Merge branch 'main' into mhoffm-smaller-blocksize-for-streamed-postings

Signed-off-by: Michael Hoffmann <mhoffm@posteo.de>

docs/blog/2023-06-02-lfx-mentorship-query-observability.md

@@ -34,15 +34,15 @@ Thanos needs to specify which engine to utilize to execute the promql queries. A
 
 Here is the sketch of how the engine switch should look (made by Giedrius):
 
-<img src="img/giedrius-sketch.png" alt="Giedrius&#39;s Sketch" width="800"/>
+![Giedrius's Sketch](img/giedrius-sketch.png)
 
 I looked into Thanos and made changes in Thanos components from the API to the UI to implement this engine switch. I tried to make the UI as close as possible to the sketch.
 
-<img src="img/engine-1.png" alt="Engine Switch 1" width="800"/>
+![Engine Switch 1](img/engine-1.png)
 
 After initial review, I move this switch to each panel. As this helps to run the same query over the different engines and compare the results.
 
-<img src="img/engine-2.png" alt="Engine Switch 2" width="800"/>
+![Engine Switch 2](img/engine-2.png)
 
 **Pull Requests**
 - Add engine param to Thanos engine constructor ([thanos-io/promql-engine#228](https://github.com/thanos-io/promql-engine/pull/228))
@@ -56,11 +56,11 @@ I started with generating query explanations through the Thanos promql-engine an
 
 Thanos UI got updated with time, resulting in the development of the explanation tree that can be seen through the screenshots provided.
 
-<img src="img/tree-1.png" alt="Tree 1" width="800"/>
+![Tree 1](img/tree-1.png)
 
-<img src="img/tree-2.png" alt="Tree 2" width="800"/>
+![Tree 2](img/tree-2.png)
 
-<img src="img/tree-3.png" alt="Tree 3" width="800"/>
+![Tree 3](img/tree-3.png)
 
 **Pull Requests**
 - Add method to explain query vector ([thanos-io/promql-engine#252](https://github.com/thanos-io/promql-engine/pull/252))

pkg/query/remote_engine.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"io"
 	"math"
+	"sync"
 	"time"
 
 	"github.com/go-kit/log"
@@ -82,6 +83,13 @@ type remoteEngine struct {
 	logger log.Logger
 
 	client Client
+
+	mintOnce      sync.Once
+	mint          int64
+	maxtOnce      sync.Once
+	maxt          int64
+	labelSetsOnce sync.Once
+	labelSets     []labels.Labels
 }
 
 func newRemoteEngine(logger log.Logger, queryClient Client, opts Opts) api.RemoteEngine {
@@ -98,43 +106,52 @@ func newRemoteEngine(logger log.Logger, queryClient Client, opts Opts) api.Remot
 // Calculating the MinT this way makes remote queries resilient to cases where one tsdb replica would delete
 // a block due to retention before other replicas did the same.
 // See https://github.com/thanos-io/promql-engine/issues/187.
-func (r remoteEngine) MinT() int64 {
-	var (
-		hashBuf               = make([]byte, 0, 128)
-		highestMintByLabelSet = make(map[uint64]int64)
-	)
-	for _, lset := range r.infosWithoutReplicaLabels() {
-		key, _ := labelpb.ZLabelsToPromLabels(lset.Labels.Labels).HashWithoutLabels(hashBuf)
-		lsetMinT, ok := highestMintByLabelSet[key]
-		if !ok {
-			highestMintByLabelSet[key] = lset.MinTime
-			continue
-		}
+func (r *remoteEngine) MinT() int64 {
+	r.mintOnce.Do(func() {
+		var (
+			hashBuf               = make([]byte, 0, 128)
+			highestMintByLabelSet = make(map[uint64]int64)
+		)
+		for _, lset := range r.infosWithoutReplicaLabels() {
+			key, _ := labelpb.ZLabelsToPromLabels(lset.Labels.Labels).HashWithoutLabels(hashBuf)
+			lsetMinT, ok := highestMintByLabelSet[key]
+			if !ok {
+				highestMintByLabelSet[key] = lset.MinTime
+				continue
+			}
 
-		if lset.MinTime > lsetMinT {
-			highestMintByLabelSet[key] = lset.MinTime
+			if lset.MinTime > lsetMinT {
+				highestMintByLabelSet[key] = lset.MinTime
+			}
 		}
-	}
 
-	var mint int64 = math.MaxInt64
-	for _, m := range highestMintByLabelSet {
-		if m < mint {
-			mint = m
+		var mint int64 = math.MaxInt64
+		for _, m := range highestMintByLabelSet {
+			if m < mint {
+				mint = m
+			}
 		}
-	}
+		r.mint = mint
+	})
 
-	return mint
+	return r.mint
 }
 
-func (r remoteEngine) MaxT() int64 {
-	return r.client.tsdbInfos.MaxT()
+func (r *remoteEngine) MaxT() int64 {
+	r.maxtOnce.Do(func() {
+		r.maxt = r.client.tsdbInfos.MaxT()
+	})
+	return r.maxt
 }
 
-func (r remoteEngine) LabelSets() []labels.Labels {
-	return r.infosWithoutReplicaLabels().LabelSets()
+func (r *remoteEngine) LabelSets() []labels.Labels {
+	r.labelSetsOnce.Do(func() {
+		r.labelSets = r.infosWithoutReplicaLabels().LabelSets()
+	})
+	return r.labelSets
 }
 
-func (r remoteEngine) infosWithoutReplicaLabels() infopb.TSDBInfos {
+func (r *remoteEngine) infosWithoutReplicaLabels() infopb.TSDBInfos {
 	replicaLabelSet := make(map[string]struct{})
 	for _, lbl := range r.opts.ReplicaLabels {
 		replicaLabelSet[lbl] = struct{}{}
@@ -161,7 +178,7 @@ func (r remoteEngine) infosWithoutReplicaLabels() infopb.TSDBInfos {
 	return infos
 }
 
-func (r remoteEngine) NewRangeQuery(_ context.Context, opts *promql.QueryOpts, qs string, start, end time.Time, interval time.Duration) (promql.Query, error) {
+func (r *remoteEngine) NewRangeQuery(_ context.Context, opts *promql.QueryOpts, qs string, start, end time.Time, interval time.Duration) (promql.Query, error) {
 	return &remoteQuery{
 		logger: r.logger,
 		client: r.client,

website/static/main.css

@@ -198,3 +198,7 @@ input[type="search"]::placeholder { /* Chrome, Firefox, Opera, Safari 10.1+ */
         padding-bottom: 15px;
     }
 }
+
+.blog-post img {
+    width: 100%;
+}