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Bring back zero-alloc label-value access for metric vecs 

Also, fix mutex copy-by-value bug.
This commit is contained in:
beorn7 2016-08-17 14:01:11 +02:00
parent 1f823ab271
commit 434a8ed85d
7 changed files with 122 additions and 94 deletions
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2
prometheus/counter.go
View File

@ -82,7 +82,7 @@ func (c *counter) Add(v float64) {
// CounterVec embeds MetricVec. See there for a full list of methods with
// detailed documentation.
type CounterVec struct {
MetricVec
*MetricVec
}
// NewCounterVec creates a new CounterVec based on the provided CounterOpts and

2
prometheus/gauge.go
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@ -58,7 +58,7 @@ func NewGauge(opts GaugeOpts) Gauge {
// (e.g. number of operations queued, partitioned by user and operation
// type). Create instances with NewGaugeVec.
type GaugeVec struct {
MetricVec
*MetricVec
}
// NewGaugeVec creates a new GaugeVec based on the provided GaugeOpts and

2
prometheus/histogram.go
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@ -287,7 +287,7 @@ func (h *histogram) Write(out *dto.Metric) error {
// (e.g. HTTP request latencies, partitioned by status code and method). Create
// instances with NewHistogramVec.
type HistogramVec struct {
MetricVec
*MetricVec
}
// NewHistogramVec creates a new HistogramVec based on the provided HistogramOpts and

2
prometheus/summary.go
View File

@ -390,7 +390,7 @@ func (s quantSort) Less(i, j int) bool {
// (e.g. HTTP request latencies, partitioned by status code and method). Create
// instances with NewSummaryVec.
type SummaryVec struct {
MetricVec
*MetricVec
}
// NewSummaryVec creates a new SummaryVec based on the provided SummaryOpts and

2
prometheus/untyped.go
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@ -56,7 +56,7 @@ func NewUntyped(opts UntypedOpts) Untyped {
// labels. This is used if you want to count the same thing partitioned by
// various dimensions. Create instances with NewUntypedVec.
type UntypedVec struct {
MetricVec
*MetricVec
}
// NewUntypedVec creates a new UntypedVec based on the provided UntypedOpts and

202
prometheus/vec.go
View File

@ -37,8 +37,8 @@ type MetricVec struct {
// newMetricVec returns an initialized MetricVec. The concrete value is
// returned for embedding into another struct.
func newMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) MetricVec {
return MetricVec{
func newMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) *MetricVec {
return &MetricVec{
children: map[uint64][]metricWithLabelValues{},
desc: desc,
newMetric: newMetric,
@ -102,7 +102,7 @@ func (m *MetricVec) GetMetricWithLabelValues(lvs ...string) (Metric, error) {
return nil, err
}
return m.getOrCreateMetric(h, lvs), nil
return m.getOrCreateMetricWithLabelValues(h, lvs), nil
}
// GetMetricWith returns the Metric for the given Labels map (the label names
@ -123,7 +123,7 @@ func (m *MetricVec) GetMetricWith(labels Labels) (Metric, error) {
return nil, err
}
return m.getOrCreateMetric(h, labels), nil
return m.getOrCreateMetricWithLabels(h, labels), nil
}
// WithLabelValues works as GetMetricWithLabelValues, but panics if an error
@ -171,7 +171,7 @@ func (m *MetricVec) DeleteLabelValues(lvs ...string) bool {
if err != nil {
return false
}
return m.deleteByHash(h, lvs)
return m.deleteByHashWithLabelValues(h, lvs)
}
// Delete deletes the metric where the variable labels are the same as those
@ -193,21 +193,40 @@ func (m *MetricVec) Delete(labels Labels) bool {
return false
}
return m.deleteByHash(h, labels)
return m.deleteByHashWithLabels(h, labels)
}
// deleteByHash removes the metric from the hash bucket h. If there are
// multiple matches in the bucket, use lvs to select a metric and remove only
// that metric.
//
// lvs MUST be of type Labels or []string or this method will panic.
func (m *MetricVec) deleteByHash(h uint64, lvs interface{}) bool {
// deleteByHashWithLabelValues removes the metric from the hash bucket h. If
// there are multiple matches in the bucket, use lvs to select a metric and
// remove only that metric.
func (m *MetricVec) deleteByHashWithLabelValues(h uint64, lvs []string) bool {
metrics, ok := m.children[h]
if !ok {
return false
}
i := m.findMetric(metrics, lvs)
i := m.findMetricWithLabelValues(metrics, lvs)
if i >= len(metrics) {
return false
}
if len(metrics) > 1 {
m.children[h] = append(metrics[:i], metrics[i+1:]...)
} else {
delete(m.children, h)
}
return true
}
// deleteByHashWithLabels removes the metric from the hash bucket h. If there
// are multiple matches in the bucket, use lvs to select a metric and remove
// only that metric.
func (m *MetricVec) deleteByHashWithLabels(h uint64, labels Labels) bool {
metrics, ok := m.children[h]
if !ok {
return false
}
i := m.findMetricWithLabels(metrics, labels)
if i >= len(metrics) {
return false
}
@ -258,15 +277,13 @@ func (m *MetricVec) hashLabels(labels Labels) (uint64, error) {
return h, nil
}
// getOrCreateMetric retrieves the metric by hash and label value or creates it
// and returns the new one.
//
// lvs MUST be of type Labels or []string or this method will panic.
// getOrCreateMetricWithLabelValues retrieves the metric by hash and label value
// or creates it and returns the new one.
//
// This function holds the mutex.
func (m *MetricVec) getOrCreateMetric(hash uint64, lvs interface{}) Metric {
func (m *MetricVec) getOrCreateMetricWithLabelValues(hash uint64, lvs []string) Metric {
m.mtx.RLock()
metric, ok := m.getMetric(hash, lvs)
metric, ok := m.getMetricWithLabelValues(hash, lvs)
m.mtx.RUnlock()
if ok {
return metric
@ -274,103 +291,114 @@ func (m *MetricVec) getOrCreateMetric(hash uint64, lvs interface{}) Metric {
m.mtx.Lock()
defer m.mtx.Unlock()
metric, ok = m.getMetric(hash, lvs)
metric, ok = m.getMetricWithLabelValues(hash, lvs)
if !ok {
lvs := m.copyLabelValues(lvs)
// Copy to avoid allocation in case wo don't go down this code path.
copiedLVs := make([]string, len(lvs))
copy(copiedLVs, lvs)
metric = m.newMetric(copiedLVs...)
m.children[hash] = append(m.children[hash], metricWithLabelValues{values: copiedLVs, metric: metric})
}
return metric
}
// getOrCreateMetricWithLabelValues retrieves the metric by hash and label value
// or creates it and returns the new one.
//
// This function holds the mutex.
func (m *MetricVec) getOrCreateMetricWithLabels(hash uint64, labels Labels) Metric {
m.mtx.RLock()
metric, ok := m.getMetricWithLabels(hash, labels)
m.mtx.RUnlock()
if ok {
return metric
}
m.mtx.Lock()
defer m.mtx.Unlock()
metric, ok = m.getMetricWithLabels(hash, labels)
if !ok {
lvs := m.extractLabelValues(labels)
metric = m.newMetric(lvs...)
m.children[hash] = append(m.children[hash], metricWithLabelValues{values: lvs, metric: metric})
}
return metric
}
// getMetric while handling possible collisions in the hash space. Must be
// called while holding read mutex.
//
// lvs must be of type Labels or []string.
func (m *MetricVec) getMetric(h uint64, lvs interface{}) (Metric, bool) {
// getMetricWithLabelValues gets a metric while handling possible collisions in
// the hash space. Must be called while holding read mutex.
func (m *MetricVec) getMetricWithLabelValues(h uint64, lvs []string) (Metric, bool) {
metrics, ok := m.children[h]
if ok {
return m.selectMetric(metrics, lvs)
if i := m.findMetricWithLabelValues(metrics, lvs); i < len(metrics) {
return metrics[i].metric, true
}
}
return nil, false
}
func (m *MetricVec) selectMetric(metrics []metricWithLabelValues, lvs interface{}) (Metric, bool) {
i := m.findMetric(metrics, lvs)
if i < len(metrics) {
return metrics[i].metric, true
// getMetricWithLabels gets a metric while handling possible collisions in
// the hash space. Must be called while holding read mutex.
func (m *MetricVec) getMetricWithLabels(h uint64, labels Labels) (Metric, bool) {
metrics, ok := m.children[h]
if ok {
if i := m.findMetricWithLabels(metrics, labels); i < len(metrics) {
return metrics[i].metric, true
}
}
return nil, false
}
// findMetric returns the index of the matching metric or len(metrics) if not
// found.
func (m *MetricVec) findMetric(metrics []metricWithLabelValues, lvs interface{}) int {
// findMetricWithLabelValues returns the index of the matching metric or
// len(metrics) if not found.
func (m *MetricVec) findMetricWithLabelValues(metrics []metricWithLabelValues, lvs []string) int {
for i, metric := range metrics {
if m.matchLabels(metric.values, lvs) {
if m.matchLabelValues(metric.values, lvs) {
return i
}
}
return len(metrics)
}
func (m *MetricVec) matchLabels(values []string, lvs interface{}) bool {
switch lvs := lvs.(type) {
case []string:
if len(values) != len(lvs) {
return false
// findMetricWithLabels returns the index of the matching metric or len(metrics)
// if not found.
func (m *MetricVec) findMetricWithLabels(metrics []metricWithLabelValues, labels Labels) int {
for i, metric := range metrics {
if m.matchLabels(metric.values, labels) {
return i
}
for i, v := range values {
if v != lvs[i] {
return false
}
}
return true
case Labels:
if len(lvs) != len(values) {
return false
}
for i, k := range m.desc.variableLabels {
if values[i] != lvs[k] {
return false
}
}
return true
default:
// If we reach this condition, there is an unexpected type being used
// as a labels value. Either add branch here for the new type or fix
// the bug causing the type to be passed in.
panic("unsupported type")
}
return len(metrics)
}
// copyLabelValues copies the labels values into common string slice format to
// use when allocating the metric and to keep track of hash collision
// ambiguity.
//
// lvs must be of type Labels or []string or this method will panic.
func (m *MetricVec) copyLabelValues(lvs interface{}) []string {
var labelValues []string
switch lvs := lvs.(type) {
case []string:
labelValues = make([]string, len(lvs))
copy(labelValues, lvs)
case Labels:
labelValues = make([]string, len(lvs))
for i, k := range m.desc.variableLabels {
labelValues[i] = lvs[k]
}
default:
panic(fmt.Sprintf("unsupported type for lvs: %#v", lvs))
func (m *MetricVec) matchLabelValues(values []string, lvs []string) bool {
if len(values) != len(lvs) {
return false
}
for i, v := range values {
if v != lvs[i] {
return false
}
}
return true
}
func (m *MetricVec) matchLabels(values []string, labels Labels) bool {
if len(labels) != len(values) {
return false
}
for i, k := range m.desc.variableLabels {
if values[i] != labels[k] {
return false
}
}
return true
}
func (m *MetricVec) extractLabelValues(labels Labels) []string {
labelValues := make([]string, len(labels))
for i, k := range m.desc.variableLabels {
labelValues[i] = labels[k]
}
return labelValues
}

4
prometheus/vec_test.go
View File

@ -225,7 +225,7 @@ func TestCounterVecEndToEndWithCollision(t *testing.T) {
t.Errorf("got label value %q, want %q", got, want)
}
if got, want := m.GetCounter().GetValue(), 1.; got != want {
t.Errorf("got value %d, want %d", got, want)
t.Errorf("got value %f, want %f", got, want)
}
m.Reset()
if err := vec.WithLabelValues("!0IC=VloaY").Write(m); err != nil {
@ -235,7 +235,7 @@ func TestCounterVecEndToEndWithCollision(t *testing.T) {
t.Errorf("got label value %q, want %q", got, want)
}
if got, want := m.GetCounter().GetValue(), 2.; got != want {
t.Errorf("got value %d, want %d", got, want)
t.Errorf("got value %f, want %f", got, want)
}
}