From ac4c19f747568348b6b44b4c1ecfa4c240ef1001 Mon Sep 17 00:00:00 2001
From: wj32 <wj32@21ef857c-d57f-4fe0-8362-d861dc6d29cd>
Date: Tue, 10 Aug 2010 08:53:17 +0000
Subject: [PATCH] improved PhfSetEvent

git-svn-id: svn://svn.code.sf.net/p/processhacker/code@3490 21ef857c-d57f-4fe0-8362-d861dc6d29cd
---
 2.x/trunk/phlib/include/phbase.h     |  1 +
 2.x/trunk/phlib/include/phsync.h     |  2 +-
 2.x/trunk/phlib/include/queuedlock.h |  2 +-
 2.x/trunk/phlib/sync.c               | 33 ++++++++++------------------
 4 files changed, 14 insertions(+), 24 deletions(-)

diff --git a/2.x/trunk/phlib/include/phbase.h b/2.x/trunk/phlib/include/phbase.h
index c4bf84668..b88c28afd 100644
--- a/2.x/trunk/phlib/include/phbase.h
+++ b/2.x/trunk/phlib/include/phbase.h
@@ -396,6 +396,7 @@ FORCEINLINE VOID PhReleaseMutex(
 // event
 
 #define PH_EVENT_SET 0x1
+#define PH_EVENT_SET_SHIFT 0
 #define PH_EVENT_REFCOUNT_SHIFT 1
 #define PH_EVENT_REFCOUNT_INC 0x2
 
diff --git a/2.x/trunk/phlib/include/phsync.h b/2.x/trunk/phlib/include/phsync.h
index 59b7a4373..ab592a5ab 100644
--- a/2.x/trunk/phlib/include/phsync.h
+++ b/2.x/trunk/phlib/include/phsync.h
@@ -98,7 +98,7 @@ FORCEINLINE BOOLEAN PhTryAcquireResourceLockExclusive(
     __inout PPH_RESOURCE_LOCK Lock
     )
 {
-    if (!_interlockedbittestandset(&Lock->Value, PH_RESOURCE_LOCK_OWNED_SHIFT))
+    if (!_interlockedbittestandset((PLONG)&Lock->Value, PH_RESOURCE_LOCK_OWNED_SHIFT))
     {
         return TRUE;
     }
diff --git a/2.x/trunk/phlib/include/queuedlock.h b/2.x/trunk/phlib/include/queuedlock.h
index 46771cdcc..0165bacfe 100644
--- a/2.x/trunk/phlib/include/queuedlock.h
+++ b/2.x/trunk/phlib/include/queuedlock.h
@@ -209,7 +209,7 @@ FORCEINLINE BOOLEAN PhTryAcquireQueuedLockExclusive(
     if (!_interlockedbittestandset64((PLONG64)&QueuedLock->Value, PH_QUEUED_LOCK_OWNED_SHIFT))
 #endif
     {
-        return TRUE; 
+        return TRUE;
     }
     else
     {
diff --git a/2.x/trunk/phlib/sync.c b/2.x/trunk/phlib/sync.c
index 4d2bee58e..f3580a5d0 100644
--- a/2.x/trunk/phlib/sync.c
+++ b/2.x/trunk/phlib/sync.c
@@ -71,32 +71,21 @@ VOID FASTCALL PhfSetEvent(
     __inout PPH_EVENT Event
     )
 {
-    ULONG value;
     HANDLE eventHandle;
 
-    // Try to set the bit.
-    do
+    // Only proceed if the event isn't set already.
+    if (!_interlockedbittestandset((PLONG)&Event->Value, PH_EVENT_SET_SHIFT))
     {
-        value = Event->Value;
+        // Do an up-to-date read.
+        eventHandle = *(volatile HANDLE *)&Event->EventHandle;
 
-        // Has the event already been set?
-        if (value & PH_EVENT_SET)
-            return;
-    } while (_InterlockedCompareExchange(
-        &Event->Value,
-        value + PH_EVENT_SET,
-        value
-        ) != value);
+        if (eventHandle)
+        {
+            NtSetEvent(eventHandle, NULL);
+        }
 
-    // Do an up-to-date read.
-    eventHandle = *(volatile HANDLE *)(&Event->EventHandle);
-
-    if (eventHandle)
-    {
-        NtSetEvent(eventHandle, NULL);
+        PhpDereferenceEvent(Event);
     }
-
-    PhpDereferenceEvent(Event);
 }
 
 /**
@@ -134,7 +123,7 @@ BOOLEAN FASTCALL PhfWaitForEvent(
     // Prevent the event from being invalidated.
     PhpReferenceEvent(Event);
 
-    eventHandle = *(volatile HANDLE *)(&Event->EventHandle);
+    eventHandle = *(volatile HANDLE *)&Event->EventHandle;
 
     // Don't bother creating an event if we already have one.
     if (!eventHandle)
@@ -156,7 +145,7 @@ BOOLEAN FASTCALL PhfWaitForEvent(
 
     // Essential: check the event one last time to see if 
     // it is set.
-    if (!(*(volatile ULONG *)(&Event->Value) & PH_EVENT_SET))
+    if (!(*(volatile ULONG *)&Event->Value & PH_EVENT_SET))
     {
         result = NtWaitForSingleObject(Event->EventHandle, FALSE, Timeout) == STATUS_WAIT_0;
     }