fix: prioritized latest buckets for crawler to finish the scans faster (#11115)

crawler should only ListBuckets once not for each serverPool,
buckets are same across all pools, across sets and ListBuckets
always returns an unified view, once list buckets returns
sort it by create time to scan the latest buckets earlier
with the assumption that latest buckets would have lesser
content than older buckets allowing them to be scanned faster
and also to be able to provide more closer to latest view.

cmd/admin-heal-ops.go

@@ -21,6 +21,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -873,6 +874,11 @@ func (h *healSequence) healBuckets(objAPI ObjectLayer, bucketsOnly bool) error {
 		return errFnHealFromAPIErr(h.ctx, err)
 	}
 
+	// Heal latest buckets first.
+	sort.Slice(buckets, func(i, j int) bool {
+		return buckets[i].Created.After(buckets[j].Created)
+	})
+
 	for _, bucket := range buckets {
 		if err = h.healBucket(objAPI, bucket.Name, bucketsOnly); err != nil {
 			return err

cmd/background-newdisks-heal-ops.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"sort"
 	"time"
 
 	"github.com/dustin/go-humanize"
@@ -161,6 +162,12 @@ wait:
 			}
 
 			buckets, _ := z.ListBuckets(ctx)
+
+			// Heal latest buckets first.
+			sort.Slice(buckets, func(i, j int) bool {
+				return buckets[i].Created.After(buckets[j].Created)
+			})
+
 			for i, setMap := range erasureSetInZoneDisksToHeal {
 				for setIndex, disks := range setMap {
 					for _, disk := range disks {

cmd/erasure-server-sets.go

@@ -23,6 +23,7 @@ import (
 	"io"
 	"math/rand"
 	"net/http"
+	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -322,23 +323,19 @@ func (z *erasureServerPools) CrawlAndGetDataUsage(ctx context.Context, bf *bloom
 	var mu sync.Mutex
 	var results []dataUsageCache
 	var firstErr error
-	var knownBuckets = make(map[string]struct{}) // used to deduplicate buckets.
+
-	var allBuckets []BucketInfo
+	allBuckets, err := z.ListBuckets(ctx)
+	if err != nil {
+		return err
+	}
+
+	// Crawl latest allBuckets first.
+	sort.Slice(allBuckets, func(i, j int) bool {
+		return allBuckets[i].Created.After(allBuckets[j].Created)
+	})
 
 	// Collect for each set in serverPools.
 	for _, z := range z.serverPools {
-		buckets, err := z.ListBuckets(ctx)
-		if err != nil {
-			return err
-		}
-		// Add new buckets.
-		for _, b := range buckets {
-			if _, ok := knownBuckets[b.Name]; ok {
-				continue
-			}
-			allBuckets = append(allBuckets, b)
-			knownBuckets[b.Name] = struct{}{}
-		}
 		for _, erObj := range z.sets {
 			wg.Add(1)
 			results = append(results, dataUsageCache{})
@@ -355,7 +352,7 @@ func (z *erasureServerPools) CrawlAndGetDataUsage(ctx context.Context, bf *bloom
 					}
 				}()
 				// Start crawler. Blocks until done.
-				err := erObj.crawlAndGetDataUsage(ctx, buckets, bf, updates)
+				err := erObj.crawlAndGetDataUsage(ctx, allBuckets, bf, updates)
 				if err != nil {
 					logger.LogIf(ctx, err)
 					mu.Lock()

cmd/erasure-sets.go

@@ -722,10 +722,14 @@ func (s *erasureSets) ListBuckets(ctx context.Context) (buckets []BucketInfo, er
 			return nil, err
 		}
 	}
+
 	for _, v := range healBuckets {
 		listBuckets = append(listBuckets, BucketInfo(v))
 	}
-	sort.Sort(byBucketName(listBuckets))
+
+	sort.Slice(listBuckets, func(i, j int) bool {
+		return listBuckets[i].Name < listBuckets[j].Name
+	})
 
 	return listBuckets, nil
 }

cmd/fs-v1.go

@@ -531,7 +531,9 @@ func (fs *FSObjects) ListBuckets(ctx context.Context) ([]BucketInfo, error) {
 	}
 
 	// Sort bucket infos by bucket name.
-	sort.Sort(byBucketName(bucketInfos))
+	sort.Slice(bucketInfos, func(i, j int) bool {
+		return bucketInfos[i].Name < bucketInfos[j].Name
+	})
 
 	// Succes.
 	return bucketInfos, nil

cmd/object-api-utils.go

@@ -536,13 +536,6 @@ func getCompressedOffsets(objectInfo ObjectInfo, offset int64) (int64, int64) {
 	return compressedOffset, offset - skipLength
 }
 
-// byBucketName is a collection satisfying sort.Interface.
-type byBucketName []BucketInfo
-
-func (d byBucketName) Len() int           { return len(d) }
-func (d byBucketName) Swap(i, j int)      { d[i], d[j] = d[j], d[i] }
-func (d byBucketName) Less(i, j int) bool { return d[i].Name < d[j].Name }
-
 // GetObjectReader is a type that wraps a reader with a lock to
 // provide a ReadCloser interface that unlocks on Close()
 type GetObjectReader struct {