dinput: prevent freeing handle despite static initializer order

2 files changed, 83 insertions, 34 deletions

diff --git a/opentrack-dinput/dinput.cpp b/opentrack-dinput/dinput.cpp
index ce80fe0e..06b5e4f2 100644
--- a/opentrack-dinput/dinput.cpp
+++ b/opentrack-dinput/dinput.cpp
@@ -3,22 +3,11 @@
 #include "dinput.hpp"
 #include <QDebug>
 
-dinput_handle dinput_handle::self;
+std::atomic<int> dinput_handle::refcnt;
+std::atomic_flag dinput_handle::init_lock = ATOMIC_FLAG_INIT;
+dinput_handle::di_t dinput_handle::handle(dinput_handle::make_di());
 
-dinput_handle::dinput_handle() : handle(init_di())
-{
-}
-
-dinput_handle::~dinput_handle()
-{
-    if (handle)
-    {
-        handle->Release();
-        handle = nullptr;
-    }
-}
-
-dinput_handle::di_t dinput_handle::init_di()
+LPDIRECTINPUT8& dinput_handle::init_di()
 {
     HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
     if (FAILED(hr))
@@ -27,13 +16,9 @@ dinput_handle::di_t dinput_handle::init_di()
     static LPDIRECTINPUT8 di_ = nullptr;
     if (di_ == nullptr)
     {
-        if (SUCCEEDED(DirectInput8Create(GetModuleHandle(NULL), DIRECTINPUT_VERSION, IID_IDirectInput8, (void**)&di_, NULL)))
-        {
-            return di_;
-        }
-        else
+        if (!SUCCEEDED(DirectInput8Create(GetModuleHandle(NULL), DIRECTINPUT_VERSION, IID_IDirectInput8, (void**)&di_, NULL)))
         {
-            return di_ = nullptr;
+            di_ = nullptr;
         }
     }
     return di_;
@@ -41,7 +26,44 @@ dinput_handle::di_t dinput_handle::init_di()
 
 dinput_handle::di_t dinput_handle::make_di()
 {
-    return self.handle;
+    while (init_lock.test_and_set()) { /* busy loop */ }
+
+    LPDIRECTINPUT8& ret = init_di();
+
+    init_lock.clear();
+
+    return di_t(ret);
 }
 
 #endif
+
+dinput_handle::di_t::di_t(LPDIRECTINPUT8& handle) : handle(handle)
+{
+    while (init_lock.test_and_set()) { /* busy loop */ }
+
+    refcnt++;
+
+    init_lock.clear();
+}
+
+void dinput_handle::di_t::free_di()
+{
+    if (handle)
+        handle->Release();
+    handle = nullptr;
+}
+
+dinput_handle::di_t::~di_t()
+{
+    while (init_lock.test_and_set()) { /* busy loop */ }
+
+    int refcnt_ = refcnt.fetch_sub(1);
+
+    if (refcnt_ == 1)
+    {
+        qDebug() << "exit: deleting di handle";
+        free_di();
+    }
+
+    init_lock.clear();
+}
diff --git a/opentrack-dinput/dinput.hpp b/opentrack-dinput/dinput.hpp
index db901887..37a6d723 100644
--- a/opentrack-dinput/dinput.hpp
+++ b/opentrack-dinput/dinput.hpp
@@ -1,28 +1,55 @@
+/* Copyright (c) 2016, Stanislaw Halik <sthalik@misaki.pl>
+
+ * Permission to use, copy, modify, and/or distribute this
+ * software for any purpose with or without fee is hereby granted,
+ * provided that the above copyright notice and this permission
+ * notice appear in all copies.
+ */
+
 #pragma once
 
 #ifdef _WIN32
 
+#include "export.hpp"
+
 #ifndef DIRECTINPUT_VERSION
 #   define DIRECTINPUT_VERSION 0x800
 #endif
-#include "export.hpp"
 #include <dinput.h>
-#include <windows.h>
 
-struct OPENTRACK_DINPUT_EXPORT dinput_handle final
+#include <atomic>
+
+class OPENTRACK_DINPUT_EXPORT dinput_handle final
 {
-    using di_t = LPDIRECTINPUT8;
+public:
+    class di_t;
+
 private:
-    static dinput_handle self;
-    dinput_handle();
-    ~dinput_handle();
-    static di_t init_di();
-    di_t handle;
+    static std::atomic<int> refcnt;
+    static std::atomic_flag init_lock;
+    static di_t handle;
+
+    static LPDIRECTINPUT8& init_di();
 public:
-     static di_t make_di();
+    class di_t final
+    {
+        friend class dinput_handle;
+
+        LPDIRECTINPUT8& handle;
+
+        di_t(LPDIRECTINPUT8& handle);
+        void free_di();
+
+    public:
+        LPDIRECTINPUT8 operator->() { return handle; }
+        operator LPDIRECTINPUT8() { return handle; }
+        LPDIRECTINPUT8 di() { return handle; }
+
+        ~di_t();
+    };
 
-     dinput_handle(const dinput_handle&) = delete;
-     dinput_handle(dinput_handle&&) = delete;
+    static di_t make_di();
+    dinput_handle() = delete;
 };
 
 #endif