From a85fc2504048165da68931e098248ca98e00c4e1 Mon Sep 17 00:00:00 2001
From: Joel Linn <jl@conductive.de>
Date: Sat, 5 Mar 2022 11:41:19 +0100
Subject: [PATCH] [Base] Add more tests for HighResolutionTimer

---
 src/xenia/base/testing/threading_test.cc | 59 +++++++++++++++++++++++-
 1 file changed, 57 insertions(+), 2 deletions(-)

diff --git a/src/xenia/base/testing/threading_test.cc b/src/xenia/base/testing/threading_test.cc
index 3a8b119c1..2643e2148 100644
--- a/src/xenia/base/testing/threading_test.cc
+++ b/src/xenia/base/testing/threading_test.cc
@@ -241,8 +241,63 @@ TEST_CASE("HighResolutionTimer") {
     REQUIRE(counter2 <= ratio2 + 1);
   }
 
-  // TODO(bwrsandman): Check on which thread callbacks are executed when
-  // spawned from differing threads
+  // Test many timers
+  {
+    const auto interval = 50ms;
+    const size_t timer_count = 128;
+    std::atomic<uint64_t> counter(0);
+    auto cb = [&counter, &timer_thread] {
+      ++counter;
+      REQUIRE(Thread::GetCurrentThread() == timer_thread);
+    };
+    std::vector<std::unique_ptr<HighResolutionTimer>> timers;
+    auto start = std::chrono::steady_clock::now();
+    for (size_t i = 0; i < timer_count; i++) {
+      timers.emplace_back(HighResolutionTimer::CreateRepeating(interval, cb));
+    }
+    Sleep(wait_time);
+    timers.clear();
+    auto duration = std::chrono::steady_clock::now() - start;
+
+    REQUIRE(duration.count() >= wait_time.count());
+    auto ratio = static_cast<uint64_t>(timer_count * duration / interval);
+    REQUIRE(counter >= ratio - timer_count);
+    REQUIRE(counter <= ratio + timer_count);
+  }
+
+  // Check timer order
+  {
+    constexpr size_t timer_count = 16;
+    using pair_t = std::pair<std::atomic<uint64_t>,
+                             std::chrono::high_resolution_clock::time_point>;
+    std::array<pair_t, timer_count> time_points{};
+    auto start = std::chrono::steady_clock::now();
+    auto gen_callback = [&timer_thread, &time_points](size_t i) {
+      return [&timer_thread, &time_points, i]() {
+        auto& pair = time_points[i];
+        if (pair.first.fetch_add(1) == 1) {
+          pair.second = std::chrono::high_resolution_clock::now();
+          pair.first++;
+        }
+        REQUIRE(Thread::GetCurrentThread() == timer_thread);
+      };
+    };
+    std::vector<std::unique_ptr<HighResolutionTimer>> timers;
+    for (size_t i = 0; i < timer_count; i++) {
+      timers.emplace_back(HighResolutionTimer::CreateRepeating(
+          10ms * (timer_count - i), gen_callback(timer_count - i - 1)));
+    }
+    REQUIRE(spin_wait_for(2s, [&] {
+      return std::all_of(time_points.cbegin(), time_points.cend(),
+                         [](auto& pair) { return pair.first >= 3; });
+    }));
+
+    timers.clear();
+
+    REQUIRE(std::is_sorted(
+        time_points.cbegin(), time_points.cend(),
+        [](auto& left, auto& right) { return left.second < right.second; }));
+  }
 }
 
 TEST_CASE("Wait on Multiple Handles", "[wait]") {