Fix module LatencyAddSample still work when latency-monitor-threshold…

… is 0

When latency-monitor-threshold is set to 0, it means the latency monitor
is disabled, and in VM_LatencyAddSample, we wrote the condition incorrectly,
causing us to record latency when latency was turned off.

Signed-off-by: Binbin <[email protected]>

src/module.c

@@ -7680,7 +7680,8 @@ void VM__Assert(const char *estr, const char *file, int line) {
  * command. The call is skipped if the latency is smaller than the configured
  * latency-monitor-threshold. */
 void VM_LatencyAddSample(const char *event, mstime_t latency) {
-    if (latency >= server.latency_monitor_threshold) latencyAddSample(event, latency);
+    if (server.latency_monitor_threshold && latency >= server.latency_monitor_threshold)
+        latencyAddSample(event, latency);
 }
 
 /* --------------------------------------------------------------------------

tests/modules/basics.c

@@ -669,6 +669,24 @@ int TestNotifications(ValkeyModuleCtx *ctx, ValkeyModuleString **argv, int argc)
     return ValkeyModule_ReplyWithSimpleString(ctx, "ERR");
 }
 
+/* test.latency latency_ms */
+int TestLatency(ValkeyModuleCtx *ctx, ValkeyModuleString **argv, int argc) {
+    if (argc != 2) {
+        ValkeyModule_WrongArity(ctx);
+        return VALKEYMODULE_OK;
+    }
+
+    long long latency_ms;
+    if (ValkeyModule_StringToLongLong(argv[1], &latency_ms) != VALKEYMODULE_OK) {
+        ValkeyModule_ReplyWithError(ctx, "Invalid integer value");
+        return VALKEYMODULE_OK;
+    }
+
+    ValkeyModule_LatencyAddSample("test", latency_ms);
+    ValkeyModule_ReplyWithSimpleString(ctx, "OK");
+    return VALKEYMODULE_OK;
+}
+
 /* TEST.CTXFLAGS -- Test GetContextFlags. */
 int TestCtxFlags(ValkeyModuleCtx *ctx, ValkeyModuleString **argv, int argc) {
     VALKEYMODULE_NOT_USED(argc);
@@ -1048,5 +1066,8 @@ int ValkeyModule_OnLoad(ValkeyModuleCtx *ctx, ValkeyModuleString **argv, int arg
         TestNotifications,"write deny-oom",1,1,1) == VALKEYMODULE_ERR)
         return VALKEYMODULE_ERR;
 
+    if (ValkeyModule_CreateCommand(ctx, "test.latency", TestLatency, "readonly", 0, 0, 0) == VALKEYMODULE_ERR)
+        return VALKEYMODULE_ERR;
+
     return VALKEYMODULE_OK;
 }

tests/unit/moduleapi/basics.tcl

@@ -39,6 +39,23 @@ start_server {tags {"modules"}} {
         verify_log_message 0 "*Module name is busy*" 0
     }
 
+    test "test latency" {
+        r config set latency-monitor-threshold 0
+        r latency reset
+        r test.latency 0
+        r test.latency 1
+        assert_equal {} [r latency latest]
+        assert_equal {} [r latency history test]
+
+        r config set latency-monitor-threshold 1
+        r test.latency 0
+        assert_equal 0 [llength [r latency history test]]
+        r test.latency 1
+        assert_match {*test * 1 1*} [r latency latest]
+        r test.latency 2
+        assert_match {*test * 2 2*} [r latency latest]
+    }
+
     test "Unload the module - basics" {
         assert_equal {OK} [r module unload test]
     }