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Merge pull request #417 from prometheus/beorn7/registry 

Relax consistency checks during gathering
This commit is contained in:
Björn Rabenstein 2018-06-07 14:36:07 +02:00 committed by GitHub
parent 208fa994be f6b1978ed4
commit faf4ec335f
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 29 additions and 41 deletions
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7
prometheus/examples_test.go
View File

@ -712,7 +712,7 @@ humidity_percent{location="inside"} 33.2
# HELP temperature_kelvin Temperature in Kelvin.
# Duplicate metric:
temperature_kelvin{location="outside"} 265.3
# Wrong labels:
# Missing location label (note that this is undesirable but valid):
temperature_kelvin 4.5
`
@ -740,15 +740,14 @@ temperature_kelvin 4.5
// temperature_kelvin{location="outside"} 273.14
// temperature_kelvin{location="somewhere else"} 4.5
// ----------
// 2 error(s) occurred:
// * collected metric temperature_kelvin label:<name:"location" value:"outside" > gauge:<value:265.3 > was collected before with the same name and label values
// * collected metric temperature_kelvin gauge:<value:4.5 > has label dimensions inconsistent with previously collected metrics in the same metric family
// collected metric temperature_kelvin label:<name:"location" value:"outside" > gauge:<value:265.3 > was collected before with the same name and label values
// # HELP humidity_percent Humidity in %.
// # TYPE humidity_percent gauge
// humidity_percent{location="inside"} 33.2
// humidity_percent{location="outside"} 45.4
// # HELP temperature_kelvin Temperature in Kelvin.
// # TYPE temperature_kelvin gauge
// temperature_kelvin 4.5
// temperature_kelvin{location="inside"} 298.44
// temperature_kelvin{location="outside"} 273.14
}

63
prometheus/registry.go
View File

@ -126,15 +126,23 @@ type Registerer interface {
type Gatherer interface {
// Gather calls the Collect method of the registered Collectors and then
// gathers the collected metrics into a lexicographically sorted slice
// of MetricFamily protobufs. Even if an error occurs, Gather attempts
// to gather as many metrics as possible. Hence, if a non-nil error is
// returned, the returned MetricFamily slice could be nil (in case of a
// fatal error that prevented any meaningful metric collection) or
// contain a number of MetricFamily protobufs, some of which might be
// incomplete, and some might be missing altogether. The returned error
// (which might be a MultiError) explains the details. In scenarios
// where complete collection is critical, the returned MetricFamily
// protobufs should be disregarded if the returned error is non-nil.
// of uniquely named MetricFamily protobufs. Gather ensures that the
// returned slice is valid and self-consistent so that it can be used
// for valid exposition. As an exception to the strict consistency
// requirements described for metric.Desc, Gather will tolerate
// different sets of label names for metrics of the same metric family.
//
// Even if an error occurs, Gather attempts to gather as many metrics as
// possible. Hence, if a non-nil error is returned, the returned
// MetricFamily slice could be nil (in case of a fatal error that
// prevented any meaningful metric collection) or contain a number of
// MetricFamily protobufs, some of which might be incomplete, and some
// might be missing altogether. The returned error (which might be a
// MultiError) explains the details. Note that this is mostly useful for
// debugging purposes. If the gathered protobufs are to be used for
// exposition in actual monitoring, it is almost always better to not
// expose an incomplete result and instead disregard the returned
// MetricFamily protobufs in case the returned error is non-nil.
Gather() ([]*dto.MetricFamily, error)
}
@ -370,7 +378,6 @@ func (r *Registry) Gather() ([]*dto.MetricFamily, error) {
var (
metricChan = make(chan Metric, capMetricChan)
metricHashes = map[uint64]struct{}{}
dimHashes = map[string]uint64{}
wg sync.WaitGroup
errs MultiError // The collected errors to return in the end.
registeredDescIDs map[uint64]struct{} // Only used for pedantic checks
@ -433,7 +440,7 @@ collectLoop:
}
errs.Append(processMetric(
metric, metricFamiliesByName,
metricHashes, dimHashes,
metricHashes,
registeredDescIDs,
))
default:
@ -445,7 +452,7 @@ collectLoop:
for metric := range metricChan {
errs.Append(processMetric(
metric, metricFamiliesByName,
metricHashes, dimHashes,
metricHashes,
registeredDescIDs,
))
}
@ -465,7 +472,6 @@ func processMetric(
metric Metric,
metricFamiliesByName map[string]*dto.MetricFamily,
metricHashes map[uint64]struct{},
dimHashes map[string]uint64,
registeredDescIDs map[uint64]struct{},
) error {
desc := metric.Desc()
@ -542,7 +548,7 @@ func processMetric(
}
metricFamiliesByName[desc.fqName] = metricFamily
}
if err := checkMetricConsistency(metricFamily, dtoMetric, metricHashes, dimHashes); err != nil {
if err := checkMetricConsistency(metricFamily, dtoMetric, metricHashes); err != nil {
return err
}
if registeredDescIDs != nil {
@ -584,7 +590,6 @@ func (gs Gatherers) Gather() ([]*dto.MetricFamily, error) {
var (
metricFamiliesByName = map[string]*dto.MetricFamily{}
metricHashes = map[uint64]struct{}{}
dimHashes = map[string]uint64{}
errs MultiError // The collected errors to return in the end.
)
@ -624,7 +629,7 @@ func (gs Gatherers) Gather() ([]*dto.MetricFamily, error) {
metricFamiliesByName[mf.GetName()] = existingMF
}
for _, m := range mf.Metric {
if err := checkMetricConsistency(existingMF, m, metricHashes, dimHashes); err != nil {
if err := checkMetricConsistency(existingMF, m, metricHashes); err != nil {
errs = append(errs, err)
continue
}
@ -701,18 +706,13 @@ func normalizeMetricFamilies(metricFamiliesByName map[string]*dto.MetricFamily)
}
// checkMetricConsistency checks if the provided Metric is consistent with the
// provided MetricFamily. It also hashed the Metric labels and the MetricFamily
// provided MetricFamily. It also hashes the Metric labels and the MetricFamily
// name. If the resulting hash is already in the provided metricHashes, an error
// is returned. If not, it is added to metricHashes. The provided dimHashes maps
// MetricFamily names to their dimHash (hashed sorted label names). If dimHashes
// doesn't yet contain a hash for the provided MetricFamily, it is
// added. Otherwise, an error is returned if the existing dimHashes in not equal
// the calculated dimHash.
// is returned. If not, it is added to metricHashes.
func checkMetricConsistency(
metricFamily *dto.MetricFamily,
dtoMetric *dto.Metric,
metricHashes map[uint64]struct{},
dimHashes map[string]uint64,
) error {
// Type consistency with metric family.
if metricFamily.GetType() == dto.MetricType_GAUGE && dtoMetric.Gauge == nil ||
@ -732,19 +732,18 @@ func checkMetricConsistency(
}
}
// Is the metric unique (i.e. no other metric with the same name and the same label values)?
// Is the metric unique (i.e. no other metric with the same name and the same labels)?
h := hashNew()
h = hashAdd(h, metricFamily.GetName())
h = hashAddByte(h, separatorByte)
dh := hashNew()
// Make sure label pairs are sorted. We depend on it for the consistency
// check.
sort.Sort(LabelPairSorter(dtoMetric.Label))
for _, lp := range dtoMetric.Label {
h = hashAdd(h, lp.GetName())
h = hashAddByte(h, separatorByte)
h = hashAdd(h, lp.GetValue())
h = hashAddByte(h, separatorByte)
dh = hashAdd(dh, lp.GetName())
dh = hashAddByte(dh, separatorByte)
}
if _, exists := metricHashes[h]; exists {
return fmt.Errorf(
@ -752,16 +751,6 @@ func checkMetricConsistency(
metricFamily.GetName(), dtoMetric,
)
}
if dimHash, ok := dimHashes[metricFamily.GetName()]; ok {
if dimHash != dh {
return fmt.Errorf(
"collected metric %s %s has label dimensions inconsistent with previously collected metrics in the same metric family",
metricFamily.GetName(), dtoMetric,
)
}
} else {
dimHashes[metricFamily.GetName()] = dh
}
metricHashes[h] = struct{}{}
return nil
}