Make getTimestamp use monotonic time (#36)

* monotonic time test

* switch to steady_clock

* remove sleep

* allow equal time

* tweaks

* see if fails with system_clock

* Revert "see if fails with system_clock"
still passes, whatever
This reverts commit 616f302.

catch_tests/utils-and-constants/ECSUtilsTests.cpp

@@ -16,6 +16,18 @@ namespace {
     };
 }
 
+// run a bunch of asserts, try to catch a leap backwards
+TEST_CASE("getTimeStamp monotonic time fuzz test") {
+    auto prevTime = getTimeStamp();
+
+    for (int i = 0; i < 20; i++){
+        auto curTime = getTimeStamp();
+
+        assert(prevTime <= curTime);
+        prevTime = curTime;
+    }
+}
+
 TEST_CASE("make_vector_unique", "[unit]") {
     std::vector<std::unique_ptr<Foo>> result = make_vector_unique<Foo>(std::make_unique<Foo>(21312),
                                                                      std::make_unique<Foo>(45342),
@@ -34,4 +46,4 @@ TEST_CASE("make_vector_unique", "[unit]") {
 TEST_CASE("filterDoubleNan", "[unit]") {
     REQUIRE_THAT(filterDoubleNan(1230.0), Catch::WithinRel(1230.0, 0.1));
     REQUIRE_THAT(filterDoubleNan(std::nan("")), Catch::WithinRel(0.0, 0.1));
-}
+}

src/utils/ECSUtils.cpp

@@ -43,7 +43,7 @@ std::string get_date(){
 
 uint64_t getTimeStamp() {
     return std::chrono::duration_cast<std::chrono::milliseconds>(
-            std::chrono::system_clock::now().time_since_epoch()
+            std::chrono::steady_clock::now().time_since_epoch()
     ).count();
 }
 
@@ -63,4 +63,4 @@ double filterDoubleNan(double check) {
 
 #ifdef _MSC_VER
 #undef _CRT_SECURE_NO_WARNINGS
-#endif
+#endif