aboutsummaryrefslogtreecommitdiff
path: root/vendor/github.com/prometheus/client_golang/prometheus/desc.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/github.com/prometheus/client_golang/prometheus/desc.go')
-rw-r--r--vendor/github.com/prometheus/client_golang/prometheus/desc.go200
1 files changed, 200 insertions, 0 deletions
diff --git a/vendor/github.com/prometheus/client_golang/prometheus/desc.go b/vendor/github.com/prometheus/client_golang/prometheus/desc.go
new file mode 100644
index 0000000..1835b16
--- /dev/null
+++ b/vendor/github.com/prometheus/client_golang/prometheus/desc.go
@@ -0,0 +1,200 @@
+// Copyright 2016 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 (
+ "errors"
+ "fmt"
+ "sort"
+ "strings"
+
+ "github.com/golang/protobuf/proto"
+ "github.com/prometheus/common/model"
+
+ dto "github.com/prometheus/client_model/go"
+)
+
+// reservedLabelPrefix is a prefix which is not legal in user-supplied
+// label names.
+const reservedLabelPrefix = "__"
+
+// Labels represents a collection of label name -> value mappings. This type is
+// commonly used with the With(Labels) and GetMetricWith(Labels) methods of
+// metric vector Collectors, e.g.:
+// myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
+//
+// The other use-case is the specification of constant label pairs in Opts or to
+// create a Desc.
+type Labels map[string]string
+
+// Desc is the descriptor used by every Prometheus Metric. It is essentially
+// the immutable meta-data of a Metric. The normal Metric implementations
+// included in this package manage their Desc under the hood. Users only have to
+// deal with Desc if they use advanced features like the ExpvarCollector or
+// custom Collectors and Metrics.
+//
+// Descriptors registered with the same registry have to fulfill certain
+// consistency and uniqueness criteria if they share the same fully-qualified
+// name: They must have the same help string and the same label names (aka label
+// dimensions) in each, constLabels and variableLabels, but they must differ in
+// the values of the constLabels.
+//
+// Descriptors that share the same fully-qualified names and the same label
+// values of their constLabels are considered equal.
+//
+// Use NewDesc to create new Desc instances.
+type Desc struct {
+ // fqName has been built from Namespace, Subsystem, and Name.
+ fqName string
+ // help provides some helpful information about this metric.
+ help string
+ // constLabelPairs contains precalculated DTO label pairs based on
+ // the constant labels.
+ constLabelPairs []*dto.LabelPair
+ // VariableLabels contains names of labels for which the metric
+ // maintains variable values.
+ variableLabels []string
+ // id is a hash of the values of the ConstLabels and fqName. This
+ // must be unique among all registered descriptors and can therefore be
+ // used as an identifier of the descriptor.
+ id uint64
+ // dimHash is a hash of the label names (preset and variable) and the
+ // Help string. Each Desc with the same fqName must have the same
+ // dimHash.
+ dimHash uint64
+ // err is an error that occurred during construction. It is reported on
+ // registration time.
+ err error
+}
+
+// NewDesc allocates and initializes a new Desc. Errors are recorded in the Desc
+// and will be reported on registration time. variableLabels and constLabels can
+// be nil if no such labels should be set. fqName and help must not be empty.
+//
+// variableLabels only contain the label names. Their label values are variable
+// and therefore not part of the Desc. (They are managed within the Metric.)
+//
+// For constLabels, the label values are constant. Therefore, they are fully
+// specified in the Desc. See the Opts documentation for the implications of
+// constant labels.
+func NewDesc(fqName, help string, variableLabels []string, constLabels Labels) *Desc {
+ d := &Desc{
+ fqName: fqName,
+ help: help,
+ variableLabels: variableLabels,
+ }
+ if help == "" {
+ d.err = errors.New("empty help string")
+ return d
+ }
+ if !model.IsValidMetricName(model.LabelValue(fqName)) {
+ d.err = fmt.Errorf("%q is not a valid metric name", fqName)
+ return d
+ }
+ // labelValues contains the label values of const labels (in order of
+ // their sorted label names) plus the fqName (at position 0).
+ labelValues := make([]string, 1, len(constLabels)+1)
+ labelValues[0] = fqName
+ labelNames := make([]string, 0, len(constLabels)+len(variableLabels))
+ labelNameSet := map[string]struct{}{}
+ // First add only the const label names and sort them...
+ for labelName := range constLabels {
+ if !checkLabelName(labelName) {
+ d.err = fmt.Errorf("%q is not a valid label name", labelName)
+ return d
+ }
+ labelNames = append(labelNames, labelName)
+ labelNameSet[labelName] = struct{}{}
+ }
+ sort.Strings(labelNames)
+ // ... so that we can now add const label values in the order of their names.
+ for _, labelName := range labelNames {
+ labelValues = append(labelValues, constLabels[labelName])
+ }
+ // Now add the variable label names, but prefix them with something that
+ // cannot be in a regular label name. That prevents matching the label
+ // dimension with a different mix between preset and variable labels.
+ for _, labelName := range variableLabels {
+ if !checkLabelName(labelName) {
+ d.err = fmt.Errorf("%q is not a valid label name", labelName)
+ return d
+ }
+ labelNames = append(labelNames, "$"+labelName)
+ labelNameSet[labelName] = struct{}{}
+ }
+ if len(labelNames) != len(labelNameSet) {
+ d.err = errors.New("duplicate label names")
+ return d
+ }
+ vh := hashNew()
+ for _, val := range labelValues {
+ vh = hashAdd(vh, val)
+ vh = hashAddByte(vh, separatorByte)
+ }
+ d.id = vh
+ // Sort labelNames so that order doesn't matter for the hash.
+ sort.Strings(labelNames)
+ // Now hash together (in this order) the help string and the sorted
+ // label names.
+ lh := hashNew()
+ lh = hashAdd(lh, help)
+ lh = hashAddByte(lh, separatorByte)
+ for _, labelName := range labelNames {
+ lh = hashAdd(lh, labelName)
+ lh = hashAddByte(lh, separatorByte)
+ }
+ d.dimHash = lh
+
+ d.constLabelPairs = make([]*dto.LabelPair, 0, len(constLabels))
+ for n, v := range constLabels {
+ d.constLabelPairs = append(d.constLabelPairs, &dto.LabelPair{
+ Name: proto.String(n),
+ Value: proto.String(v),
+ })
+ }
+ sort.Sort(LabelPairSorter(d.constLabelPairs))
+ return d
+}
+
+// NewInvalidDesc returns an invalid descriptor, i.e. a descriptor with the
+// provided error set. If a collector returning such a descriptor is registered,
+// registration will fail with the provided error. NewInvalidDesc can be used by
+// a Collector to signal inability to describe itself.
+func NewInvalidDesc(err error) *Desc {
+ return &Desc{
+ err: err,
+ }
+}
+
+func (d *Desc) String() string {
+ lpStrings := make([]string, 0, len(d.constLabelPairs))
+ for _, lp := range d.constLabelPairs {
+ lpStrings = append(
+ lpStrings,
+ fmt.Sprintf("%s=%q", lp.GetName(), lp.GetValue()),
+ )
+ }
+ return fmt.Sprintf(
+ "Desc{fqName: %q, help: %q, constLabels: {%s}, variableLabels: %v}",
+ d.fqName,
+ d.help,
+ strings.Join(lpStrings, ","),
+ d.variableLabels,
+ )
+}
+
+func checkLabelName(l string) bool {
+ return model.LabelName(l).IsValid() &&
+ !strings.HasPrefix(l, reservedLabelPrefix)
+}