From e85450e19d43ec2c8c18ae4319a8967705887b61 Mon Sep 17 00:00:00 2001
From: Robert Nix <mischanix@gmail.com>
Date: Wed, 23 Nov 2022 20:01:05 -0600
Subject: [PATCH] Use unordered_set for LatchCounter storage

---
 storage/innobase/include/sync0types.h | 31 ++++++++-------------------
 1 file changed, 9 insertions(+), 22 deletions(-)

diff --git a/storage/innobase/include/sync0types.h b/storage/innobase/include/sync0types.h
index 0b4ff55acba..48595fabea3 100644
--- a/storage/innobase/include/sync0types.h
+++ b/storage/innobase/include/sync0types.h
@@ -34,6 +34,7 @@ this program; if not, write to the Free Software Foundation, Inc.,
 #define sync0types_h
 
 #include <iostream>
+#include <unordered_set>
 #include <vector>
 
 #include "sync0sync.h"
@@ -661,23 +662,7 @@ class LatchCounter {
   }
 
   /** @return the aggregate counter */
-  Count *sum_register() UNIV_NOTHROW {
-    m_mutex.enter();
-
-    Count *count;
-
-    if (m_counters.empty()) {
-      count = ut::new_withkey<Count>(UT_NEW_THIS_FILE_PSI_KEY);
-      m_counters.push_back(count);
-    } else {
-      ut_a(m_counters.size() == 1);
-      count = m_counters[0];
-    }
-
-    m_mutex.exit();
-
-    return (count);
-  }
+  Count *sum_register() UNIV_NOTHROW { return &m_sum; }
 
   /** Deregister the count. We don't do anything
   @param[in]    count           The count instance to deregister */
@@ -689,7 +674,7 @@ class LatchCounter {
   void single_register(Count *count) UNIV_NOTHROW {
     m_mutex.enter();
 
-    m_counters.push_back(count);
+    m_counters.insert(count);
 
     m_mutex.exit();
   }
@@ -699,8 +684,7 @@ class LatchCounter {
   void single_deregister(Count *count) UNIV_NOTHROW {
     m_mutex.enter();
 
-    m_counters.erase(std::remove(m_counters.begin(), m_counters.end(), count),
-                     m_counters.end());
+    m_counters.erase(count);
 
     m_mutex.exit();
   }
@@ -751,13 +735,16 @@ class LatchCounter {
 
  private:
   typedef OSMutex Mutex;
-  typedef std::vector<Count *> Counters;
+  typedef std::unordered_set<Count *> CountSet;
 
   /** Mutex protecting m_counters */
   mutable Mutex m_mutex;
 
   /** Counters for the latches */
-  Counters m_counters;
+  CountSet m_counters;
+
+  /** Aggregate counter */
+  Count m_sum;
 
   /** if true then we collect the data */
   bool m_active;
-- 
2.34.1