ent/entc/gen/template/dialect/sql/feature/lock.tmpl

{{/*
Copyright 2019-present Facebook Inc. All rights reserved.
This source code is licensed under the Apache 2.0 license found
in the LICENSE file in the root directory of this source tree.
*/}}

{{/* gotype: entgo.io/ent/entc/gen.Type */}}

{{/* Templates used by the "sql/lock" feature-flag to add "SELECT ... FOR UPDATE/SHARE" capabilities. */}}

{{ define "dialect/sql/query/additional/locking" }}
    {{ if $.FeatureEnabled "sql/lock" }}
        {{ template "helper/sqlock" $ }}
    {{ end }}
{{ end }}

{{ define "helper/sqlock" }}
{{ $builder := pascal $.Scope.Builder }}
{{ $receiver := $.Scope.Receiver }}

// ForUpdate locks the selected rows against concurrent updates, and prevent them from being
// updated, deleted or "selected ... for update" by other sessions, until the transaction is
// either committed or rolled-back.
func ({{ $receiver }} *{{ $builder }}) ForUpdate(opts ...sql.LockOption) *{{ $builder }} {
    if {{ $receiver }}.driver.Dialect() == dialect.Postgres {
        {{ $receiver }}.Unique(false)
    }
    {{ $receiver }}.modifiers = append({{ $receiver }}.modifiers, func(s *sql.Selector) {
        s.ForUpdate(opts...)
    })
    return {{ $receiver }}
}

// ForShare behaves similarly to ForUpdate, except that it acquires a shared mode lock
// on any rows that are read. Other sessions can read the rows, but cannot modify them
// until your transaction commits.
func ({{ $receiver }} *{{ $builder }}) ForShare(opts ...sql.LockOption) *{{ $builder }} {
    if {{ $receiver }}.driver.Dialect() == dialect.Postgres {
        {{ $receiver }}.Unique(false)
    }
    {{ $receiver }}.modifiers = append({{ $receiver }}.modifiers, func(s *sql.Selector) {
        s.ForShare(opts...)
    })
    return {{ $receiver }}
}
{{ end }}