From 32e9a240ed446d4c1f8ac7eca97e3fe87e6bd530 Mon Sep 17 00:00:00 2001 From: Patrick Begley Date: Thu, 28 May 2026 10:57:09 -0400 Subject: [PATCH 1/3] Emit replication and heartbeat lag --- go/base/context.go | 2 +- go/logic/migrator.go | 9 +++++- go/logic/migrator_test.go | 50 +++++++++++++++++++++++++++++++++ go/metrics/client.go | 23 +++++++++++++++ go/metrics/go_runtime.go | 5 ---- go/metrics/lag.go | 19 +++++++++++++ go/metrics/lag_test.go | 59 +++++++++++++++++++++++++++++++++++++++ 7 files changed, 160 insertions(+), 7 deletions(-) create mode 100644 go/metrics/lag.go create mode 100644 go/metrics/lag_test.go diff --git a/go/base/context.go b/go/base/context.go index 5a06d0d4d..4d0c3b09d 100644 --- a/go/base/context.go +++ b/go/base/context.go @@ -238,7 +238,7 @@ type MigrationContext struct { AbortError error abortMutex *sync.Mutex - Metrics metrics.MemStatsGaugeEmitter + Metrics metrics.Emitter OriginalTableColumnsOnApplier *sql.ColumnList OriginalTableColumns *sql.ColumnList diff --git a/go/logic/migrator.go b/go/logic/migrator.go index 5ed2e2d9a..f19098eb8 100644 --- a/go/logic/migrator.go +++ b/go/logic/migrator.go @@ -1168,7 +1168,7 @@ func (mgtr *Migrator) initiateInspector() (err error) { return nil } -// emitProgressMetrics emits StatsD gauges from a progress snapshot. +// emitProgressMetrics emits StatsD gauges func (mgtr *Migrator) emitProgressMetrics(snap migrationProgressSnapshot) { metrics.EmitProgressGauges( mgtr.migrationContext.Metrics, @@ -1181,6 +1181,13 @@ func (mgtr *Migrator) emitProgressMetrics(snap migrationProgressSnapshot) { snap.applyEventsBacklog, snap.applyEventsCapacity, ) + isThrottled, _, _ := mgtr.migrationContext.IsThrottled() + metrics.EmitLagHistograms( + mgtr.migrationContext.Metrics, + snap.replicationLagSeconds, + snap.heartbeatLagSeconds, + isThrottled, + ) } // reportStatus samples progress, emits metrics, and optionally prints status output. diff --git a/go/logic/migrator_test.go b/go/logic/migrator_test.go index 31e161b5e..31cb642dd 100644 --- a/go/logic/migrator_test.go +++ b/go/logic/migrator_test.go @@ -417,6 +417,21 @@ func (s *progressGaugeSpy) Gauge(name string, value float64, _ ...string) { s.values = append(s.values, value) } +func (s *progressGaugeSpy) Histogram(string, float64, ...string) {} + +type statusMetricsSpy struct { + progressGaugeSpy + histogramNames []string + histogramValues []float64 + histogramTags [][]string +} + +func (s *statusMetricsSpy) Histogram(name string, value float64, tags ...string) { + s.histogramNames = append(s.histogramNames, name) + s.histogramValues = append(s.histogramValues, value) + s.histogramTags = append(s.histogramTags, append([]string(nil), tags...)) +} + func TestReportStatusEmitsProgressGaugesEveryTick(t *testing.T) { spy := &progressGaugeSpy{} ctx := base.NewMigrationContext() @@ -504,6 +519,41 @@ func TestReportStatusEmitsGaugesWhenPrintSuppressed(t *testing.T) { assert.Equal(t, []float64{1000, 5000, 0, 0, float64(cap(migrator.applyEventsQueue)), 0}, spy.values) } +func TestReportStatusEmitsLagHistogramsWhenNotThrottled(t *testing.T) { + spy := &statusMetricsSpy{} + ctx := base.NewMigrationContext() + ctx.Metrics = spy + atomic.StoreInt64(&ctx.CurrentLag, int64(3*time.Second)) + ctx.SetLastHeartbeatOnChangelogTime(time.Now().Add(-2 * time.Second)) + + migrator := NewMigrator(ctx, "test") + migrator.reportStatus(NoPrintStatusRule, io.Discard) + + require.Len(t, spy.histogramNames, 2) + assert.Equal(t, []string{"lag.replication_seconds", "lag.heartbeat_seconds"}, spy.histogramNames) + assert.InDelta(t, 3.0, spy.histogramValues[0], 0.01) + assert.InDelta(t, 2.0, spy.histogramValues[1], 0.5) + require.Len(t, spy.histogramTags[0], 1) + assert.Equal(t, "throttled:false", spy.histogramTags[0][0]) + assert.Equal(t, "throttled:false", spy.histogramTags[1][0]) +} + +func TestReportStatusEmitsLagHistogramsWhenThrottled(t *testing.T) { + spy := &statusMetricsSpy{} + ctx := base.NewMigrationContext() + ctx.Metrics = spy + ctx.SetThrottled(true, "max-lag-millis", base.NoThrottleReasonHint) + atomic.StoreInt64(&ctx.CurrentLag, int64(5*time.Second)) + ctx.SetLastHeartbeatOnChangelogTime(time.Now().Add(-4 * time.Second)) + + migrator := NewMigrator(ctx, "test") + migrator.reportStatus(NoPrintStatusRule, io.Discard) + + require.Len(t, spy.histogramNames, 2) + assert.Equal(t, "throttled:true", spy.histogramTags[0][0]) + assert.Equal(t, "throttled:true", spy.histogramTags[1][0]) +} + func TestMigratorShouldPrintStatus(t *testing.T) { migrationContext := base.NewMigrationContext() migrator := NewMigrator(migrationContext, "1.2.3") diff --git a/go/metrics/client.go b/go/metrics/client.go index ed6acc096..e7953ae82 100644 --- a/go/metrics/client.go +++ b/go/metrics/client.go @@ -21,6 +21,22 @@ type Client struct { sd *statsd.Client } +// MemStatsGaugeEmitter is implemented by *Client; used for tests without UDP. +type MemStatsGaugeEmitter interface { + Gauge(name string, value float64, tags ...string) +} + +// HistogramEmitter is implemented by *Client; used for tests without UDP. +type HistogramEmitter interface { + Histogram(name string, value float64, tags ...string) +} + +// Emitter combines gauge and histogram emission for migration status metrics. +type Emitter interface { + MemStatsGaugeEmitter + HistogramEmitter +} + // NewClient connects to addr for StatsD. If addr is empty, returns Noop and nil error. // namespace is typically "gh_ost." (metrics are named namespace + short name, e.g. gh_ost.startup). // tags are global tags applied to every metric (repeatable --statsd-tags). @@ -60,6 +76,13 @@ func (c *Client) Count(name string, value int64, tags ...string) { _ = c.sd.Count(name, value, tags, 1.0) } +func (c *Client) Histogram(name string, value float64, tags ...string) { + if c.sd == nil { + return + } + _ = c.sd.Histogram(name, value, tags, 1.0) +} + // Close flushes buffered metrics; safe for Noop. func (c *Client) Close() error { if c.sd == nil { diff --git a/go/metrics/go_runtime.go b/go/metrics/go_runtime.go index 24ae2c6b5..021e987bf 100644 --- a/go/metrics/go_runtime.go +++ b/go/metrics/go_runtime.go @@ -11,11 +11,6 @@ import ( "time" ) -// MemStatsGaugeEmitter is implemented by *Client; used for tests without UDP. -type MemStatsGaugeEmitter interface { - Gauge(name string, value float64, tags ...string) -} - // EmitGoRuntimeGauges emits gh_ost.go_runtime.* gauges (namespace is applied by the client). // m and numGoroutine are typically from runtime.ReadMemStats and runtime.NumGoroutine. func EmitGoRuntimeGauges(emit MemStatsGaugeEmitter, m *runtime.MemStats, numGoroutine int) { diff --git a/go/metrics/lag.go b/go/metrics/lag.go new file mode 100644 index 000000000..2683aac54 --- /dev/null +++ b/go/metrics/lag.go @@ -0,0 +1,19 @@ +/* + Copyright 2022 GitHub Inc. + See https://github.com/github/gh-ost/blob/master/LICENSE +*/ + +package metrics + +import "fmt" + +// EmitLagHistograms emits replication and heartbeat lag histograms (namespace is applied by the client): +// gh_ost.lag.replication_seconds, gh_ost.lag.heartbeat_seconds, each tagged throttled:true|false. +func EmitLagHistograms(emit HistogramEmitter, replicationLagSeconds, heartbeatLagSeconds float64, throttled bool) { + if emit == nil { + return + } + tags := []string{fmt.Sprintf("throttled:%t", throttled)} + emit.Histogram("lag.replication_seconds", replicationLagSeconds, tags...) + emit.Histogram("lag.heartbeat_seconds", heartbeatLagSeconds, tags...) +} diff --git a/go/metrics/lag_test.go b/go/metrics/lag_test.go new file mode 100644 index 000000000..2a0b21418 --- /dev/null +++ b/go/metrics/lag_test.go @@ -0,0 +1,59 @@ +/* + Copyright 2022 GitHub Inc. + See https://github.com/github/gh-ost/blob/master/LICENSE +*/ + +package metrics + +import "testing" + +type histogramSpy struct { + names []string + values []float64 + tags [][]string +} + +func (s *histogramSpy) Histogram(name string, value float64, tags ...string) { + s.names = append(s.names, name) + s.values = append(s.values, value) + s.tags = append(s.tags, append([]string(nil), tags...)) +} + +func TestEmitLagHistograms_notThrottled(t *testing.T) { + spy := &histogramSpy{} + EmitLagHistograms(spy, 2.5, 1.25, false) + + wantNames := []string{"lag.replication_seconds", "lag.heartbeat_seconds"} + wantVals := []float64{2.5, 1.25} + wantTags := []string{"throttled:false"} + + if len(spy.names) != 2 { + t.Fatalf("got %d histograms, want 2", len(spy.names)) + } + for i := range wantNames { + if spy.names[i] != wantNames[i] || spy.values[i] != wantVals[i] { + t.Fatalf("[%d] got %s=%v want %s=%v", i, spy.names[i], spy.values[i], wantNames[i], wantVals[i]) + } + if len(spy.tags[i]) != 1 || spy.tags[i][0] != wantTags[0] { + t.Fatalf("[%d] got tags %v want [%s]", i, spy.tags[i], wantTags[0]) + } + } +} + +func TestEmitLagHistograms_throttled(t *testing.T) { + spy := &histogramSpy{} + EmitLagHistograms(spy, 4.0, 3.0, true) + + if len(spy.names) != 2 { + t.Fatalf("got %d histograms, want 2", len(spy.names)) + } + for i := range spy.names { + if len(spy.tags[i]) != 1 || spy.tags[i][0] != "throttled:true" { + t.Fatalf("[%d] got tags %v want [throttled:true]", i, spy.tags[i]) + } + } +} + +func TestEmitLagHistograms_nilSafe(t *testing.T) { + EmitLagHistograms(nil, 1, 2, false) +} From 1b13b78395730b9544a550626d7faf3462373fcf Mon Sep 17 00:00:00 2001 From: Patrick Begley Date: Thu, 28 May 2026 10:59:45 -0400 Subject: [PATCH 2/3] pruning comments --- go/metrics/client.go | 4 ---- 1 file changed, 4 deletions(-) diff --git a/go/metrics/client.go b/go/metrics/client.go index e7953ae82..283f476d1 100644 --- a/go/metrics/client.go +++ b/go/metrics/client.go @@ -21,17 +21,13 @@ type Client struct { sd *statsd.Client } -// MemStatsGaugeEmitter is implemented by *Client; used for tests without UDP. type MemStatsGaugeEmitter interface { Gauge(name string, value float64, tags ...string) } - -// HistogramEmitter is implemented by *Client; used for tests without UDP. type HistogramEmitter interface { Histogram(name string, value float64, tags ...string) } -// Emitter combines gauge and histogram emission for migration status metrics. type Emitter interface { MemStatsGaugeEmitter HistogramEmitter From 7b25a866dc38c68ceba13b1b225e5d4931ebe398 Mon Sep 17 00:00:00 2001 From: Patrick Begley Date: Thu, 28 May 2026 11:37:41 -0400 Subject: [PATCH 3/3] use gauge not histogram --- go/base/context.go | 2 +- go/logic/migrator.go | 2 +- go/logic/migrator_test.go | 69 +++++++++++------------------------ go/metrics/client.go | 16 +------- go/metrics/go_runtime_test.go | 4 +- go/metrics/lag.go | 12 ++++-- go/metrics/lag_test.go | 34 ++++++----------- 7 files changed, 46 insertions(+), 93 deletions(-) diff --git a/go/base/context.go b/go/base/context.go index 4d0c3b09d..5a06d0d4d 100644 --- a/go/base/context.go +++ b/go/base/context.go @@ -238,7 +238,7 @@ type MigrationContext struct { AbortError error abortMutex *sync.Mutex - Metrics metrics.Emitter + Metrics metrics.MemStatsGaugeEmitter OriginalTableColumnsOnApplier *sql.ColumnList OriginalTableColumns *sql.ColumnList diff --git a/go/logic/migrator.go b/go/logic/migrator.go index f19098eb8..5c51505e5 100644 --- a/go/logic/migrator.go +++ b/go/logic/migrator.go @@ -1182,7 +1182,7 @@ func (mgtr *Migrator) emitProgressMetrics(snap migrationProgressSnapshot) { snap.applyEventsCapacity, ) isThrottled, _, _ := mgtr.migrationContext.IsThrottled() - metrics.EmitLagHistograms( + metrics.EmitLagGauges( mgtr.migrationContext.Metrics, snap.replicationLagSeconds, snap.heartbeatLagSeconds, diff --git a/go/logic/migrator_test.go b/go/logic/migrator_test.go index 31cb642dd..74b09a47c 100644 --- a/go/logic/migrator_test.go +++ b/go/logic/migrator_test.go @@ -410,26 +410,13 @@ func TestMigratorGetMigrationStateAndETA(t *testing.T) { type progressGaugeSpy struct { names []string values []float64 + tags [][]string } -func (s *progressGaugeSpy) Gauge(name string, value float64, _ ...string) { +func (s *progressGaugeSpy) Gauge(name string, value float64, tags ...string) { s.names = append(s.names, name) s.values = append(s.values, value) -} - -func (s *progressGaugeSpy) Histogram(string, float64, ...string) {} - -type statusMetricsSpy struct { - progressGaugeSpy - histogramNames []string - histogramValues []float64 - histogramTags [][]string -} - -func (s *statusMetricsSpy) Histogram(name string, value float64, tags ...string) { - s.histogramNames = append(s.histogramNames, name) - s.histogramValues = append(s.histogramValues, value) - s.histogramTags = append(s.histogramTags, append([]string(nil), tags...)) + s.tags = append(s.tags, append([]string(nil), tags...)) } func TestReportStatusEmitsProgressGaugesEveryTick(t *testing.T) { @@ -442,7 +429,7 @@ func TestReportStatusEmitsProgressGaugesEveryTick(t *testing.T) { migrator := NewMigrator(ctx, "test") migrator.reportStatus(NoPrintStatusRule, io.Discard) - require.Len(t, spy.names, 6) + require.Len(t, spy.names, 8) assert.Equal(t, []string{ "row_copy.rows_copied", "row_copy.rows_estimate", @@ -450,16 +437,18 @@ func TestReportStatusEmitsProgressGaugesEveryTick(t *testing.T) { "binlog.backlog_size", "binlog.backlog_capacity", "binlog.backlog_utilization", + "lag.replication_seconds", + "lag.heartbeat_seconds", }, spy.names) - assert.Equal(t, []float64{1000, 5000, 42, 0, float64(cap(migrator.applyEventsQueue)), 0}, spy.values) + assert.Equal(t, []float64{1000, 5000, 42, 0, float64(cap(migrator.applyEventsQueue)), 0}, spy.values[:6]) assert.InDelta(t, 20.0, ctx.GetProgressPct(), 0.01) spy.names = nil spy.values = nil atomic.StoreInt64(&ctx.TotalDMLEventsApplied, 100) migrator.reportStatus(NoPrintStatusRule, io.Discard) - require.Len(t, spy.names, 6) - assert.Equal(t, []float64{1000, 5000, 100, 0, float64(cap(migrator.applyEventsQueue)), 0}, spy.values) + require.Len(t, spy.names, 8) + assert.Equal(t, []float64{1000, 5000, 100, 0, float64(cap(migrator.applyEventsQueue)), 0}, spy.values[:6]) } func TestReportStatusEmitsBinlogBacklogGauges(t *testing.T) { @@ -478,7 +467,7 @@ func TestReportStatusEmitsBinlogBacklogGauges(t *testing.T) { migrator.reportStatus(NoPrintStatusRule, io.Discard) capacity := float64(cap(migrator.applyEventsQueue)) - require.Len(t, spy.names, 6) + require.Len(t, spy.names, 8) assert.Equal(t, float64(2), spy.values[3]) assert.Equal(t, capacity, spy.values[4]) assert.InDelta(t, 2/capacity, spy.values[5], 1e-9) @@ -495,7 +484,7 @@ func TestReportStatusEmitsGaugesWhenRowCopyComplete(t *testing.T) { atomic.StoreInt64(&migrator.rowCopyCompleteFlag, 1) migrator.reportStatus(NoPrintStatusRule, io.Discard) - require.Len(t, spy.names, 6) + require.Len(t, spy.names, 8) assert.Equal(t, float64(5000), spy.values[0]) assert.Equal(t, float64(5000), spy.values[1], "rows_estimate tracks rows_copied when row copy is complete") } @@ -515,31 +504,12 @@ func TestReportStatusEmitsGaugesWhenPrintSuppressed(t *testing.T) { require.False(t, migrator.shouldPrintStatus(HeuristicPrintStatusRule, snap.elapsedSeconds, etaDuration)) migrator.reportStatus(HeuristicPrintStatusRule, io.Discard) - require.Len(t, spy.names, 6) - assert.Equal(t, []float64{1000, 5000, 0, 0, float64(cap(migrator.applyEventsQueue)), 0}, spy.values) -} - -func TestReportStatusEmitsLagHistogramsWhenNotThrottled(t *testing.T) { - spy := &statusMetricsSpy{} - ctx := base.NewMigrationContext() - ctx.Metrics = spy - atomic.StoreInt64(&ctx.CurrentLag, int64(3*time.Second)) - ctx.SetLastHeartbeatOnChangelogTime(time.Now().Add(-2 * time.Second)) - - migrator := NewMigrator(ctx, "test") - migrator.reportStatus(NoPrintStatusRule, io.Discard) - - require.Len(t, spy.histogramNames, 2) - assert.Equal(t, []string{"lag.replication_seconds", "lag.heartbeat_seconds"}, spy.histogramNames) - assert.InDelta(t, 3.0, spy.histogramValues[0], 0.01) - assert.InDelta(t, 2.0, spy.histogramValues[1], 0.5) - require.Len(t, spy.histogramTags[0], 1) - assert.Equal(t, "throttled:false", spy.histogramTags[0][0]) - assert.Equal(t, "throttled:false", spy.histogramTags[1][0]) + require.Len(t, spy.names, 8) + assert.Equal(t, []float64{1000, 5000, 0, 0, float64(cap(migrator.applyEventsQueue)), 0}, spy.values[:6]) } -func TestReportStatusEmitsLagHistogramsWhenThrottled(t *testing.T) { - spy := &statusMetricsSpy{} +func TestReportStatusEmitsLagGaugesWhenThrottled(t *testing.T) { + spy := &progressGaugeSpy{} ctx := base.NewMigrationContext() ctx.Metrics = spy ctx.SetThrottled(true, "max-lag-millis", base.NoThrottleReasonHint) @@ -549,9 +519,12 @@ func TestReportStatusEmitsLagHistogramsWhenThrottled(t *testing.T) { migrator := NewMigrator(ctx, "test") migrator.reportStatus(NoPrintStatusRule, io.Discard) - require.Len(t, spy.histogramNames, 2) - assert.Equal(t, "throttled:true", spy.histogramTags[0][0]) - assert.Equal(t, "throttled:true", spy.histogramTags[1][0]) + require.GreaterOrEqual(t, len(spy.names), 8) + assert.Equal(t, "lag.replication_seconds", spy.names[6]) + assert.Equal(t, "lag.heartbeat_seconds", spy.names[7]) + require.Len(t, spy.tags[6], 1) + assert.Equal(t, "throttled:true", spy.tags[6][0]) + assert.Equal(t, "throttled:true", spy.tags[7][0]) } func TestMigratorShouldPrintStatus(t *testing.T) { diff --git a/go/metrics/client.go b/go/metrics/client.go index 283f476d1..4600df8e9 100644 --- a/go/metrics/client.go +++ b/go/metrics/client.go @@ -21,17 +21,10 @@ type Client struct { sd *statsd.Client } +// MemStatsGaugeEmitter is implemented by *Client; used for tests without UDP. type MemStatsGaugeEmitter interface { Gauge(name string, value float64, tags ...string) } -type HistogramEmitter interface { - Histogram(name string, value float64, tags ...string) -} - -type Emitter interface { - MemStatsGaugeEmitter - HistogramEmitter -} // NewClient connects to addr for StatsD. If addr is empty, returns Noop and nil error. // namespace is typically "gh_ost." (metrics are named namespace + short name, e.g. gh_ost.startup). @@ -72,13 +65,6 @@ func (c *Client) Count(name string, value int64, tags ...string) { _ = c.sd.Count(name, value, tags, 1.0) } -func (c *Client) Histogram(name string, value float64, tags ...string) { - if c.sd == nil { - return - } - _ = c.sd.Histogram(name, value, tags, 1.0) -} - // Close flushes buffered metrics; safe for Noop. func (c *Client) Close() error { if c.sd == nil { diff --git a/go/metrics/go_runtime_test.go b/go/metrics/go_runtime_test.go index 24811206b..0a8a5d7e2 100644 --- a/go/metrics/go_runtime_test.go +++ b/go/metrics/go_runtime_test.go @@ -15,11 +15,13 @@ import ( type gaugeSpy struct { names []string values []float64 + tags [][]string } -func (g *gaugeSpy) Gauge(name string, value float64, _ ...string) { +func (g *gaugeSpy) Gauge(name string, value float64, tags ...string) { g.names = append(g.names, name) g.values = append(g.values, value) + g.tags = append(g.tags, append([]string(nil), tags...)) } func TestEmitGoRuntimeGauges(t *testing.T) { diff --git a/go/metrics/lag.go b/go/metrics/lag.go index 2683aac54..b6dc6995a 100644 --- a/go/metrics/lag.go +++ b/go/metrics/lag.go @@ -7,13 +7,17 @@ package metrics import "fmt" -// EmitLagHistograms emits replication and heartbeat lag histograms (namespace is applied by the client): +// EmitLagGauges emits replication and heartbeat lag gauges (namespace is applied by the client): // gh_ost.lag.replication_seconds, gh_ost.lag.heartbeat_seconds, each tagged throttled:true|false. -func EmitLagHistograms(emit HistogramEmitter, replicationLagSeconds, heartbeatLagSeconds float64, throttled bool) { +// +// These are point-in-time readings each status tick (not a distribution), so gauges are used +// rather than histograms — DogStatsD histogram aggregation exposes count/max series that do not +// match the log line lag values in Prometheus/Grafana. +func EmitLagGauges(emit MemStatsGaugeEmitter, replicationLagSeconds, heartbeatLagSeconds float64, throttled bool) { if emit == nil { return } tags := []string{fmt.Sprintf("throttled:%t", throttled)} - emit.Histogram("lag.replication_seconds", replicationLagSeconds, tags...) - emit.Histogram("lag.heartbeat_seconds", heartbeatLagSeconds, tags...) + emit.Gauge("lag.replication_seconds", replicationLagSeconds, tags...) + emit.Gauge("lag.heartbeat_seconds", heartbeatLagSeconds, tags...) } diff --git a/go/metrics/lag_test.go b/go/metrics/lag_test.go index 2a0b21418..c330344e3 100644 --- a/go/metrics/lag_test.go +++ b/go/metrics/lag_test.go @@ -7,28 +7,16 @@ package metrics import "testing" -type histogramSpy struct { - names []string - values []float64 - tags [][]string -} - -func (s *histogramSpy) Histogram(name string, value float64, tags ...string) { - s.names = append(s.names, name) - s.values = append(s.values, value) - s.tags = append(s.tags, append([]string(nil), tags...)) -} - -func TestEmitLagHistograms_notThrottled(t *testing.T) { - spy := &histogramSpy{} - EmitLagHistograms(spy, 2.5, 1.25, false) +func TestEmitLagGauges_notThrottled(t *testing.T) { + spy := &gaugeSpy{} + EmitLagGauges(spy, 2.5, 1.25, false) wantNames := []string{"lag.replication_seconds", "lag.heartbeat_seconds"} wantVals := []float64{2.5, 1.25} wantTags := []string{"throttled:false"} - if len(spy.names) != 2 { - t.Fatalf("got %d histograms, want 2", len(spy.names)) + if len(spy.names) != len(wantNames) { + t.Fatalf("got %d gauges, want %d", len(spy.names), len(wantNames)) } for i := range wantNames { if spy.names[i] != wantNames[i] || spy.values[i] != wantVals[i] { @@ -40,12 +28,12 @@ func TestEmitLagHistograms_notThrottled(t *testing.T) { } } -func TestEmitLagHistograms_throttled(t *testing.T) { - spy := &histogramSpy{} - EmitLagHistograms(spy, 4.0, 3.0, true) +func TestEmitLagGauges_throttled(t *testing.T) { + spy := &gaugeSpy{} + EmitLagGauges(spy, 4.0, 3.0, true) if len(spy.names) != 2 { - t.Fatalf("got %d histograms, want 2", len(spy.names)) + t.Fatalf("got %d gauges, want 2", len(spy.names)) } for i := range spy.names { if len(spy.tags[i]) != 1 || spy.tags[i][0] != "throttled:true" { @@ -54,6 +42,6 @@ func TestEmitLagHistograms_throttled(t *testing.T) { } } -func TestEmitLagHistograms_nilSafe(t *testing.T) { - EmitLagHistograms(nil, 1, 2, false) +func TestEmitLagGauges_nilSafe(t *testing.T) { + EmitLagGauges(nil, 1, 2, false) }