Enable metadata caching by blocks scanner. (#2640)

* Blocks scanner can benefit from metadata caching.

Signed-off-by: Peter Štibraný <[email protected]>

* CHANGELOG.md

Signed-off-by: Peter Štibraný <[email protected]>

Author: pstibrany

CHANGELOG.md

@@ -48,7 +48,7 @@
   * `cortex_compactor_block_cleanup_completed_total`
   * `cortex_compactor_block_cleanup_failed_total`
   * `cortex_compactor_block_cleanup_last_successful_run_timestamp_seconds`
-* [ENHANCEMENT] Experimental TSDB: Use shared cache for metadata. This is especially useful when running multiple querier and store-gateway components to reduce number of object store API calls. #2626
+* [ENHANCEMENT] Experimental TSDB: Use shared cache for metadata. This is especially useful when running multiple querier and store-gateway components to reduce number of object store API calls. #2626 #2640
 * [ENHANCEMENT] Upgrade Thanos to [f7802edbf830](https://github.com/thanos-io/thanos/commit/f7802edbf830) and Prometheus to [f4dd45609a05](https://github.com/prometheus/prometheus/commit/f4dd45609a05) which is after v2.18.1. #2634
   * TSDB now does memory-mapping of Head chunks and reduces memory usage.
 * [ENHANCEMENT] Experimental TSDB: when `-querier.query-store-after` is configured and running the experimental blocks storage, the time range of the query sent to the store is now manipulated to ensure the query end time is not more recent than 'now - query-store-after'. #2642

pkg/querier/blocks_store_queryable.go

@@ -18,6 +18,7 @@ import (
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/storage"
 	"github.com/thanos-io/thanos/pkg/block/metadata"
+	"github.com/thanos-io/thanos/pkg/extprom"
 	"github.com/thanos-io/thanos/pkg/store/hintspb"
 	"github.com/thanos-io/thanos/pkg/store/storepb"
 	"github.com/weaveworks/common/user"
@@ -131,6 +132,13 @@ func NewBlocksStoreQueryableFromConfig(querierCfg Config, gatewayCfg storegatewa
 		return nil, errors.Wrap(err, "failed to create bucket client")
 	}
 
+	// Blocks scanner doesn't use chunks, but we pass config for consistency.
+	cachingBucket, err := cortex_tsdb.CreateCachingBucket(storageCfg.BucketStore.ChunksCache, storageCfg.BucketStore.MetadataCache, bucketClient, logger, extprom.WrapRegistererWith(prometheus.Labels{"component": "querier"}, reg))
+	if err != nil {
+		return nil, errors.Wrapf(err, "create caching bucket")
+	}
+	bucketClient = cachingBucket
+
 	scanner := NewBlocksScanner(BlocksScannerConfig{
 		ScanInterval:             storageCfg.BucketStore.SyncInterval,
 		TenantsConcurrency:       storageCfg.BucketStore.TenantSyncConcurrency,