Merge pull request #6563 from ReinUsesLisp/thread-worker

common: Add stateful thread worker and unique function utilities

1 files changed, 94 insertions, 8 deletions

diff --git a/src/common/thread_worker.h b/src/common/thread_worker.h
index f1859971f..8272985ff 100644
--- a/src/common/thread_worker.h
+++ b/src/common/thread_worker.h
@@ -7,24 +7,110 @@
 #include <atomic>
 #include <functional>
 #include <mutex>
+#include <stop_token>
 #include <string>
+#include <thread>
+#include <type_traits>
 #include <vector>
 #include <queue>
 
+#include "common/thread.h"
+#include "common/unique_function.h"
+
 namespace Common {
 
-class ThreadWorker final {
+template <class StateType = void>
+class StatefulThreadWorker {
+    static constexpr bool with_state = !std::is_same_v<StateType, void>;
+
+    struct DummyCallable {
+        int operator()() const noexcept {
+            return 0;
+        }
+    };
+
+    using Task =
+        std::conditional_t<with_state, UniqueFunction<void, StateType*>, UniqueFunction<void>>;
+    using StateMaker = std::conditional_t<with_state, std::function<StateType()>, DummyCallable>;
+
 public:
-    explicit ThreadWorker(std::size_t num_workers, const std::string& name);
-    ~ThreadWorker();
-    void QueueWork(std::function<void()>&& work);
+    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](std::stop_token stop_token) {
+            Common::SetCurrentThreadName(thread_name.c_str());
+            {
+                std::conditional_t<with_state, StateType, int> state{func()};
+                while (!stop_token.stop_requested()) {
+                    Task task;
+                    {
+                        std::unique_lock lock{queue_mutex};
+                        if (requests.empty()) {
+                            wait_condition.notify_all();
+                        }
+                        condition.wait(lock, stop_token, [this] { return !requests.empty(); });
+                        if (stop_token.stop_requested()) {
+                            break;
+                        }
+                        task = std::move(requests.front());
+                        requests.pop();
+                    }
+                    if constexpr (with_state) {
+                        task(&state);
+                    } else {
+                        task();
+                    }
+                    ++work_done;
+                }
+            }
+            ++workers_stopped;
+            wait_condition.notify_all();
+        };
+        threads.reserve(num_workers);
+        for (size_t i = 0; i < num_workers; ++i) {
+            threads.emplace_back(lambda);
+        }
+    }
+
+    StatefulThreadWorker& operator=(const StatefulThreadWorker&) = delete;
+    StatefulThreadWorker(const StatefulThreadWorker&) = delete;
+
+    StatefulThreadWorker& operator=(StatefulThreadWorker&&) = delete;
+    StatefulThreadWorker(StatefulThreadWorker&&) = delete;
+
+    void QueueWork(Task work) {
+        {
+            std::unique_lock lock{queue_mutex};
+            requests.emplace(std::move(work));
+            ++work_scheduled;
+        }
+        condition.notify_one();
+    }
+
+    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;
+        });
+    }
 
 private:
-    std::vector<std::thread> threads;
-    std::queue<std::function<void()>> requests;
+    std::queue<Task> requests;
     std::mutex queue_mutex;
-    std::condition_variable condition;
-    std::atomic_bool stop{};
+    std::condition_variable_any condition;
+    std::condition_variable wait_condition;
+    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<>;
+
 } // namespace Common