From ce559a77cf0cdc83a562717c6d3c15cb90ede1c2 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@ionos.com>
Date: Fri, 20 Sep 2024 10:34:44 +0200
Subject: [PATCH] MDEV-34973: innobase/dict0dict: add `noexcept` to lock/unlock
 methods

Another chance for cutting back overhead due to C++ exceptions being
enabled; the `dict_sys_t` class is a good candidate because its
locking methods are called frequently.

Binary size reduction this time:

    text	  data	   bss	   dec	   hex	filename
 24448622	2436488	9473537	36358647	22ac9f7	build/release/sql/mariadbd
 24448474	2436488	9473601	36358563	22ac9a3	build/release/sql/mariadbd
---
 storage/innobase/dict/dict0dict.cc   |  8 ++++----
 storage/innobase/include/dict0dict.h | 24 ++++++++++++------------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/storage/innobase/dict/dict0dict.cc b/storage/innobase/dict/dict0dict.cc
index 3c6d1ce9e48e9..70afa0a30f3c5 100644
--- a/storage/innobase/dict/dict0dict.cc
+++ b/storage/innobase/dict/dict0dict.cc
@@ -955,7 +955,7 @@ void dict_sys_t::create()
 }
 
 
-void dict_sys_t::lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line))
+void dict_sys_t::lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line)) noexcept
 {
   ulonglong now= my_hrtime_coarse().val, old= 0;
   if (latch_ex_wait_start.compare_exchange_strong
@@ -981,17 +981,17 @@ void dict_sys_t::lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line))
 }
 
 #ifdef UNIV_PFS_RWLOCK
-ATTRIBUTE_NOINLINE void dict_sys_t::unlock()
+ATTRIBUTE_NOINLINE void dict_sys_t::unlock() noexcept
 {
   latch.wr_unlock();
 }
 
-ATTRIBUTE_NOINLINE void dict_sys_t::freeze(const char *file, unsigned line)
+ATTRIBUTE_NOINLINE void dict_sys_t::freeze(const char *file, unsigned line) noexcept
 {
   latch.rd_lock(file, line);
 }
 
-ATTRIBUTE_NOINLINE void dict_sys_t::unfreeze()
+ATTRIBUTE_NOINLINE void dict_sys_t::unfreeze() noexcept
 {
   latch.rd_unlock();
 }
diff --git a/storage/innobase/include/dict0dict.h b/storage/innobase/include/dict0dict.h
index a62a1ec004e18..b9a8c0e70e7e1 100644
--- a/storage/innobase/include/dict0dict.h
+++ b/storage/innobase/include/dict0dict.h
@@ -1493,24 +1493,24 @@ class dict_sys_t
 
 #ifdef UNIV_DEBUG
   /** @return whether the current thread is holding the latch */
-  bool frozen() const { return latch.have_any(); }
+  bool frozen() const noexcept { return latch.have_any(); }
   /** @return whether the current thread is holding a shared latch */
-  bool frozen_not_locked() const { return latch.have_rd(); }
+  bool frozen_not_locked() const noexcept { return latch.have_rd(); }
   /** @return whether the current thread holds the exclusive latch */
-  bool locked() const { return latch.have_wr(); }
+  bool locked() const noexcept { return latch.have_wr(); }
 #endif
 private:
   /** Acquire the exclusive latch */
   ATTRIBUTE_NOINLINE
-  void lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line));
+  void lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line)) noexcept;
 public:
   /** @return the my_hrtime_coarse().val of the oldest lock_wait() start,
   assuming that requests are served on a FIFO basis */
-  ulonglong oldest_wait() const
+  ulonglong oldest_wait() const noexcept
   { return latch_ex_wait_start.load(std::memory_order_relaxed); }
 
   /** Exclusively lock the dictionary cache. */
-  void lock(SRW_LOCK_ARGS(const char *file, unsigned line))
+  void lock(SRW_LOCK_ARGS(const char *file, unsigned line)) noexcept
   {
     if (!latch.wr_lock_try())
       lock_wait(SRW_LOCK_ARGS(file, line));
@@ -1518,18 +1518,18 @@ class dict_sys_t
 
 #ifdef UNIV_PFS_RWLOCK
   /** Unlock the data dictionary cache. */
-  ATTRIBUTE_NOINLINE void unlock();
+  ATTRIBUTE_NOINLINE void unlock() noexcept;
   /** Acquire a shared lock on the dictionary cache. */
-  ATTRIBUTE_NOINLINE void freeze(const char *file, unsigned line);
+  ATTRIBUTE_NOINLINE void freeze(const char *file, unsigned line) noexcept;
   /** Release a shared lock on the dictionary cache. */
-  ATTRIBUTE_NOINLINE void unfreeze();
+  ATTRIBUTE_NOINLINE void unfreeze() noexcept;
 #else
   /** Unlock the data dictionary cache. */
-  void unlock() { latch.wr_unlock(); }
+  void unlock() noexcept { latch.wr_unlock(); }
   /** Acquire a shared lock on the dictionary cache. */
-  void freeze() { latch.rd_lock(); }
+  void freeze() noexcept { latch.rd_lock(); }
   /** Release a shared lock on the dictionary cache. */
-  void unfreeze() { latch.rd_unlock(); }
+  void unfreeze() noexcept { latch.rd_unlock(); }
 #endif
 
   /** Estimate the used memory occupied by the data dictionary