[proxy] replace the batch cancellation queue, shorten the TTL for cancel keys (#11943)

See #11942 

Idea: 
* if connections are short lived, they can get enqueued and then also
remove themselves later if they never made it to redis. This reduces the
load on the queue.
* short lived connections (<10m, most?) will only issue 1 command, we
remove the delete command and rely on ttl.
* we can enqueue as many commands as we want, as we can always cancel
the enqueue, thanks to the ~~intrusive linked lists~~ `BTreeMap`.

libs/proxy/tokio-postgres2/src/cancel_query.rs

@@ -1,5 +1,3 @@
-use std::io;
-
 use tokio::net::TcpStream;
 
 use crate::client::SocketConfig;
@@ -8,7 +6,7 @@ use crate::tls::MakeTlsConnect;
 use crate::{Error, cancel_query_raw, connect_socket};
 
 pub(crate) async fn cancel_query<T>(
-    config: Option<SocketConfig>,
+    config: SocketConfig,
     ssl_mode: SslMode,
     tls: T,
     process_id: i32,
@@ -17,16 +15,6 @@ pub(crate) async fn cancel_query<T>(
 where
     T: MakeTlsConnect<TcpStream>,
 {
-    let config = match config {
-        Some(config) => config,
-        None => {
-            return Err(Error::connect(io::Error::new(
-                io::ErrorKind::InvalidInput,
-                "unknown host",
-            )));
-        }
-    };
-
     let hostname = match &config.host {
         Host::Tcp(host) => &**host,
     };

libs/proxy/tokio-postgres2/src/cancel_token.rs

@@ -7,11 +7,16 @@ use crate::config::SslMode;
 use crate::tls::{MakeTlsConnect, TlsConnect};
 use crate::{Error, cancel_query, cancel_query_raw};
 
-/// The capability to request cancellation of in-progress queries on a
-/// connection.
-#[derive(Clone, Serialize, Deserialize)]
+/// A cancellation token that allows easy cancellation of a query.
+#[derive(Clone)]
 pub struct CancelToken {
-    pub socket_config: Option<SocketConfig>,
+    pub socket_config: SocketConfig,
+    pub raw: RawCancelToken,
+}
+
+/// A raw cancellation token that allows cancellation of a query, given a fresh connection to postgres.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RawCancelToken {
     pub ssl_mode: SslMode,
     pub process_id: i32,
     pub secret_key: i32,
@@ -36,14 +41,16 @@ impl CancelToken {
     {
         cancel_query::cancel_query(
             self.socket_config.clone(),
-            self.ssl_mode,
+            self.raw.ssl_mode,
             tls,
-            self.process_id,
-            self.secret_key,
+            self.raw.process_id,
+            self.raw.secret_key,
         )
         .await
     }
+}
 
+impl RawCancelToken {
     /// Like `cancel_query`, but uses a stream which is already connected to the server rather than opening a new
     /// connection itself.
     pub async fn cancel_query_raw<S, T>(&self, stream: S, tls: T) -> Result<(), Error>

libs/proxy/tokio-postgres2/src/client.rs

@@ -12,6 +12,7 @@ use postgres_protocol2::message::frontend;
 use serde::{Deserialize, Serialize};
 use tokio::sync::mpsc;
 
+use crate::cancel_token::RawCancelToken;
 use crate::codec::{BackendMessages, FrontendMessage};
 use crate::config::{Host, SslMode};
 use crate::query::RowStream;
@@ -331,10 +332,12 @@ impl Client {
     /// connection associated with this client.
     pub fn cancel_token(&self) -> CancelToken {
         CancelToken {
-            socket_config: Some(self.socket_config.clone()),
-            ssl_mode: self.ssl_mode,
-            process_id: self.process_id,
-            secret_key: self.secret_key,
+            socket_config: self.socket_config.clone(),
+            raw: RawCancelToken {
+                ssl_mode: self.ssl_mode,
+                process_id: self.process_id,
+                secret_key: self.secret_key,
+            },
         }
     }
 

libs/proxy/tokio-postgres2/src/lib.rs

@@ -3,7 +3,7 @@
 
 use postgres_protocol2::message::backend::ReadyForQueryBody;
 
-pub use crate::cancel_token::CancelToken;
+pub use crate::cancel_token::{CancelToken, RawCancelToken};
 pub use crate::client::{Client, SocketConfig};
 pub use crate::config::Config;
 pub use crate::connect_raw::RawConnection;