ACL LOG: make max log entries configurable.

src/acl.c

@@ -1576,6 +1576,12 @@ void addACLLogEntry(client *c, int reason, int keypos, sds username) {
         /* Add it to our list of entires. We'll have to trim the list
          * to its maximum size. */
         listAddNodeHead(ACLLog, le);
+        while(listLength(ACLLog) > server.acllog_max_len) {
+            listNode *ln = listLast(ACLLog);
+            ACLLogEntry *le = listNodeValue(ln);
+            ACLFreeLogEntry(le);
+            listDelNode(ACLLog,ln);
+        }
     }
 }
 

src/config.c

@@ -2233,6 +2233,7 @@ standardConfig configs[] = {
     /* Unsigned Long configs */
     createULongConfig("active-defrag-max-scan-fields", NULL, MODIFIABLE_CONFIG, 1, LONG_MAX, server.active_defrag_max_scan_fields, 1000, INTEGER_CONFIG, NULL, NULL), /* Default: keys with more than 1000 fields will be processed separately */
     createULongConfig("slowlog-max-len", NULL, MODIFIABLE_CONFIG, 0, LONG_MAX, server.slowlog_max_len, 128, INTEGER_CONFIG, NULL, NULL),
+    createULongConfig("acllog-max-len", NULL, MODIFIABLE_CONFIG, 0, LONG_MAX, server.acllog_max_len, 128, INTEGER_CONFIG, NULL, NULL),
 
     /* Long Long configs */
     createLongLongConfig("lua-time-limit", NULL, MODIFIABLE_CONFIG, 0, LONG_MAX, server.lua_time_limit, 5000, INTEGER_CONFIG, NULL, NULL),/* milliseconds */

src/server.h

@@ -1385,6 +1385,7 @@ struct redisServer {
     dict *latency_events;
     /* ACLs */
     char *acl_filename;     /* ACL Users file. NULL if not configured. */
+    unsigned long acllog_max_len; /* Maximum length of the ACL LOG list. */
     /* Assert & bug reporting */
     const char *assert_failed;
     const char *assert_file;

tests/unit/acl.tcl

@@ -237,4 +237,15 @@ start_server {tags {"acl"}} {
         assert {[dict get $entry object] eq {AUTH}}
         assert {[dict get $entry username] eq {antirez}}
     }
+
+    test {ACL LOG entries are limited to a maximum amount} {
+        r ACL LOG RESET
+        r CONFIG SET acllog-max-len 5
+        r AUTH antirez foo
+        for {set j 0} {$j < 10} {incr j} {
+            catch {r SET obj:$j 123}
+        }
+        r AUTH default ""
+        assert {[llength [r ACL LOG]] == 5}
+    }
 }