wine-staging/patches/ntdll-futex-condition-var/0001-ntdll-Add-a-futex-based-condition-variable-implement.patch

From 3c82febd61f706aa12dc7a183a4fed5dff4b39e4 Mon Sep 17 00:00:00 2001
From: Zebediah Figura <z.figura12@gmail.com>
Date: Tue, 24 Jul 2018 11:26:39 -0600
Subject: [PATCH] ntdll: Add a futex-based condition variable implementation.

---
 dlls/ntdll/sync.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 137 insertions(+), 11 deletions(-)

diff --git a/dlls/ntdll/sync.c b/dlls/ntdll/sync.c
index 8e406ce..83bf199 100644
--- a/dlls/ntdll/sync.c
+++ b/dlls/ntdll/sync.c
@@ -26,6 +26,7 @@
 
 #include <assert.h>
 #include <errno.h>
+#include <limits.h>
 #include <signal.h>
 #ifdef HAVE_SYS_TIME_H
 # include <sys/time.h>
@@ -36,6 +37,9 @@
 #ifdef HAVE_SYS_POLL_H
 # include <sys/poll.h>
 #endif
+#ifdef HAVE_SYS_SYSCALL_H
+# include <sys/syscall.h>
+#endif
 #ifdef HAVE_UNISTD_H
 # include <unistd.h>
 #endif
@@ -61,6 +65,107 @@ WINE_DEFAULT_DEBUG_CHANNEL(ntdll);
 
 HANDLE keyed_event = NULL;
 
+#define TICKSPERSEC        10000000
+
+#ifdef __linux__
+
+static int wait_op = 128; /*FUTEX_WAIT|FUTEX_PRIVATE_FLAG*/
+static int wake_op = 129; /*FUTEX_WAKE|FUTEX_PRIVATE_FLAG*/
+
+static inline int futex_wait( int *addr, int val, struct timespec *timeout )
+{
+    return syscall( __NR_futex, addr, wait_op, val, timeout, 0, 0 );
+}
+
+static inline int futex_wake( int *addr, int val )
+{
+    return syscall( __NR_futex, addr, wake_op, val, NULL, 0, 0 );
+}
+
+static inline int use_futexes(void)
+{
+    static int supported = -1;
+
+    if (supported == -1)
+    {
+        futex_wait( &supported, 10, NULL );
+        if (errno == ENOSYS)
+        {
+            wait_op = 0; /*FUTEX_WAIT*/
+            wake_op = 1; /*FUTEX_WAKE*/
+            futex_wait( &supported, 10, NULL );
+        }
+        supported = (errno != ENOSYS);
+    }
+    return supported;
+}
+
+static inline NTSTATUS fast_wait( RTL_CONDITION_VARIABLE *variable, const LARGE_INTEGER *timeout)
+{
+    int val, ret;
+
+    if (!use_futexes()) return STATUS_NOT_IMPLEMENTED;
+
+    if (timeout && timeout->QuadPart != TIMEOUT_INFINITE)
+    {
+        struct timespec timespec;
+        LONGLONG end, timeleft;
+        LARGE_INTEGER now;
+
+        if (timeout->QuadPart >= 0)
+            end = timeout->QuadPart;
+        else
+        {
+            NtQuerySystemTime( &now );
+            end = now.QuadPart - timeout->QuadPart;
+        }
+
+        do
+        {
+            val = *((int *)&variable->Ptr);
+
+            NtQuerySystemTime( &now );
+            timeleft = end - now.QuadPart;
+            if (timeleft < 0) timeleft = 0;
+            timespec.tv_sec = timeleft / TICKSPERSEC;
+            timespec.tv_nsec = (timeleft % TICKSPERSEC) * 100;
+        }
+        while (val && (ret = futex_wait( (int *)&variable->Ptr, val, &timespec )) == -1
+               && errno != ETIMEDOUT);
+    }
+    else
+    {
+        do
+            val = *((int *)&variable->Ptr);
+        while (val && (ret = futex_wait( (int *)&variable->Ptr, val, NULL )) == -1);
+    }
+
+    if (!val) return STATUS_WAIT_0;
+    else if (ret == -1 && errno == ETIMEDOUT) return STATUS_TIMEOUT;
+    else if (ret == -1) ERR("wait failed: %s\n", strerror(errno));
+    return STATUS_WAIT_0;
+}
+
+static inline NTSTATUS fast_wake( RTL_CONDITION_VARIABLE *variable, int val )
+{
+    if (!use_futexes()) return STATUS_NOT_IMPLEMENTED;
+
+    futex_wake( (int *)&variable->Ptr, val );
+    return STATUS_SUCCESS;
+}
+
+#else
+static inline NTSTATUS fast_wait( RTL_CRITICAL_SECTION *crit, int timeout )
+{
+    return STATUS_NOT_IMPLEMENTED;
+}
+
+static inline NTSTATUS fast_wake( RTL_CRITICAL_SECTION *crit )
+{
+    return STATUS_NOT_IMPLEMENTED;
+}
+#endif
+
 static inline int interlocked_dec_if_nonzero( int *dest )
 {
     int val, tmp;
@@ -1814,7 +1919,11 @@ void WINAPI RtlInitializeConditionVariable( RTL_CONDITION_VARIABLE *variable )
 void WINAPI RtlWakeConditionVariable( RTL_CONDITION_VARIABLE *variable )
 {
     if (interlocked_dec_if_nonzero( (int *)&variable->Ptr ))
-        NtReleaseKeyedEvent( keyed_event, &variable->Ptr, FALSE, NULL );
+    {
+        NTSTATUS ret;
+        if ((ret = fast_wake( variable, 1 )) == STATUS_NOT_IMPLEMENTED)
+            NtReleaseKeyedEvent( keyed_event, &variable->Ptr, FALSE, NULL );
+    }
 }
 
 /***********************************************************************
@@ -1825,8 +1934,15 @@ void WINAPI RtlWakeConditionVariable( RTL_CONDITION_VARIABLE *variable )
 void WINAPI RtlWakeAllConditionVariable( RTL_CONDITION_VARIABLE *variable )
 {
     int val = interlocked_xchg( (int *)&variable->Ptr, 0 );
-    while (val-- > 0)
-        NtReleaseKeyedEvent( keyed_event, &variable->Ptr, FALSE, NULL );
+    if (val)
+    {
+        NTSTATUS ret;
+        if ((ret = fast_wake( variable, INT_MAX )) == STATUS_NOT_IMPLEMENTED)
+        {
+            while (val-- > 0)
+                NtReleaseKeyedEvent( keyed_event, &variable->Ptr, FALSE, NULL );
+        }
+    }
 }
 
 /***********************************************************************
@@ -1851,12 +1967,17 @@ NTSTATUS WINAPI RtlSleepConditionVariableCS( RTL_CONDITION_VARIABLE *variable, R
     interlocked_xchg_add( (int *)&variable->Ptr, 1 );
     RtlLeaveCriticalSection( crit );
 
-    status = NtWaitForKeyedEvent( keyed_event, &variable->Ptr, FALSE, timeout );
-    if (status != STATUS_SUCCESS)
+    if ((status = fast_wait( variable, timeout )) == STATUS_NOT_IMPLEMENTED)
     {
-        if (!interlocked_dec_if_nonzero( (int *)&variable->Ptr ))
-            status = NtWaitForKeyedEvent( keyed_event, &variable->Ptr, FALSE, NULL );
+        status = NtWaitForKeyedEvent( keyed_event, &variable->Ptr, FALSE, timeout );
+        if (status != STATUS_SUCCESS)
+        {
+            if (!interlocked_dec_if_nonzero( (int *)&variable->Ptr ))
+                status = NtWaitForKeyedEvent( keyed_event, &variable->Ptr, FALSE, NULL );
+        }
     }
+    else if (status != STATUS_SUCCESS)
+        interlocked_dec_if_nonzero( (int *)&variable->Ptr );
 
     RtlEnterCriticalSection( crit );
     return status;
@@ -1892,12 +2013,17 @@ NTSTATUS WINAPI RtlSleepConditionVariableSRW( RTL_CONDITION_VARIABLE *variable,
     else
         RtlReleaseSRWLockExclusive( lock );
 
-    status = NtWaitForKeyedEvent( keyed_event, &variable->Ptr, FALSE, timeout );
-    if (status != STATUS_SUCCESS)
+    if ((status = fast_wait( variable, timeout )) == STATUS_NOT_IMPLEMENTED)
     {
-        if (!interlocked_dec_if_nonzero( (int *)&variable->Ptr ))
-            status = NtWaitForKeyedEvent( keyed_event, &variable->Ptr, FALSE, NULL );
+        status = NtWaitForKeyedEvent( keyed_event, &variable->Ptr, FALSE, timeout );
+        if (status != STATUS_SUCCESS)
+        {
+            if (!interlocked_dec_if_nonzero( (int *)&variable->Ptr ))
+                status = NtWaitForKeyedEvent( keyed_event, &variable->Ptr, FALSE, NULL );
+        }
     }
+    else if (status != STATUS_SUCCESS)
+        interlocked_dec_if_nonzero( (int *)&variable->Ptr );
 
     if (flags & RTL_CONDITION_VARIABLE_LOCKMODE_SHARED)
         RtlAcquireSRWLockShared( lock );
-- 
2.7.4