// Handlers have no versioning, so non-compatible handler changes must result in new IDs.
	handlerTest
	handlerTest2
	handlerLast
)

// handlerPrefixes are prefixes for handler IDs used for tracing.
// If a handler is not listed here, it will be traced with "grid" prefix.
var handlerPrefixes = [handlerLast]string{
	HandlerLockLock:                    lockPrefix,
	HandlerLockRLock:                   lockPrefix,

		// Put an empty object with a trailing slash
		30: {bucketName: bucket, objName: "emptydir/", inputData: []byte{}, expectedMd5: getMD5Hash([]byte{})},
		// Put an object inside the empty directory
		31: {bucketName: bucket, objName: "emptydir/" + object, inputData: data, inputDataSize: int64(len(data)), expectedMd5: getMD5Hash(data)},
		// Put the empty object with a trailing slash again (refer to Test case 30), this needs to succeed

	case metacacheSharePrefix:
		return
	case o.Prefix == o.BaseDir:
		// No additional prefix
		return
	}
	// Remove basedir.
	o.FilterPrefix = strings.TrimPrefix(o.Prefix, o.BaseDir)
	// Remove leading and trailing slashes.
	o.FilterPrefix = strings.Trim(o.FilterPrefix, slashSeparator)

	if strings.Contains(o.FilterPrefix, slashSeparator) {
		// Sanity check, should not happen.
		o.FilterPrefix = ""
	}
}

//
// 1 Integer, metacacheStreamVersion of the writer.
// This can be used for managing breaking changes.
//
// For each element:
// 1. Bool. If false at end of stream.
// 2. String. Name of object. Directories contains a trailing slash.
// 3. Binary. Blob of metadata. Length 0 on directories.
// ... Next element.
//
// Streams can be assumed to be sorted in ascending order.

		writeErrorResponse(ctx, w, apiErr, r.URL)
		return
	}
	if checksum != nil && checksum.Type.Trailing() {
		// Not officially supported in POST requests.
		apiErr := errorCodes.ToAPIErr(ErrMalformedPOSTRequest)
		apiErr.Description = fmt.Sprintf("%s (%v)", apiErr.Description, errors.New("Trailing checksums not available for POST operations"))
		writeErrorResponse(ctx, w, apiErr, r.URL)
		return
	}

┌─────┬─────────────────────────────────┬──────────────────────────────────┬──────────┐
│ ID  │ Pools                           │ Capacity                         │ Status   │
│ 1st │ http://minio{1...2}/data{1...4} │ 439 GiB (used) / 561 GiB (total) │ Draining │
└─────┴─────────────────────────────────┴──────────────────────────────────┴──────────┘
```

			st.Status = siteResyncStatus(st.Status, st.BucketStatuses)
			st.LastUpdate = UTCNow()
			sm.resyncStatus[o.resyncID] = st
		}
	}
}

// remove deleted bucket from active resync tracking
func (sm *siteResyncMetrics) deleteBucket(b string) {
	if !globalSiteReplicationSys.isEnabled() {
		return
	}
	sm.Lock()
	defer sm.Unlock()
	for _, rs := range sm.peerResyncMap {

	reqTimeMinute := reqStartTime.Truncate(time.Minute)
	if reqTimeMinute.After(h.currentMinute.statsTime) {
		// Drop the last full minute now, since we got a request for a time we
		// are not yet tracking.
		h.updateLastFullMinute(reqTimeMinute)
	}
	var entry *serviceRTTMinuteStats
	switch {
	case reqTimeMinute.Equal(h.currentMinute.statsTime):
		entry = &h.currentMinute

	// MinIOSnowballIgnoreDirs will skip creating empty directory objects.
	MinIOSnowballIgnoreDirs = "X-Amz-Meta-Minio-Snowball-Ignore-Dirs"
	// MinIOSnowballIgnoreErrors will ignore recoverable errors, typically single files failing to upload.
	// An error will be printed to console instead.
	MinIOSnowballIgnoreErrors = "X-Amz-Meta-Minio-Snowball-Ignore-Errors"
	// MinIOSnowballPrefix will apply this prefix (plus / at end) to all extracted objects

// using a delete-marker and MetaSys entries. It's used to track tiered content of a
// deleted/overwritten version. This version is visible _only_to the scanner routine, for subsequent deletion.
// This kind of tracking is necessary since a version's tiered content is deleted asynchronously.

// Backend directory tree structure:
// disk1/
// └── bucket
//     └── object
//         ├── a192c1d5-9bd5-41fd-9a90-ab10e165398d