msg/async/ProtocolV2: pass desc as std::string_view to write()

All callers really pass a C string literal, and declaring a `std::string` parameter will implicitly create two `std::string` instances: one on the caller's stack, and another one inside write() as parameter to the continuation lambda. This causes considerable and unnecessary overhead. Signed-off-by: Max Kellermann <[email protected]>
smanjara · Oct 7, 2024 · 966920e · 966920e
1 parent 7e5ebb7
commit 966920e
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Showing 2 changed files with 4 additions and 4 deletions.
diff --git a/src/msg/async/ProtocolV2.cc b/src/msg/async/ProtocolV2.cc
@@ -796,7 +796,7 @@ CtPtr ProtocolV2::read(CONTINUATION_RXBPTR_TYPE<ProtocolV2> &next,
 }
 
 template <class F>
-CtPtr ProtocolV2::write(const std::string &desc,
+CtPtr ProtocolV2::write(std::string_view desc,
                         CONTINUATION_TYPE<ProtocolV2> &next,
                         F &frame) {
   ceph::bufferlist bl;
@@ -812,7 +812,7 @@ CtPtr ProtocolV2::write(const std::string &desc,
   return write(desc, next, bl);
 }
 
-CtPtr ProtocolV2::write(const std::string &desc,
+CtPtr ProtocolV2::write(std::string_view desc,
                         CONTINUATION_TYPE<ProtocolV2> &next,
                         ceph::bufferlist &buffer) {
   if (unlikely(pre_auth.enabled)) {

diff --git a/src/msg/async/ProtocolV2.h b/src/msg/async/ProtocolV2.h
@@ -130,10 +130,10 @@ class ProtocolV2 : public Protocol {
   Ct<ProtocolV2> *read(CONTINUATION_RXBPTR_TYPE<ProtocolV2> &next,
                        rx_buffer_t&& buffer);
   template <class F>
-  Ct<ProtocolV2> *write(const std::string &desc,
+  Ct<ProtocolV2> *write(std::string_view desc,
                         CONTINUATION_TYPE<ProtocolV2> &next,
 			F &frame);
-  Ct<ProtocolV2> *write(const std::string &desc,
+  Ct<ProtocolV2> *write(std::string_view desc,
                         CONTINUATION_TYPE<ProtocolV2> &next,
                         ceph::bufferlist &buffer);