From c304284773227f70d1d0e8747aa9b18b01f82538 Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Thu, 20 Apr 2023 12:57:00 -0700
Subject: [PATCH] Update tests to use condition variables for work
 synchronization instead of sleeps

---
 test/cfoa/constructor_tests.cpp | 45 +++++++++++++++++++++++++++------
 test/cfoa/helpers.hpp           | 21 +++++++++++++--
 2 files changed, 56 insertions(+), 10 deletions(-)

diff --git a/test/cfoa/constructor_tests.cpp b/test/cfoa/constructor_tests.cpp
index 86760863..457d27e3 100644
--- a/test/cfoa/constructor_tests.cpp
+++ b/test/cfoa/constructor_tests.cpp
@@ -297,11 +297,20 @@ namespace {
       boost::unordered_flat_map<raii, raii>(values.begin(), values.end());
     raii::reset_counts();
 
+    std::mutex m;
+    std::condition_variable cv;
+    bool ready = false;
+
     {
       map_type x(0, hasher(1), key_equal(2), allocator_type{});
 
-      auto f = [&x, &values] {
-        std::this_thread::sleep_for(std::chrono::milliseconds(75));
+      auto f = [&x, &values, &m, &cv, &ready] {
+        {
+          std::lock_guard<std::mutex> guard(m);
+          ready = true;
+        }
+        cv.notify_all();
+
         for (auto const& val : values) {
           x.insert(val);
         }
@@ -311,9 +320,15 @@ namespace {
       std::thread t2(f);
 
       thread_runner(
-        values, [&x, &reference_map, &values, rg](
+        values, [&x, &reference_map, &values, rg, &m, &cv, &ready](
                   boost::span<span_value_type<decltype(values)> > s) {
           (void)s;
+
+          {
+            std::unique_lock<std::mutex> lk(m);
+            cv.wait(lk, [&] { return ready; });
+          }
+
           map_type y(x);
 
           BOOST_TEST_LE(y.size(), values.size());
@@ -483,12 +498,12 @@ namespace {
             BOOST_TEST_EQ(y.hash_function(), hasher(1));
             BOOST_TEST_EQ(y.key_eq(), key_equal(2));
           } else {
-            BOOST_TEST_EQ(y.size(), 0);
+            BOOST_TEST_EQ(y.size(), 0u);
             BOOST_TEST_EQ(y.hash_function(), hasher());
             BOOST_TEST_EQ(y.key_eq(), key_equal());
           }
 
-          BOOST_TEST_EQ(x.size(), 0);
+          BOOST_TEST_EQ(x.size(), 0u);
           BOOST_TEST_EQ(x.hash_function(), hasher());
           BOOST_TEST_EQ(x.key_eq(), key_equal());
 
@@ -511,11 +526,20 @@ namespace {
       boost::unordered_flat_map<raii, raii>(values.begin(), values.end());
     raii::reset_counts();
 
+    std::mutex m;
+    std::condition_variable cv;
+    bool ready = false;
+
     {
       map_type x(0, hasher(1), key_equal(2), allocator_type{});
 
-      auto f = [&x, &values] {
-        std::this_thread::sleep_for(std::chrono::milliseconds(25));
+      auto f = [&x, &values, &m, &cv, &ready] {
+        {
+          std::lock_guard<std::mutex> guard(m);
+          ready = true;
+        }
+        cv.notify_all();
+
         for (auto const& val : values) {
           x.insert(val);
         }
@@ -527,10 +551,15 @@ namespace {
       std::thread t2(f);
 
       thread_runner(
-        values, [&x, &reference_map, &num_transfers, rg](
+        values, [&x, &reference_map, &num_transfers, rg, &m, &ready, &cv](
                   boost::span<span_value_type<decltype(values)> > s) {
           (void)s;
 
+          {
+            std::unique_lock<std::mutex> lk(m);
+            cv.wait(lk, [&] { return ready; });
+          }
+
           map_type y(std::move(x));
 
           if (!y.empty()) {
diff --git a/test/cfoa/helpers.hpp b/test/cfoa/helpers.hpp
index 02f22d86..a830c032 100644
--- a/test/cfoa/helpers.hpp
+++ b/test/cfoa/helpers.hpp
@@ -9,8 +9,10 @@
 #include <boost/unordered/unordered_flat_map.hpp>
 
 #include <atomic>
+#include <condition_variable>
 #include <cstddef>
 #include <iostream>
+#include <mutex>
 #include <thread>
 #include <vector>
 
@@ -272,16 +274,31 @@ std::vector<boost::span<T> > split(
 
 template <class T, class F> void thread_runner(std::vector<T>& values, F f)
 {
+  std::mutex m;
+  std::condition_variable cv;
+  bool ready = false;
+
   std::vector<std::thread> threads;
   auto subslices = split<T>(values, num_threads);
 
   for (std::size_t i = 0; i < num_threads; ++i) {
-    threads.emplace_back([&f, &subslices, i] {
-      std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    threads.emplace_back([&f, &subslices, i, &m, &cv, &ready] {
+      {
+        std::unique_lock<std::mutex> lk(m);
+        cv.wait(lk, [&] { return ready; });
+      }
+
       auto s = subslices[i];
       f(s);
     });
   }
+
+  {
+    std::lock_guard<std::mutex> guard(m);
+    ready = true;
+  }
+  cv.notify_all();
+
   for (auto& t : threads) {
     t.join();
   }