mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-26 22:19:40 -08:00
110 lines
4 KiB
Go
110 lines
4 KiB
Go
// Copyright 2017 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 (
|
|
"context"
|
|
"sync"
|
|
|
|
"github.com/prometheus/prometheus/model/labels"
|
|
"github.com/prometheus/prometheus/util/annotations"
|
|
)
|
|
|
|
// secondaryQuerier is a wrapper that allows a querier to be treated in a best effort manner.
|
|
// This means that an error on any method returned by Querier except Close will be returned as a warning,
|
|
// and the result will be empty.
|
|
//
|
|
// Additionally, Querier ensures that if ANY SeriesSet returned by this querier's Select failed on an initial Next,
|
|
// All other SeriesSet will be return no response as well. This ensures consistent partial response strategy, where you
|
|
// have either full results or none from each secondary Querier.
|
|
// NOTE: This works well only for implementations that only fail during first Next() (e.g fetch from network). If implementation fails
|
|
// during further iterations, set will panic. If Select is invoked after first Next of any returned SeriesSet, querier will panic.
|
|
//
|
|
// Not go-routine safe.
|
|
// NOTE: Prometheus treats all remote storages as secondary / best effort.
|
|
type secondaryQuerier struct {
|
|
genericQuerier
|
|
|
|
once sync.Once
|
|
done bool
|
|
asyncSets []genericSeriesSet
|
|
}
|
|
|
|
func newSecondaryQuerierFrom(q Querier) genericQuerier {
|
|
return &secondaryQuerier{genericQuerier: newGenericQuerierFrom(q)}
|
|
}
|
|
|
|
func newSecondaryQuerierFromChunk(cq ChunkQuerier) genericQuerier {
|
|
return &secondaryQuerier{genericQuerier: newGenericQuerierFromChunk(cq)}
|
|
}
|
|
|
|
func (s *secondaryQuerier) LabelValues(ctx context.Context, name string, hints *LabelHints, matchers ...*labels.Matcher) ([]string, annotations.Annotations, error) {
|
|
vals, w, err := s.genericQuerier.LabelValues(ctx, name, hints, matchers...)
|
|
if err != nil {
|
|
return nil, w.Add(err), nil
|
|
}
|
|
return vals, w, nil
|
|
}
|
|
|
|
func (s *secondaryQuerier) LabelNames(ctx context.Context, hints *LabelHints, matchers ...*labels.Matcher) ([]string, annotations.Annotations, error) {
|
|
names, w, err := s.genericQuerier.LabelNames(ctx, hints, matchers...)
|
|
if err != nil {
|
|
return nil, w.Add(err), nil
|
|
}
|
|
return names, w, nil
|
|
}
|
|
|
|
func (s *secondaryQuerier) Select(ctx context.Context, sortSeries bool, hints *SelectHints, matchers ...*labels.Matcher) genericSeriesSet {
|
|
if s.done {
|
|
panic("secondaryQuerier: Select invoked after first Next of any returned SeriesSet was done")
|
|
}
|
|
|
|
s.asyncSets = append(s.asyncSets, s.genericQuerier.Select(ctx, sortSeries, hints, matchers...))
|
|
curr := len(s.asyncSets) - 1
|
|
return &lazyGenericSeriesSet{init: func() (genericSeriesSet, bool) {
|
|
s.once.Do(func() {
|
|
// At first init invocation we iterate over all async sets and ensure its Next() returns some value without
|
|
// errors. This is to ensure we support consistent partial failures.
|
|
for i, set := range s.asyncSets {
|
|
if set.Next() {
|
|
continue
|
|
}
|
|
ws := set.Warnings()
|
|
if err := set.Err(); err != nil {
|
|
// One of the sets failed, ensure current one returning errors as warnings, and rest of the sets return nothing.
|
|
// (All or nothing logic).
|
|
s.asyncSets[curr] = warningsOnlySeriesSet(ws.Add(err))
|
|
for i := range s.asyncSets {
|
|
if curr == i {
|
|
continue
|
|
}
|
|
s.asyncSets[i] = noopGenericSeriesSet{}
|
|
}
|
|
break
|
|
}
|
|
// Exhausted set.
|
|
s.asyncSets[i] = warningsOnlySeriesSet(ws)
|
|
}
|
|
s.done = true
|
|
})
|
|
|
|
switch s.asyncSets[curr].(type) {
|
|
case warningsOnlySeriesSet, noopGenericSeriesSet:
|
|
return s.asyncSets[curr], false
|
|
default:
|
|
return s.asyncSets[curr], true
|
|
}
|
|
}}
|
|
}
|