From 5047e64dee7c80d90a1a6edeb77882e5cb8071a6 Mon Sep 17 00:00:00 2001
From: John Sully <john@csquare.ca>
Date: Mon, 12 Sep 2022 15:05:09 +0000
Subject: [PATCH] Fix O(n) algorithm in INFO command

---
 src/object.cpp       |  5 ++---
 src/semiorderedset.h | 12 +++++-------
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/src/object.cpp b/src/object.cpp
index 44dcbd6e9..4f6a56338 100644
--- a/src/object.cpp
+++ b/src/object.cpp
@@ -1140,10 +1140,9 @@ struct redisMemOverhead *getMemoryOverheadData(void) {
               db->size() * sizeof(robj);
         mh->db[mh->num_dbs].overhead_ht_main = mem;
         mem_total+=mem;
-        
+
         std::unique_lock<fastlock> ul(g_expireLock);
-        mem = db->setexpire()->bytes_used();
-        
+        mem = db->setexpire()->estimated_bytes_used();
         mh->db[mh->num_dbs].overhead_ht_expires = mem;
         mem_total+=mem;
 
diff --git a/src/semiorderedset.h b/src/semiorderedset.h
index fe463fe31..c9ff10bac 100644
--- a/src/semiorderedset.h
+++ b/src/semiorderedset.h
@@ -240,14 +240,12 @@ public:
     bool empty() const noexcept { return celem == 0; }
     size_t size() const noexcept { return celem; }
 
-    size_t bytes_used() const
+    size_t estimated_bytes_used() const
     {
-        size_t cb = sizeof(this) + (m_data.capacity()-m_data.size())*sizeof(T);
-        for (auto &vec : m_data)
-        {
-            if (vec != nullptr)
-                cb += vec->bytes_used();
-        }
+        // This estimate does't include all the overhead of the internal vectors
+        size_t cb = sizeof(this)
+            + (m_data.capacity() * sizeof(m_data[0]))
+            + sizeof(T) * size();
         return cb;
     }