Exit early if slowlog/acllog max len set to zero (redis#12965)

Currently slowlog gets disabled if slowlog-log-slower-than is set to less than zero. I think we should also disable it if slowlog-max-len is set to zero. We apply the same logic to acllog-max-len.

src/acl.c

@@ -2661,6 +2661,15 @@ void ACLUpdateInfoMetrics(int reason){
     }
 }
 
+static void trimACLLogEntriesToMaxLen(void) {
+    while(listLength(ACLLog) > server.acllog_max_len) {
+        listNode *ln = listLast(ACLLog);
+        ACLLogEntry *le = listNodeValue(ln);
+        ACLFreeLogEntry(le);
+        listDelNode(ACLLog,ln);
+    }
+}
+
 /* Adds a new entry in the ACL log, making sure to delete the old entry
  * if we reach the maximum length allowed for the log. This function attempts
  * to find similar entries in the current log in order to bump the counter of
@@ -2680,6 +2689,11 @@ void addACLLogEntry(client *c, int reason, int context, int argpos, sds username
     /* Update ACL info metrics */
     ACLUpdateInfoMetrics(reason);
 
+    if (server.acllog_max_len == 0) {
+        trimACLLogEntriesToMaxLen();
+        return;
+    }
+
     /* Create a new entry. */
     struct ACLLogEntry *le = zmalloc(sizeof(*le));
     le->count = 1;
@@ -2742,12 +2756,7 @@ void addACLLogEntry(client *c, int reason, int context, int argpos, sds username
          * to its maximum size. */
         ACLLogEntryCount++; /* Incrementing the entry_id count to make each record in the log unique. */
         listAddNodeHead(ACLLog, le);
-        while(listLength(ACLLog) > server.acllog_max_len) {
-            listNode *ln = listLast(ACLLog);
-            ACLLogEntry *le = listNodeValue(ln);
-            ACLFreeLogEntry(le);
-            listDelNode(ACLLog,ln);
-        }
+        trimACLLogEntriesToMaxLen();
     }
 }
 

src/latency.c

@@ -279,7 +279,7 @@ sds createLatencyReport(void) {
 
         /* Potentially commands. */
         if (!strcasecmp(event,"command")) {
-            if (server.slowlog_log_slower_than < 0) {
+            if (server.slowlog_log_slower_than < 0 || server.slowlog_max_len == 0) {
                 advise_slowlog_enabled = 1;
                 advices++;
             } else if (server.slowlog_log_slower_than/1000 >

src/slowlog.c

@@ -121,7 +121,7 @@ void slowlogInit(void) {
  * This function will make sure to trim the slow log accordingly to the
  * configured max length. */
 void slowlogPushEntryIfNeeded(client *c, robj **argv, int argc, long long duration) {
-    if (server.slowlog_log_slower_than < 0) return; /* Slowlog disabled */
+    if (server.slowlog_log_slower_than < 0 || server.slowlog_max_len == 0) return; /* Slowlog disabled */
     if (duration >= server.slowlog_log_slower_than)
         listAddNodeHead(server.slowlog,
                         slowlogCreateEntry(c,argv,argc,duration));

tests/unit/acl.tcl

@@ -802,6 +802,16 @@ start_server {tags {"acl external:skip"}} {
         assert {[dict get $entry username] eq {antirez}}
     }
 
+    test {ACLLOG - zero max length is correctly handled} {
+        r ACL LOG RESET
+        r CONFIG SET acllog-max-len 0
+        for {set j 0} {$j < 10} {incr j} {
+            catch {r SET obj:$j 123}
+        }
+        r AUTH default ""
+        assert {[llength [r ACL LOG]] == 0}
+    }
+
     test {ACL LOG entries are limited to a maximum amount} {
         r ACL LOG RESET
         r CONFIG SET acllog-max-len 5
@@ -813,6 +823,11 @@ start_server {tags {"acl external:skip"}} {
         assert {[llength [r ACL LOG]] == 5}
     }
 
+    test {ACL LOG entries are still present on update of max len config} {
+        r CONFIG SET acllog-max-len 0
+        assert {[llength [r ACL LOG]] == 5}
+    }
+
     test {When default user is off, new connections are not authenticated} {
         r ACL setuser default off
         catch {set rd1 [redis_deferring_client]} e

tests/unit/slowlog.tcl

@@ -14,6 +14,16 @@ start_server {tags {"slowlog"} overrides {slowlog-log-slower-than 1000000}} {
         assert_equal [r slowlog len] 1
     } {} {needs:debug}
 
+    test {SLOWLOG - zero max length is correctly handled} {
+        r SLOWLOG reset
+        r config set slowlog-max-len 0
+        r config set slowlog-log-slower-than 0
+        for {set i 0} {$i < 100} {incr i} {
+            r ping
+        }
+        r slowlog len
+    } {0}
+
     test {SLOWLOG - max entries is correctly handled} {
         r config set slowlog-log-slower-than 0
         r config set slowlog-max-len 10
@@ -42,7 +52,7 @@ start_server {tags {"slowlog"} overrides {slowlog-log-slower-than 1000000}} {
         set e [lindex [r slowlog get] 0]
         assert_equal [llength $e] 6
         if {!$::external} {
-            assert_equal [lindex $e 0] 107
+            assert_equal [lindex $e 0] 106
         }
         assert_equal [expr {[lindex $e 2] > 100000}] 1
         assert_equal [lindex $e 3] {debug sleep 0.2}