chore/enterpriseportal: properly close DB handle (#63426)

Adds a clean shutdown for our primary DB handle, and removes some unused
code.

## Test plan

`sg run enterprise-portal` and stop it

Author: bobheadxi

cmd/enterprise-portal/internal/database/BUILD.bazel

@@ -15,7 +15,6 @@ go_library(
         "//lib/errors",
         "//lib/managedservicesplatform/runtime",
         "//lib/redislock",
-        "@com_github_jackc_pgx_v5//:pgx",
         "@com_github_jackc_pgx_v5//pgxpool",
         "@com_github_redis_go_redis_v9//:go-redis",
         "@com_github_sourcegraph_log//:log",

cmd/enterprise-portal/internal/database/database.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"os"
 
-	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/redis/go-redis/v9"
 	"github.com/sourcegraph/log"
@@ -52,27 +51,8 @@ func NewHandle(ctx context.Context, logger log.Logger, contract runtime.Contract
 	return &DB{db: pool}, nil
 }
 
-// transaction executes the given function within a transaction. If the function
-// returns an error, the transaction will be rolled back.
-func transaction(ctx context.Context, db *pgxpool.Pool, fn func(tx pgx.Tx) error) (err error) {
-	tx, err := db.Begin(ctx)
-	if err != nil {
-		return errors.Wrap(err, "begin")
-	}
-	defer func() {
-		rollbackErr := tx.Rollback(ctx)
-		// Only return the rollback error if there is no other error.
-		if err == nil {
-			err = errors.Wrap(rollbackErr, "rollback")
-		}
-	}()
-
-	if err = fn(tx); err != nil {
-		return err
-	}
-
-	if err = tx.Commit(ctx); err != nil {
-		return errors.Wrap(err, "commit")
-	}
-	return nil
+// Close closes all connections in the pool and rejects future Acquire calls.
+// Blocks until all connections are returned to pool and closed.
+func (db *DB) Close() {
+	db.db.Close()
 }

cmd/enterprise-portal/service/service.go

@@ -166,24 +166,39 @@ func (Service) Initialize(ctx context.Context, logger log.Logger, contract runti
 		},
 	)
 	return background.LIFOStopRoutine{
-		background.CallbackRoutine{
-			NameFunc: func() string { return "close IAM client" },
-			StopFunc: func(context.Context) error {
-				closeIAMClient()
-				return nil
+		// Everything else can be stopped in conjunction
+		background.CombinedRoutine{
+			background.CallbackRoutine{
+				NameFunc: func() string { return "close IAM client" },
+				StopFunc: func(context.Context) error {
+					closeIAMClient()
+					return nil
+				},
 			},
-		},
-		background.CallbackRoutine{
-			NameFunc: func() string { return "close dotcom database connection pool" },
-			StopFunc: func(context.Context) error {
-				start := time.Now()
-				// NOTE: If we simply shut down, some in-fly requests may be dropped as the
-				// service exits, so we attempt to gracefully shutdown first.
-				dotcomDB.Close()
-				logger.Info("database connection pool closed", log.Duration("elapsed", time.Since(start)))
-				return nil
+			background.CallbackRoutine{
+				NameFunc: func() string { return "close database handle" },
+				StopFunc: func(context.Context) error {
+					start := time.Now()
+					// NOTE: If we simply shut down, some in-fly requests may be dropped as the
+					// service exits, so we attempt to gracefully shutdown first.
+					dbHandle.Close()
+					logger.Info("database handle closed", log.Duration("elapsed", time.Since(start)))
+					return nil
+				},
+			},
+			background.CallbackRoutine{
+				NameFunc: func() string { return "close dotcom database connection pool" },
+				StopFunc: func(context.Context) error {
+					start := time.Now()
+					// NOTE: If we simply shut down, some in-fly requests may be dropped as the
+					// service exits, so we attempt to gracefully shutdown first.
+					dotcomDB.Close()
+					logger.Info("dotcom database connection pool closed", log.Duration("elapsed", time.Since(start)))
+					return nil
+				},
 			},
 		},
-		server, // stop server first
+		// Stop server first
+		server,
 	}, nil
 }