early-access version 1611

externals/SDL/src/thread/stdcpp/SDL_syscond.cpp

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+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 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"
+
+extern "C" {
+#include "SDL_thread.h"
+}
+
+#include <chrono>
+#include <condition_variable>
+#include <ratio>
+#include <system_error>
+
+#include "SDL_sysmutex_c.h"
+
+struct SDL_cond
+{
+    std::condition_variable_any cpp_cond;
+};
+
+/* Create a condition variable */
+extern "C"
+SDL_cond *
+SDL_CreateCond(void)
+{
+    /* Allocate and initialize the condition variable */
+    try {
+        SDL_cond * cond = new SDL_cond;
+        return cond;
+    } catch (std::system_error & ex) {
+        SDL_SetError("unable to create a C++ condition variable: code=%d; %s", ex.code(), ex.what());
+        return NULL;
+    } catch (std::bad_alloc &) {
+        SDL_OutOfMemory();
+        return NULL;
+    }
+}
+
+/* Destroy a condition variable */
+extern "C"
+void
+SDL_DestroyCond(SDL_cond * cond)
+{
+    if (cond) {
+        delete cond;
+    }
+}
+
+/* Restart one of the threads that are waiting on the condition variable */
+extern "C"
+int
+SDL_CondSignal(SDL_cond * cond)
+{
+    if (!cond) {
+        SDL_SetError("Passed a NULL condition variable");
+        return -1;
+    }
+
+    cond->cpp_cond.notify_one();
+    return 0;
+}
+
+/* Restart all threads that are waiting on the condition variable */
+extern "C"
+int
+SDL_CondBroadcast(SDL_cond * cond)
+{
+    if (!cond) {
+        SDL_SetError("Passed a NULL condition variable");
+        return -1;
+    }
+
+    cond->cpp_cond.notify_all();
+    return 0;
+}
+
+/* Wait on the condition variable for at most 'ms' milliseconds.
+   The mutex must be locked before entering this function!
+   The mutex is unlocked during the wait, and locked again after the wait.
+
+Typical use:
+
+Thread A:
+    SDL_LockMutex(lock);
+    while ( ! condition ) {
+        SDL_CondWait(cond, lock);
+    }
+    SDL_UnlockMutex(lock);
+
+Thread B:
+    SDL_LockMutex(lock);
+    ...
+    condition = true;
+    ...
+    SDL_CondSignal(cond);
+    SDL_UnlockMutex(lock);
+ */
+extern "C"
+int
+SDL_CondWaitTimeout(SDL_cond * cond, SDL_mutex * mutex, Uint32 ms)
+{
+    if (!cond) {
+        SDL_SetError("Passed a NULL condition variable");
+        return -1;
+    }
+
+    if (!mutex) {
+        SDL_SetError("Passed a NULL mutex variable");
+        return -1;
+    }
+
+    try {
+        std::unique_lock<std::recursive_mutex> cpp_lock(mutex->cpp_mutex, std::adopt_lock_t());
+        if (ms == SDL_MUTEX_MAXWAIT) {
+            cond->cpp_cond.wait(
+                cpp_lock
+                );
+            cpp_lock.release();
+            return 0;
+        } else {
+            auto wait_result = cond->cpp_cond.wait_for(
+                cpp_lock,
+                std::chrono::duration<Uint32, std::milli>(ms)
+                );
+            cpp_lock.release();
+            if (wait_result == std::cv_status::timeout) {
+                return SDL_MUTEX_TIMEDOUT;
+            } else {
+                return 0;
+            }
+        }
+    } catch (std::system_error & ex) {
+        SDL_SetError("unable to wait on a C++ condition variable: code=%d; %s", ex.code(), ex.what());
+        return -1;
+    }
+}
+
+/* Wait on the condition variable forever */
+extern "C"
+int
+SDL_CondWait(SDL_cond * cond, SDL_mutex * mutex)
+{
+    return SDL_CondWaitTimeout(cond, mutex, SDL_MUTEX_MAXWAIT);
+}
+
+/* vi: set ts=4 sw=4 expandtab: */