From 20e01e24b66148478d8243c3cb483efae41935b2 Mon Sep 17 00:00:00 2001
From: Saad Karim <skarim@us.ibm.com>
Date: Wed, 24 Oct 2018 12:46:29 -0400
Subject: [PATCH] FAB-12592 Create a stats handler for the server

Create counters for grpc connections. There will be
one counter that will track number of connections opened,
and the second counter will track the number of connections
closed.

Change-Id: I218886e4b7f3710bd342129526d5555c9fe9701c
Signed-off-by: Saad Karim <skarim@us.ibm.com>
---
 Gopkg.lock                           |  1 +
 core/comm/serverstatshandler.go      | 38 ++++++++++++++++++++++++++++
 core/comm/serverstatshandler_test.go | 37 +++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)
 create mode 100644 core/comm/serverstatshandler.go
 create mode 100644 core/comm/serverstatshandler_test.go

diff --git a/Gopkg.lock b/Gopkg.lock
index 531a0c4fc71..5b8a0cb30f8 100644
--- a/Gopkg.lock
+++ b/Gopkg.lock
@@ -903,6 +903,7 @@
     "google.golang.org/grpc/keepalive",
     "google.golang.org/grpc/metadata",
     "google.golang.org/grpc/peer",
+    "google.golang.org/grpc/stats",
     "google.golang.org/grpc/status",
     "gopkg.in/alecthomas/kingpin.v2",
     "gopkg.in/cheggaaa/pb.v1",
diff --git a/core/comm/serverstatshandler.go b/core/comm/serverstatshandler.go
new file mode 100644
index 00000000000..10ccf7be4f1
--- /dev/null
+++ b/core/comm/serverstatshandler.go
@@ -0,0 +1,38 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package comm
+
+import (
+	"context"
+
+	"github.com/go-kit/kit/metrics"
+	"google.golang.org/grpc/stats"
+)
+
+type ServerStatsHandler struct {
+	OpenConnCounter   metrics.Counter
+	ClosedConnCounter metrics.Counter
+}
+
+func (h *ServerStatsHandler) TagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
+	return ctx
+}
+
+func (h *ServerStatsHandler) HandleRPC(ctx context.Context, s stats.RPCStats) {
+	switch s.(type) {
+	case *stats.Begin:
+		h.OpenConnCounter.Add(1)
+	case *stats.End:
+		h.ClosedConnCounter.Add(1)
+	}
+}
+
+func (h *ServerStatsHandler) TagConn(ctx context.Context, info *stats.ConnTagInfo) context.Context {
+	return ctx
+}
+
+func (h *ServerStatsHandler) HandleConn(ctx context.Context, s stats.ConnStats) {}
diff --git a/core/comm/serverstatshandler_test.go b/core/comm/serverstatshandler_test.go
new file mode 100644
index 00000000000..d88922ecc51
--- /dev/null
+++ b/core/comm/serverstatshandler_test.go
@@ -0,0 +1,37 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package comm_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/hyperledger/fabric/common/metrics/metricsfakes"
+	"github.com/hyperledger/fabric/core/comm"
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/grpc/stats"
+)
+
+func TestConnectionCounters(t *testing.T) {
+	openConn := &metricsfakes.Counter{}
+	closedConn := &metricsfakes.Counter{}
+	sh := &comm.ServerStatsHandler{
+		OpenConnCounter:   openConn,
+		ClosedConnCounter: closedConn,
+	}
+
+	for i := 1; i <= 10; i++ {
+		sh.HandleRPC(context.Background(), &stats.Begin{})
+	}
+	assert.Equal(t, 10, openConn.AddCallCount())
+
+	for i := 1; i <= 5; i++ {
+		sh.HandleRPC(context.Background(), &stats.End{})
+	}
+	assert.Equal(t, 5, closedConn.AddCallCount())
+
+}