Let MetricTimer be target duration type agnostic

Will now transparently convert to the appropriate value with either
truncation or floating point conversion, depending on the target type.

3 files changed, 54 insertions, 7 deletions

diff --git a/metrics/src/tests/CMakeLists.txt b/metrics/src/tests/CMakeLists.txt
index fdc2f290be8..7e0414b1ca1 100644
--- a/metrics/src/tests/CMakeLists.txt
+++ b/metrics/src/tests/CMakeLists.txt
@@ -11,6 +11,7 @@ vespa_add_executable(metrics_testrunner_app TEST
     snapshottest.cpp
     stresstest.cpp
     metrictest.cpp
+    metric_timer_test.cpp
     DEPENDS
     metrics
     vdstestlib
diff --git a/metrics/src/tests/metric_timer_test.cpp b/metrics/src/tests/metric_timer_test.cpp
new file mode 100644
index 00000000000..da5ab0c3dfe
--- /dev/null
+++ b/metrics/src/tests/metric_timer_test.cpp
@@ -0,0 +1,47 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <vespa/fastos/fastos.h>
+#include <vespa/vdstestlib/cppunit/macros.h>
+#include <vespa/metrics/valuemetric.h>
+#include <vespa/metrics/metrictimer.h>
+#include <thread>
+
+namespace metrics {
+
+struct MetricTimerTest : public CppUnit::TestFixture {
+    CPPUNIT_TEST_SUITE(MetricTimerTest);
+    CPPUNIT_TEST(timer_duration_is_correct_for_double_value_metric);
+    CPPUNIT_TEST(timer_duration_is_correct_for_long_value_metric);
+    CPPUNIT_TEST_SUITE_END();
+
+    void timer_duration_is_correct_for_double_value_metric();
+    void timer_duration_is_correct_for_long_value_metric();
+
+    template <typename MetricType>
+    void do_test_metric_timer_for_metric_type();
+};
+
+CPPUNIT_TEST_SUITE_REGISTRATION(MetricTimerTest);
+
+using namespace std::literals::chrono_literals;
+
+template <typename MetricType>
+void MetricTimerTest::do_test_metric_timer_for_metric_type() {
+    MetricTimer timer;
+    MetricType metric("foo", "", "");
+    std::this_thread::sleep_for(5ms); // Guaranteed to be monotonic time
+    timer.stop(metric);
+    // getDoubleValue() is present for both long and double metric types
+    CPPUNIT_ASSERT(metric.getDoubleValue("last") >= 5.0);
+}
+
+void MetricTimerTest::timer_duration_is_correct_for_double_value_metric() {
+    do_test_metric_timer_for_metric_type<DoubleAverageMetric>();
+}
+
+void MetricTimerTest::timer_duration_is_correct_for_long_value_metric() {
+    do_test_metric_timer_for_metric_type<LongAverageMetric>();
+}
+
+} // metrics
+
diff --git a/metrics/src/vespa/metrics/metrictimer.h b/metrics/src/vespa/metrics/metrictimer.h
index 7228daced34..18eaf86ecae 100644
--- a/metrics/src/vespa/metrics/metrictimer.h
+++ b/metrics/src/vespa/metrics/metrictimer.h
@@ -14,8 +14,7 @@
 
 namespace metrics {
 
-class MetricTimer
-{
+class MetricTimer {
 public:
     MetricTimer();
 
@@ -27,17 +26,17 @@ public:
      * underflow or be affected by system clock changes.
      */
     template<typename AvgVal, typename TotVal, bool SumOnAdd>
-    uint64_t stop(ValueMetric<AvgVal, TotVal, SumOnAdd>& metric) {
+    AvgVal stop(ValueMetric<AvgVal, TotVal, SumOnAdd>& metric) {
         const auto delta = std::chrono::steady_clock::now() - _startTime;
-        const uint64_t deltaMs(
-                std::chrono::duration_cast<std::chrono::milliseconds>(delta)
-                    .count());
+        using ToDuration = std::chrono::duration<AvgVal, std::milli>;
+        const auto deltaMs(
+                std::chrono::duration_cast<ToDuration>(delta).count());
         metric.addValue(deltaMs);
         return deltaMs;
     }
 
 private:
-    std::chrono::time_point<std::chrono::steady_clock> _startTime;
+    std::chrono::steady_clock::time_point _startTime;
 };
 
 } // metrics