added time.h to simplify chrono use

5 files changed, 111 insertions, 1 deletions

diff --git a/vespalib/src/tests/time/CMakeLists.txt b/vespalib/src/tests/time/CMakeLists.txt
index 4fa8bad5eed..e43bd9097e5 100644
--- a/vespalib/src/tests/time/CMakeLists.txt
+++ b/vespalib/src/tests/time/CMakeLists.txt
@@ -6,3 +6,11 @@ vespa_add_executable(vespalib_time_box_test_app TEST
     vespalib
 )
 vespa_add_test(NAME vespalib_time_box_test_app COMMAND vespalib_time_box_test_app)
+vespa_add_executable(vespalib_time_test_app TEST
+    SOURCES
+    time_test.cpp
+    DEPENDS
+    vespalib
+    gtest
+)
+vespa_add_test(NAME vespalib_time_test_app COMMAND vespalib_time_test_app)
diff --git a/vespalib/src/tests/time/time_test.cpp b/vespalib/src/tests/time/time_test.cpp
new file mode 100644
index 00000000000..667511f6a94
--- /dev/null
+++ b/vespalib/src/tests/time/time_test.cpp
@@ -0,0 +1,39 @@
+// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <vespa/vespalib/util/time.h>
+#include <vespa/vespalib/gtest/gtest.h>
+#include <thread>
+
+using namespace vespalib;
+
+TEST(TimeTest, steady_time_is_compatible_with_steady_clock) {
+    steady_time t = steady_clock::now();
+    (void) t;
+}
+
+TEST(TimeTest, system_time_is_compatible_with_system_clock) {
+    system_time t = system_clock::now();
+    (void) t;
+}
+
+TEST(TimeTest, timer_can_measure_elapsed_time) {
+    Timer timer;
+    std::this_thread::sleep_for(10ms);
+    auto elapsed = timer.elapsed();
+    EXPECT_GE(elapsed, 10ms);
+    fprintf(stderr, "sleep(10ms) took %ld us\n", count_us(elapsed));
+}
+
+TEST(TimeTest, double_conversion_works_as_expected) {
+    EXPECT_EQ(to_s(10ms), 0.010);
+    EXPECT_EQ(10ms, from_s(0.010));
+}
+
+TEST(TimeTest, unit_counting_works_as_expected) {
+    auto d = 3ms + 5us + 7ns;
+    EXPECT_EQ(count_ns(d), 3005007);
+    EXPECT_EQ(count_us(d), 3005);
+    EXPECT_EQ(count_ms(d), 3);
+}
+
+GTEST_MAIN_RUN_ALL_TESTS()
diff --git a/vespalib/src/vespa/vespalib/util/CMakeLists.txt b/vespalib/src/vespa/vespalib/util/CMakeLists.txt
index c6fb5f572d1..da81556bb61 100644
--- a/vespalib/src/vespa/vespalib/util/CMakeLists.txt
+++ b/vespalib/src/vespa/vespalib/util/CMakeLists.txt
@@ -11,8 +11,8 @@ vespa_add_library(vespalib_vespalib_util OBJECT
     barrier.cpp
     benchmark_timer.cpp
     blockingthreadstackexecutor.cpp
-    bufferwriter.cpp
     box.cpp
+    bufferwriter.cpp
     classname.cpp
     closuretask.cpp
     compress.cpp
@@ -52,6 +52,7 @@ vespa_add_library(vespalib_vespalib_util OBJECT
     thread_bundle.cpp
     threadstackexecutor.cpp
     threadstackexecutorbase.cpp
+    time.cpp
     valgrind.cpp
     zstdcompressor.cpp
     DEPENDS
diff --git a/vespalib/src/vespa/vespalib/util/time.cpp b/vespalib/src/vespa/vespalib/util/time.cpp
new file mode 100644
index 00000000000..d38e40a6d6a
--- /dev/null
+++ b/vespalib/src/vespa/vespalib/util/time.cpp
@@ -0,0 +1,9 @@
+// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include "time.h"
+
+namespace vespalib {
+
+Timer::~Timer() = default;
+
+}
diff --git a/vespalib/src/vespa/vespalib/util/time.h b/vespalib/src/vespa/vespalib/util/time.h
new file mode 100644
index 00000000000..bab410f040d
--- /dev/null
+++ b/vespalib/src/vespa/vespalib/util/time.h
@@ -0,0 +1,53 @@
+// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include <chrono>
+
+using namespace std::literals::chrono_literals;
+
+namespace vespalib {
+
+using steady_clock = std::chrono::steady_clock;
+using steady_time  = std::chrono::steady_clock::time_point;
+
+using system_clock = std::chrono::system_clock;
+using system_time  = std::chrono::system_clock::time_point;
+
+using duration = std::chrono::nanoseconds;
+
+constexpr double to_s(duration d) {
+    return std::chrono::duration_cast<std::chrono::duration<double>>(d).count();
+}
+
+constexpr duration from_s(double seconds) {
+    return std::chrono::duration_cast<duration>(std::chrono::duration<double>(seconds));
+}
+
+constexpr int64_t count_ms(duration d) {
+    return std::chrono::duration_cast<std::chrono::milliseconds>(d).count();
+}
+
+constexpr int64_t count_us(duration d) {
+    return std::chrono::duration_cast<std::chrono::microseconds>(d).count();
+}
+
+constexpr int64_t count_ns(duration d) {
+    return std::chrono::duration_cast<std::chrono::nanoseconds>(d).count();
+}
+
+/**
+ * Simple utility class used to measure how much time has elapsed
+ * since it was constructed.
+ **/
+class Timer
+{
+private:
+    steady_time _start;
+public:
+    Timer() : _start(steady_clock::now()) {}
+    ~Timer();
+    duration elapsed() const { return (steady_clock::now() - _start); }
+};
+
+}