initial commit, 4.5 stable

thirdparty/sdl/thread/windows/SDL_sysrwlock_srw.c

@@ -0,0 +1,231 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+/**
+ * Implementation based on Slim Reader/Writer (SRW) Locks for Win 7 and newer.
+ */
+
+// This header makes sure SRWLOCK is actually declared, even on ancient WinSDKs.
+#include "SDL_sysmutex_c.h"
+
+typedef VOID(WINAPI *pfnInitializeSRWLock)(PSRWLOCK);
+typedef VOID(WINAPI *pfnReleaseSRWLockShared)(PSRWLOCK);
+typedef VOID(WINAPI *pfnAcquireSRWLockShared)(PSRWLOCK);
+typedef BOOLEAN(WINAPI *pfnTryAcquireSRWLockShared)(PSRWLOCK);
+typedef VOID(WINAPI *pfnReleaseSRWLockExclusive)(PSRWLOCK);
+typedef VOID(WINAPI *pfnAcquireSRWLockExclusive)(PSRWLOCK);
+typedef BOOLEAN(WINAPI *pfnTryAcquireSRWLockExclusive)(PSRWLOCK);
+
+static pfnInitializeSRWLock pInitializeSRWLock = NULL;
+static pfnReleaseSRWLockShared pReleaseSRWLockShared = NULL;
+static pfnAcquireSRWLockShared pAcquireSRWLockShared = NULL;
+static pfnTryAcquireSRWLockShared  pTryAcquireSRWLockShared = NULL;
+static pfnReleaseSRWLockExclusive pReleaseSRWLockExclusive = NULL;
+static pfnAcquireSRWLockExclusive pAcquireSRWLockExclusive = NULL;
+static pfnTryAcquireSRWLockExclusive pTryAcquireSRWLockExclusive = NULL;
+
+typedef SDL_RWLock *(*pfnSDL_CreateRWLock)(void);
+typedef void (*pfnSDL_DestroyRWLock)(SDL_RWLock *);
+typedef void (*pfnSDL_LockRWLockForReading)(SDL_RWLock *);
+typedef void (*pfnSDL_LockRWLockForWriting)(SDL_RWLock *);
+typedef bool (*pfnSDL_TryLockRWLockForReading)(SDL_RWLock *);
+typedef bool (*pfnSDL_TryLockRWLockForWriting)(SDL_RWLock *);
+typedef void (*pfnSDL_UnlockRWLock)(SDL_RWLock *);
+
+typedef struct SDL_rwlock_impl_t
+{
+    pfnSDL_CreateRWLock Create;
+    pfnSDL_DestroyRWLock Destroy;
+    pfnSDL_LockRWLockForReading LockForReading;
+    pfnSDL_LockRWLockForWriting LockForWriting;
+    pfnSDL_TryLockRWLockForReading TryLockForReading;
+    pfnSDL_TryLockRWLockForWriting TryLockForWriting;
+    pfnSDL_UnlockRWLock Unlock;
+} SDL_rwlock_impl_t;
+
+// Implementation will be chosen at runtime based on available Kernel features
+static SDL_rwlock_impl_t SDL_rwlock_impl_active = { 0 };
+
+// rwlock implementation using Win7+ slim read/write locks (SRWLOCK)
+
+typedef struct SDL_rwlock_srw
+{
+    SRWLOCK srw;
+    SDL_ThreadID write_owner;
+} SDL_rwlock_srw;
+
+static SDL_RWLock *SDL_CreateRWLock_srw(void)
+{
+    SDL_rwlock_srw *rwlock = (SDL_rwlock_srw *)SDL_calloc(1, sizeof(*rwlock));
+    if (rwlock) {
+        pInitializeSRWLock(&rwlock->srw);
+    }
+    return (SDL_RWLock *)rwlock;
+}
+
+static void SDL_DestroyRWLock_srw(SDL_RWLock *_rwlock)
+{
+    SDL_rwlock_srw *rwlock = (SDL_rwlock_srw *) _rwlock;
+    // There are no kernel allocated resources
+    SDL_free(rwlock);
+}
+
+static void SDL_LockRWLockForReading_srw(SDL_RWLock *_rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS  // clang doesn't know about NULL mutexes
+{
+    SDL_rwlock_srw *rwlock = (SDL_rwlock_srw *) _rwlock;
+    pAcquireSRWLockShared(&rwlock->srw);
+}
+
+static void SDL_LockRWLockForWriting_srw(SDL_RWLock *_rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS  // clang doesn't know about NULL mutexes
+{
+    SDL_rwlock_srw *rwlock = (SDL_rwlock_srw *) _rwlock;
+    pAcquireSRWLockExclusive(&rwlock->srw);
+    rwlock->write_owner = SDL_GetCurrentThreadID();
+}
+
+static bool SDL_TryLockRWLockForReading_srw(SDL_RWLock *_rwlock)
+{
+    SDL_rwlock_srw *rwlock = (SDL_rwlock_srw *) _rwlock;
+    return pTryAcquireSRWLockShared(&rwlock->srw);
+}
+
+static bool SDL_TryLockRWLockForWriting_srw(SDL_RWLock *_rwlock)
+{
+    SDL_rwlock_srw *rwlock = (SDL_rwlock_srw *) _rwlock;
+    if (pTryAcquireSRWLockExclusive(&rwlock->srw)) {
+        rwlock->write_owner = SDL_GetCurrentThreadID();
+        return true;
+    } else {
+        return false;
+    }
+}
+
+static void SDL_UnlockRWLock_srw(SDL_RWLock *_rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS  // clang doesn't know about NULL mutexes
+{
+    SDL_rwlock_srw *rwlock = (SDL_rwlock_srw *) _rwlock;
+    if (rwlock->write_owner == SDL_GetCurrentThreadID()) {
+        rwlock->write_owner = 0;
+        pReleaseSRWLockExclusive(&rwlock->srw);
+    } else {
+        pReleaseSRWLockShared(&rwlock->srw);
+    }
+}
+
+static const SDL_rwlock_impl_t SDL_rwlock_impl_srw = {
+    &SDL_CreateRWLock_srw,
+    &SDL_DestroyRWLock_srw,
+    &SDL_LockRWLockForReading_srw,
+    &SDL_LockRWLockForWriting_srw,
+    &SDL_TryLockRWLockForReading_srw,
+    &SDL_TryLockRWLockForWriting_srw,
+    &SDL_UnlockRWLock_srw
+};
+
+
+#include "../generic/SDL_sysrwlock_c.h"
+
+// Generic rwlock implementation using SDL_Mutex, SDL_Condition, and SDL_AtomicInt
+static const SDL_rwlock_impl_t SDL_rwlock_impl_generic = {
+    &SDL_CreateRWLock_generic,
+    &SDL_DestroyRWLock_generic,
+    &SDL_LockRWLockForReading_generic,
+    &SDL_LockRWLockForWriting_generic,
+    &SDL_TryLockRWLockForReading_generic,
+    &SDL_TryLockRWLockForWriting_generic,
+    &SDL_UnlockRWLock_generic
+};
+
+SDL_RWLock *SDL_CreateRWLock(void)
+{
+    if (!SDL_rwlock_impl_active.Create) {
+        // Default to generic implementation, works with all mutex implementations
+        const SDL_rwlock_impl_t *impl = &SDL_rwlock_impl_generic;
+        {
+            HMODULE kernel32 = GetModuleHandle(TEXT("kernel32.dll"));
+            if (kernel32) {
+                bool okay = true;
+                #define LOOKUP_SRW_SYM(sym) if (okay) { if ((p##sym = (pfn##sym)GetProcAddress(kernel32, #sym)) == NULL) { okay = false; } }
+                LOOKUP_SRW_SYM(InitializeSRWLock);
+                LOOKUP_SRW_SYM(ReleaseSRWLockShared);
+                LOOKUP_SRW_SYM(AcquireSRWLockShared);
+                LOOKUP_SRW_SYM(TryAcquireSRWLockShared);
+                LOOKUP_SRW_SYM(ReleaseSRWLockExclusive);
+                LOOKUP_SRW_SYM(AcquireSRWLockExclusive);
+                LOOKUP_SRW_SYM(TryAcquireSRWLockExclusive);
+                #undef LOOKUP_SRW_SYM
+                if (okay) {
+                    impl = &SDL_rwlock_impl_srw;  // Use the Windows provided API instead of generic fallback
+                }
+            }
+        }
+
+        SDL_copyp(&SDL_rwlock_impl_active, impl);
+    }
+    return SDL_rwlock_impl_active.Create();
+}
+
+void SDL_DestroyRWLock(SDL_RWLock *rwlock)
+{
+    if (rwlock) {
+        SDL_rwlock_impl_active.Destroy(rwlock);
+    }
+}
+
+void SDL_LockRWLockForReading(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS  // clang doesn't know about NULL mutexes
+{
+    if (rwlock) {
+        SDL_rwlock_impl_active.LockForReading(rwlock);
+    }
+}
+
+void SDL_LockRWLockForWriting(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS  // clang doesn't know about NULL mutexes
+{
+    if (rwlock) {
+        SDL_rwlock_impl_active.LockForWriting(rwlock);
+    }
+}
+
+bool SDL_TryLockRWLockForReading(SDL_RWLock *rwlock)
+{
+    bool result = true;
+    if (rwlock) {
+        result = SDL_rwlock_impl_active.TryLockForReading(rwlock);
+    }
+    return result;
+}
+
+bool SDL_TryLockRWLockForWriting(SDL_RWLock *rwlock)
+{
+    bool result = true;
+    if (rwlock) {
+        result = SDL_rwlock_impl_active.TryLockForWriting(rwlock);
+    }
+    return result;
+}
+
+void SDL_UnlockRWLock(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS  // clang doesn't know about NULL mutexes
+{
+    if (rwlock) {
+        SDL_rwlock_impl_active.Unlock(rwlock);
+    }
+}
+