From 1cefcae2a95402055f2f392a1dd0dce580a20d90 Mon Sep 17 00:00:00 2001
From: Casey Bodley <cbodley@redhat.com>
Date: Thu, 24 Jul 2025 09:25:41 -0400
Subject: [PATCH] common/async: remove null_yield support for
 max_concurrent_for_each()

max_concurrent_for_each() is a thin wrapper around spawn_throttle.
remove its support for null_yield too

Signed-off-by: Casey Bodley <cbodley@redhat.com>
---
 src/common/async/max_concurrent_for_each.h    | 15 ++--
 .../test_async_max_concurrent_for_each.cc     | 78 -------------------
 2 files changed, 7 insertions(+), 86 deletions(-)

diff --git a/src/common/async/max_concurrent_for_each.h b/src/common/async/max_concurrent_for_each.h
index dd272b957eb0a..da8b5c0d9cffb 100644
--- a/src/common/async/max_concurrent_for_each.h
+++ b/src/common/async/max_concurrent_for_each.h
@@ -22,7 +22,6 @@
 #include <boost/asio/spawn.hpp>
 #include "cancel_on_error.h"
 #include "co_throttle.h"
-#include "yield_context.h"
 #include "spawn_throttle.h"
 
 namespace ceph::async {
@@ -37,10 +36,10 @@ namespace ceph::async {
 /// \code
 /// void child(task& t, boost::asio::yield_context yield);
 ///
-/// void parent(std::span<task> tasks, optional_yield y)
+/// void parent(std::span<task> tasks, boost::asio::yield_context yield)
 /// {
 ///   // process all tasks, up to 10 at a time
-///   max_concurrent_for_each(tasks, 10, y, child);
+///   max_concurrent_for_each(tasks, 10, yield, child);
 /// }
 /// \endcode
 template <typename Iterator, typename Sentinel, typename Func,
@@ -51,14 +50,14 @@ template <typename Iterator, typename Sentinel, typename Func,
 void max_concurrent_for_each(Iterator begin,
                              Sentinel end,
                              size_t max_concurrent,
-                             optional_yield y,
+                             boost::asio::yield_context yield,
                              Func&& func,
                              cancel_on_error on_error = cancel_on_error::none)
 {
   if (begin == end) {
     return;
   }
-  auto throttle = spawn_throttle{y, max_concurrent, on_error};
+  auto throttle = spawn_throttle{yield, max_concurrent, on_error};
   for (Iterator i = begin; i != end; ++i) {
     throttle.spawn([&func, &val = *i] (boost::asio::yield_context yield) {
         func(val, yield);
@@ -74,13 +73,13 @@ template <typename Range, typename Func,
               std::invocable<Func, Reference, boost::asio::yield_context>)
 auto max_concurrent_for_each(Range&& range,
                              size_t max_concurrent,
-                             optional_yield y,
+                             boost::asio::yield_context yield,
                              Func&& func,
                              cancel_on_error on_error = cancel_on_error::none)
 {
   return max_concurrent_for_each(std::begin(range), std::end(range),
-                                 max_concurrent, y, std::forward<Func>(func),
-                                 on_error);
+                                 max_concurrent, yield,
+                                 std::forward<Func>(func), on_error);
 }
 
 // \overload
diff --git a/src/test/common/test_async_max_concurrent_for_each.cc b/src/test/common/test_async_max_concurrent_for_each.cc
index b0880dfdb8538..1656df5bcb194 100644
--- a/src/test/common/test_async_max_concurrent_for_each.cc
+++ b/src/test/common/test_async_max_concurrent_for_each.cc
@@ -49,84 +49,6 @@ struct null_sentinel {};
 bool operator==(const char* c, null_sentinel) { return !*c; }
 static_assert(std::sentinel_for<null_sentinel, const char*>);
 
-TEST(iterator_null_yield, empty)
-{
-  int* end = nullptr;
-  auto cr = [] (int, asio::yield_context) {};
-  max_concurrent_for_each(end, end, 10, null_yield, cr);
-}
-
-TEST(iterator_null_yield, over_limit)
-{
-  int concurrent = 0;
-  int max_concurrent = 0;
-  int completed = 0;
-
-  auto cr = [&] (int, asio::yield_context yield) {
-    ++concurrent;
-    if (max_concurrent < concurrent) {
-      max_concurrent = concurrent;
-    }
-
-    wait_for(1ms, yield);
-
-    --concurrent;
-    ++completed;
-  };
-
-  constexpr auto arr = std::array{1,2,3,4,5,6,7,8,9,10};
-  max_concurrent_for_each(begin(arr), end(arr), 2, null_yield, cr);
-
-  EXPECT_EQ(0, concurrent);
-  EXPECT_EQ(2, max_concurrent);
-  EXPECT_EQ(10, completed);
-}
-
-TEST(iterator_null_yield, sentinel)
-{
-  const char* begin = "hello";
-  null_sentinel end;
-
-  size_t completed = 0;
-  auto cr = [&completed] (char c, asio::yield_context) { ++completed; };
-  max_concurrent_for_each(begin, end, 10, null_yield, cr);
-  EXPECT_EQ(completed, 5);
-}
-
-TEST(range_null_yield, empty)
-{
-  constexpr std::array<int, 0> arr{};
-  auto cr = [] (int, asio::yield_context) {};
-  max_concurrent_for_each(arr, 10, null_yield, cr);
-}
-
-TEST(range_null_yield, over_limit)
-{
-  int concurrent = 0;
-  int max_concurrent = 0;
-  int completed = 0;
-
-  auto cr = [&] (int, asio::yield_context yield) {
-    ++concurrent;
-    if (max_concurrent < concurrent) {
-      max_concurrent = concurrent;
-    }
-
-    wait_for(1ms, yield);
-
-    --concurrent;
-    ++completed;
-  };
-
-  constexpr auto arr = std::array{1,2,3,4,5,6,7,8,9,10};
-  max_concurrent_for_each(arr, 2, null_yield, cr);
-
-  EXPECT_EQ(0, concurrent);
-  EXPECT_EQ(2, max_concurrent);
-  EXPECT_EQ(10, completed);
-}
-
-
 TEST(iterator_yield, empty)
 {
   int* end = nullptr;
-- 
2.39.5