feat: init PgElection with candidate registration (#5209)

* feat: init PgElection

fix: release advisory lock

fix: handle duplicate keys

chore: update comments

fix: unlock if acquired the lock

chore: add TODO and avoid unwrap

refactor: check both lock and expire time, add more comments

chore: fmt

fix: deal with multiple edge cases

feat: init PgElection with candidate registration

chore: fmt

chore: remove

* test: add unit test for pg candidate registration

* test: add unit test for pg candidate registration

* chore: update pg env

* chore: make ci happy

* fix: spawn a background connection thread

* chore: typo

* fix: shadow the election client for now

* fix: fix ci

* chore: readability

* chore: follow review comments

* refactor: use kvbackend for pg election

* chore: rename

* chore: make clippy happy

* refactor: use pg server time instead of local ones

* chore: typo

* chore: rename infancy to leader_infancy for clarification

* chore: clean up

* chore: follow review comments

* chore: follow review comments

* ci: unit test should test all features

* ci: fix

* ci: just test pg

src/common/meta/src/kv_backend/postgres.rs

@@ -16,6 +16,7 @@ use std::any::Any;
 use std::borrow::Cow;
 use std::sync::Arc;
 
+use common_telemetry::error;
 use snafu::ResultExt;
 use tokio_postgres::types::ToSql;
 use tokio_postgres::{Client, NoTls};
@@ -97,7 +98,11 @@ impl PgStore {
         let (client, conn) = tokio_postgres::connect(url, NoTls)
             .await
             .context(ConnectPostgresSnafu)?;
-        tokio::spawn(async move { conn.await.context(ConnectPostgresSnafu) });
+        tokio::spawn(async move {
+            if let Err(e) = conn.await {
+                error!(e; "connection error");
+            }
+        });
         Self::with_pg_client(client).await
     }