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Diffstat (limited to 'kube2msb/src/vendor/github.com/prometheus/client_golang/prometheus/vec.go')
-rw-r--r-- | kube2msb/src/vendor/github.com/prometheus/client_golang/prometheus/vec.go | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/kube2msb/src/vendor/github.com/prometheus/client_golang/prometheus/vec.go b/kube2msb/src/vendor/github.com/prometheus/client_golang/prometheus/vec.go new file mode 100644 index 0000000..a1f3bdf --- /dev/null +++ b/kube2msb/src/vendor/github.com/prometheus/client_golang/prometheus/vec.go @@ -0,0 +1,247 @@ +// Copyright 2014 The Prometheus Authors +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package prometheus + +import ( + "bytes" + "fmt" + "hash" + "sync" +) + +// MetricVec is a Collector to bundle metrics of the same name that +// differ in their label values. MetricVec is usually not used directly but as a +// building block for implementations of vectors of a given metric +// type. GaugeVec, CounterVec, SummaryVec, and UntypedVec are examples already +// provided in this package. +type MetricVec struct { + mtx sync.RWMutex // Protects not only children, but also hash and buf. + children map[uint64]Metric + desc *Desc + + // hash is our own hash instance to avoid repeated allocations. + hash hash.Hash64 + // buf is used to copy string contents into it for hashing, + // again to avoid allocations. + buf bytes.Buffer + + newMetric func(labelValues ...string) Metric +} + +// Describe implements Collector. The length of the returned slice +// is always one. +func (m *MetricVec) Describe(ch chan<- *Desc) { + ch <- m.desc +} + +// Collect implements Collector. +func (m *MetricVec) Collect(ch chan<- Metric) { + m.mtx.RLock() + defer m.mtx.RUnlock() + + for _, metric := range m.children { + ch <- metric + } +} + +// GetMetricWithLabelValues returns the Metric for the given slice of label +// values (same order as the VariableLabels in Desc). If that combination of +// label values is accessed for the first time, a new Metric is created. +// +// It is possible to call this method without using the returned Metric to only +// create the new Metric but leave it at its start value (e.g. a Summary or +// Histogram without any observations). See also the SummaryVec example. +// +// Keeping the Metric for later use is possible (and should be considered if +// performance is critical), but keep in mind that Reset, DeleteLabelValues and +// Delete can be used to delete the Metric from the MetricVec. In that case, the +// Metric will still exist, but it will not be exported anymore, even if a +// Metric with the same label values is created later. See also the CounterVec +// example. +// +// An error is returned if the number of label values is not the same as the +// number of VariableLabels in Desc. +// +// Note that for more than one label value, this method is prone to mistakes +// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as +// an alternative to avoid that type of mistake. For higher label numbers, the +// latter has a much more readable (albeit more verbose) syntax, but it comes +// with a performance overhead (for creating and processing the Labels map). +// See also the GaugeVec example. +func (m *MetricVec) GetMetricWithLabelValues(lvs ...string) (Metric, error) { + m.mtx.Lock() + defer m.mtx.Unlock() + + h, err := m.hashLabelValues(lvs) + if err != nil { + return nil, err + } + return m.getOrCreateMetric(h, lvs...), nil +} + +// GetMetricWith returns the Metric for the given Labels map (the label names +// must match those of the VariableLabels in Desc). If that label map is +// accessed for the first time, a new Metric is created. Implications of +// creating a Metric without using it and keeping the Metric for later use are +// the same as for GetMetricWithLabelValues. +// +// An error is returned if the number and names of the Labels are inconsistent +// with those of the VariableLabels in Desc. +// +// This method is used for the same purpose as +// GetMetricWithLabelValues(...string). See there for pros and cons of the two +// methods. +func (m *MetricVec) GetMetricWith(labels Labels) (Metric, error) { + m.mtx.Lock() + defer m.mtx.Unlock() + + h, err := m.hashLabels(labels) + if err != nil { + return nil, err + } + lvs := make([]string, len(labels)) + for i, label := range m.desc.variableLabels { + lvs[i] = labels[label] + } + return m.getOrCreateMetric(h, lvs...), nil +} + +// WithLabelValues works as GetMetricWithLabelValues, but panics if an error +// occurs. The method allows neat syntax like: +// httpReqs.WithLabelValues("404", "POST").Inc() +func (m *MetricVec) WithLabelValues(lvs ...string) Metric { + metric, err := m.GetMetricWithLabelValues(lvs...) + if err != nil { + panic(err) + } + return metric +} + +// With works as GetMetricWith, but panics if an error occurs. The method allows +// neat syntax like: +// httpReqs.With(Labels{"status":"404", "method":"POST"}).Inc() +func (m *MetricVec) With(labels Labels) Metric { + metric, err := m.GetMetricWith(labels) + if err != nil { + panic(err) + } + return metric +} + +// DeleteLabelValues removes the metric where the variable labels are the same +// as those passed in as labels (same order as the VariableLabels in Desc). It +// returns true if a metric was deleted. +// +// It is not an error if the number of label values is not the same as the +// number of VariableLabels in Desc. However, such inconsistent label count can +// never match an actual Metric, so the method will always return false in that +// case. +// +// Note that for more than one label value, this method is prone to mistakes +// caused by an incorrect order of arguments. Consider Delete(Labels) as an +// alternative to avoid that type of mistake. For higher label numbers, the +// latter has a much more readable (albeit more verbose) syntax, but it comes +// with a performance overhead (for creating and processing the Labels map). +// See also the CounterVec example. +func (m *MetricVec) DeleteLabelValues(lvs ...string) bool { + m.mtx.Lock() + defer m.mtx.Unlock() + + h, err := m.hashLabelValues(lvs) + if err != nil { + return false + } + if _, has := m.children[h]; !has { + return false + } + delete(m.children, h) + return true +} + +// Delete deletes the metric where the variable labels are the same as those +// passed in as labels. It returns true if a metric was deleted. +// +// It is not an error if the number and names of the Labels are inconsistent +// with those of the VariableLabels in the Desc of the MetricVec. However, such +// inconsistent Labels can never match an actual Metric, so the method will +// always return false in that case. +// +// This method is used for the same purpose as DeleteLabelValues(...string). See +// there for pros and cons of the two methods. +func (m *MetricVec) Delete(labels Labels) bool { + m.mtx.Lock() + defer m.mtx.Unlock() + + h, err := m.hashLabels(labels) + if err != nil { + return false + } + if _, has := m.children[h]; !has { + return false + } + delete(m.children, h) + return true +} + +// Reset deletes all metrics in this vector. +func (m *MetricVec) Reset() { + m.mtx.Lock() + defer m.mtx.Unlock() + + for h := range m.children { + delete(m.children, h) + } +} + +func (m *MetricVec) hashLabelValues(vals []string) (uint64, error) { + if len(vals) != len(m.desc.variableLabels) { + return 0, errInconsistentCardinality + } + m.hash.Reset() + for _, val := range vals { + m.buf.Reset() + m.buf.WriteString(val) + m.hash.Write(m.buf.Bytes()) + } + return m.hash.Sum64(), nil +} + +func (m *MetricVec) hashLabels(labels Labels) (uint64, error) { + if len(labels) != len(m.desc.variableLabels) { + return 0, errInconsistentCardinality + } + m.hash.Reset() + for _, label := range m.desc.variableLabels { + val, ok := labels[label] + if !ok { + return 0, fmt.Errorf("label name %q missing in label map", label) + } + m.buf.Reset() + m.buf.WriteString(val) + m.hash.Write(m.buf.Bytes()) + } + return m.hash.Sum64(), nil +} + +func (m *MetricVec) getOrCreateMetric(hash uint64, labelValues ...string) Metric { + metric, ok := m.children[hash] + if !ok { + // Copy labelValues. Otherwise, they would be allocated even if we don't go + // down this code path. + copiedLabelValues := append(make([]string, 0, len(labelValues)), labelValues...) + metric = m.newMetric(copiedLabelValues...) + m.children[hash] = metric + } + return metric +} |