chore: added usefull comments

Signed-off-by: Yash Patel <[email protected]>

Author: yp969803

bpf/kmesh/probes/probe.h

@@ -4,11 +4,11 @@
 #ifndef __KMESH_BPF_PROBE_H__
 #define __KMESH_BPF_PROBE_H__
 
-#define LONG_CONN_THRESHOLD_TIME (5 * 1000000000ULL) // 5s
-
 #include "tcp_probe.h"
 #include "performance_probe.h"
 
+#define LONG_CONN_THRESHOLD_TIME (5 * 1000000000ULL) // 5s
+
 volatile __u32 enable_monitoring = 0;
 
 static inline bool is_monitoring_enable()

pkg/controller/telemetry/accesslog.go

@@ -26,7 +26,7 @@ import (
 
 type logInfo struct {
 	direction       string
-	status          string
+	state           string
 	sourceAddress   string
 	sourceWorkload  string
 	sourceNamespace string
@@ -89,7 +89,7 @@ func buildAccesslog(data requestMetric, conn_metrics connMetric, accesslog logIn
 	timeInfo := fmt.Sprintf("%v", uptime)
 	sourceInfo := fmt.Sprintf("src.addr=%s, src.workload=%s, src.namespace=%s", accesslog.sourceAddress, accesslog.sourceWorkload, accesslog.sourceNamespace)
 	destinationInfo := fmt.Sprintf("dst.addr=%s, dst.service=%s, dst.workload=%s, dst.namespace=%s", accesslog.destinationAddress, accesslog.destinationService, accesslog.destinationWorkload, accesslog.destinationNamespace)
-	connectionInfo := fmt.Sprintf("connection_id=%d, start_time=%s, direction=%s, status=%s, sent_bytes=%d, received_bytes=%d, packet_loss=%d, retransmissions=%d, srtt=%dus, min_rtt=%dus, duration=%vms", conn_metrics.connId, startTimeInfo, accesslog.direction, accesslog.status, conn_metrics.sentBytes, conn_metrics.receivedBytes, conn_metrics.packetLost, conn_metrics.totalRetrans, data.srtt, data.minRtt, (float64(data.duration) / 1000000.0))
+	connectionInfo := fmt.Sprintf("connection_id=%d, start_time=%s, direction=%s, state=%s, sent_bytes=%d, received_bytes=%d, packet_loss=%d, retransmissions=%d, srtt=%dus, min_rtt=%dus, duration=%vms", conn_metrics.connId, startTimeInfo, accesslog.direction, accesslog.state, conn_metrics.sentBytes, conn_metrics.receivedBytes, conn_metrics.packetLost, conn_metrics.totalRetrans, data.srtt, data.minRtt, (float64(data.duration) / 1000000.0))
 
 	logResult := fmt.Sprintf("%s %s, %s, %s", timeInfo, sourceInfo, destinationInfo, connectionInfo)
 	return logResult

pkg/controller/telemetry/accesslog_test.go

@@ -56,10 +56,10 @@ func Test_buildAccesslog(t *testing.T) {
 					destinationService:   "httpbin.ambient-demo.svc.cluster.local",
 					destinationWorkload:  "httpbin-86b8ffc5ff-bhvxx",
 					destinationNamespace: "kmesh-system",
-					status:               "BPF_TCP_SYN_RECV",
+					state:                "BPF_TCP_SYN_RECV",
 				},
 			},
-			want: "2024-08-14 10:11:27.005837715 +0000 UTC src.addr=10.244.0.10:47667, src.workload=sleep-7656cf8794-9v2gv, src.namespace=kmesh-system, dst.addr=10.244.0.7:8080, dst.service=httpbin.ambient-demo.svc.cluster.local, dst.workload=httpbin-86b8ffc5ff-bhvxx, dst.namespace=kmesh-system, connection_id=12345678, start_time=2024-08-14 10:11:27.005837715 +0000 UTC, direction=INBOUND, status=BPF_TCP_SYN_RECV, sent_bytes=60, received_bytes=172, packet_loss=0, retransmissions=0, srtt=0us, min_rtt=0us, duration=2.236ms",
+			want: "2024-08-14 10:11:27.005837715 +0000 UTC src.addr=10.244.0.10:47667, src.workload=sleep-7656cf8794-9v2gv, src.namespace=kmesh-system, dst.addr=10.244.0.7:8080, dst.service=httpbin.ambient-demo.svc.cluster.local, dst.workload=httpbin-86b8ffc5ff-bhvxx, dst.namespace=kmesh-system, connection_id=12345678, start_time=2024-08-14 10:11:27.005837715 +0000 UTC, direction=INBOUND, state=BPF_TCP_SYN_RECV, sent_bytes=60, received_bytes=172, packet_loss=0, retransmissions=0, srtt=0us, min_rtt=0us, duration=2.236ms",
 		},
 	}
 	osStartTime = time.Date(2024, 7, 4, 20, 14, 0, 0, time.UTC)

pkg/controller/telemetry/metric.go

@@ -101,16 +101,16 @@ type statistics struct {
 	ReceivedBytes  uint32
 	ConnectSuccess uint32
 	Direction      uint32
-	State          uint32
+	State          uint32 // TCP state ex: BPF_TCP_ESTABLISHED
 	_              uint32
-	Duration       uint64
-	StartTime      uint64
-	LastReportTime uint64
+	Duration       uint64 // duration of the connection till now
+	StartTime      uint64 // time when the connection is established
+	LastReportTime uint64 // time when the metric is reported
 	Protocol       uint32
-	SRttTime       uint32
-	RttMin         uint32
-	Retransmits    uint32
-	LostPackets    uint32
+	SRttTime       uint32 // smoothed RTT
+	RttMin         uint32 // minimum RTT
+	Retransmits    uint32 // total retransmits
+	LostPackets    uint32 // total lost packets
 }
 
 // connectionDataV4 read from ebpf km_tcp_probe ringbuf and padding with `_`
@@ -146,10 +146,10 @@ type connectionDataV6 struct {
 
 type connMetric struct {
 	connId        uint64
-	receivedBytes uint32
-	sentBytes     uint32
-	totalRetrans  uint32
-	packetLost    uint32
+	receivedBytes uint32 // total bytes received till now
+	sentBytes     uint32 // total bytes sent till now
+	totalRetrans  uint32 // total retransmits till now
+	packetLost    uint32 // total packets lost till now
 }
 
 type requestMetric struct {
@@ -161,17 +161,17 @@ type requestMetric struct {
 	origDstPort    uint16
 	currentConnId  uint64
 	direction      uint32
-	receivedBytes  uint32
-	sentBytes      uint32
+	receivedBytes  uint32 // total bytes received after previous report
+	sentBytes      uint32 // total bytes sent after previous report
 	state          uint32
 	success        uint32
 	duration       uint64
 	startTime      uint64
 	lastReportTime uint64
 	srtt           uint32
 	minRtt         uint32
-	totalRetrans   uint32
-	packetLost     uint32
+	totalRetrans   uint32 // total retransmits after previous report
+	packetLost     uint32 // total packets lost after previous report
 }
 
 type workloadMetricLabels struct {
@@ -414,6 +414,7 @@ func (m *MetricController) Run(ctx context.Context, mapOfTcpInfo *ebpf.Map) {
 			}
 
 			if m.EnableAccesslog.Load() {
+				// accesslogs at start of connection, at interval of 5 sec during connection lifecycle and at close of connection
 				OutputAccesslog(data, tcp_conns[data.currentConnId], accesslog)
 			}
 
@@ -660,7 +661,7 @@ func (m *MetricController) buildServiceMetric(data *requestMetric) (serviceMetri
 		accesslog.direction = "OUTBOUND"
 	}
 
-	accesslog.status = TCP_STATES[data.state]
+	accesslog.state = TCP_STATES[data.state]
 	return *trafficLabels, *accesslog
 }