common: compute SimpleLRU's size with contents.size() instead of lru.size()

As libstdc++ earlier than version 5 implement the list::size() as a O(n) operation,
this should be needed to avoid regression of various ceph component's performance.

Signed-off-by: Xuehan Xu <xuxuehan@360.cn>
(cherry picked from commit 7e0a27a5c8b7d12d378de4d700ed7a95af7860c3)

diff --git a/src/common/simple_cache.hpp b/src/common/simple_cache.hpp
index 1ff4ae911cdc5b48461a53e3c7f4ffc0c7697100..4006576d00bd5184fdf2f24da799b07830044091 100644 (file)
--- a/src/common/simple_cache.hpp
+++ b/src/common/simple_cache.hpp
@@ -27,7 +27,7 @@ class SimpleLRU {
   map<K, V, C> pinned;
 
   void trim_cache() {
-    while (lru.size() > max_size) {
+    while (contents.size() > max_size) {
       contents.erase(lru.back().first);
       lru.pop_back();
     }