refactor: use BackendPid instead of BackendKeyData where secret is not required

integration/rust/tests/integration/cancel.rs

@@ -0,0 +1,221 @@
+use std::time::Duration;
+
+use bytes::{BufMut, BytesMut};
+use rust::setup::{admin_tokio, connection_sqlx_direct};
+use sqlx::PgPool;
+use tokio::{io::AsyncWriteExt, net::TcpStream, task::JoinHandle, time::timeout};
+use tokio_postgres::{CancelToken, Error as PgError, NoTls, SimpleQueryMessage};
+
+/// Returns whether `pid` has an active `pg_sleep` query visible in `pg_stat_activity`.
+/// Uses a direct PostgreSQL connection so the result bypasses pgdog completely.
+async fn is_sleeping(direct: &PgPool, pid: i32) -> bool {
+    let count: i64 = sqlx::query_scalar(
+        "SELECT COUNT(*) \
+         FROM pg_stat_activity \
+         WHERE pid = $1 \
+           AND state = 'active' \
+           AND query LIKE '%pg_sleep%'",
+    )
+    .bind(pid)
+    .fetch_one(direct)
+    .await
+    .unwrap();
+    count == 1
+}
+
+/// Connect to pgdog, pin to a specific PG backend via BEGIN, capture the backend pid
+/// via `pg_backend_pid()`, and launch `SELECT pg_sleep(60)` in a background task.
+///
+/// `application_name` is embedded in the connection string so the caller can identify
+/// this connection in `SHOW CLIENTS` if needed.
+///
+/// Returns `(backend_pid, cancel_token, query_handle)`. The caller owns `cancel_token`
+/// and `query_handle`; both must be driven to completion to keep the test clean.
+async fn start_sleeping_connection(
+    application_name: &str,
+) -> (
+    i32,
+    CancelToken,
+    JoinHandle<Result<Vec<SimpleQueryMessage>, PgError>>,
+) {
+    let (client, connection) = tokio_postgres::connect(
+        &format!(
+            "host=127.0.0.1 user=pgdog dbname=pgdog password=pgdog port=6432 application_name={application_name}"
+        ),
+        NoTls,
+    )
+    .await
+    .unwrap();
+
+    tokio::spawn(async move {
+        if let Err(e) = connection.await {
+            eprintln!("pgdog connection error: {}", e);
+        }
+    });
+
+    let cancel_token = client.cancel_token();
+
+    // BEGIN pins the client to one backend for the duration of the transaction.
+    // Without this, transaction-mode pooling may assign a different backend to
+    // pg_sleep than the one whose pid we captured.
+    client.simple_query("BEGIN").await.unwrap();
+
+    let row = client
+        .query_one("SELECT pg_backend_pid()", &[])
+        .await
+        .unwrap();
+    let backend_pid: i32 = row.get(0);
+
+    let handle = tokio::spawn(async move { client.simple_query("SELECT pg_sleep(60)").await });
+
+    (backend_pid, cancel_token, handle)
+}
+
+/// Assert that a query handle returned by `start_sleeping_connection` was cancelled:
+/// it must resolve to SQLSTATE 57014 (canceling statement due to user request).
+async fn assert_cancelled(
+    handle: JoinHandle<Result<Vec<SimpleQueryMessage>, PgError>>,
+    label: &str,
+) {
+    let result = timeout(Duration::from_secs(5), handle)
+        .await
+        .expect(&format!(
+            "{label}: cancelled query did not unblock within 5 seconds"
+        ))
+        .expect(&format!("{label}: task panicked"));
+
+    let err = result.expect_err(&format!(
+        "{label}: query should have been cancelled, but it succeeded"
+    ));
+    let db_err = err.as_db_error().expect(&format!(
+        "{label}: expected a PostgreSQL error, not a network error"
+    ));
+
+    assert_eq!(
+        db_err.code().code(),
+        "57014",
+        "{label}: expected SQLSTATE 57014, got {}",
+        db_err.code().code()
+    );
+}
+
+/// Verify that cancellation is precise: two independent connections both run a long
+/// query and each cancel request stops exactly one of them.
+///
+/// Steps:
+/// 1. Two clients connect through pgdog; each starts `SELECT pg_sleep(60)`.
+/// 2. Both queries are confirmed active on specific PG backends via `pg_stat_activity`.
+/// 3. Cancel connection 1 → only backend 1 stops; backend 2 remains active.
+/// 4. Cancel connection 2 → backend 2 stops.
+#[tokio::test]
+async fn test_cancel_query() {
+    let direct = connection_sqlx_direct().await;
+
+    let (pid1, token1, handle1) = start_sleeping_connection("cancel_test").await;
+    let (pid2, token2, handle2) = start_sleeping_connection("cancel_test").await;
+
+    // Give both queries time to reach their respective backends.
+    tokio::time::sleep(Duration::from_millis(300)).await;
+
+    assert!(
+        is_sleeping(&direct, pid1).await,
+        "connection 1 (backend {pid1}) should be active before any cancel"
+    );
+    assert!(
+        is_sleeping(&direct, pid2).await,
+        "connection 2 (backend {pid2}) should be active before any cancel"
+    );
+
+    // ── Cancel connection 1 ────────────────────────────────────────────────
+    token1.cancel_query(NoTls).await.unwrap();
+
+    // Wait for the client to receive the cancellation error.
+    // By the time the handle resolves, the backend has already stopped.
+    assert_cancelled(handle1, "connection 1").await;
+
+    // Connection 1's backend is gone; connection 2 must still be running.
+    tokio::time::sleep(Duration::from_millis(100)).await;
+    assert!(
+        !is_sleeping(&direct, pid1).await,
+        "backend {pid1} should be idle after cancelling connection 1"
+    );
+    assert!(
+        is_sleeping(&direct, pid2).await,
+        "backend {pid2} should still be active after cancelling connection 1 only"
+    );
+
+    // ── Cancel connection 2 ────────────────────────────────────────────────
+    token2.cancel_query(NoTls).await.unwrap();
+
+    assert_cancelled(handle2, "connection 2").await;
+
+    tokio::time::sleep(Duration::from_millis(100)).await;
+    assert!(
+        !is_sleeping(&direct, pid2).await,
+        "backend {pid2} should be idle after cancelling connection 2"
+    );
+}
+
+/// Verify that a cancel request carrying a wrong pid and secret is silently rejected:
+/// the running query is unaffected and the client does not receive a cancellation error.
+///
+/// pgdog's `verify_cancel` gate must reject the request before it reaches the pool,
+/// so the backend continues executing as if nothing happened.
+#[tokio::test]
+async fn test_cancel_query_wrong_secret() {
+    let direct = connection_sqlx_direct().await;
+    let app_name = "cancel_test_wrong_secret";
+    let (backend_pid, real_cancel_token, query_handle) = start_sleeping_connection(app_name).await;
+
+    // Give the query time to reach the backend.
+    tokio::time::sleep(Duration::from_millis(300)).await;
+
+    assert!(
+        is_sleeping(&direct, backend_pid).await,
+        "query should be running before wrong-secret cancel"
+    );
+
+    // Look up the pgdog client pid from the admin interface.
+    // SHOW CLIENTS exposes the pid (the 'id' column) that pgdog assigned during login —
+    // the same value that was sent in the K message and that verify_cancel checks against.
+    let admin = admin_tokio().await;
+    let messages = admin.simple_query("SHOW CLIENTS").await.unwrap();
+    let pgdog_pid: i32 = messages
+        .iter()
+        .filter_map(|m| match m {
+            SimpleQueryMessage::Row(row) => Some(row),
+            _ => None,
+        })
+        .find(|row| row.get("application_name") == Some(app_name))
+        .expect("connection should appear in SHOW CLIENTS")
+        .get("id")
+        .expect("id column should be present")
+        .parse()
+        .expect("id should be a valid i32");
+
+    // Send a CancelRequest with the real pgdog client pid but a wrong secret.
+    // pgdog will find the client in comms by pid, then reject it because
+    // the secret doesn't match — verify_cancel returns false.
+    let mut raw = TcpStream::connect("127.0.0.1:6432").await.unwrap();
+    let mut buf = BytesMut::new();
+    buf.put_i32(16); // total message length (including the length field)
+    buf.put_i32(80877102); // CancelRequest magic code
+    buf.put_i32(pgdog_pid); // correct pid
+    buf.put_i32(0); // wrong secret
+    raw.write_all(&buf).await.unwrap();
+    // pgdog closes the connection silently after processing; no response is sent.
+    drop(raw);
+
+    // Give pgdog enough time to receive and process the bogus cancel.
+    tokio::time::sleep(Duration::from_millis(300)).await;
+
+    // The query must still be running — the secret mismatch was caught by verify_cancel.
+    assert!(
+        is_sleeping(&direct, backend_pid).await,
+        "query should still be running after wrong-secret cancel — verify_cancel must have rejected it"
+    );
+
+    // Clean up: cancel for real.
+    real_cancel_token.cancel_query(NoTls).await.unwrap();
+    assert_cancelled(query_handle, "wrong-secret test cleanup").await;
+}

integration/rust/tests/integration/mod.rs

@@ -3,6 +3,7 @@ pub mod auth;
 pub mod auto_id;
 pub mod avg;
 pub mod ban;
+pub mod cancel;
 pub mod client_ids;
 pub mod connection_recovery;
 pub mod cross_shard_disabled;

pgdog-postgres-types/src/interface.rs

@@ -48,19 +48,10 @@ impl ToDataRowColumn for i64 {
     }
 }
 
-impl ToDataRowColumn for Option<i64> {
+impl<T: ToDataRowColumn> ToDataRowColumn for Option<T> {
     fn to_data_row_column(&self) -> Data {
         match self {
-            Some(value) => ToDataRowColumn::to_data_row_column(value),
-            None => Data::null(),
-        }
-    }
-}
-
-impl ToDataRowColumn for Option<String> {
-    fn to_data_row_column(&self) -> Data {
-        match self {
-            Some(value) => ToDataRowColumn::to_data_row_column(value),
+            Some(value) => value.to_data_row_column(),
             None => Data::null(),
         }
     }

pgdog/Cargo.toml

@@ -24,7 +24,7 @@ tracing-subscriber = { version = "0.3", features = ["env-filter", "json", "std"]
 tracing-throttle = "0.4"
 parking_lot = "0.12"
 thiserror = "2"
-derive_more = { version = "2", features = ["display", "error"] }
+derive_more = { version = "2", features = ["display", "error", "from", "into"] }
 bytes = "1"
 clap = { version = "4", features = ["derive"] }
 serde = { version = "1", features = ["derive"] }
@@ -77,6 +77,7 @@ azure_identity = "0.34.0"
 azure_core = "0.34.0"
 crc32c = "0.6.8"
 bit-vec = "0.8"
+smallvec = "1"
 reqwest = { version = "0.12", default-features = false, features = ["rustls-tls-webpki-roots-no-provider"] }
 hex = "0.4"
 x509-parser = "0.18"

pgdog/src/admin/server.rs

@@ -9,8 +9,8 @@ use tracing::debug;
 use crate::frontend::ClientRequest;
 use crate::net::messages::command_complete::CommandComplete;
 use crate::net::messages::{ErrorResponse, FromBytes, Protocol, Query, ReadyForQuery};
+use crate::net::ProtocolMessage;
 use crate::net::ToBytes;
-use crate::net::{BackendKeyData, ProtocolMessage};
 
 use super::parser::Parser;
 use super::prelude::Message;
@@ -63,10 +63,7 @@ impl AdminServer {
         self.messages.extend(messages);
         self.messages.push_back(ReadyForQuery::idle().message()?);
 
-        self.messages = std::mem::take(&mut self.messages)
-            .into_iter()
-            .map(|m| m.backend(BackendKeyData::default()))
-            .collect();
+        self.messages = std::mem::take(&mut self.messages).into_iter().collect();
 
         Ok(())
     }

pgdog/src/admin/show_client_memory.rs

@@ -42,7 +42,7 @@ impl Command for ShowClientMemory {
             let user = client.paramters.get_default("user", "postgres");
             let database = client.paramters.get_default("database", user);
 
-            row.add(client.id.pid as i64)
+            row.add(client.key.pid())
                 .add(database)
                 .add(user)
                 .add(client.addr.ip().to_string().as_str())

pgdog/src/admin/show_clients.rs

@@ -77,7 +77,7 @@ impl Command for ShowClients {
             let row = self
                 .filter
                 .clone()
-                .add("id", client.id.pid as i64)
+                .add("id", client.key.pid())
                 .add("user", user)
                 .add("database", client.paramters.get_default("database", user))
                 .add("addr", client.addr.ip().to_string())

pgdog/src/admin/show_server_memory.rs

@@ -36,7 +36,7 @@ impl Command for ShowServerMemory {
         let mut messages = vec![rd.message()?];
 
         let stats = stats();
-        for (_, server) in stats {
+        for server in stats {
             let mut row = DataRow::new();
             let memory = &server.stats.memory;
 
@@ -45,7 +45,7 @@ impl Command for ShowServerMemory {
                 .add(server.addr.user.as_str())
                 .add(server.addr.host.as_str())
                 .add(server.addr.port as i64)
-                .add(server.stats.id.pid as i64)
+                .add(server.stats.id)
                 .add(memory.buffer.reallocs as i64)
                 .add(memory.buffer.reclaims as i64)
                 .add(memory.buffer.bytes_used as i64)

pgdog/src/admin/show_servers.rs

@@ -79,7 +79,7 @@ impl Command for ShowServers {
         let now = Instant::now();
         let now_time = SystemTime::now();
 
-        for (_, server) in stats {
+        for server in stats {
             let age = now.duration_since(server.stats.created_at);
             let request_age = now.duration_since(server.stats.last_used);
             let request_time = now_time - request_age;
@@ -98,11 +98,8 @@ impl Command for ShowServers {
                     format_time(server.stats.created_at_time.into()),
                 )
                 .add("request_time", format_time(request_time.into()))
-                .add("remote_pid", server.stats.id.pid as i64)
-                .add(
-                    "client_id",
-                    server.stats.client_id.map(|client| client.pid as i64),
-                )
+                .add("remote_pid", server.stats.id)
+                .add("client_id", server.stats.client_id)
                 .add("transactions", server.stats.total.transactions)
                 .add("queries", server.stats.total.queries)
                 .add("rollbacks", server.stats.total.rollbacks)

pgdog/src/backend/databases.rs

@@ -23,7 +23,7 @@ use crate::frontend::PreparedStatements;
 use crate::{
     backend::pool::PoolConfig,
     config::{config, load, set, ConfigAndUsers, ManualQuery, Role, User as ConfigUser},
-    net::{messages::BackendKeyData, tls},
+    net::{messages::BackendPid, tls},
 };
 
 use super::{
@@ -399,7 +399,7 @@ impl Databases {
     }
 
     /// Cancel a query running on one of the databases proxied by the pooler.
-    pub async fn cancel(&self, id: &BackendKeyData) -> Result<(), Error> {
+    pub async fn cancel(&self, id: BackendPid) -> Result<(), Error> {
         for cluster in self.databases.values() {
             cluster.cancel(id).await?;
         }

pgdog/src/backend/pool/cluster.rs

@@ -28,7 +28,7 @@ use crate::{
         ShardedTable, User,
     },
     frontend::{ClientRequest, RegexParser},
-    net::{messages::BackendKeyData, Query},
+    net::{messages::BackendPid, Query},
 };
 
 use super::{Address, Config, Error, Guard, MirrorStats, Request, Shard, ShardConfig};
@@ -388,7 +388,7 @@ impl Cluster {
     }
 
     /// Cancel a query executed by one of the shards.
-    pub async fn cancel(&self, id: &BackendKeyData) -> Result<(), super::super::Error> {
+    pub async fn cancel(&self, id: BackendPid) -> Result<(), super::super::Error> {
         for shard in &self.shards {
             shard.cancel(id).await?;
         }