Move prepared-file work into app runtime

src/app_events.cpp

@@ -6,12 +6,7 @@
 #include "app_core/document_sharing.h"
 #include "platform_api/platform_services.h"
 
-#include <condition_variable>
-#include <deque>
 #include <functional>
-#include <mutex>
-#include <stop_token>
-#include <thread>
 
 #ifdef __LINUX__
 #include <GLFW/glfw3.h>
@@ -22,88 +17,6 @@
 
 namespace {
 
-class LegacyPreparedFileWorker final {
-public:
-    LegacyPreparedFileWorker()
-        : worker_([this](std::stop_token stop_token) {
-            run(stop_token);
-        })
-    {
-    }
-
-    ~LegacyPreparedFileWorker()
-    {
-        shutdown();
-    }
-
-    void post(std::function<void()> task)
-    {
-        {
-            std::lock_guard<std::mutex> lock(mutex_);
-            if (stopping_)
-                return;
-            tasks_.push_back(std::move(task));
-        }
-        cv_.notify_one();
-    }
-
-private:
-    void shutdown()
-    {
-        {
-            std::lock_guard<std::mutex> lock(mutex_);
-            stopping_ = true;
-        }
-        cv_.notify_all();
-    }
-
-    void run(std::stop_token stop_token)
-    {
-        for (;;) {
-            std::function<void()> task;
-            {
-                std::unique_lock<std::mutex> lock(mutex_);
-                cv_.wait(lock, [&] {
-                    return stopping_ || stop_token.stop_requested() || !tasks_.empty();
-                });
-                if ((stopping_ || stop_token.stop_requested()) && tasks_.empty())
-                    break;
-                task = std::move(tasks_.front());
-                tasks_.pop_front();
-            }
-
-            if (task) {
-                try {
-                    task();
-                } catch (...) {
-                    LOG("prepared file worker task failed");
-                }
-            }
-        }
-    }
-
-    std::mutex mutex_;
-    std::condition_variable cv_;
-    std::deque<std::function<void()>> tasks_;
-    bool stopping_ = false;
-    std::jthread worker_;
-};
-
-struct RetainedPreparedFileWorkerState final {
-    void post(std::function<void()> task)
-    {
-        worker.post(std::move(task));
-    }
-
-    LegacyPreparedFileWorker worker;
-};
-
-RetainedPreparedFileWorkerState& retained_prepared_file_worker_state()
-{
-    static RetainedPreparedFileWorkerState state;
-    return state;
-}
-
 [[nodiscard]] GLint rgba8_internal_format() noexcept
 {
     return static_cast<GLint>(pp::renderer::gl::rgba8_internal_format());
@@ -293,7 +206,7 @@ void App::pick_file_save(const std::string& type, const std::string& default_nam
     LOG("App::pick_file_save %s", target.path.c_str());
     if (target.write_on_background_thread) {
         auto* app = this;
-        retained_prepared_file_worker_state().post([
+        runtime_.prepared_file_task([
             app,
             writer = std::move(writer),
             callback = std::move(callback),