feat: add module init method

Author: RivenZoo

init_sqlagent.go

@@ -1 +1,62 @@
 package sqlagent
+
+import (
+	"github.com/RivenZoo/dsncfg"
+	"sync"
+	"gopkg.in/yaml.v2"
+	"path"
+	"strings"
+	"io/ioutil"
+	"encoding/json"
+)
+
+var (
+	initOnce = &sync.Once{}
+)
+
+// Init module SqlAgent with database config.
+func Init(cfg *dsncfg.Database) error {
+	return initSqlAgent(cfg)
+}
+
+// Init module SqlAgent with database config.
+// cfgFile: config file path, support file type [.json | .yaml/.yml], default decoder is json.
+func InitFromConfig(cfgFile string) error {
+	cfg, err := readDBConfig(cfgFile)
+	if err != nil {
+		return err
+	}
+	return initSqlAgent(cfg)
+}
+
+// cfgFile: config file path, support file type [.json | .yaml/.yml], default decoder is json.
+func readDBConfig(cfgFile string) (*dsncfg.Database, error) {
+	c, err := ioutil.ReadFile(cfgFile)
+	if err != nil {
+		return nil, err
+	}
+
+	ext := path.Ext(cfgFile)
+	ext = strings.ToLower(ext)
+
+	dbCfg := &dsncfg.Database{}
+	switch ext {
+	case ".yaml", ".yml":
+		err = yaml.Unmarshal(c, dbCfg)
+	default:
+		// default: .json
+		err = json.Unmarshal(c, dbCfg)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return dbCfg, nil
+}
+
+// initSqlAgent init module SqlAgent only once.
+func initSqlAgent(cfg *dsncfg.Database) (err error) {
+	initOnce.Do(func() {
+		defaultAgent, err = NewSqlAgent(cfg)
+	})
+	return
+}