Allow sqlutils clients to register their own loggers.

sqlutils/sqlutils.go

@@ -26,6 +26,8 @@ import (
 	"sync"
 	"time"
 
+	_ "github.com/go-sql-driver/mysql"
+	_ "github.com/mattn/go-sqlite3"
 	"github.com/openark/golib/log"
 )
 
@@ -170,11 +172,18 @@ func (this *RowMap) GetTime(key string) time.Time {
 
 // knownDBs is a DB cache by uri
 var knownDBs map[string]*sql.DB = make(map[string]*sql.DB)
-var knownDBsMutex = &sync.Mutex{}
+var knownDBsMutex = &sync.RWMutex{}
+
+type Logger interface {
+	OnError(context string, query string, err error) error
+}
+// it is also protected by knownDBsMutex
+var DB2logger map[*sql.DB]Logger = make(map[*sql.DB]Logger)
 
 // GetDB returns a DB instance based on uri.
+// logger parameter is optional. If nil, internal logging will be used.
 // bool result indicates whether the DB was returned from cache; err
-func GetGenericDB(driverName, dataSourceName string) (*sql.DB, bool, error) {
+func GetGenericDB(driverName, dataSourceName string ,logger Logger) (*sql.DB, bool, error) {
 	knownDBsMutex.Lock()
 	defer func() {
 		knownDBsMutex.Unlock()
@@ -188,19 +197,23 @@ func GetGenericDB(driverName, dataSourceName string) (*sql.DB, bool, error) {
 			return db, exists, err
 		}
 	}
-	return knownDBs[dataSourceName], exists, nil
+	db := knownDBs[dataSourceName]
+	DB2logger[db] = logger
+	return db, exists, nil
 }
 
 // GetDB returns a MySQL DB instance based on uri.
+// logger parameter is optional. If nil, internal logging will be used.
 // bool result indicates whether the DB was returned from cache; err
-func GetDB(mysql_uri string) (*sql.DB, bool, error) {
-	return GetGenericDB("mysql", mysql_uri)
+func GetDB(mysql_uri string, logger Logger) (*sql.DB, bool, error) {
+	return GetGenericDB("mysql", mysql_uri, logger)
 }
 
 // GetDB returns a SQLite DB instance based on DB file name.
+// logger parameter is optional. If nil, internal logging will be used.
 // bool result indicates whether the DB was returned from cache; err
-func GetSQLiteDB(dbFile string) (*sql.DB, bool, error) {
-	return GetGenericDB("sqlite3", dbFile)
+func GetSQLiteDB(dbFile string, logger Logger) (*sql.DB, bool, error) {
+	return GetGenericDB("sqlite3", dbFile, logger)
 }
 
 // RowToArray is a convenience function, typically not called directly, which maps a
@@ -252,6 +265,20 @@ func ScanRowsToMaps(rows *sql.Rows, on_row func(RowMap) error) error {
 	return err
 }
 
+func logErrorInternal(context string, db *sql.DB, query string, err error) error{
+	// find logger registered by the client
+	knownDBsMutex.RLock()
+	defer func() {
+		knownDBsMutex.RUnlock()
+	}()
+
+	if logger, exists := DB2logger[db]; exists && logger != nil {
+		return logger.OnError(context, query, err)
+	}
+
+	return log.Errore(err)
+}
+
 // QueryRowsMap is a convenience function allowing querying a result set while poviding a callback
 // function activated per read row.
 func QueryRowsMap(db *sql.DB, query string, on_row func(RowMap) error, args ...interface{}) (err error) {
@@ -267,7 +294,7 @@ func QueryRowsMap(db *sql.DB, query string, on_row func(RowMap) error, args ...i
 		defer rows.Close()
 	}
 	if err != nil && err != sql.ErrNoRows {
-		return log.Errore(err)
+		return logErrorInternal("QueryRowsMap", db, query, err)
 	}
 	err = ScanRowsToMaps(rows, on_row)
 	return
@@ -285,7 +312,7 @@ func queryResultData(db *sql.DB, query string, retrieveColumns bool, args ...int
 	rows, err = db.Query(query, args...)
 	defer rows.Close()
 	if err != nil && err != sql.ErrNoRows {
-		return EmptyResultData, columns, err
+		return EmptyResultData, columns, logErrorInternal("queryResultData", db, query, err)
 	}
 	if retrieveColumns {
 		// Don't pay if you don't want to
@@ -339,7 +366,7 @@ func ExecNoPrepare(db *sql.DB, query string, args ...interface{}) (res sql.Resul
 
 	res, err = db.Exec(query, args...)
 	if err != nil {
-		log.Errore(err)
+		logErrorInternal("ExecNoPrepare", db, query, err)
 	}
 	return res, err
 }
@@ -360,7 +387,7 @@ func execInternal(silent bool, db *sql.DB, query string, args ...interface{}) (r
 	defer stmt.Close()
 	res, err = stmt.Exec(args...)
 	if err != nil && !silent {
-		log.Errore(err)
+		logErrorInternal("execInternal", db, query, err)
 	}
 	return res, err
 }