From 5b2f049d4ce9c5ef3701874504c8c392bda199a7 Mon Sep 17 00:00:00 2001
From: Ben Vanik <ben.vanik@gmail.com>
Date: Mon, 29 Jun 2015 12:02:08 -0700
Subject: [PATCH] Adding deferred xoverlapped completion helper.

---
 src/xenia/kernel/kernel_state.cc | 57 ++++++++++++++++++++++++++++++++
 src/xenia/kernel/kernel_state.h  | 16 +++++++++
 2 files changed, 73 insertions(+)

diff --git a/src/xenia/kernel/kernel_state.cc b/src/xenia/kernel/kernel_state.cc
index b50d64164..86994216f 100644
--- a/src/xenia/kernel/kernel_state.cc
+++ b/src/xenia/kernel/kernel_state.cc
@@ -36,6 +36,8 @@ DEFINE_string(content_root, "content",
 namespace xe {
 namespace kernel {
 
+constexpr uint32_t kDeferredOverlappedDelayMillis = 100;
+
 // This is a global object initialized with the XboxkrnlModule.
 // It references the current kernel state object that all kernel methods should
 // be using to stash their variables.
@@ -88,6 +90,12 @@ KernelState::KernelState(Emulator* emulator)
 KernelState::~KernelState() {
   SetExecutableModule(nullptr);
 
+  if (dispatch_thread_running_) {
+    dispatch_thread_running_ = false;
+    dispatch_cond_.notify_all();
+    dispatch_thread_->Wait(0, 0, 0, nullptr);
+  }
+
   if (process_info_block_address_) {
     memory_->SystemHeapFree(process_info_block_address_);
   }
@@ -202,6 +210,30 @@ void KernelState::SetExecutableModule(object_ref<XUserModule> module) {
         memory()->TranslateVirtual<xe::be<uint32_t>*>(export->variable_ptr);
     *variable_ptr = executable_module_->hmodule_ptr();
   }
+
+  // Spin up deferred dispatch worker.
+  // TODO(benvanik): move someplace more appropriate (out of ctor, but around
+  // here).
+  assert_false(dispatch_thread_running_);
+  dispatch_thread_running_ = true;
+  dispatch_thread_ =
+      object_ref<XHostThread>(new XHostThread(this, 128 * 1024, 0, [this]() {
+        while (dispatch_thread_running_) {
+          std::unique_lock<std::mutex> lock(dispatch_mutex_);
+          if (dispatch_queue_.empty()) {
+            dispatch_cond_.wait(lock);
+            if (!dispatch_thread_running_) {
+              break;
+            }
+          }
+          auto fn = std::move(dispatch_queue_.front());
+          dispatch_queue_.pop_front();
+          fn();
+        }
+        return 0;
+      }));
+  dispatch_thread_->set_name("Kernel Dispatch Thread");
+  dispatch_thread_->Create();
 }
 
 void KernelState::LoadKernelModule(object_ref<XKernelModule> kernel_module) {
@@ -430,5 +462,30 @@ void KernelState::CompleteOverlappedImmediateEx(uint32_t overlapped_ptr,
   CompleteOverlappedEx(overlapped_ptr, result, extended_error, length);
 }
 
+void KernelState::CompleteOverlappedDeferred(
+    std::function<void()> completion_callback, uint32_t overlapped_ptr,
+    X_RESULT result) {
+  CompleteOverlappedDeferredEx(std::move(completion_callback), overlapped_ptr,
+                               result, result, 0);
+}
+
+void KernelState::CompleteOverlappedDeferredEx(
+    std::function<void()> completion_callback, uint32_t overlapped_ptr,
+    X_RESULT result, uint32_t extended_error, uint32_t length) {
+  auto ptr = memory()->TranslateVirtual(overlapped_ptr);
+  XOverlappedSetResult(ptr, X_ERROR_IO_PENDING);
+  XOverlappedSetContext(ptr, XThread::GetCurrentThreadHandle());
+  std::unique_lock<std::mutex> lock(dispatch_mutex_);
+  dispatch_queue_.push_back([this, completion_callback, overlapped_ptr, result,
+                             extended_error, length]() {
+    xe::threading::Sleep(
+        std::chrono::milliseconds::duration(kDeferredOverlappedDelayMillis));
+    completion_callback();
+    auto ptr = memory()->TranslateVirtual(overlapped_ptr);
+    CompleteOverlappedEx(overlapped_ptr, result, extended_error, length);
+  });
+  dispatch_cond_.notify_all();
+}
+
 }  // namespace kernel
 }  // namespace xe
diff --git a/src/xenia/kernel/kernel_state.h b/src/xenia/kernel/kernel_state.h
index c2ac47c3b..8b448ea5f 100644
--- a/src/xenia/kernel/kernel_state.h
+++ b/src/xenia/kernel/kernel_state.h
@@ -12,6 +12,10 @@
 
 #include <gflags/gflags.h>
 
+#include <atomic>
+#include <condition_variable>
+#include <functional>
+#include <list>
 #include <memory>
 #include <mutex>
 
@@ -38,6 +42,7 @@ namespace xe {
 namespace kernel {
 
 class Dispatcher;
+class XHostThread;
 class XKernelModule;
 class XModule;
 class XNotifyListener;
@@ -133,6 +138,11 @@ class KernelState {
   void CompleteOverlappedImmediate(uint32_t overlapped_ptr, X_RESULT result);
   void CompleteOverlappedImmediateEx(uint32_t overlapped_ptr, X_RESULT result,
                                      uint32_t extended_error, uint32_t length);
+  void CompleteOverlappedDeferred(std::function<void()> completion_callback,
+                                  uint32_t overlapped_ptr, X_RESULT result);
+  void CompleteOverlappedDeferredEx(std::function<void()> completion_callback,
+                                    uint32_t overlapped_ptr, X_RESULT result,
+                                    uint32_t extended_error, uint32_t length);
 
  private:
   void LoadKernelModule(object_ref<XKernelModule> kernel_module);
@@ -161,6 +171,12 @@ class KernelState {
 
   uint32_t process_info_block_address_;
 
+  std::atomic<bool> dispatch_thread_running_ = false;
+  object_ref<XHostThread> dispatch_thread_;
+  std::mutex dispatch_mutex_;
+  std::condition_variable dispatch_cond_;
+  std::list<std::function<void()>> dispatch_queue_;
+
   friend class XObject;
 };