From e10643add21e9c35d41f60288f13352da754d2b9 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@meta.com>
Date: Sun, 14 Jul 2024 14:17:39 -0700
Subject: [PATCH] Add a perf-sanity test

---
 test/CMakeLists.txt |  5 ++++-
 test/perf-sanity.cc | 26 ++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 test/perf-sanity.cc

diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index fac82392..a14dfc24 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -110,6 +110,9 @@ add_fmt_test(enforce-checks-test)
 target_compile_definitions(enforce-checks-test PRIVATE
                            -DFMT_ENFORCE_COMPILE_STRING)
 
+add_executable(perf-sanity perf-sanity.cc)
+target_link_libraries(perf-sanity fmt::fmt)
+
 if (FMT_MODULE)
   # The tests need {fmt} to be compiled as traditional library
   # because of visibility of implementation details.
@@ -233,7 +236,7 @@ if (FMT_PEDANTIC AND NOT WIN32 AND NOT (
     "-DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}")
 endif ()
 
-# This test are disabled on Windows because it is only *NIX issue.
+# This test is disabled on Windows because it is POSIX-specific.
 if (FMT_PEDANTIC AND NOT WIN32)
   add_test(static-export-test ${CMAKE_CTEST_COMMAND}
     -C ${CMAKE_BUILD_TYPE}
diff --git a/test/perf-sanity.cc b/test/perf-sanity.cc
new file mode 100644
index 00000000..7696b2f1
--- /dev/null
+++ b/test/perf-sanity.cc
@@ -0,0 +1,26 @@
+// A quick and dirty performance test.
+// For actual benchmarks see https://github.com/fmtlib/format-benchmark.
+
+#include <atomic>
+#include <chrono>
+#include <iterator>
+
+#include "fmt/format.h"
+
+int main() {
+  const int n = 10000000;
+
+  auto start = std::chrono::steady_clock::now();
+  for (int iteration = 0; iteration < n; ++iteration) {
+    auto buf = fmt::memory_buffer();
+    fmt::format_to(std::back_inserter(buf),
+                   "Hello, {}. The answer is {} and {}.", 1, 2345, 6789);
+  }
+  std::atomic_signal_fence(std::memory_order_acq_rel);  // Clobber memory.
+  auto end = std::chrono::steady_clock::now();
+
+  std::chrono::duration<double> duration = end - start;
+  double total_time = duration.count() * 1000;  // Convert to milliseconds.
+  fmt::print("Total time for formatting {} strings: {:.1f} ms.\n", n,
+             total_time);
+}