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// 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 storage
import (
"sort"
"time"
dto "github.com/prometheus/client_model/go"
)
// MetricStore is the interface to the storage layer for metrics. All its
// methods must be safe to be called concurrently.
type MetricStore interface {
// SubmitWriteRequest submits a WriteRequest for processing. There is no
// guarantee when a request will be processed, but it is guaranteed that
// the requests are processed in the order of submission.
SubmitWriteRequest(req WriteRequest)
// GetMetricFamilies returns all the currently saved MetricFamilies. The
// returned MetricFamilies are guaranteed to not be modified by the
// MetricStore anymore. However, they may still be read somewhere else,
// so the caller is not allowed to modify the returned MetricFamilies.
// If different groups have saved MetricFamilies of the same name, they
// are all merged into one MetricFamily by concatenating the contained
// Metrics. Inconsistent help strings or types are logged, and one of
// the versions will "win". Inconsistent and duplicate label sets will
// go undetected.
GetMetricFamilies() []*dto.MetricFamily
// GetMetricFamiliesMap returns a map grouping-key -> MetricGroup. The
// MetricFamily pointed to by the Metrics map in each MetricGroup is
// guaranteed to not be modified by the MetricStore anymore. However,
// they may still be read somewhere else, so the caller is not allowed
// to modify it. Otherwise, the returned nested map is a deep copy of
// the internal state of the MetricStore and completely owned by the
// caller.
GetMetricFamiliesMap() GroupingKeyToMetricGroup
// Shutdown must only be called after the caller has made sure that
// SubmitWriteRequests is not called anymore. (If it is called later,
// the request might get submitted, but not processed anymore.) The
// Shutdown method waits for the write request queue to empty, then it
// persists the content of the MetricStore (if supported by the
// implementation). Also, all internal goroutines are stopped. This
// method blocks until all of that is complete. If an error is
// encountered, it is returned (whereupon the MetricStorage is in an
// undefinded state). If nil is returned, the MetricStore cannot be
// "restarted" again, but it can still be used for read operations.
Shutdown() error
}
// WriteRequest is a request to change the MetricStore, i.e. to process it, a
// write lock has to be acquired. If MetricFamilies is nil, this is a request to
// delete metrics that share the given Labels as a grouping key. Otherwise, this
// is a request to update the MetricStore with the MetricFamilies. The key in
// MetricFamilies is the name of the mapped metric family. All metrics in
// MetricFamilies MUST have already set job and other labels that are consistent
// with the Labels fields. The Timestamp field marks the time the request was
// received from the network. It is not related to the timestamp_ms field in the
// Metric proto message.
type WriteRequest struct {
Labels map[string]string
Timestamp time.Time
MetricFamilies map[string]*dto.MetricFamily
}
// TimestampedMetricFamily adds the push timestamp to a MetricFamily-DTO.
type TimestampedMetricFamily struct {
Timestamp time.Time
MetricFamily *dto.MetricFamily
}
// GroupingKeyToMetricGroup is the first level of the metric store, keyed by
// grouping key.
type GroupingKeyToMetricGroup map[uint64]MetricGroup
// MetricGroup adds the grouping labels to a NameToTimestampedMetricFamilyMap.
type MetricGroup struct {
Labels map[string]string
Metrics NameToTimestampedMetricFamilyMap
}
// SortedLabels returns the label names of the grouping labels sorted
// lexicographically but with the "job" label always first. This method exists
// for presentation purposes, see template.html.
func (mg MetricGroup) SortedLabels() []string {
lns := make([]string, 1, len(mg.Labels))
lns[0] = "job"
for ln := range mg.Labels {
if ln != "job" {
lns = append(lns, ln)
}
}
sort.Strings(lns[1:])
return lns
}
// NameToTimestampedMetricFamilyMap is the second level of the metric store,
// keyed by metric name.
type NameToTimestampedMetricFamilyMap map[string]TimestampedMetricFamily
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