Route app thread orchestration through app core

src/app_core/app_thread.h

@@ -0,0 +1,200 @@
+#pragma once
+
+#include "foundation/result.h"
+
+#include <cmath>
+#include <cstddef>
+
+namespace pp::app {
+
+struct AppTaskDispatchPlan {
+    bool execute_immediately = false;
+    bool queue_task = false;
+    bool remove_matching_unique_task = false;
+    bool notify_worker = false;
+    bool wait_for_completion = false;
+    bool request_redraw = false;
+};
+
+struct AppAsyncRedrawPlan {
+    bool set_redraw = true;
+    bool notify_ui = true;
+};
+
+struct AppQueueDrainPlan {
+    bool mark_running = true;
+    bool drain_tasks = false;
+    bool wrap_in_render_context = false;
+    std::size_t task_count = 0;
+};
+
+struct AppUiTickPlan {
+    bool mark_running = true;
+    bool execute_tasks = false;
+    bool tick_app = true;
+    bool update_before_render = false;
+    bool enqueue_render_frame = false;
+    std::size_t task_count = 0;
+};
+
+struct AppUiLoopTimerPlan {
+    bool update_platform_frame = true;
+    float frame_accumulator = 0.0F;
+    float fps_accumulator = 0.0F;
+    float reload_accumulator = 0.0F;
+    bool report_rendered_frames = false;
+    int reported_frame_count = 0;
+    int rendered_frames_after_report = 0;
+    bool check_live_asset_reload = false;
+};
+
+struct AppUiLoopRedrawPlan {
+    bool tick_app = true;
+    bool update_before_render = false;
+    bool enqueue_render_frame = false;
+    bool reset_frame_accumulator = false;
+    int rendered_frames = 0;
+};
+
+struct AppThreadStartPlan {
+    bool start_thread = true;
+    bool mark_running = true;
+};
+
+struct AppThreadStopPlan {
+    bool mark_not_running = true;
+    bool notify_worker = true;
+    bool join_thread = false;
+};
+
+[[nodiscard]] constexpr AppTaskDispatchPlan plan_app_task_dispatch(
+    bool already_on_target_thread,
+    bool unique,
+    std::size_t queued_task_count,
+    bool worker_running,
+    bool wait_for_completion,
+    bool request_redraw_after_dispatch) noexcept
+{
+    const bool queue_task = !already_on_target_thread;
+    return AppTaskDispatchPlan {
+        .execute_immediately = already_on_target_thread,
+        .queue_task = queue_task,
+        .remove_matching_unique_task = queue_task && unique && queued_task_count > 0U,
+        .notify_worker = queue_task,
+        .wait_for_completion = queue_task && worker_running && wait_for_completion,
+        .request_redraw = request_redraw_after_dispatch,
+    };
+}
+
+[[nodiscard]] constexpr AppAsyncRedrawPlan plan_app_async_redraw() noexcept
+{
+    return AppAsyncRedrawPlan {};
+}
+
+[[nodiscard]] constexpr AppQueueDrainPlan plan_app_render_queue_drain(std::size_t queued_task_count) noexcept
+{
+    const bool drain = queued_task_count > 0U;
+    return AppQueueDrainPlan {
+        .mark_running = true,
+        .drain_tasks = drain,
+        .wrap_in_render_context = drain,
+        .task_count = queued_task_count,
+    };
+}
+
+[[nodiscard]] constexpr AppQueueDrainPlan plan_app_ui_queue_drain(std::size_t queued_task_count) noexcept
+{
+    return AppQueueDrainPlan {
+        .mark_running = true,
+        .drain_tasks = queued_task_count > 0U,
+        .wrap_in_render_context = false,
+        .task_count = queued_task_count,
+    };
+}
+
+[[nodiscard]] constexpr AppUiTickPlan plan_app_ui_thread_tick(
+    std::size_t queued_task_count,
+    bool redraw) noexcept
+{
+    return AppUiTickPlan {
+        .mark_running = true,
+        .execute_tasks = queued_task_count > 0U,
+        .tick_app = true,
+        .update_before_render = redraw,
+        .enqueue_render_frame = redraw,
+        .task_count = queued_task_count,
+    };
+}
+
+[[nodiscard]] inline pp::foundation::Result<AppUiLoopTimerPlan> plan_app_ui_loop_timers(
+    float delta_time_seconds,
+    float frame_accumulator,
+    float fps_accumulator,
+    float reload_accumulator,
+    int rendered_frames,
+    bool live_asset_reloading_enabled)
+{
+    if (!std::isfinite(delta_time_seconds) || !std::isfinite(frame_accumulator)
+        || !std::isfinite(fps_accumulator) || !std::isfinite(reload_accumulator)) {
+        return pp::foundation::Result<AppUiLoopTimerPlan>::failure(
+            pp::foundation::Status::invalid_argument("UI loop timer values must be finite"));
+    }
+
+    if (delta_time_seconds < 0.0F || frame_accumulator < 0.0F
+        || fps_accumulator < 0.0F || reload_accumulator < 0.0F || rendered_frames < 0) {
+        return pp::foundation::Result<AppUiLoopTimerPlan>::failure(
+            pp::foundation::Status::invalid_argument("UI loop timer values must not be negative"));
+    }
+
+    AppUiLoopTimerPlan plan;
+    plan.frame_accumulator = frame_accumulator + delta_time_seconds;
+    plan.fps_accumulator = fps_accumulator + delta_time_seconds;
+    plan.reload_accumulator = reload_accumulator;
+    plan.rendered_frames_after_report = rendered_frames;
+
+    if (plan.fps_accumulator > 1.0F) {
+        plan.report_rendered_frames = true;
+        plan.reported_frame_count = rendered_frames;
+        plan.fps_accumulator = 0.0F;
+        plan.rendered_frames_after_report = 0;
+    }
+
+    if (live_asset_reloading_enabled) {
+        plan.reload_accumulator += delta_time_seconds;
+        if (plan.reload_accumulator > 1.0F) {
+            plan.reload_accumulator = 0.0F;
+            plan.check_live_asset_reload = true;
+        }
+    }
+
+    return pp::foundation::Result<AppUiLoopTimerPlan>::success(plan);
+}
+
+[[nodiscard]] constexpr AppUiLoopRedrawPlan plan_app_ui_loop_redraw(
+    bool redraw,
+    int rendered_frames) noexcept
+{
+    return AppUiLoopRedrawPlan {
+        .tick_app = true,
+        .update_before_render = redraw,
+        .enqueue_render_frame = redraw,
+        .reset_frame_accumulator = redraw,
+        .rendered_frames = rendered_frames + (redraw ? 1 : 0),
+    };
+}
+
+[[nodiscard]] constexpr AppThreadStartPlan plan_app_thread_start() noexcept
+{
+    return AppThreadStartPlan {};
+}
+
+[[nodiscard]] constexpr AppThreadStopPlan plan_app_thread_stop(bool thread_joinable) noexcept
+{
+    return AppThreadStopPlan {
+        .mark_not_running = true,
+        .notify_worker = true,
+        .join_thread = thread_joinable,
+    };
+}
+
+} // namespace pp::app