diff options
Diffstat (limited to 'src/kube2msb/vendor/github.com/prometheus/client_golang/prometheus/desc.go')
-rw-r--r-- | src/kube2msb/vendor/github.com/prometheus/client_golang/prometheus/desc.go | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/src/kube2msb/vendor/github.com/prometheus/client_golang/prometheus/desc.go b/src/kube2msb/vendor/github.com/prometheus/client_golang/prometheus/desc.go new file mode 100644 index 0000000..fcde784 --- /dev/null +++ b/src/kube2msb/vendor/github.com/prometheus/client_golang/prometheus/desc.go @@ -0,0 +1,201 @@ +package prometheus + +import ( + "bytes" + "errors" + "fmt" + "hash/fnv" + "regexp" + "sort" + "strings" + + "github.com/golang/protobuf/proto" + + dto "github.com/prometheus/client_model/go" +) + +var ( + metricNameRE = regexp.MustCompile(`^[a-zA-Z_][a-zA-Z0-9_:]*$`) + labelNameRE = regexp.MustCompile("^[a-zA-Z_][a-zA-Z0-9_]*$") +) + +// 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 occured 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 !metricNameRE.MatchString(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 + } + h := fnv.New64a() + var b bytes.Buffer // To copy string contents into, avoiding []byte allocations. + for _, val := range labelValues { + b.Reset() + b.WriteString(val) + b.WriteByte(separatorByte) + h.Write(b.Bytes()) + } + d.id = h.Sum64() + // 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. + h.Reset() + b.Reset() + b.WriteString(help) + b.WriteByte(separatorByte) + h.Write(b.Bytes()) + for _, labelName := range labelNames { + b.Reset() + b.WriteString(labelName) + b.WriteByte(separatorByte) + h.Write(b.Bytes()) + } + d.dimHash = h.Sum64() + + 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 labelNameRE.MatchString(l) && + !strings.HasPrefix(l, reservedLabelPrefix) +} |