#[macro_use]
extern crate diesel;
use diesel::result::Error;
use actix_web::web;
use diesel::{PgConnection, QueryDsl, RunQueryDsl};
use r2d2::{Pool, PooledConnection};
use r2d2_diesel::ConnectionManager;
use schema::tests::dsl::*;
pub mod schema;
pub type MyDBConnectionManager = ConnectionManager<PgConnection>;
pub type MyPool = Pool<MyDBConnectionManager>;
pub type MyDBConnection = PooledConnection<MyDBConnectionManager>;
struct S { }
impl S {
async fn download_and_store_object(pool: web::Data<MyPool>) -> Result<(), Error>
{
let conn_ = pool.get().expect("couldn't get db connection from pool");
let conn = &conn_;
let v_data_size: Option<i64> = web::block(move || -> Result<_, Error> {
Ok(tests.select(b).get_result::<Option<i64>>(&**conn)?)
}).await.unwrap();
Ok(())
}
}
#[actix_web::main]
async fn main() -> std::io::Result<()> {
Ok(())
}
`NonNull<pq_sys::pg_conn>` cannot be shared between threads safely
within `PooledConnection<ConnectionManager<PgConnection>>`, the trait `Sync` is not implemented for `NonNull<pq_sys::pg_conn>`
required because of the requirements on the impl of `std::marker::Send` for `&PooledConnection<ConnectionManager<PgConnection>>`
required because it appears within the type `[closure@src/main.rs:26:51: 28:10]`rustcE0277
架構：
table! {
tests (seq) {
seq -> Int4,
a -> Nullable<Bytea>,
b -> Nullable<Int8>,
}
}
錯誤是什么？以及如何糾正？
uj5u.com熱心網友回復：
正如評論中所說，Conn不能在執行緒之間共享，因此在這種情況下，您需要移動Pool句柄，并從 clusure 本身獲取連接：
#[macro_use]
extern crate diesel;
use diesel::result::Error;
use actix_web::web;
use diesel::{PgConnection, QueryDsl, RunQueryDsl};
use r2d2::{Pool, PooledConnection};
use r2d2_diesel::ConnectionManager;
use schema::tests::dsl::*;
pub mod schema;
pub type MyDBConnectionManager = ConnectionManager<PgConnection>;
pub type MyPool = Pool<MyDBConnectionManager>;
pub type MyDBConnection = PooledConnection<MyDBConnectionManager>;
struct S { }
impl S {
async fn download_and_store_object(pool: web::Data<MyPool>) -> Result<(), Error>
{
let v_data_size: Option<i64> = web::block(move || -> Result<_, Error> {
let conn = pool.get().expect("couldn't get db connection from pool");
Ok(tests.select(b).get_result::<Option<i64>>(&conn)?)
}).await.unwrap();
Ok(())
}
}
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