Manually load CONDITION_VARIABLE methods on Windows, checking for failure (XP).

src/utils/SkCondVar.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCondVar.h"
 
+#if defined(SK_BUILD_FOR_WIN32)
+    static void (WINAPI *initialize_condition_variable)(PCONDITION_VARIABLE);
+    static BOOL (WINAPI *sleep_condition_variable)(PCONDITION_VARIABLE, PCRITICAL_SECTION, DWORD);
+    static void (WINAPI *wake_condition_variable)(PCONDITION_VARIABLE);
+    static void (WINAPI *wake_all_condition_variable)(PCONDITION_VARIABLE);
+
+    template <typename T>
+    static void set_fn_ptr(T* ptr, FARPROC fn) { *ptr = reinterpret_cast<T>(fn); }
+#endif
+
+bool SkCondVar::Supported() {
+#ifdef SK_USE_POSIX_THREADS
+    return true;
+#elif defined(SK_BUILD_FOR_WIN32)
+    // If we're >= Vista we'll find these functions.  Otherwise (XP) SkCondVar is not supported.
+    HMODULE kernel32 = GetModuleHandleA("kernel32.dll");
+    set_fn_ptr(&initialize_condition_variable,
+               GetProcAddress(kernel32, "InitializeConditionVariable"));
+    set_fn_ptr(&sleep_condition_variable,
+               GetProcAddress(kernel32, "SleepConditionVariableCS"));
+    set_fn_ptr(&wake_condition_variable,
+               GetProcAddress(kernel32, "WakeConditionVariable"));
+    set_fn_ptr(&wake_all_condition_variable,
+               GetProcAddress(kernel32, "WakeAllConditionVariable"));
+    return initialize_condition_variable
+        && sleep_condition_variable
+        && wake_condition_variable
+        && wake_all_condition_variable;
+#else
+    return false;
+#endif
+}
+
 SkCondVar::SkCondVar() {
 #ifdef SK_USE_POSIX_THREADS
     pthread_mutex_init(&fMutex, NULL /* default mutex attr */);
     pthread_cond_init(&fCond, NULL /* default cond attr */);
 #elif defined(SK_BUILD_FOR_WIN32)
     InitializeCriticalSection(&fCriticalSection);
-    InitializeConditionVariable(&fCondition);
+    SkASSERT(initialize_condition_variable);
+    initialize_condition_variable(&fCondition);
 #endif
 }
 
 SkCondVar::~SkCondVar() {
 #ifdef SK_USE_POSIX_THREADS
     pthread_mutex_destroy(&fMutex);
     pthread_cond_destroy(&fCond);
 #elif defined(SK_BUILD_FOR_WIN32)
     DeleteCriticalSection(&fCriticalSection);
     // No need to clean up fCondition.
@@ skipping 13 matching lines @@
     pthread_mutex_unlock(&fMutex);
 #elif defined(SK_BUILD_FOR_WIN32)
     LeaveCriticalSection(&fCriticalSection);
 #endif
 }
 
 void SkCondVar::wait() {
 #ifdef SK_USE_POSIX_THREADS
     pthread_cond_wait(&fCond, &fMutex);
 #elif defined(SK_BUILD_FOR_WIN32)
-    SleepConditionVariableCS(&fCondition, &fCriticalSection, INFINITE);
+    SkASSERT(sleep_condition_variable);
+    sleep_condition_variable(&fCondition, &fCriticalSection, INFINITE);
 #endif
 }
 
 void SkCondVar::signal() {
 #ifdef SK_USE_POSIX_THREADS
     pthread_cond_signal(&fCond);
 #elif defined(SK_BUILD_FOR_WIN32)
-    WakeConditionVariable(&fCondition);
+    SkASSERT(wake_condition_variable);
+    wake_condition_variable(&fCondition);
 #endif
 }
 
 void SkCondVar::broadcast() {
 #ifdef SK_USE_POSIX_THREADS
     pthread_cond_broadcast(&fCond);
 #elif defined(SK_BUILD_FOR_WIN32)
-    WakeAllConditionVariable(&fCondition);
+    SkASSERT(wake_all_condition_variable);
+    wake_all_condition_variable(&fCondition);
 #endif
 }