1 files changed, 263 insertions, 0 deletions
diff --git a/winpr/libwinpr/synch/barrier.c b/winpr/libwinpr/synch/barrier.c
new file mode 100644
index 0000000..0021408
--- /dev/null
+++ b/winpr/libwinpr/synch/barrier.c
@@ -0,0 +1,263 @@
+/**
+ * WinPR: Windows Portable Runtime
+ * Synchronization Functions
+ *
+ * Copyright 2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
+ * Copyright 2016 Norbert Federa <norbert.federa@thincast.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <winpr/config.h>
+
+#include <winpr/synch.h>
+#include <winpr/assert.h>
+
+#include "synch.h"
+
+#include <winpr/crt.h>
+
+#ifdef WINPR_SYNCHRONIZATION_BARRIER
+
+#include <winpr/sysinfo.h>
+#include <winpr/library.h>
+#include <winpr/interlocked.h>
+#include <winpr/thread.h>
+
+/**
+ * WinPR uses the internal RTL_BARRIER struct members exactly like Windows:
+ *
+ * DWORD Reserved1:          number of threads that have not yet entered the barrier
+ * DWORD Reserved2:          number of threads required to enter the barrier
+ * ULONG_PTR Reserved3[2];   two synchronization events (manual reset events)
+ * DWORD Reserved4;          number of processors
+ * DWORD Reserved5;          spincount
+ */
+
+#ifdef _WIN32
+
+static HMODULE g_Kernel32 = NULL;
+static BOOL g_NativeBarrier = FALSE;
+static INIT_ONCE g_InitOnce = INIT_ONCE_STATIC_INIT;
+
+typedef BOOL(WINAPI* fnInitializeSynchronizationBarrier)(LPSYNCHRONIZATION_BARRIER lpBarrier,
+                                                         LONG lTotalThreads, LONG lSpinCount);
+typedef BOOL(WINAPI* fnEnterSynchronizationBarrier)(LPSYNCHRONIZATION_BARRIER lpBarrier,
+                                                    DWORD dwFlags);
+typedef BOOL(WINAPI* fnDeleteSynchronizationBarrier)(LPSYNCHRONIZATION_BARRIER lpBarrier);
+
+static fnInitializeSynchronizationBarrier pfnInitializeSynchronizationBarrier = NULL;
+static fnEnterSynchronizationBarrier pfnEnterSynchronizationBarrier = NULL;
+static fnDeleteSynchronizationBarrier pfnDeleteSynchronizationBarrier = NULL;
+
+static BOOL CALLBACK InitOnce_Barrier(PINIT_ONCE once, PVOID param, PVOID* context)
+{
+	g_Kernel32 = LoadLibraryA("kernel32.dll");
+
+	if (!g_Kernel32)
+		return TRUE;
+
+	pfnInitializeSynchronizationBarrier = (fnInitializeSynchronizationBarrier)GetProcAddress(
+	    g_Kernel32, "InitializeSynchronizationBarrier");
+
+	pfnEnterSynchronizationBarrier =
+	    (fnEnterSynchronizationBarrier)GetProcAddress(g_Kernel32, "EnterSynchronizationBarrier");
+
+	pfnDeleteSynchronizationBarrier =
+	    (fnDeleteSynchronizationBarrier)GetProcAddress(g_Kernel32, "DeleteSynchronizationBarrier");
+
+	if (pfnInitializeSynchronizationBarrier && pfnEnterSynchronizationBarrier &&
+	    pfnDeleteSynchronizationBarrier)
+	{
+		g_NativeBarrier = TRUE;
+	}
+
+	return TRUE;
+}
+
+#endif
+
+BOOL WINAPI winpr_InitializeSynchronizationBarrier(LPSYNCHRONIZATION_BARRIER lpBarrier,
+                                                   LONG lTotalThreads, LONG lSpinCount)
+{
+	SYSTEM_INFO sysinfo;
+	HANDLE hEvent0 = NULL;
+	HANDLE hEvent1 = NULL;
+
+#ifdef _WIN32
+	InitOnceExecuteOnce(&g_InitOnce, InitOnce_Barrier, NULL, NULL);
+
+	if (g_NativeBarrier)
+		return pfnInitializeSynchronizationBarrier(lpBarrier, lTotalThreads, lSpinCount);
+#endif
+
+	if (!lpBarrier || lTotalThreads < 1 || lSpinCount < -1)
+	{
+		SetLastError(ERROR_INVALID_PARAMETER);
+		return FALSE;
+	}
+
+	ZeroMemory(lpBarrier, sizeof(SYNCHRONIZATION_BARRIER));
+
+	if (lSpinCount == -1)
+		lSpinCount = 2000;
+
+	if (!(hEvent0 = CreateEvent(NULL, TRUE, FALSE, NULL)))
+		return FALSE;
+
+	if (!(hEvent1 = CreateEvent(NULL, TRUE, FALSE, NULL)))
+	{
+		CloseHandle(hEvent0);
+		return FALSE;
+	}
+
+	GetNativeSystemInfo(&sysinfo);
+
+	WINPR_ASSERT(lTotalThreads >= 0);
+	lpBarrier->Reserved1 = (DWORD)lTotalThreads;
+	lpBarrier->Reserved2 = (DWORD)lTotalThreads;
+	lpBarrier->Reserved3[0] = (ULONG_PTR)hEvent0;
+	lpBarrier->Reserved3[1] = (ULONG_PTR)hEvent1;
+	lpBarrier->Reserved4 = sysinfo.dwNumberOfProcessors;
+	WINPR_ASSERT(lSpinCount >= 0);
+	lpBarrier->Reserved5 = (DWORD)lSpinCount;
+
+	return TRUE;
+}
+
+BOOL WINAPI winpr_EnterSynchronizationBarrier(LPSYNCHRONIZATION_BARRIER lpBarrier, DWORD dwFlags)
+{
+	LONG remainingThreads = 0;
+	HANDLE hCurrentEvent = NULL;
+	HANDLE hDormantEvent = NULL;
+
+#ifdef _WIN32
+	if (g_NativeBarrier)
+		return pfnEnterSynchronizationBarrier(lpBarrier, dwFlags);
+#endif
+
+	if (!lpBarrier)
+		return FALSE;
+
+	/**
+	 * dwFlags according to
+	 * https://msdn.microsoft.com/en-us/library/windows/desktop/hh706889(v=vs.85).aspx
+	 *
+	 * SYNCHRONIZATION_BARRIER_FLAGS_BLOCK_ONLY (0x01)
+	 * Specifies that the thread entering the barrier should block
+	 * immediately until the last thread enters the barrier.
+	 *
+	 * SYNCHRONIZATION_BARRIER_FLAGS_SPIN_ONLY (0x02)
+	 * Specifies that the thread entering the barrier should spin until the
+	 * last thread enters the barrier, even if the spinning thread exceeds
+	 * the barrier's maximum spin count.
+	 *
+	 * SYNCHRONIZATION_BARRIER_FLAGS_NO_DELETE (0x04)
+	 * Specifies that the function can skip the work required to ensure
+	 * that it is safe to delete the barrier, which can improve
+	 * performance. All threads that enter this barrier must specify the
+	 * flag; otherwise, the flag is ignored. This flag should be used only
+	 * if the barrier will never be deleted.
+	 */
+
+	hCurrentEvent = (HANDLE)lpBarrier->Reserved3[0];
+	hDormantEvent = (HANDLE)lpBarrier->Reserved3[1];
+
+	remainingThreads = InterlockedDecrement((LONG*)&lpBarrier->Reserved1);
+
+	WINPR_ASSERT(remainingThreads >= 0);
+
+	if (remainingThreads > 0)
+	{
+		DWORD dwProcessors = lpBarrier->Reserved4;
+		BOOL spinOnly = (dwFlags & SYNCHRONIZATION_BARRIER_FLAGS_SPIN_ONLY) ? TRUE : FALSE;
+		BOOL blockOnly = (dwFlags & SYNCHRONIZATION_BARRIER_FLAGS_BLOCK_ONLY) ? TRUE : FALSE;
+		BOOL block = TRUE;
+
+		/**
+		 * If SYNCHRONIZATION_BARRIER_FLAGS_SPIN_ONLY is set we will
+		 * always spin and trust that the user knows what he/she/it
+		 * is doing. Otherwise we'll only spin if the flag
+		 * SYNCHRONIZATION_BARRIER_FLAGS_BLOCK_ONLY is not set and
+		 * the number of remaining threads is less than the number
+		 * of processors.
+		 */
+
+		if (spinOnly || (((ULONG)remainingThreads < dwProcessors) && !blockOnly))
+		{
+			DWORD dwSpinCount = lpBarrier->Reserved5;
+			DWORD sp = 0;
+			/**
+			 * nb: we must let the compiler know that our comparand
+			 * can change between the iterations in the loop below
+			 */
+			volatile ULONG_PTR* cmp = &lpBarrier->Reserved3[0];
+			/* we spin until the last thread _completed_ the event switch */
+			while ((block = (*cmp == (ULONG_PTR)hCurrentEvent)))
+				if (!spinOnly && ++sp > dwSpinCount)
+					break;
+		}
+
+		if (block)
+			WaitForSingleObject(hCurrentEvent, INFINITE);
+
+		return FALSE;
+	}
+
+	/* reset the dormant event first */
+	ResetEvent(hDormantEvent);
+
+	/* reset the remaining counter */
+	lpBarrier->Reserved1 = lpBarrier->Reserved2;
+
+	/* switch events - this will also unblock the spinning threads */
+	lpBarrier->Reserved3[1] = (ULONG_PTR)hCurrentEvent;
+	lpBarrier->Reserved3[0] = (ULONG_PTR)hDormantEvent;
+
+	/* signal the blocked threads */
+	SetEvent(hCurrentEvent);
+
+	return TRUE;
+}
+
+BOOL WINAPI winpr_DeleteSynchronizationBarrier(LPSYNCHRONIZATION_BARRIER lpBarrier)
+{
+#ifdef _WIN32
+	if (g_NativeBarrier)
+		return pfnDeleteSynchronizationBarrier(lpBarrier);
+#endif
+
+	/**
+	 * According to https://msdn.microsoft.com/en-us/library/windows/desktop/hh706887(v=vs.85).aspx
+	 * Return value:
+	 * The DeleteSynchronizationBarrier function always returns TRUE.
+	 */
+
+	if (!lpBarrier)
+		return TRUE;
+
+	while (lpBarrier->Reserved1 != lpBarrier->Reserved2)
+		SwitchToThread();
+
+	if (lpBarrier->Reserved3[0])
+		CloseHandle((HANDLE)lpBarrier->Reserved3[0]);
+
+	if (lpBarrier->Reserved3[1])
+		CloseHandle((HANDLE)lpBarrier->Reserved3[1]);
+
+	ZeroMemory(lpBarrier, sizeof(SYNCHRONIZATION_BARRIER));
+
+	return TRUE;
+}
+
+#endif