Struct CancelToken 

#[non_exhaustive]
pub struct CancelToken { /* private fields */ }

A token that can be used to cancel a running query on a connection.

The token contains the host, port, process ID, and secret key needed to send an out-of-band cancellation request. It can be cloned and sent to another task or thread.

Example

let token = conn.cancel_token();

// Spawn a task that will cancel the query after 5 seconds
tokio::spawn(async move {
    tokio::time::sleep(Duration::from_secs(5)).await;
    token.cancel().await.unwrap();
});

// This long-running query will be cancelled
conn.query("SELECT pg_sleep(60)").await?;

Implementations

impl CancelToken

pub async fn cancel(&self) -> Result<()>

Send a cancellation request to the server.

This opens a new TCP connection to the server, sends a CancelRequest message, and closes the connection. The server will then attempt to cancel the running query on the original connection.

Note that cancellation is not guaranteed — the server may not be able to cancel the query if it’s in a non-interruptible state. The cancellation request itself is always acknowledged.

Errors

Returns an error if the TCP connection cannot be established or the cancellation message cannot be sent.

pub async fn cancel_with_timeout(&self, timeout: Option<Duration>) -> Result<()>

Send a cancellation request with an optional connection timeout.

pub fn process_id(&self) -> i32

Returns the process ID of the backend this token can cancel.

pub fn secret_key(&self) -> i32

Returns the secret key of the backend this token can cancel.

Trait Implementations

impl Clone for CancelToken

fn clone(&self) -> CancelToken

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CancelToken

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.