w32pthreads: Load dynamically loaded functions on demand
[ffmpeg.git] / compat / w32pthreads.h
index 8b7ff6b..ac9a814 100644 (file)
@@ -39,6 +39,7 @@
 #include <windows.h>
 #include <process.h>
 
+#include "libavutil/attributes.h"
 #include "libavutil/internal.h"
 #include "libavutil/mem.h"
 
@@ -53,29 +54,30 @@ typedef struct pthread_t {
  * not mutexes */
 typedef CRITICAL_SECTION pthread_mutex_t;
 
-/* This is the CONDITIONAL_VARIABLE typedef for using Window's native
- * conditional variables on kernels 6.0+.
- * MinGW does not currently have this typedef. */
+/* This is the CONDITION_VARIABLE typedef for using Windows' native
+ * conditional variables on kernels 6.0+. */
+#if HAVE_CONDITION_VARIABLE_PTR
+typedef CONDITION_VARIABLE pthread_cond_t;
+#else
 typedef struct pthread_cond_t {
-    void *ptr;
+    void *Ptr;
 } pthread_cond_t;
+#endif
 
-/* function pointers to conditional variable API on windows 6.0+ kernels */
-static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
-static void (WINAPI *cond_init)(pthread_cond_t *cond);
-static void (WINAPI *cond_signal)(pthread_cond_t *cond);
-static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
-                                DWORD milliseconds);
+#if _WIN32_WINNT >= 0x0600
+#define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
+#define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
+#endif
 
-static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
+static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
 {
     pthread_t *h = arg;
     h->ret = h->func(h->arg);
     return 0;
 }
 
-static int pthread_create(pthread_t *thread, const void *unused_attr,
-                          void *(*start_routine)(void*), void *arg)
+static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
+                                    void *(*start_routine)(void*), void *arg)
 {
     thread->func   = start_routine;
     thread->arg    = arg;
@@ -84,7 +86,7 @@ static int pthread_create(pthread_t *thread, const void *unused_attr,
     return !thread->handle;
 }
 
-static void pthread_join(pthread_t thread, void **value_ptr)
+static av_unused void pthread_join(pthread_t thread, void **value_ptr)
 {
     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
     if (ret != WAIT_OBJECT_0)
@@ -115,8 +117,113 @@ static inline int pthread_mutex_unlock(pthread_mutex_t *m)
     return 0;
 }
 
+#if _WIN32_WINNT >= 0x0600
+
+typedef INIT_ONCE pthread_once_t;
+#define PTHREAD_ONCE_INIT INIT_ONCE_STATIC_INIT
+
+static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
+{
+    BOOL pending = FALSE;
+    InitOnceBeginInitialize(once_control, 0, &pending, NULL);
+    if (pending)
+        init_routine();
+    InitOnceComplete(once_control, 0, NULL);
+    return 0;
+}
+
+static inline void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
+{
+    InitializeConditionVariable(cond);
+}
+
+/* native condition variables do not destroy */
+static inline void pthread_cond_destroy(pthread_cond_t *cond)
+{
+    return;
+}
+
+static inline void pthread_cond_broadcast(pthread_cond_t *cond)
+{
+    WakeAllConditionVariable(cond);
+}
+
+static inline int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
+{
+    SleepConditionVariableCS(cond, mutex, INFINITE);
+    return 0;
+}
+
+static inline void pthread_cond_signal(pthread_cond_t *cond)
+{
+    WakeConditionVariable(cond);
+}
+
+#else // _WIN32_WINNT < 0x0600
+
+/* atomic init state of dynamically loaded functions */
+static LONG w32thread_init_state = 0;
+static av_unused void w32thread_init(void);
+
+/* for pre-Windows 6.0 platforms, define INIT_ONCE struct,
+ * compatible to the one used in the native API */
+
+typedef union pthread_once_t  {
+    void * Ptr;    ///< For the Windows 6.0+ native functions
+    LONG state;    ///< For the pre-Windows 6.0 compat code
+} pthread_once_t;
+
+#define PTHREAD_ONCE_INIT {0}
+
+/* function pointers to init once API on windows 6.0+ kernels */
+static BOOL (WINAPI *initonce_begin)(pthread_once_t *lpInitOnce, DWORD dwFlags, BOOL *fPending, void **lpContext);
+static BOOL (WINAPI *initonce_complete)(pthread_once_t *lpInitOnce, DWORD dwFlags, void *lpContext);
+
+/* pre-Windows 6.0 compat using a spin-lock */
+static inline void w32thread_once_fallback(LONG volatile *state, void (*init_routine)(void))
+{
+    switch (InterlockedCompareExchange(state, 1, 0)) {
+    /* Initial run */
+    case 0:
+        init_routine();
+        InterlockedExchange(state, 2);
+        break;
+    /* Another thread is running init */
+    case 1:
+        while (1) {
+            MemoryBarrier();
+            if (*state == 2)
+                break;
+            Sleep(0);
+        }
+        break;
+    /* Initialization complete */
+    case 2:
+        break;
+    }
+}
+
+static av_unused int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
+{
+    w32thread_once_fallback(&w32thread_init_state, w32thread_init);
+
+    /* Use native functions on Windows 6.0+ */
+    if (initonce_begin && initonce_complete) {
+        BOOL pending = FALSE;
+        initonce_begin(once_control, 0, &pending, NULL);
+        if (pending)
+            init_routine();
+        initonce_complete(once_control, 0, NULL);
+        return 0;
+    }
+
+    w32thread_once_fallback(&once_control->state, init_routine);
+    return 0;
+}
+
 /* for pre-Windows 6.0 platforms we need to define and use our own condition
  * variable and api */
+
 typedef struct  win32_cond_t {
     pthread_mutex_t mtx_broadcast;
     pthread_mutex_t mtx_waiter_count;
@@ -126,9 +233,19 @@ typedef struct  win32_cond_t {
     volatile int is_broadcast;
 } win32_cond_t;
 
-static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
+/* function pointers to conditional variable API on windows 6.0+ kernels */
+static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
+static void (WINAPI *cond_init)(pthread_cond_t *cond);
+static void (WINAPI *cond_signal)(pthread_cond_t *cond);
+static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
+                                DWORD milliseconds);
+
+static av_unused void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 {
     win32_cond_t *win32_cond = NULL;
+
+    w32thread_once_fallback(&w32thread_init_state, w32thread_init);
+
     if (cond_init) {
         cond_init(cond);
         return;
@@ -138,7 +255,7 @@ static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
     win32_cond = av_mallocz(sizeof(win32_cond_t));
     if (!win32_cond)
         return;
-    cond->ptr = win32_cond;
+    cond->Ptr = win32_cond;
     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
     if (!win32_cond->semaphore)
         return;
@@ -150,9 +267,9 @@ static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 }
 
-static void pthread_cond_destroy(pthread_cond_t *cond)
+static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
 {
-    win32_cond_t *win32_cond = cond->ptr;
+    win32_cond_t *win32_cond = cond->Ptr;
     /* native condition variables do not destroy */
     if (cond_init)
         return;
@@ -163,12 +280,12 @@ static void pthread_cond_destroy(pthread_cond_t *cond)
     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
     av_freep(&win32_cond);
-    cond->ptr = NULL;
+    cond->Ptr = NULL;
 }
 
-static void pthread_cond_broadcast(pthread_cond_t *cond)
+static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 {
-    win32_cond_t *win32_cond = cond->ptr;
+    win32_cond_t *win32_cond = cond->Ptr;
     int have_waiter;
 
     if (cond_broadcast) {
@@ -197,9 +314,9 @@ static void pthread_cond_broadcast(pthread_cond_t *cond)
     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 }
 
-static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
+static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 {
-    win32_cond_t *win32_cond = cond->ptr;
+    win32_cond_t *win32_cond = cond->Ptr;
     int last_waiter;
     if (cond_wait) {
         cond_wait(cond, mutex, INFINITE);
@@ -229,9 +346,9 @@ static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
     return pthread_mutex_lock(mutex);
 }
 
-static void pthread_cond_signal(pthread_cond_t *cond)
+static av_unused void pthread_cond_signal(pthread_cond_t *cond)
 {
-    win32_cond_t *win32_cond = cond->ptr;
+    win32_cond_t *win32_cond = cond->Ptr;
     int have_waiter;
     if (cond_signal) {
         cond_signal(cond);
@@ -253,8 +370,9 @@ static void pthread_cond_signal(pthread_cond_t *cond)
 
     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 }
+#endif
 
-static void w32thread_init(void)
+static av_unused void w32thread_init(void)
 {
 #if _WIN32_WINNT < 0x0600
     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
@@ -267,11 +385,10 @@ static void w32thread_init(void)
         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
     cond_wait      =
         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
-#else
-    cond_init      = InitializeConditionVariable;
-    cond_broadcast = WakeAllConditionVariable;
-    cond_signal    = WakeConditionVariable;
-    cond_wait      = SleepConditionVariableCS;
+    initonce_begin =
+        (void*)GetProcAddress(kernel_dll, "InitOnceBeginInitialize");
+    initonce_complete =
+        (void*)GetProcAddress(kernel_dll, "InitOnceComplete");
 #endif
 
 }