msg/async/ProtocolV[12]: reverse the std::map sort order

This allows eliminating one lookup in `_get_next_outgoing()` because
we can pass the iterator instead of the key to `erase()`.

Signed-off-by: Max Kellermann <max.kellermann@ionos.com>

4 files changed, 16 insertions, 6 deletions

diff --git a/src/msg/async/ProtocolV1.cc b/src/msg/async/ProtocolV1.cc
index fe8f7eb43ca..1a6a2e6e688 100644
--- a/src/msg/async/ProtocolV1.cc
+++ b/src/msg/async/ProtocolV1.cc
@@ -1326,12 +1326,12 @@ void ProtocolV1::reset_recv_state()
 ProtocolV1::out_q_entry_t ProtocolV1::_get_next_outgoing() {
   out_q_entry_t out_entry;
   if (!out_q.empty()) {
-    const auto it = out_q.rbegin();
+    const auto it = out_q.begin();
     ceph_assert(!it->second.empty());
     const auto p = it->second.begin();
     out_entry = *p;
     it->second.erase(p);
-    if (it->second.empty()) out_q.erase(it->first);
+    if (it->second.empty()) out_q.erase(it);
   }
   return out_entry;
 }
diff --git a/src/msg/async/ProtocolV1.h b/src/msg/async/ProtocolV1.h
index 1b7c1d2b5f8..63bc1cd0946 100644
--- a/src/msg/async/ProtocolV1.h
+++ b/src/msg/async/ProtocolV1.h
@@ -112,7 +112,12 @@ protected:
     bool is_prepared {false};
   };
   // priority queue for outbound msgs
-  std::map<int, std::list<out_q_entry_t>> out_q;
+
+  /**
+   * A queue for each priority value, highest priority first.
+   */
+  std::map<int, std::list<out_q_entry_t>, std::greater<int>> out_q;
+
   bool keepalive;
   bool write_in_progress = false;
 
diff --git a/src/msg/async/ProtocolV2.cc b/src/msg/async/ProtocolV2.cc
index 7e6e2ec0d87..463b9b84191 100644
--- a/src/msg/async/ProtocolV2.cc
+++ b/src/msg/async/ProtocolV2.cc
@@ -508,13 +508,13 @@ ProtocolV2::out_queue_entry_t ProtocolV2::_get_next_outgoing() {
   out_queue_entry_t out_entry;
 
   if (!out_queue.empty()) {
-    auto it = out_queue.rbegin();
+    auto it = out_queue.begin();
     auto& entries = it->second;
     ceph_assert(!entries.empty());
     out_entry = entries.front();
     entries.pop_front();
     if (entries.empty()) {
-      out_queue.erase(it->first);
+      out_queue.erase(it);
     }
   }
   return out_entry;
diff --git a/src/msg/async/ProtocolV2.h b/src/msg/async/ProtocolV2.h
index 6441866fea4..78e3c49436b 100644
--- a/src/msg/async/ProtocolV2.h
+++ b/src/msg/async/ProtocolV2.h
@@ -93,7 +93,12 @@ private:
     bool is_prepared {false};
     Message* m {nullptr};
   };
-  std::map<int, std::list<out_queue_entry_t>> out_queue;
+
+  /**
+   * A queue for each priority value, highest priority first.
+   */
+  std::map<int, std::list<out_queue_entry_t>, std::greater<int>> out_queue;
+
   std::list<Message *> sent;
   std::atomic<uint64_t> out_seq{0};
   std::atomic<uint64_t> in_seq{0};