diesel/query_builder/
locking_clause.rs

1use crate::backend::{Backend, DieselReserveSpecialization};
2use crate::query_builder::{AstPass, QueryFragment, QueryId};
3use crate::result::QueryResult;
4
5#[derive(Debug, Clone, Copy, QueryId)]
6pub struct NoLockingClause;
7
8impl<DB> QueryFragment<DB> for NoLockingClause
9where
10    DB: Backend + DieselReserveSpecialization,
11{
12    fn walk_ast<'b>(&'b self, _: AstPass<'_, 'b, DB>) -> QueryResult<()> {
13        Ok(())
14    }
15}
16
17#[derive(Debug, Clone, Copy, QueryId)]
18pub struct LockingClause<LockMode = ForUpdate, Modifier = NoModifier> {
19    pub(crate) lock_mode: LockMode,
20    modifier: Modifier,
21}
22
23impl<LockMode, Modifier> LockingClause<LockMode, Modifier> {
24    pub(crate) fn new(lock_mode: LockMode, modifier: Modifier) -> Self {
25        LockingClause {
26            lock_mode,
27            modifier,
28        }
29    }
30}
31
32impl<DB, L, M> QueryFragment<DB> for LockingClause<L, M>
33where
34    DB: Backend + DieselReserveSpecialization,
35    L: QueryFragment<DB>,
36    M: QueryFragment<DB>,
37{
38    fn walk_ast<'b>(&'b self, mut out: AstPass<'_, 'b, DB>) -> QueryResult<()> {
39        self.lock_mode.walk_ast(out.reborrow())?;
40        self.modifier.walk_ast(out.reborrow())
41    }
42}
43
44// `LockMode` parameters
45// All the different types of row locks that can be acquired.
46#[derive(Debug, Clone, Copy, QueryId)]
47pub struct ForUpdate;
48
49#[derive(Debug, Clone, Copy, QueryId)]
50pub struct ForNoKeyUpdate;
51
52#[derive(Debug, Clone, Copy, QueryId)]
53pub struct ForShare;
54
55#[derive(Debug, Clone, Copy, QueryId)]
56pub struct ForKeyShare;
57
58// Modifiers
59// To be used in conjunction with a lock mode.
60#[derive(Debug, Clone, Copy, QueryId)]
61pub struct NoModifier;
62
63#[derive(Debug, Clone, Copy, QueryId)]
64pub struct SkipLocked;
65
66#[derive(Debug, Clone, Copy, QueryId)]
67pub struct NoWait;