From 0ddbbb64e514ea9bba6a4f8bd6908d654e7f114c Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Tue, 29 Jun 2021 01:47:13 -0300
Subject: common/thread_worker: Stop workers on stop_token when waiting

---
 src/common/thread_worker.h | 38 ++++++++++++++++++++------------------
 1 file changed, 20 insertions(+), 18 deletions(-)

(limited to 'src/common/thread_worker.h')

diff --git a/src/common/thread_worker.h b/src/common/thread_worker.h
index 16aa673bd..8272985ff 100644
--- a/src/common/thread_worker.h
+++ b/src/common/thread_worker.h
@@ -7,7 +7,9 @@
 #include <atomic>
 #include <functional>
 #include <mutex>
+#include <stop_token>
 #include <string>
+#include <thread>
 #include <type_traits>
 #include <vector>
 #include <queue>
@@ -34,19 +36,19 @@ class StatefulThreadWorker {
 public:
     explicit StatefulThreadWorker(size_t num_workers, std::string name, StateMaker func = {})
         : workers_queued{num_workers}, thread_name{std::move(name)} {
-        const auto lambda = [this, func] {
+        const auto lambda = [this, func](std::stop_token stop_token) {
             Common::SetCurrentThreadName(thread_name.c_str());
             {
                 std::conditional_t<with_state, StateType, int> state{func()};
-                while (!stop) {
+                while (!stop_token.stop_requested()) {
                     Task task;
                     {
                         std::unique_lock lock{queue_mutex};
                         if (requests.empty()) {
                             wait_condition.notify_all();
                         }
-                        condition.wait(lock, [this] { return stop || !requests.empty(); });
-                        if (stop) {
+                        condition.wait(lock, stop_token, [this] { return !requests.empty(); });
+                        if (stop_token.stop_requested()) {
                             break;
                         }
                         task = std::move(requests.front());
@@ -63,21 +65,17 @@ public:
             ++workers_stopped;
             wait_condition.notify_all();
         };
+        threads.reserve(num_workers);
         for (size_t i = 0; i < num_workers; ++i) {
             threads.emplace_back(lambda);
         }
     }
 
-    ~StatefulThreadWorker() {
-        {
-            std::unique_lock lock{queue_mutex};
-            stop = true;
-        }
-        condition.notify_all();
-        for (std::thread& thread : threads) {
-            thread.join();
-        }
-    }
+    StatefulThreadWorker& operator=(const StatefulThreadWorker&) = delete;
+    StatefulThreadWorker(const StatefulThreadWorker&) = delete;
+
+    StatefulThreadWorker& operator=(StatefulThreadWorker&&) = delete;
+    StatefulThreadWorker(StatefulThreadWorker&&) = delete;
 
     void QueueWork(Task work) {
         {
@@ -88,7 +86,12 @@ public:
         condition.notify_one();
     }
 
-    void WaitForRequests() {
+    void WaitForRequests(std::stop_token stop_token = {}) {
+        std::stop_callback callback(stop_token, [this] {
+            for (auto& thread : threads) {
+                thread.request_stop();
+            }
+        });
         std::unique_lock lock{queue_mutex};
         wait_condition.wait(lock, [this] {
             return workers_stopped >= workers_queued || work_done >= work_scheduled;
@@ -96,17 +99,16 @@ public:
     }
 
 private:
-    std::vector<std::thread> threads;
     std::queue<Task> requests;
     std::mutex queue_mutex;
-    std::condition_variable condition;
+    std::condition_variable_any condition;
     std::condition_variable wait_condition;
-    std::atomic_bool stop{};
     std::atomic<size_t> work_scheduled{};
     std::atomic<size_t> work_done{};
     std::atomic<size_t> workers_stopped{};
     std::atomic<size_t> workers_queued{};
     std::string thread_name;
+    std::vector<std::jthread> threads;
 };
 
 using ThreadWorker = StatefulThreadWorker<>;
-- 
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