Pool Postgres connections

crates/factor-outbound-pg/Cargo.toml

@@ -7,6 +7,7 @@ edition = { workspace = true }
 [dependencies]
 anyhow = { workspace = true }
 chrono = "0.4"
+deadpool-postgres = { version = "0.14", features = ["rt_tokio_1"] }
 native-tls = "0.2"
 postgres-native-tls = "0.5"
 spin-core = { path = "../core" }

crates/factor-outbound-pg/src/client.rs

@@ -1,20 +1,83 @@
-use anyhow::{anyhow, Result};
+use anyhow::{anyhow, Context, Result};
 use native_tls::TlsConnector;
 use postgres_native_tls::MakeTlsConnector;
 use spin_world::async_trait;
 use spin_world::spin::postgres::postgres::{
     self as v3, Column, DbDataType, DbValue, ParameterValue, RowSet,
 };
 use tokio_postgres::types::Type;
-use tokio_postgres::{config::SslMode, types::ToSql, Row};
-use tokio_postgres::{Client as TokioClient, NoTls, Socket};
+use tokio_postgres::{config::SslMode, types::ToSql, NoTls, Row};
+
+const CONNECTION_POOL_SIZE: usize = 64;
 
 #[async_trait]
-pub trait Client {
-    async fn build_client(address: &str) -> Result<Self>
-    where
-        Self: Sized;
+pub trait ClientFactory: Send + Sync {
+    type Client: Client + Send + Sync + 'static;
+    fn new() -> Self;
+    async fn build_client(&mut self, address: &str) -> Result<Self::Client>;
+}
+
+pub struct PooledTokioClientFactory {
+    pools: std::collections::HashMap<String, deadpool_postgres::Pool>,
+}
+
+#[async_trait]
+impl ClientFactory for PooledTokioClientFactory {
+    type Client = deadpool_postgres::Object;
+    fn new() -> Self {
+        Self {
+            pools: Default::default(),
+        }
+    }
+    async fn build_client(&mut self, address: &str) -> Result<Self::Client> {
+        let pool_entry = self.pools.entry(address.to_owned());
+        let pool = match pool_entry {
+            std::collections::hash_map::Entry::Occupied(entry) => entry.into_mut(),
+            std::collections::hash_map::Entry::Vacant(entry) => {
+                let pool = create_connection_pool(address)
+                    .context("establishing PostgreSQL connection pool")?;
+                entry.insert(pool)
+            }
+        };
+
+        Ok(pool.get().await?)
+    }
+}
+
+fn create_connection_pool(address: &str) -> Result<deadpool_postgres::Pool> {
+    let config = address
+        .parse::<tokio_postgres::Config>()
+        .context("parsing Postgres connection string")?;
+
+    tracing::debug!("Build new connection: {}", address);
+
+    // TODO: This is slower but safer. Is it the right tradeoff?
+    // https://docs.rs/deadpool-postgres/latest/deadpool_postgres/enum.RecyclingMethod.html
+    let mgr_config = deadpool_postgres::ManagerConfig {
+        recycling_method: deadpool_postgres::RecyclingMethod::Clean,
+    };
+
+    let mgr = if config.get_ssl_mode() == SslMode::Disable {
+        deadpool_postgres::Manager::from_config(config, NoTls, mgr_config)
+    } else {
+        let builder = TlsConnector::builder();
+        let connector = MakeTlsConnector::new(builder.build()?);
+        deadpool_postgres::Manager::from_config(config, connector, mgr_config)
+    };
 
+    // TODO: what is our max size heuristic?  Should this be passed in soe that different
+    // hosts can manage it according to their needs?  Will a plain number suffice for
+    // sophisticated hosts anyway?
+    let pool = deadpool_postgres::Pool::builder(mgr)
+        .max_size(CONNECTION_POOL_SIZE)
+        .build()
+        .context("building Postgres connection pool")?;
+
+    Ok(pool)
+}
+
+#[async_trait]
+pub trait Client {
     async fn execute(
         &self,
         statement: String,
@@ -29,28 +92,7 @@ pub trait Client {
 }
 
 #[async_trait]
-impl Client for TokioClient {
-    async fn build_client(address: &str) -> Result<Self>
-    where
-        Self: Sized,
-    {
-        let config = address.parse::<tokio_postgres::Config>()?;
-
-        tracing::debug!("Build new connection: {}", address);
-
-        if config.get_ssl_mode() == SslMode::Disable {
-            let (client, connection) = config.connect(NoTls).await?;
-            spawn_connection(connection);
-            Ok(client)
-        } else {
-            let builder = TlsConnector::builder();
-            let connector = MakeTlsConnector::new(builder.build()?);
-            let (client, connection) = config.connect(connector).await?;
-            spawn_connection(connection);
-            Ok(client)
-        }
-    }
-
+impl Client for deadpool_postgres::Object {
     async fn execute(
         &self,
         statement: String,
@@ -67,7 +109,8 @@ impl Client for TokioClient {
             .map(|b| b.as_ref() as &(dyn ToSql + Sync))
             .collect();
 
-        self.execute(&statement, params_refs.as_slice())
+        self.as_ref()
+            .execute(&statement, params_refs.as_slice())
             .await
             .map_err(|e| v3::Error::QueryFailed(format!("{:?}", e)))
     }
@@ -89,6 +132,7 @@ impl Client for TokioClient {
             .collect();
 
         let results = self
+            .as_ref()
             .query(&statement, params_refs.as_slice())
             .await
             .map_err(|e| v3::Error::QueryFailed(format!("{:?}", e)))?;
@@ -111,17 +155,6 @@ impl Client for TokioClient {
     }
 }
 
-fn spawn_connection<T>(connection: tokio_postgres::Connection<Socket, T>)
-where
-    T: tokio_postgres::tls::TlsStream + std::marker::Unpin + std::marker::Send + 'static,
-{
-    tokio::spawn(async move {
-        if let Err(e) = connection.await {
-            tracing::error!("Postgres connection error: {}", e);
-        }
-    });
-}
-
 fn to_sql_parameter(value: &ParameterValue) -> Result<Box<dyn ToSql + Send + Sync>> {
     match value {
         ParameterValue::Boolean(v) => Ok(Box::new(*v)),

crates/factor-outbound-pg/src/host.rs

@@ -9,17 +9,20 @@ use tracing::field::Empty;
 use tracing::instrument;
 use tracing::Level;
 
-use crate::client::Client;
+use crate::client::{Client, ClientFactory};
 use crate::InstanceState;
 
-impl<C: Client> InstanceState<C> {
+impl<CF: ClientFactory> InstanceState<CF> {
     async fn open_connection<Conn: 'static>(
         &mut self,
         address: &str,
     ) -> Result<Resource<Conn>, v3::Error> {
         self.connections
             .push(
-                C::build_client(address)
+                self.client_factory
+                    .write()
+                    .await
+                    .build_client(address)
                     .await
                     .map_err(|e| v3::Error::ConnectionFailed(format!("{e:?}")))?,
             )
@@ -30,7 +33,7 @@ impl<C: Client> InstanceState<C> {
     async fn get_client<Conn: 'static>(
         &mut self,
         connection: Resource<Conn>,
-    ) -> Result<&C, v3::Error> {
+    ) -> Result<&CF::Client, v3::Error> {
         self.connections
             .get(connection.rep())
             .ok_or_else(|| v3::Error::ConnectionFailed("no connection found".into()))
@@ -71,8 +74,8 @@ fn v2_params_to_v3(
     params.into_iter().map(|p| p.try_into()).collect()
 }
 
-impl<C: Send + Sync + Client> spin_world::spin::postgres::postgres::HostConnection
-    for InstanceState<C>
+impl<CF: ClientFactory + Send + Sync> spin_world::spin::postgres::postgres::HostConnection
+    for InstanceState<CF>
 {
     #[instrument(name = "spin_outbound_pg.open", skip(self, address), err(level = Level::INFO), fields(otel.kind = "client", db.system = "postgresql", db.address = Empty, server.port = Empty, db.namespace = Empty))]
     async fn open(&mut self, address: String) -> Result<Resource<v3::Connection>, v3::Error> {
@@ -122,13 +125,13 @@ impl<C: Send + Sync + Client> spin_world::spin::postgres::postgres::HostConnecti
     }
 }
 
-impl<C: Send> v2_types::Host for InstanceState<C> {
+impl<CF: ClientFactory + Send> v2_types::Host for InstanceState<CF> {
     fn convert_error(&mut self, error: v2::Error) -> Result<v2::Error> {
         Ok(error)
     }
 }
 
-impl<C: Send + Sync + Client> v3::Host for InstanceState<C> {
+impl<CF: Send + Sync + ClientFactory> v3::Host for InstanceState<CF> {
     fn convert_error(&mut self, error: v3::Error) -> Result<v3::Error> {
         Ok(error)
     }
@@ -152,9 +155,9 @@ macro_rules! delegate {
     }};
 }
 
-impl<C: Send + Sync + Client> v2::Host for InstanceState<C> {}
+impl<CF: Send + Sync + ClientFactory> v2::Host for InstanceState<CF> {}
 
-impl<C: Send + Sync + Client> v2::HostConnection for InstanceState<C> {
+impl<CF: Send + Sync + ClientFactory> v2::HostConnection for InstanceState<CF> {
     #[instrument(name = "spin_outbound_pg.open", skip(self, address), err(level = Level::INFO), fields(otel.kind = "client", db.system = "postgresql", db.address = Empty, server.port = Empty, db.namespace = Empty))]
     async fn open(&mut self, address: String) -> Result<Resource<v2::Connection>, v2::Error> {
         spin_factor_outbound_networking::record_address_fields(&address);
@@ -206,7 +209,7 @@ impl<C: Send + Sync + Client> v2::HostConnection for InstanceState<C> {
     }
 }
 
-impl<C: Send + Sync + Client> v1::Host for InstanceState<C> {
+impl<CF: Send + Sync + ClientFactory> v1::Host for InstanceState<CF> {
     async fn execute(
         &mut self,
         address: String,

crates/factor-outbound-pg/src/lib.rs

@@ -1,21 +1,23 @@
 pub mod client;
 mod host;
 
-use client::Client;
+use std::sync::Arc;
+
+use client::ClientFactory;
 use spin_factor_outbound_networking::{OutboundAllowedHosts, OutboundNetworkingFactor};
 use spin_factors::{
     anyhow, ConfigureAppContext, Factor, PrepareContext, RuntimeFactors, SelfInstanceBuilder,
 };
-use tokio_postgres::Client as PgClient;
+use tokio::sync::RwLock;
 
-pub struct OutboundPgFactor<C = PgClient> {
-    _phantom: std::marker::PhantomData<C>,
+pub struct OutboundPgFactor<CF = crate::client::PooledTokioClientFactory> {
+    _phantom: std::marker::PhantomData<CF>,
 }
 
-impl<C: Send + Sync + Client + 'static> Factor for OutboundPgFactor<C> {
+impl<CF: ClientFactory + Send + Sync + 'static> Factor for OutboundPgFactor<CF> {
     type RuntimeConfig = ();
-    type AppState = ();
-    type InstanceBuilder = InstanceState<C>;
+    type AppState = Arc<RwLock<CF>>;
+    type InstanceBuilder = InstanceState<CF>;
 
     fn init<T: Send + 'static>(
         &mut self,
@@ -31,7 +33,7 @@ impl<C: Send + Sync + Client + 'static> Factor for OutboundPgFactor<C> {
         &self,
         _ctx: ConfigureAppContext<T, Self>,
     ) -> anyhow::Result<Self::AppState> {
-        Ok(())
+        Ok(Arc::new(RwLock::new(CF::new())))
     }
 
     fn prepare<T: RuntimeFactors>(
@@ -43,6 +45,7 @@ impl<C: Send + Sync + Client + 'static> Factor for OutboundPgFactor<C> {
             .allowed_hosts();
         Ok(InstanceState {
             allowed_hosts,
+            client_factory: ctx.app_state().clone(),
             connections: Default::default(),
         })
     }
@@ -62,9 +65,10 @@ impl<C> OutboundPgFactor<C> {
     }
 }
 
-pub struct InstanceState<C> {
+pub struct InstanceState<CF: ClientFactory> {
     allowed_hosts: OutboundAllowedHosts,
-    connections: spin_resource_table::Table<C>,
+    client_factory: Arc<RwLock<CF>>,
+    connections: spin_resource_table::Table<CF::Client>,
 }
 
-impl<C: Send + 'static> SelfInstanceBuilder for InstanceState<C> {}
+impl<CF: ClientFactory + Send + 'static> SelfInstanceBuilder for InstanceState<CF> {}

crates/factor-outbound-pg/tests/factor_test.rs

@@ -1,6 +1,7 @@
 use anyhow::{bail, Result};
 use spin_factor_outbound_networking::OutboundNetworkingFactor;
 use spin_factor_outbound_pg::client::Client;
+use spin_factor_outbound_pg::client::ClientFactory;
 use spin_factor_outbound_pg::OutboundPgFactor;
 use spin_factor_variables::VariablesFactor;
 use spin_factors::{anyhow, RuntimeFactors};
@@ -15,14 +16,14 @@ use spin_world::spin::postgres::postgres::{ParameterValue, RowSet};
 struct TestFactors {
     variables: VariablesFactor,
     networking: OutboundNetworkingFactor,
-    pg: OutboundPgFactor<MockClient>,
+    pg: OutboundPgFactor<MockClientFactory>,
 }
 
 fn factors() -> TestFactors {
     TestFactors {
         variables: VariablesFactor::default(),
         networking: OutboundNetworkingFactor::new(),
-        pg: OutboundPgFactor::<MockClient>::new(),
+        pg: OutboundPgFactor::<MockClientFactory>::new(),
     }
 }
 
@@ -104,17 +105,22 @@ async fn exercise_query() -> anyhow::Result<()> {
 }
 
 // TODO: We can expand this mock to track calls and simulate return values
+pub struct MockClientFactory {}
 pub struct MockClient {}
 
 #[async_trait]
-impl Client for MockClient {
-    async fn build_client(_address: &str) -> anyhow::Result<Self>
-    where
-        Self: Sized,
-    {
+impl ClientFactory for MockClientFactory {
+    type Client = MockClient;
+    fn new() -> Self {
+        Self {}
+    }
+    async fn build_client(&mut self, _address: &str) -> Result<Self::Client> {
         Ok(MockClient {})
     }
+}
 
+#[async_trait]
+impl Client for MockClient {
     async fn execute(
         &self,
         _statement: String,