| // 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 ( |
| "fmt" |
| "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 the children. |
| children map[uint64]Metric |
| desc *Desc |
| |
| 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) { |
| h, err := m.hashLabelValues(lvs) |
| if err != nil { |
| return nil, err |
| } |
| |
| m.mtx.RLock() |
| metric, ok := m.children[h] |
| m.mtx.RUnlock() |
| if ok { |
| return metric, nil |
| } |
| |
| m.mtx.Lock() |
| defer m.mtx.Unlock() |
| 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) { |
| h, err := m.hashLabels(labels) |
| if err != nil { |
| return nil, err |
| } |
| |
| m.mtx.RLock() |
| metric, ok := m.children[h] |
| m.mtx.RUnlock() |
| if ok { |
| return metric, nil |
| } |
| |
| lvs := make([]string, len(labels)) |
| for i, label := range m.desc.variableLabels { |
| lvs[i] = labels[label] |
| } |
| m.mtx.Lock() |
| defer m.mtx.Unlock() |
| 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 _, ok := m.children[h]; !ok { |
| 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 _, ok := m.children[h]; !ok { |
| 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 |
| } |
| h := hashNew() |
| for _, val := range vals { |
| h = hashAdd(h, val) |
| } |
| return h, nil |
| } |
| |
| func (m *MetricVec) hashLabels(labels Labels) (uint64, error) { |
| if len(labels) != len(m.desc.variableLabels) { |
| return 0, errInconsistentCardinality |
| } |
| h := hashNew() |
| for _, label := range m.desc.variableLabels { |
| val, ok := labels[label] |
| if !ok { |
| return 0, fmt.Errorf("label name %q missing in label map", label) |
| } |
| h = hashAdd(h, val) |
| } |
| return h, 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 |
| } |