postgres_backend: stop using async_trait

Cargo.lock

@@ -4064,7 +4064,6 @@ name = "postgres_backend"
 version = "0.1.0"
 dependencies = [
  "anyhow",
- "async-trait",
  "bytes",
  "futures",
  "once_cell",

libs/postgres_backend/Cargo.toml

@@ -5,7 +5,6 @@ edition.workspace = true
 license.workspace = true
 
 [dependencies]
-async-trait.workspace = true
 anyhow.workspace = true
 bytes.workspace = true
 futures.workspace = true

libs/postgres_backend/src/lib.rs

@@ -78,7 +78,7 @@ pub fn is_expected_io_error(e: &io::Error) -> bool {
     )
 }
 
-#[async_trait::async_trait]
+#[allow(async_fn_in_trait)]
 pub trait Handler<IO> {
     /// Handle single query.
     /// postgres_backend will issue ReadyForQuery after calling this (this

libs/postgres_backend/tests/simple_select.rs

@@ -22,7 +22,6 @@ async fn make_tcp_pair() -> (TcpStream, TcpStream) {
 
 struct TestHandler {}
 
-#[async_trait::async_trait]
 impl<IO: AsyncRead + AsyncWrite + Unpin + Send> Handler<IO> for TestHandler {
     // return single col 'hey' for any query
     async fn process_query(

pageserver/src/page_service.rs

@@ -1478,7 +1478,6 @@ impl PageServerHandler {
     }
 }
 
-#[async_trait::async_trait]
 impl<IO> postgres_backend::Handler<IO> for PageServerHandler
 where
     IO: AsyncRead + AsyncWrite + Send + Sync + Unpin,

proxy/src/console/mgmt.rs

@@ -75,7 +75,6 @@ pub type ComputeReady = DatabaseInfo;
 
 // TODO: replace with an http-based protocol.
 struct MgmtHandler;
-#[async_trait::async_trait]
 impl postgres_backend::Handler<tokio::net::TcpStream> for MgmtHandler {
     async fn process_query(
         &mut self,

safekeeper/src/handler.rs

@@ -95,7 +95,6 @@ fn cmd_to_string(cmd: &SafekeeperPostgresCommand) -> &str {
     }
 }
 
-#[async_trait::async_trait]
 impl<IO: AsyncRead + AsyncWrite + Unpin + Send> postgres_backend::Handler<IO>
     for SafekeeperPostgresHandler
 {