Merge pull request #23 from matheusoliveira/feat/map-sync

Use sync.Map on global caches to avoid race-condition

internal/structs/structs.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
+	"sync"
 )
 
 // StructInfo stores metainformation of the struct
@@ -66,7 +67,7 @@ func (s StructInfo) NumFields() int {
 // because the total number of types on a program
 // should be finite. So keeping a single cache here
 // works fine.
-var tagInfoCache = map[reflect.Type]StructInfo{}
+var tagInfoCache = &sync.Map{}
 
 // GetTagInfo efficiently returns the type information
 // using a global private cache
@@ -78,9 +79,13 @@ func GetTagInfo(key reflect.Type) (StructInfo, error) {
 	return getCachedTagInfo(tagInfoCache, key)
 }
 
-func getCachedTagInfo(tagInfoCache map[reflect.Type]StructInfo, key reflect.Type) (StructInfo, error) {
+func getCachedTagInfo(tagInfoCache *sync.Map, key reflect.Type) (StructInfo, error) {
-	if info, found := tagInfoCache[key]; found {
+	if data, found := tagInfoCache.Load(key); found {
-		return info, nil
+		if info, ok := data.(StructInfo); !ok {
+			return StructInfo{}, fmt.Errorf("invalid cache entry, expected type StructInfo, found %T", data)
+		} else {
+			return info, nil
+		}
 	}
 
 	info, err := getTagNames(key)
@@ -88,7 +93,7 @@ func getCachedTagInfo(tagInfoCache map[reflect.Type]StructInfo, key reflect.Type
 		return StructInfo{}, err
 	}
 
-	tagInfoCache[key] = info
+	tagInfoCache.Store(key, info)
 	return info, nil
 }
 

kbuilder/query.go

@@ -5,6 +5,7 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/pkg/errors"
 	"github.com/vingarcia/ksql"
@@ -121,7 +122,7 @@ func (w WhereQueries) build(dialect ksql.Dialect) (query string, params []interf
 	return strings.Join(conds, " AND "), params
 }
 
-// Where adds a new bollean condition to an existing
+// Where adds a new boolean condition to an existing
 // WhereQueries helper.
 func (w WhereQueries) Where(cond string, params ...interface{}) WhereQueries {
 	return append(w, WhereQuery{
@@ -130,7 +131,7 @@ func (w WhereQueries) Where(cond string, params ...interface{}) WhereQueries {
 	})
 }
 
-// WhereIf condionally adds a new boolean expression to the WhereQueries helper.
+// WhereIf conditionally adds a new boolean expression to the WhereQueries helper.
 func (w WhereQueries) WhereIf(cond string, param interface{}) WhereQueries {
 	if param == nil || reflect.ValueOf(param).IsNil() {
 		return w
@@ -142,7 +143,7 @@ func (w WhereQueries) WhereIf(cond string, param interface{}) WhereQueries {
 	})
 }
 
-// Where adds a new bollean condition to an existing
+// Where adds a new boolean condition to an existing
 // WhereQueries helper.
 func Where(cond string, params ...interface{}) WhereQueries {
 	return WhereQueries{{
@@ -151,7 +152,7 @@ func Where(cond string, params ...interface{}) WhereQueries {
 	}}
 }
 
-// WhereIf condionally adds a new boolean expression to the WhereQueries helper
+// WhereIf conditionally adds a new boolean expression to the WhereQueries helper
 func WhereIf(cond string, param interface{}) WhereQueries {
 	if param == nil || reflect.ValueOf(param).IsNil() {
 		return WhereQueries{}
@@ -187,7 +188,7 @@ func OrderBy(fields string) OrderByQuery {
 	}
 }
 
-var cachedSelectQueries = map[reflect.Type]string{}
+var cachedSelectQueries = &sync.Map{}
 
 // Builds the select query using cached info so that its efficient
 func buildSelectQuery(obj interface{}, dialect ksql.Dialect) (string, error) {
@@ -200,8 +201,12 @@ func buildSelectQuery(obj interface{}, dialect ksql.Dialect) (string, error) {
 		return "", fmt.Errorf("expected to receive a pointer to struct, but got: %T", obj)
 	}
 
-	if query, found := cachedSelectQueries[t]; found {
+	if data, found := cachedSelectQueries.Load(t); found {
-		return query, nil
+		if query, ok := data.(string); !ok {
+			return "", fmt.Errorf("invalid cache entry, expected type string, found %T", data)
+		} else {
+			return query, nil
+		}
 	}
 
 	info, err := structs.GetTagInfo(t)
@@ -216,6 +221,6 @@ func buildSelectQuery(obj interface{}, dialect ksql.Dialect) (string, error) {
 	}
 
 	query := strings.Join(escapedNames, ", ")
-	cachedSelectQueries[t] = query
+	cachedSelectQueries.Store(t, query)
 	return query, nil
 }

ksql.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"reflect"
 	"strings"
+	"sync"
 	"unicode"
 
 	"github.com/pkg/errors"
@@ -16,10 +17,10 @@ import (
 
 var selectQueryCache = initializeQueryCache()
 
-func initializeQueryCache() map[string]map[reflect.Type]string {
+func initializeQueryCache() map[string]*sync.Map {
-	cache := map[string]map[reflect.Type]string{}
+	cache := map[string]*sync.Map{}
 	for dname := range supportedDialects {
-		cache[dname] = map[reflect.Type]string{}
+		cache[dname] = &sync.Map{}
 	}
 
 	return cache
@@ -1062,10 +1063,14 @@ func buildSelectQuery(
 	dialect Dialect,
 	structType reflect.Type,
 	info structs.StructInfo,
-	selectQueryCache map[reflect.Type]string,
+	selectQueryCache *sync.Map,
 ) (query string, err error) {
-	if selectQuery, found := selectQueryCache[structType]; found {
+	if data, found := selectQueryCache.Load(structType); found {
-		return selectQuery, nil
+		if selectQuery, ok := data.(string); !ok {
+			return "", fmt.Errorf("invalid cache entry, expected type string, found %T", data)
+		} else {
+			return selectQuery, nil
+		}
 	}
 
 	if info.IsNestedStruct {
@@ -1077,7 +1082,7 @@ func buildSelectQuery(
 		query = buildSelectQueryForPlainStructs(dialect, structType, info)
 	}
 
-	selectQueryCache[structType] = query
+	selectQueryCache.Store(structType, query)
 	return query, nil
 }