github.com/filecoin-project/lotus/api"
+	"github.com/filecoin-project/lotus/api/apistruct"
+)
+
+func MetricedStorMinerAPI(a api.StorageMiner) api.StorageMiner {
+	var out apistruct.StorageMinerStruct
+	proxy(a, &out.Internal)
+	proxy(a, &out.CommonStruct.Internal)
+	return &out
+}
+
+func MetricedFullAPI(a api.FullNode) api.FullNode {
+	var out apistruct.FullNodeStruct
+	proxy(a, &out.Internal)
+	proxy(a, &out.CommonStruct.Internal)
+	return &out
+}
+
+func MetricedWorkerAPI(a api.WorkerAPI) api.WorkerAPI {
+	var out apistruct.WorkerStruct
+	proxy(a, &out.Internal)
+	return &out
+}
+
+func MetricedWalletAPI(a api.WalletAPI) api.WalletAPI {
+	var out apistruct.WalletStruct
+	proxy(a, &out.Internal)
+	return &out
+}
+
+func MetricedGatewayAPI(a api.GatewayAPI) api.GatewayAPI {
+	var out apistruct.GatewayStruct
+	proxy(a, &out.Internal)
+	return &out
+}
+
+func proxy(in interface{}, out interface{}) {
+	rint := reflect.ValueOf(out).Elem()
+	ra := reflect.ValueOf(in)
+
+	for f := 0; f < rint.NumField(); f++ {
+		field := rint.Type().Field(f)
+		fn := ra.MethodByName(field.Name)
+
+		rint.Field(f).Set(reflect.MakeFunc(field.Type, func(args []reflect.Value) (results []reflect.Value) {
+			ctx := args[0].Interface().(context.Context)
+			// upsert function name into context
+			ctx, _ = tag.New(ctx, tag.Upsert(Endpoint, field.Name))
+			stop := Timer(ctx, APIRequestDuration)
+			defer stop()
+			// pass tagged ctx back into function call
+			args[0] = reflect.ValueOf(ctx)
+			return fn.Call(args)
+		}))
+
+	}
+}
\ No newline at end of file