Merge pull request #18 from doug-martin/race_cond

Fixing race condition with struct_map_cache in crud_exec

.travis.yml

@@ -18,3 +18,5 @@ before_script:
   - mv -vfT $DEFAULT_TRAVIS_BUILD_DIR $TRAVIS_BUILD_DIR
   - psql -c 'create database goqupostgres;' -U postgres
   - mysql -e 'create database goqumysql;'
+
+script: go test -v -race ./...

crud_exec.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
+	"sync"
 )
 
 type (
@@ -25,6 +26,7 @@ type (
 )
 
 var struct_map_cache = make(map[interface{}]columnMap)
+var struct_map_cache_lock = sync.Mutex{}
 
 func newCrudExec(database database, err error, sql string, args ...interface{}) *CrudExec {
 	return &CrudExec{database: database, err: err, Sql: sql, Args: args}
@@ -278,6 +280,9 @@ func getColumnMap(i interface{}) (columnMap, error) {
 	if valKind != reflect.Struct {
 		return nil, NewGoquError(fmt.Sprintf("Cannot SELECT into this type: %v", t))
 	}
+
+	struct_map_cache_lock.Lock()
+	defer struct_map_cache_lock.Unlock()
 	if _, ok := struct_map_cache[t]; !ok {
 		struct_map_cache[t] = createColumnMap(t)
 	}

crud_exec_test.go

@@ -2,11 +2,12 @@ package goqu
 
 import (
 	"fmt"
+	"sync"
 	"testing"
 
-	"gopkg.in/DATA-DOG/go-sqlmock.v1"
 	"github.com/c2fo/testify/assert"
 	"github.com/c2fo/testify/suite"
+	"gopkg.in/DATA-DOG/go-sqlmock.v1"
 )
 
 type testCrudActionItem struct {
@@ -265,6 +266,37 @@ func (me *crudExecTest) TestScanVal() {
 	assert.Equal(t, ptrId, 1)
 }
 
+func (me *crudExecTest) TestParallelGetColumnMap() {
+	t := me.T()
+
+	type item struct {
+		id   uint
+		name string
+	}
+
+	wg := sync.WaitGroup{}
+
+	wg.Add(1)
+	go func() {
+		i := item{}
+		m, err := getColumnMap(i)
+		assert.NoError(t, err)
+		assert.NotNil(t, m)
+		wg.Done()
+	}()
+
+	wg.Add(1)
+	go func() {
+		i := item{}
+		m, err := getColumnMap(i)
+		assert.NoError(t, err)
+		assert.NotNil(t, m)
+		wg.Done()
+	}()
+
+	wg.Wait()
+}
+
 func TestCrudExecSuite(t *testing.T) {
 	suite.Run(t, new(crudExecTest))
 }