filter: refine comments and function visibility (#2308) (#2311)

pkg/filter/filter.go

@@ -22,15 +22,16 @@ import (
 	filterV2 "github.com/pingcap/tidb-tools/pkg/table-filter"
 )
 
-// Filter is a event filter implementation
+// Filter is a event filter implementation.
 type Filter struct {
 	filter           filterV2.Filter
 	ignoreTxnStartTs []uint64
 	ddlAllowlist     []model.ActionType
 	isCyclicEnabled  bool
 }
 
-// VerifyRules ...
+// VerifyRules checks the filter rules in the configuration
+// and returns an invalid rule error if the verification fails, otherwise it will return the parsed filter.
 func VerifyRules(cfg *config.ReplicaConfig) (filterV2.Filter, error) {
 	var f filterV2.Filter
 	var err error
@@ -50,7 +51,7 @@ func VerifyRules(cfg *config.ReplicaConfig) (filterV2.Filter, error) {
 	return f, nil
 }
 
-// NewFilter creates a filter
+// NewFilter creates a filter.
 func NewFilter(cfg *config.ReplicaConfig) (*Filter, error) {
 	f, err := VerifyRules(cfg)
 	if err != nil {
@@ -78,9 +79,9 @@ func (f *Filter) shouldIgnoreStartTs(ts uint64) bool {
 }
 
 // ShouldIgnoreTable returns true if the specified table should be ignored by this change feed.
-// Set `tbl` to an empty string to test against the whole database.
+// NOTICE: Set `tbl` to an empty string to test against the whole database.
 func (f *Filter) ShouldIgnoreTable(db, tbl string) bool {
-	if IsSysSchema(db) {
+	if isSysSchema(db) {
 		return true
 	}
 	if f.isCyclicEnabled && mark.IsMarkTable(db, tbl) {
@@ -110,7 +111,7 @@ func (f *Filter) ShouldIgnoreDDLEvent(ts uint64, ddlType model.ActionType, schem
 	return f.shouldIgnoreStartTs(ts) || shouldIgnoreTableOrSchema
 }
 
-// ShouldDiscardDDL returns true if this DDL should be discarded
+// ShouldDiscardDDL returns true if this DDL should be discarded.
 func (f *Filter) ShouldDiscardDDL(ddlType model.ActionType) bool {
 	if !f.shouldDiscardByBuiltInDDLAllowlist(ddlType) {
 		return false
@@ -180,7 +181,7 @@ func (f *Filter) shouldDiscardByBuiltInDDLAllowlist(ddlType model.ActionType) bo
 	return true
 }
 
-// IsSysSchema returns true if the given schema is a system schema
-func IsSysSchema(db string) bool {
+// isSysSchema returns true if the given schema is a system schema
+func isSysSchema(db string) bool {
 	return filterV1.IsSystemSchema(db)
 }