From 1b30d228da0da00eda99756281dd62fcb8e9c92a Mon Sep 17 00:00:00 2001
From: Denis Kirillov <denis@nspcc.ru>
Date: Wed, 13 Jul 2022 12:55:38 +0300
Subject: [PATCH] [#283] pool: Expose statistic

Signed-off-by: Denis Kirillov <denis@nspcc.ru>
---
 pool/pool.go      | 21 +++++++++++++++
 pool/pool_test.go | 30 ++++++++++++++++-----
 pool/statistic.go | 67 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 112 insertions(+), 6 deletions(-)
 create mode 100644 pool/statistic.go

diff --git a/pool/pool.go b/pool/pool.go
index 080bc95..fa5d368 100644
--- a/pool/pool.go
+++ b/pool/pool.go
@@ -1900,6 +1900,27 @@ func (p *Pool) Balance(ctx context.Context, prm PrmBalanceGet) (*accounting.Deci
 	return cp.balanceGet(ctx, prm)
 }
 
+// Statistic returns connection statistics.
+func (p Pool) Statistic() Statistic {
+	stat := Statistic{}
+	for _, inner := range p.innerPools {
+		inner.lock.RLock()
+		for _, cl := range inner.clients {
+			node := &NodeStatistic{
+				address:       cl.address(),
+				latency:       cl.latency(),
+				overallErrors: cl.overallErrorRate(),
+				currentErrors: cl.currentErrorRate(),
+			}
+			stat.nodes = append(stat.nodes, node)
+			stat.overallErrors += node.overallErrors
+		}
+		inner.lock.RUnlock()
+	}
+
+	return stat
+}
+
 // waitForContainerPresence waits until the container is found on the NeoFS network.
 func waitForContainerPresence(ctx context.Context, cli client, cnrID *cid.ID, waitParams *WaitParams) error {
 	var prm PrmContainerGet
diff --git a/pool/pool_test.go b/pool/pool_test.go
index 3b5a507..ec1053b 100644
--- a/pool/pool_test.go
+++ b/pool/pool_test.go
@@ -510,13 +510,31 @@ func TestWaitPresence(t *testing.T) {
 
 func newTestStatusMonitor(addr string) *clientStatusMonitor {
 	return &clientStatusMonitor{
-		addr:           addr,
-		healthy:        atomic.NewBool(true),
-		errorCount:     atomic.NewUint32(0),
-		errorThreshold: 10,
+		addr:              addr,
+		healthy:           atomic.NewBool(true),
+		currentErrorCount: atomic.NewUint32(0),
+		overallErrorCount: atomic.NewUint64(0),
+		errorThreshold:    10,
+		allTime:           atomic.NewUint64(0),
+		allRequests:       atomic.NewUint64(0),
 	}
 }
 
+func TestStatusMonitor(t *testing.T) {
+	monitor := newTestStatusMonitor("")
+
+	count := 10
+	for i := 0; i < 10; i++ {
+		monitor.incErrorRate()
+		if i%3 == 0 {
+			monitor.resetErrorCounter()
+		}
+	}
+
+	require.Equal(t, uint64(count), monitor.overallErrorRate())
+	require.Equal(t, uint32(0), monitor.currentErrorRate())
+}
+
 func TestHandleError(t *testing.T) {
 	monitor := newTestStatusMonitor("")
 
@@ -582,7 +600,7 @@ func TestHandleError(t *testing.T) {
 		},
 	} {
 		t.Run(strconv.Itoa(i), func(t *testing.T) {
-			errCount := monitor.errorRate()
+			errCount := monitor.currentErrorRate()
 			err := monitor.handleError(tc.status, tc.err)
 			if tc.expectedError {
 				require.Error(t, err)
@@ -592,7 +610,7 @@ func TestHandleError(t *testing.T) {
 			if tc.countError {
 				errCount++
 			}
-			require.Equal(t, errCount, monitor.errorRate())
+			require.Equal(t, errCount, monitor.currentErrorRate())
 		})
 	}
 }
diff --git a/pool/statistic.go b/pool/statistic.go
new file mode 100644
index 0000000..f7256a8
--- /dev/null
+++ b/pool/statistic.go
@@ -0,0 +1,67 @@
+package pool
+
+import (
+	"errors"
+	"time"
+)
+
+// Statistic is metrics of the pool.
+type Statistic struct {
+	overallErrors uint64
+	nodes         []*NodeStatistic
+}
+
+// OverallErrors returns sum of errors on all connections. It doesn't decrease.
+func (s Statistic) OverallErrors() uint64 {
+	return s.overallErrors
+}
+
+// Nodes returns list of nodes statistic.
+func (s Statistic) Nodes() []*NodeStatistic {
+	return s.nodes
+}
+
+// ErrUnknownNode indicate that node with current address is not found in list.
+var ErrUnknownNode = errors.New("unknown node")
+
+// Node returns NodeStatistic by node address.
+// If such node doesn't exist ErrUnknownNode error is returned.
+func (s Statistic) Node(address string) (*NodeStatistic, error) {
+	for i := range s.nodes {
+		if s.nodes[i].address == address {
+			return s.nodes[i], nil
+		}
+	}
+
+	return nil, ErrUnknownNode
+}
+
+// NodeStatistic is metrics of certain connections.
+type NodeStatistic struct {
+	address       string
+	latency       time.Duration
+	overallErrors uint64
+	currentErrors uint32
+}
+
+// OverallErrors returns all errors on current node.
+// This value never decreases.
+func (n NodeStatistic) OverallErrors() uint64 {
+	return n.overallErrors
+}
+
+// CurrentErrors returns errors on current node.
+// This value is always less than 'errorThreshold' from InitParameters.
+func (n NodeStatistic) CurrentErrors() uint32 {
+	return n.currentErrors
+}
+
+// Latency returns average latency for node request.
+func (n NodeStatistic) Latency() time.Duration {
+	return n.latency
+}
+
+// Address returns node endpoint address.
+func (n NodeStatistic) Address() string {
+	return n.address
+}