Updated stopwatch example to README.md

README.md

@@ -169,6 +169,20 @@ spdlog::flush_every(std::chrono::seconds(3));
 
 ```
 
+---
+#### Stopwatch
+```c++
+// Stopwatch support for spdlog
+#include "spdlog/stopwatch.h"
+void stopwatch_example()
+{
+    spdlog::stopwatch sw;    
+    spdlog::debug("Elapsed {}", sw);
+    spdlog::debug("Elapsed {:.3}", sw);       
+}
+
+```
+
 ---
 #### Log binary data in hex
 ```c++

example/example.cpp

@@ -13,6 +13,7 @@ void rotating_example();
 void daily_example();
 void async_example();
 void binary_example();
+void stopwatch_example();
 void trace_example();
 void multi_sink_example();
 void user_defined_example();
@@ -71,6 +72,7 @@ int main(int, char *[])
         user_defined_example();
         err_handler_example();
         trace_example();
+        stopwatch_example();
         custom_flags_example();
 
         // Flush all *registered* loggers using a worker thread every 3 seconds.
@@ -192,6 +194,16 @@ void trace_example()
     SPDLOG_LOGGER_TRACE(logger, "another trace message");
 }
 
+// stopwatch example
+#include "spdlog/stopwatch.h"
+#include <thread>
+void stopwatch_example()
+{
+    spdlog::stopwatch sw;
+    std::this_thread::sleep_for(std::chrono::milliseconds(123));
+    spdlog::info("Stopwatch: {} seconds", sw);
+}
+
 // A logger with multiple sinks (stdout and file) - each with a different format and log level.
 void multi_sink_example()
 {

include/spdlog/stopwatch.h

@@ -0,0 +1,61 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#include <spdlog/fmt/fmt.h>
+
+// Stopwatch support for spdlog  (using std::chrono::high_resolution_clock).
+// Displays elapsed seconds since construction as double.
+//
+// Usage:
+//
+// spdlog::stopwatch sw;
+// ...
+// spdlog::debug("Elapsed: {} seconds", sw);    =>  "Elapsed 0.005116733 seconds"
+// spdlog::info("Elapsed: {:.6} seconds", sw);  =>  "Elapsed 0.005163 seconds"
+//
+//
+// If other units are needed (e.g. millis instead of double), include "fmt/chrono.h" and use "duration_cast<..>(sw.elapsed())":
+//
+// #include <fmt/chrono.h>
+//..
+// using std::chrono::duration_cast;
+// using std::chrono::milliseconds;
+// spdlog::info("Elapsed {}", duration_cast<milliseconds>(sw.elapsed())); => "Elapsed 5ms"
+
+namespace spdlog {
+class stopwatch
+{
+    using clock = std::chrono::high_resolution_clock;
+    std::chrono::time_point<clock> start_tp_;
+
+public:
+    stopwatch()
+        : start_tp_{clock::now()}
+    {}
+
+    std::chrono::duration<double> elapsed() const
+    {
+        return std::chrono::duration<double>(clock::now() - start_tp_);
+    }
+
+    void reset()
+    {
+        start_tp_ = clock ::now();
+    }
+};
+} // namespace spdlog
+
+// Support for fmt formatting  (e.g. "{:012.9}" or just "{}")
+namespace fmt {
+template<>
+struct formatter<spdlog::stopwatch> : formatter<double>
+{
+    template<typename FormatContext>
+    auto format(const spdlog::stopwatch &sw, FormatContext &ctx) -> decltype(ctx.out())
+    {
+        return formatter<double>::format(sw.elapsed().count(), ctx);
+    }
+};
+} // namespace fmt

tests/CMakeLists.txt

@@ -1,46 +1,47 @@
 cmake_minimum_required(VERSION 3.10)
 project(spdlog_utests CXX)
 
-if(NOT TARGET spdlog)
+if (NOT TARGET spdlog)
     # Stand-alone build
     find_package(spdlog REQUIRED)
-endif()
+endif ()
 
 include(../cmake/utils.cmake)
 
 find_package(PkgConfig)
-if(PkgConfig_FOUND)
+if (PkgConfig_FOUND)
     pkg_check_modules(systemd libsystemd)
-endif()
+endif ()
 
 set(SPDLOG_UTESTS_SOURCES
-    test_file_helper.cpp
-    test_file_logging.cpp
-    test_daily_logger.cpp
-    test_misc.cpp
-    test_eventlog.cpp
-    test_pattern_formatter.cpp
-    test_async.cpp
-    test_registry.cpp
-    test_macros.cpp
-    utils.cpp
-    main.cpp
-    test_mpmc_q.cpp
-    test_dup_filter.cpp
-    test_fmt_helper.cpp
-    test_stdout_api.cpp
-    test_backtrace.cpp
-    test_create_dir.cpp
-    test_cfg.cpp
-    test_time_point.cpp)
+        test_file_helper.cpp
+        test_file_logging.cpp
+        test_daily_logger.cpp
+        test_misc.cpp
+        test_eventlog.cpp
+        test_pattern_formatter.cpp
+        test_async.cpp
+        test_registry.cpp
+        test_macros.cpp
+        utils.cpp
+        main.cpp
+        test_mpmc_q.cpp
+        test_dup_filter.cpp
+        test_fmt_helper.cpp
+        test_stdout_api.cpp
+        test_backtrace.cpp
+        test_create_dir.cpp
+        test_cfg.cpp
+        test_time_point.cpp
+        test_stopwatch.cpp)
 
-if(NOT SPDLOG_NO_EXCEPTIONS)
+if (NOT SPDLOG_NO_EXCEPTIONS)
     list(APPEND SPDLOG_UTESTS_SOURCES test_errors.cpp)
-endif()
+endif ()
 
-if(systemd_FOUND)
+if (systemd_FOUND)
     list(APPEND SPDLOG_UTESTS_SOURCES test_systemd.cpp)
-endif()
+endif ()
 
 enable_testing()
 
@@ -48,22 +49,22 @@ function(spdlog_prepare_test test_target spdlog_lib)
     add_executable(${test_target} ${SPDLOG_UTESTS_SOURCES})
     spdlog_enable_warnings(${test_target})
     target_link_libraries(${test_target} PRIVATE ${spdlog_lib})
-    if(systemd_FOUND)
+    if (systemd_FOUND)
         target_link_libraries(${test_target} PRIVATE ${systemd_LIBRARIES})
-    endif()
-    if(SPDLOG_SANITIZE_ADDRESS)
+    endif ()
+    if (SPDLOG_SANITIZE_ADDRESS)
         spdlog_enable_sanitizer(${test_target})
-    endif()
+    endif ()
     add_test(NAME ${test_target} COMMAND ${test_target})
     set_tests_properties(${test_target} PROPERTIES RUN_SERIAL ON)
 endfunction()
 
 # The compiled library tests
-if(SPDLOG_BUILD_TESTS OR SPDLOG_BUILD_ALL)
+if (SPDLOG_BUILD_TESTS OR SPDLOG_BUILD_ALL)
     spdlog_prepare_test(spdlog-utests spdlog::spdlog)
-endif()
+endif ()
 
 # The header-only library version tests
-if(SPDLOG_BUILD_TESTS_HO OR SPDLOG_BUILD_ALL)
+if (SPDLOG_BUILD_TESTS_HO OR SPDLOG_BUILD_ALL)
     spdlog_prepare_test(spdlog-utests-ho spdlog::spdlog_header_only)
-endif()
+endif ()

tests/test_stopwatch.cpp

@@ -0,0 +1,35 @@
+#include "includes.h"
+#include "test_sink.h"
+#include "spdlog/stopwatch.h"
+
+TEST_CASE("stopwatch1", "[stopwatch]")
+{
+    using std::chrono::milliseconds;
+    milliseconds wait_ms(250);
+    milliseconds tolerance_ms(250);
+
+    spdlog::stopwatch sw;
+    std::this_thread::sleep_for(wait_ms);
+    REQUIRE(sw.elapsed() >= wait_ms);
+    REQUIRE(sw.elapsed() <= wait_ms + tolerance_ms);
+}
+
+TEST_CASE("stopwatch2", "[stopwatch]")
+{
+    using spdlog::sinks::test_sink_st;
+
+    std::chrono::duration<double> wait_duration(0.250);
+    std::chrono::duration<double> tolerance_duration(0.250);
+
+    auto test_sink = std::make_shared<test_sink_st>();
+
+    spdlog::stopwatch sw;
+    spdlog::logger logger("test-stopwatch", test_sink);
+    logger.set_pattern("%v");
+    std::this_thread::sleep_for(wait_duration);
+    logger.info("{}", sw);
+    auto val = std::stod(test_sink->lines()[0]);
+
+    REQUIRE(val >= wait_duration.count());
+    REQUIRE(val <= (wait_duration + tolerance_duration).count());
+}