1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
//! module for canceling ongoing queries
use postgres_protocol::message::frontend;
use xitca_io::bytes::BytesMut;
use super::{
error::{Error, RuntimeError},
session::Session,
};
impl Session {
/// Attempts to cancel the in-progress query on the connection associated with Self.
///
/// The server provides no information about whether a cancellation attempt was successful or not. An error will
/// only be returned if the client was unable to connect to the database.
///
/// Cancellation is inherently racy. There is no guarantee that the cancellation request will reach the server
/// before the query terminates normally, or that the connection associated with this token is still active.
pub async fn query_cancel(self) -> Result<(), Error> {
let Session { id, key, info } = self;
let (_tx, mut drv) = super::driver::connect_info(info).await?;
let mut buf = BytesMut::new();
frontend::cancel_request(id, key, &mut buf);
drv.send(buf).await
}
/// blocking version of [`Session::query_cancel`]
pub fn query_cancel_blocking(self) -> Result<(), Error> {
match tokio::runtime::Handle::try_current() {
Ok(_) => Err(RuntimeError::RequireNoTokio.into()),
Err(_) => tokio::runtime::Builder::new_current_thread()
.enable_all()
.build()?
.block_on(self.query_cancel()),
}
}
}