如何获取对 RwLock 中对象的引用?
How to get a reference to the object inside an RwLock?
此代码有效:
use serde::{Deserialize, Serialize};
use std::sync::{RwLock, Arc};
use ron;
#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
struct Foo {
first: u8,
second: u16,
}
fn main() {
let foo = Foo {first: 1, second: 2};
let lock = Arc::new(RwLock::new(foo));
let state = lock.read().unwrap().clone(); // FIXME: remove clone()
let string = ron::ser::to_string(&state).unwrap();
println!("{}", string);
}
我想去掉.clone()
,因为我程序中的foo
是100MB+,我需要多次引用这个引用。
当我摆脱 .clone()
时,我得到错误:
error[E0277]: the trait bound `std::sync::RwLockReadGuard<'_, Foo>: _::_serde::Serialize` is not satisfied
--> src/bin/sandbox7.rs:16:35
|
16 | let string = ron::ser::to_string(&state).unwrap();
| ^^^^^^ the trait `_::_serde::Serialize` is not implemented for `std::sync::RwLockReadGuard<'_, Foo>`
|
::: /home/chris/.cargo/registry/src/github.com-1ecc6299db9ec823/ron-0.6.0/src/ser/mod.rs:25:8
|
25 | T: Serialize,
| --------- required by this bound in `ron::ser::to_string`
我想序列化 foo
(来自另一个线程,在真实代码中,因此是 Arc)。
我怎样才能从 lock
得到 &Foo
,而不浪费 .clone()
?
RWLockReadGuard
derefs 到基础类型。
操场上没有 ron
,所以我无法确定,但这应该可以解决问题:
let state = lock.read().unwrap();
let string = ron::ser::to_string(&*state).unwrap();
此代码有效:
use serde::{Deserialize, Serialize};
use std::sync::{RwLock, Arc};
use ron;
#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
struct Foo {
first: u8,
second: u16,
}
fn main() {
let foo = Foo {first: 1, second: 2};
let lock = Arc::new(RwLock::new(foo));
let state = lock.read().unwrap().clone(); // FIXME: remove clone()
let string = ron::ser::to_string(&state).unwrap();
println!("{}", string);
}
我想去掉.clone()
,因为我程序中的foo
是100MB+,我需要多次引用这个引用。
当我摆脱 .clone()
时,我得到错误:
error[E0277]: the trait bound `std::sync::RwLockReadGuard<'_, Foo>: _::_serde::Serialize` is not satisfied
--> src/bin/sandbox7.rs:16:35
|
16 | let string = ron::ser::to_string(&state).unwrap();
| ^^^^^^ the trait `_::_serde::Serialize` is not implemented for `std::sync::RwLockReadGuard<'_, Foo>`
|
::: /home/chris/.cargo/registry/src/github.com-1ecc6299db9ec823/ron-0.6.0/src/ser/mod.rs:25:8
|
25 | T: Serialize,
| --------- required by this bound in `ron::ser::to_string`
我想序列化 foo
(来自另一个线程,在真实代码中,因此是 Arc)。
我怎样才能从 lock
得到 &Foo
,而不浪费 .clone()
?
RWLockReadGuard
derefs 到基础类型。
操场上没有 ron
,所以我无法确定,但这应该可以解决问题:
let state = lock.read().unwrap();
let string = ron::ser::to_string(&*state).unwrap();