From db1d3cc342da2abc5da2a32eb6e4d2fba5052d50 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Zakrzewski?= <pawel.zakrzewski@scylladb.com>
Date: Sun, 22 Sep 2024 12:53:33 +0200
Subject: [PATCH] auth: coroutinize the standard_role_manager start() function

This change is a preparation for the next change. Moving to coroutines
makes the code more readable and easier to process.

(cherry picked from commit 04fc82620bca39ad7f14b966365e238f6be745bf)
---
 auth/standard_role_manager.cc | 50 ++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 24 deletions(-)

diff --git a/auth/standard_role_manager.cc b/auth/standard_role_manager.cc
index 1fe925385b..ef36de5fed 100644
--- a/auth/standard_role_manager.cc
+++ b/auth/standard_role_manager.cc
@@ -241,35 +241,37 @@ future<> standard_role_manager::migrate_legacy_metadata() {
 }
 
 future<> standard_role_manager::start() {
-    return once_among_shards([this] {
-        return futurize_invoke([this] () {
-            if (legacy_mode(_qp)) {
-                return create_legacy_metadata_tables_if_missing();
-            }
-            return make_ready_future<>();
-        }).then([this] {
-            _stopped = auth::do_after_system_ready(_as, [this] {
-                return seastar::async([this] {
-                    if (legacy_mode(_qp)) {
-                        _migration_manager.wait_for_schema_agreement(_qp.db().real_database(), db::timeout_clock::time_point::max(), &_as).get();
+    return once_among_shards([this] () -> future<> {
+        if (legacy_mode(_qp)) {
+            co_await create_legacy_metadata_tables_if_missing();
+        }
 
-                        if (any_nondefault_role_row_satisfies(_qp, &has_can_login).get()) {
-                            if (legacy_metadata_exists()) {
-                                log.warn("Ignoring legacy user metadata since nondefault roles already exist.");
-                            }
-
-                            return;
-                        }
+        auto handler = [this] () -> future<> {
+            try {
+                if (legacy_mode(_qp)) {
+                    co_await _migration_manager.wait_for_schema_agreement(_qp.db().real_database(), db::timeout_clock::time_point::max(), &_as);
 
+                    if (co_await any_nondefault_role_row_satisfies(_qp, &has_can_login)) {
                         if (legacy_metadata_exists()) {
-                            migrate_legacy_metadata().get();
-                            return;
+                            log.warn("Ignoring legacy user metadata since nondefault roles already exist.");
                         }
+                        co_return;
                     }
-                    create_default_role_if_missing().get();
-                });
-            });
-        });
+
+                    if (legacy_metadata_exists()) {
+                        co_await migrate_legacy_metadata();
+                        co_return;
+                    }
+                }
+                co_await create_default_role_if_missing();
+            } catch (...) {
+                log.error("Failed to create default role: unknown error");
+                throw;
+            }
+        };
+
+        _stopped = auth::do_after_system_ready(_as, handler);
+        co_return;
     });
 }