From 338af5055cc9616fbba8eda96fafb24561cbb01e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Botond=20D=C3=A9nes?= <bdenes@scylladb.com>
Date: Tue, 30 Apr 2024 01:36:56 -0400
Subject: [PATCH] replica/database: introduce
 foreach_reader_concurrency_semaphore

Currently we have a single method -- detach_column_family() -- which
does something with each semaphore. Soon there will be another one.
Introduce a method to do something with all semaphores, to make this
smoother. Enterprise has a different set of semaphores, and this will
reduce friction.
---
 replica/database.cc | 12 +++++++++---
 replica/database.hh |  2 ++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/replica/database.cc b/replica/database.cc
index a69214280f..9a9f70c953 100644
--- a/replica/database.cc
+++ b/replica/database.cc
@@ -976,9 +976,9 @@ future<> database::detach_column_family(table& cf) {
     co_await remove(cf);
     cf.clear_views();
     co_await cf.await_pending_ops();
-    for (auto* sem : {&_read_concurrency_sem, &_streaming_concurrency_sem, &_compaction_concurrency_sem, &_system_read_concurrency_sem}) {
-        co_await sem->evict_inactive_reads_for_table(uuid);
-    }
+    co_await foreach_reader_concurrency_semaphore([uuid] (reader_concurrency_semaphore& sem) -> future<> {
+        co_await sem.evict_inactive_reads_for_table(uuid);
+    });
 }
 
 global_table_ptr::global_table_ptr() {
@@ -1696,6 +1696,12 @@ bool database::is_user_semaphore(const reader_concurrency_semaphore& semaphore)
         && &semaphore != &_system_read_concurrency_sem;
 }
 
+future<> database::foreach_reader_concurrency_semaphore(std::function<future<>(reader_concurrency_semaphore&)> func) {
+    for (auto* sem : {&_read_concurrency_sem, &_streaming_concurrency_sem, &_compaction_concurrency_sem, &_system_read_concurrency_sem}) {
+        co_await func(*sem);
+    }
+}
+
 std::ostream& operator<<(std::ostream& out, const column_family& cf) {
     fmt::print(out, "{{column_family: {}/{}}}", cf._schema->ks_name(), cf._schema->cf_name());
     return out;
diff --git a/replica/database.hh b/replica/database.hh
index 1790fe64b7..e69218ed28 100644
--- a/replica/database.hh
+++ b/replica/database.hh
@@ -1551,6 +1551,8 @@ private:
     void drop_keyspace(const sstring& name);
     future<> update_keyspace(const keyspace_metadata& tmp_ksm);
     static future<> modify_keyspace_on_all_shards(sharded<database>& sharded_db, std::function<future<>(replica::database&)> func, std::function<future<>(replica::database&)> notifier);
+
+    future<> foreach_reader_concurrency_semaphore(std::function<future<>(reader_concurrency_semaphore&)> func);
 public:
     static table_schema_version empty_version;