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feat: expose RTT jitter in Statistics struct #158

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feat: expose RTT jitter in Statistics struct #158

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24 changes: 24 additions & 0 deletions ping.go
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Original file line number Diff line number Diff line change
Expand Up @@ -164,6 +164,12 @@ type Pinger struct {
stddevm2 float64
statsMu sync.RWMutex

// Jitter calculation fields
prevRtt time.Duration
jitterSum time.Duration
jitterCount int
Jitter time.Duration

// If true, keep a record of rtts of all received packets.
// Set to false to avoid memory bloat for long running pings.
RecordRtts bool
Expand Down Expand Up @@ -315,6 +321,9 @@ type Statistics struct {
// StdDevRtt is the standard deviation of the round-trip times sent via
// this pinger.
StdDevRtt time.Duration

// Jitter calculation based on mean absolute differences between consecutive RTTs
Jitter time.Duration
}

func (p *Pinger) updateStatistics(pkt *Packet) {
Expand All @@ -324,6 +333,20 @@ func (p *Pinger) updateStatistics(pkt *Packet) {
p.PacketsRecv++
if p.RecordRtts {
p.rtts = append(p.rtts, pkt.Rtt)

// Jitter calculation (mean absolute difference between RTTs)
if p.jitterCount == 0 {
p.jitterCount = 1
} else {
diff := pkt.Rtt - p.prevRtt
if diff < 0 {
diff = -diff
}
p.jitterSum += diff
p.Jitter = p.jitterSum / time.Duration(p.jitterCount)
p.jitterCount++
}
p.prevRtt = pkt.Rtt
}

if p.RecordTTLs {
Expand Down Expand Up @@ -705,6 +728,7 @@ func (p *Pinger) Statistics() *Statistics {
MinRtt: p.minRtt,
AvgRtt: p.avgRtt,
StdDevRtt: p.stdDevRtt,
Jitter: p.Jitter,
}
return &s
}
Expand Down
98 changes: 98 additions & 0 deletions ping_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -376,6 +376,98 @@ func TestEmptyIPAddr(t *testing.T) {
AssertError(t, err, "empty pinger did not return an error")
}

func TestStatistics1(t *testing.T) {
// Create a localhost ipv4 pinger
p := New("localhost")
err := p.Resolve()
AssertNoError(t, err)
AssertEqualStrings(t, "localhost", p.Addr())

p.PacketsSent = 10
p.updateStatistics(&Packet{Rtt: time.Duration(2890)})
p.updateStatistics(&Packet{Rtt: time.Duration(2330)})
p.updateStatistics(&Packet{Rtt: time.Duration(2450)})
p.updateStatistics(&Packet{Rtt: time.Duration(2990)})
p.updateStatistics(&Packet{Rtt: time.Duration(3150)})
p.updateStatistics(&Packet{Rtt: time.Duration(2700)})
p.updateStatistics(&Packet{Rtt: time.Duration(3420)})
p.updateStatistics(&Packet{Rtt: time.Duration(2400)})
p.updateStatistics(&Packet{Rtt: time.Duration(3080)})
p.updateStatistics(&Packet{Rtt: time.Duration(2850)})

stats := p.Statistics()
if stats.PacketsRecv != 10 {
t.Errorf("Expected %v, got %v", 10, stats.PacketsRecv)
}
if stats.PacketsSent != 10 {
t.Errorf("Expected %v, got %v", 10, stats.PacketsSent)
}
if stats.PacketLoss != 0 {
t.Errorf("Expected %v, got %v", 0, stats.PacketLoss)
}
if stats.MinRtt != time.Duration(2330) {
t.Errorf("Expected %v, got %v", time.Duration(2330), stats.MinRtt)
}
if stats.MaxRtt != time.Duration(3420) {
t.Errorf("Expected %v, got %v", time.Duration(3420), stats.MaxRtt)
}
if stats.AvgRtt != time.Duration(2826) {
t.Errorf("Expected %v, got %v", time.Duration(2826), stats.AvgRtt)
}
if stats.StdDevRtt != time.Duration(337) {
t.Errorf("Expected %v, got %v", time.Duration(337), stats.StdDevRtt)
}
if stats.Jitter != time.Duration(497) {
t.Errorf("Expected %v, got %v", time.Duration(497), stats.Jitter)
}
}

func TestStatistics2(t *testing.T) {
// Create a localhost ipv4 pinger
p := New("localhost")
err := p.Resolve()
AssertNoError(t, err)
AssertEqualStrings(t, "localhost", p.Addr())

p.PacketsSent = 10
p.updateStatistics(&Packet{Rtt: time.Duration(36700)})
p.updateStatistics(&Packet{Rtt: time.Duration(36900)})
p.updateStatistics(&Packet{Rtt: time.Duration(37600)})
p.updateStatistics(&Packet{Rtt: time.Duration(37500)})
p.updateStatistics(&Packet{Rtt: time.Duration(37400)})
p.updateStatistics(&Packet{Rtt: time.Duration(37200)})
p.updateStatistics(&Packet{Rtt: time.Duration(36700)})
p.updateStatistics(&Packet{Rtt: time.Duration(37000)})
p.updateStatistics(&Packet{Rtt: time.Duration(37200)})
p.updateStatistics(&Packet{Rtt: time.Duration(38100)})

stats := p.Statistics()
if stats.PacketsRecv != 10 {
t.Errorf("Expected %v, got %v", 10, stats.PacketsRecv)
}
if stats.PacketsSent != 10 {
t.Errorf("Expected %v, got %v", 10, stats.PacketsSent)
}
if stats.PacketLoss != 0 {
t.Errorf("Expected %v, got %v", 0, stats.PacketLoss)
}
if stats.MinRtt != time.Duration(36700) {
t.Errorf("Expected %v, got %v", time.Duration(36700), stats.MinRtt)
}
if stats.MaxRtt != time.Duration(38100) {
t.Errorf("Expected %v, got %v", time.Duration(38100), stats.MaxRtt)
}
if stats.AvgRtt != time.Duration(37230) {
t.Errorf("Expected %v, got %v", time.Duration(37230), stats.AvgRtt)
}
if stats.StdDevRtt != time.Duration(414) {
t.Errorf("Expected %v, got %v", time.Duration(414), stats.StdDevRtt)
}
if stats.Jitter != time.Duration(355) {
t.Errorf("Expected %v, got %v", time.Duration(355), stats.Jitter)
}
}

func TestStatisticsSunny(t *testing.T) {
// Create a localhost ipv4 pinger
p := New("localhost")
Expand Down Expand Up @@ -417,6 +509,9 @@ func TestStatisticsSunny(t *testing.T) {
if stats.StdDevRtt != time.Duration(0) {
t.Errorf("Expected %v, got %v", time.Duration(0), stats.StdDevRtt)
}
if stats.Jitter != time.Duration(0) {
t.Errorf("Expected %v, got %v", time.Duration(0), stats.Jitter)
}
}

func TestStatisticsLossy(t *testing.T) {
Expand Down Expand Up @@ -460,6 +555,9 @@ func TestStatisticsLossy(t *testing.T) {
if stats.StdDevRtt != time.Duration(29603) {
t.Errorf("Expected %v, got %v", time.Duration(29603), stats.StdDevRtt)
}
if stats.Jitter != time.Duration(24367) {
t.Errorf("Expected %v, got %v", time.Duration(24367), stats.Jitter)
}
}

func TestStatisticsZeroDivision(t *testing.T) {
Expand Down