[PATCH v5 2/2] ntdll: Implement thread-ID alerts using ulock.

[Marc-Aurel Zent]

From: Marc-Aurel Zent

---
 dlls/ntdll/unix/sync.c | 68 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 62 insertions(+), 6 deletions(-)

diff --git a/dlls/ntdll/unix/sync.c b/dlls/ntdll/unix/sync.c
index 066717e800c..7333c58bae9 100644
--- a/dlls/ntdll/unix/sync.c
+++ b/dlls/ntdll/unix/sync.c
@@ -148,6 +148,13 @@ static inline int use_futexes(void)

#endif

+#ifdef __APPLE__
+
+#define UL_COMPARE_AND_WAIT 1
+extern int __ulock_wait( uint32_t operation, void *addr, uint64_t value, uint32_t timeout );
+extern int __ulock_wake( uint32_t operation, void *addr, uint64_t wake_value );
+
+#endif

/* create a struct security_descriptor and contained information in one contiguous piece of memory */
 unsigned int alloc_object_attributes( const OBJECT_ATTRIBUTES *attr, struct object_attributes **ret,
@@ -2354,14 +2361,17 @@ NTSTATUS WINAPI NtQueryInformationAtom( RTL_ATOM atom, ATOM_INFORMATION_CLASS cl

union tid_alert_entry
 {
-#ifdef HAVE_KQUEUE
+#ifdef __APPLE__
+    LONG ulock;
+#elif defined(HAVE_KQUEUE)
     int kq;
 #else
     HANDLE event;
+#endif
+
 #ifdef __linux__
     LONG futex;
 #endif
-#endif
 };

#define TID_ALERT_BLOCK_SIZE (65536 / sizeof(union tid_alert_entry))
@@ -2395,8 +2405,9 @@ static union tid_alert_entry *get_tid_alert_entry( HANDLE tid )
     }

entry = &tid_alert_blocks[block_idx][idx % TID_ALERT_BLOCK_SIZE];
-
-#ifdef HAVE_KQUEUE
+#if defined(__APPLE__)
+    return entry;
+#elif defined(HAVE_KQUEUE)
     if (!entry->kq)
     {
         int kq = kqueue();
@@ -2458,7 +2469,12 @@ NTSTATUS WINAPI NtAlertThreadByThreadId( HANDLE tid )

if (!entry) return STATUS_INVALID_CID;

-#ifdef HAVE_KQUEUE
+#ifdef __APPLE__
+    LONG *ulock = &entry->ulock;
+    if (!InterlockedExchange( ulock, 1 ))
+        __ulock_wake( UL_COMPARE_AND_WAIT, (void*)ulock, 0 );
+    return STATUS_SUCCESS;
+#elif defined(HAVE_KQUEUE)
     static const struct kevent signal_event =
     {
         .ident = 1,
@@ -2509,8 +2525,48 @@ static LONGLONG update_timeout( ULONGLONG end )
 }
 #endif

+#ifdef __APPLE__

-#ifdef HAVE_KQUEUE
+/***********************************************************************
+ *             NtWaitForAlertByThreadId (NTDLL.@)
+ */
+NTSTATUS WINAPI NtWaitForAlertByThreadId( const void *address, const LARGE_INTEGER *timeout )
+{
+    union tid_alert_entry *entry = get_tid_alert_entry( NtCurrentTeb()->ClientId.UniqueThread );
+    NTSTATUS status;
+    LONG *ulock = &entry->ulock;
+    ULONGLONG end;
+    int ret;
+
+    TRACE( "%p %s\n", address, debugstr_timeout( timeout ) );
+
+    if (!entry) return STATUS_INVALID_CID;
+
+    if (timeout)
+    {
+        if (timeout->QuadPart == TIMEOUT_INFINITE)
+            timeout = NULL;
+        else
+            end = get_absolute_timeout( timeout );
+    }
+
+    while (!InterlockedExchange( ulock, 0 ))
+    {
+        if (timeout)
+        {
+            LONGLONG us_timeleft = update_timeout( end ) / 10;
+            if (!us_timeleft) return STATUS_TIMEOUT;
+            ret = __ulock_wait( UL_COMPARE_AND_WAIT, (void*)ulock, 0, us_timeleft );
+        }
+        else
+            ret = __ulock_wait( UL_COMPARE_AND_WAIT, (void*)ulock, 0, 0);
+
+        if (ret == -1 && errno == ETIMEDOUT) return STATUS_TIMEOUT;
+    }
+    return STATUS_ALERTED;
+}
+
+#elif defined(HAVE_KQUEUE)

/***********************************************************************
  *             NtWaitForAlertByThreadId (NTDLL.@)