all: simplify boolean expressions

- !(a == b) => a != b
- !(a != b) => a == b

Signed-off-by: Iskander Sharipov <quasilyte@gmail.com>

cache/memcache/memcache.go

@@ -146,7 +146,7 @@ func (rc *Cache) IsExist(key string) bool {
 		}
 	}
 	_, err := rc.conn.Get(key)
-	return !(err != nil)
+	return err == nil
 }
 
 // ClearAll clear all cached in memcache.

session/ledis/ledis_session.go

@@ -133,7 +133,7 @@ func (lp *Provider) SessionRead(sid string) (session.Store, error) {
 // SessionExist check ledis session exist by sid
 func (lp *Provider) SessionExist(sid string) bool {
 	count, _ := c.Exists([]byte(sid))
-	return !(count == 0)
+	return count != 0
 }
 
 // SessionRegenerate generate new sid for ledis session

session/mysql/sess_mysql.go

@@ -170,7 +170,7 @@ func (mp *Provider) SessionExist(sid string) bool {
 	row := c.QueryRow("select session_data from "+TableName+" where session_key=?", sid)
 	var sessiondata []byte
 	err := row.Scan(&sessiondata)
-	return !(err == sql.ErrNoRows)
+	return err != sql.ErrNoRows
 }
 
 // SessionRegenerate generate new sid for mysql session

session/postgres/sess_postgresql.go

@@ -184,7 +184,7 @@ func (mp *Provider) SessionExist(sid string) bool {
 	row := c.QueryRow("select session_data from session where session_key=$1", sid)
 	var sessiondata []byte
 	err := row.Scan(&sessiondata)
-	return !(err == sql.ErrNoRows)
+	return err != sql.ErrNoRows
 }
 
 // SessionRegenerate generate new sid for postgresql session