Update "Total" message and used_memory_human log information in serverCron() function (#594)

At the VERBOSE/DEBUG log level, which is output once every 5 seconds,
added to show the "Total" message of all clients and to show memory
usage (used_memory) with used_memory_human.
Also, it seems clearer to show "total" number of keys and the number of
volatile in entire keys.

---------

Signed-off-by: NAM UK KIM <namuk2004@naver.com>

src/server.c

@@ -1331,9 +1331,13 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
     /* Show information about connected clients */
     if (!server.sentinel_mode) {
         run_with_period(5000) {
-            serverLog(LL_DEBUG, "%lu clients connected (%lu replicas), %zu bytes in use",
+            char hmem[64];
+            size_t zmalloc_used = zmalloc_used_memory();
+            bytesToHuman(hmem, sizeof(hmem), zmalloc_used);
+
+            serverLog(LL_DEBUG, "Total: %lu clients connected (%lu replicas), %zu (%s) bytes in use",
                       listLength(server.clients) - listLength(server.replicas), listLength(server.replicas),
-                      zmalloc_used_memory());
+                      zmalloc_used, hmem);
         }
     }
 

src/server.h

@@ -3303,6 +3303,7 @@ void adjustOpenFilesLimit(void);
 void incrementErrorCount(const char *fullerr, size_t namelen);
 void closeListeningSockets(int unlink_unix_socket);
 void updateCachedTime(int update_daylight_info);
+void bytesToHuman(char *s, size_t size, unsigned long long n);
 void enterExecutionUnit(int update_cached_time, long long us);
 void exitExecutionUnit(void);
 void resetServerStats(void);