flatten out audit tags, do not send as free-form (#20256)

move away from map[string]interface{} to map[string]string
to simplify the audit, and also provide concise information.

avoids large allocations under load(), reduces the amount
of audit information generated, as the current implementation
was a bit free-form. instead all datastructures must be
flattened.

cmd/erasure-object.go

@@ -70,7 +70,7 @@ func countOnlineDisks(onlineDisks []StorageAPI) (online int) {
 // update metadata.
 func (er erasureObjects) CopyObject(ctx context.Context, srcBucket, srcObject, dstBucket, dstObject string, srcInfo ObjectInfo, srcOpts, dstOpts ObjectOptions) (oi ObjectInfo, err error) {
 	if !dstOpts.NoAuditLog {
-		auditObjectErasureSet(ctx, dstObject, &er)
+		auditObjectErasureSet(ctx, "CopyObject", dstObject, &er)
 	}
 
 	// This call shouldn't be used for anything other than metadata updates or adding self referential versions.
@@ -199,7 +199,7 @@ func (er erasureObjects) CopyObject(ctx context.Context, srcBucket, srcObject, d
 // Read(Closer). When err != nil, the returned reader is always nil.
 func (er erasureObjects) GetObjectNInfo(ctx context.Context, bucket, object string, rs *HTTPRangeSpec, h http.Header, opts ObjectOptions) (gr *GetObjectReader, err error) {
 	if !opts.NoAuditLog {
-		auditObjectErasureSet(ctx, object, &er)
+		auditObjectErasureSet(ctx, "GetObject", object, &er)
 	}
 
 	var unlockOnDefer bool
@@ -439,7 +439,7 @@ func (er erasureObjects) getObjectWithFileInfo(ctx context.Context, bucket, obje
 // GetObjectInfo - reads object metadata and replies back ObjectInfo.
 func (er erasureObjects) GetObjectInfo(ctx context.Context, bucket, object string, opts ObjectOptions) (info ObjectInfo, err error) {
 	if !opts.NoAuditLog {
-		auditObjectErasureSet(ctx, object, &er)
+		auditObjectErasureSet(ctx, "GetObjectInfo", object, &er)
 	}
 
 	if !opts.NoLock {
@@ -456,7 +456,7 @@ func (er erasureObjects) GetObjectInfo(ctx context.Context, bucket, object strin
 	return er.getObjectInfo(ctx, bucket, object, opts)
 }
 
-func auditDanglingObjectDeletion(ctx context.Context, bucket, object, versionID string, tags map[string]interface{}) {
+func auditDanglingObjectDeletion(ctx context.Context, bucket, object, versionID string, tags map[string]string) {
 	if len(logger.AuditTargets()) == 0 {
 		return
 	}
@@ -472,13 +472,16 @@ func auditDanglingObjectDeletion(ctx context.Context, bucket, object, versionID
 	auditLogInternal(ctx, opts)
 }
 
-func joinErrs(errs []error) []string {
-	s := make([]string, len(errs))
+func joinErrs(errs []error) string {
+	var s string
 	for i := range s {
+		if s != "" {
+			s += ","
+		}
 		if errs[i] == nil {
-			s[i] = "<nil>"
+			s += "<nil>"
 		} else {
-			s[i] = errs[i].Error()
+			s += errs[i].Error()
 		}
 	}
 	return s
@@ -491,20 +494,18 @@ func (er erasureObjects) deleteIfDangling(ctx context.Context, bucket, object st
 		// can be deleted safely, in such a scenario return ReadQuorum error.
 		return FileInfo{}, errErasureReadQuorum
 	}
-	tags := make(map[string]interface{}, 4)
-	tags["set"] = er.setIndex
-	tags["pool"] = er.poolIndex
+	tags := make(map[string]string, 16)
+	tags["set"] = strconv.Itoa(er.setIndex)
+	tags["pool"] = strconv.Itoa(er.poolIndex)
 	tags["merrs"] = joinErrs(errs)
-	tags["derrs"] = dataErrsByPart
+	tags["derrs"] = fmt.Sprintf("%v", dataErrsByPart)
 	if m.IsValid() {
-		tags["size"] = m.Size
-		tags["mtime"] = m.ModTime.Format(http.TimeFormat)
-		tags["data"] = m.Erasure.DataBlocks
-		tags["parity"] = m.Erasure.ParityBlocks
+		tags["sz"] = strconv.FormatInt(m.Size, 10)
+		tags["mt"] = m.ModTime.Format(iso8601Format)
+		tags["d:p"] = fmt.Sprintf("%d:%d", m.Erasure.DataBlocks, m.Erasure.ParityBlocks)
 	} else {
-		tags["invalid-meta"] = true
-		tags["data"] = er.setDriveCount - er.defaultParityCount
-		tags["parity"] = er.defaultParityCount
+		tags["invalid"] = "1"
+		tags["d:p"] = fmt.Sprintf("%d:%d", er.setDriveCount-er.defaultParityCount, er.defaultParityCount)
 	}
 
 	// count the number of offline disks
@@ -527,7 +528,7 @@ func (er erasureObjects) deleteIfDangling(ctx context.Context, bucket, object st
 		}
 	}
 	if offline > 0 {
-		tags["offline"] = offline
+		tags["offline"] = strconv.Itoa(offline)
 	}
 
 	_, file, line, cok := runtime.Caller(1)
@@ -556,22 +557,16 @@ func (er erasureObjects) deleteIfDangling(ctx context.Context, bucket, object st
 		}, index)
 	}
 
-	rmDisks := make(map[string]string, len(disks))
 	for index, err := range g.Wait() {
-		var errStr, diskName string
+		var errStr string
 		if err != nil {
 			errStr = err.Error()
 		} else {
 			errStr = "<nil>"
 		}
-		if disks[index] != nil {
-			diskName = disks[index].String()
-		} else {
-			diskName = fmt.Sprintf("disk-%d", index)
-		}
-		rmDisks[diskName] = errStr
+		tags[fmt.Sprintf("ddisk-%d", index)] = errStr
 	}
-	tags["cleanupResult"] = rmDisks
+
 	return m, nil
 }
 
@@ -1251,7 +1246,7 @@ func (er erasureObjects) PutObject(ctx context.Context, bucket string, object st
 // putObject wrapper for erasureObjects PutObject
 func (er erasureObjects) putObject(ctx context.Context, bucket string, object string, r *PutObjReader, opts ObjectOptions) (objInfo ObjectInfo, err error) {
 	if !opts.NoAuditLog {
-		auditObjectErasureSet(ctx, object, &er)
+		auditObjectErasureSet(ctx, "PutObject", object, &er)
 	}
 
 	data := r.Reader
@@ -1626,7 +1621,7 @@ func (er erasureObjects) deleteObjectVersion(ctx context.Context, bucket, object
 func (er erasureObjects) DeleteObjects(ctx context.Context, bucket string, objects []ObjectToDelete, opts ObjectOptions) ([]DeletedObject, []error) {
 	if !opts.NoAuditLog {
 		for _, obj := range objects {
-			auditObjectErasureSet(ctx, obj.ObjectV.ObjectName, &er)
+			auditObjectErasureSet(ctx, "DeleteObjects", obj.ObjectV.ObjectName, &er)
 		}
 	}
 
@@ -1846,7 +1841,7 @@ func (er erasureObjects) deletePrefix(ctx context.Context, bucket, prefix string
 // response to the client request.
 func (er erasureObjects) DeleteObject(ctx context.Context, bucket, object string, opts ObjectOptions) (objInfo ObjectInfo, err error) {
 	if !opts.NoAuditLog {
-		auditObjectErasureSet(ctx, object, &er)
+		auditObjectErasureSet(ctx, "DeleteObject", object, &er)
 	}
 
 	var lc *lifecycle.Lifecycle