From 507f418b8104f92376356bf7a6a929964668cbbe Mon Sep 17 00:00:00 2001
From: Jamie Reece Wilson <me@reece.sx>
Date: Fri, 1 Dec 2023 11:09:18 +0000
Subject: [PATCH] [*] Attempt to optimize AuLoop::WaitMultipleLoopSources

---
 Source/IO/Loop/Loop.cpp | 81 +++++++++++++++++++++++++++++++++--------
 1 file changed, 65 insertions(+), 16 deletions(-)

diff --git a/Source/IO/Loop/Loop.cpp b/Source/IO/Loop/Loop.cpp
index e2a0930c..ed568d1d 100644
--- a/Source/IO/Loop/Loop.cpp
+++ b/Source/IO/Loop/Loop.cpp
@@ -8,6 +8,7 @@
 #include <Source/RuntimeInternal.hpp>
 #include "Loop.hpp"
 #include "ILoopSourceEx.hpp"
+#include <Source/Threading/Primitives/SMTYield.hpp>
 
 namespace Aurora::IO::Loop
 {
@@ -92,8 +93,6 @@ namespace Aurora::IO::Loop
                                           bool bAny,
                                           AuOptionalEx<AuUInt32> uTimeoutMS)
     {
-        AU_DEBUG_MEMCRUNCH;
-
         signaled.clear();
         AuList<AuUInt32> reverseList;
 
@@ -102,10 +101,30 @@ namespace Aurora::IO::Loop
             return true;
         }
 
+        if (lsList.size() == 1)
+        {
+            auto pSource = lsList[0];
+            if (!pSource)
+            {
+                return false;
+            }
+
+            if (uTimeoutMS)
+            {
+                return pSource->WaitOn(uTimeoutMS.value());
+            }
+            else
+            {
+                return pSource->IsSignaled();
+            }
+        }
+
         auto uTimeoutEnd = uTimeoutMS ?
             AuTime::SteadyClockNS() + AuMSToNS<AuUInt64>(uTimeoutMS) :
             0;
         
+        AU_DEBUG_MEMCRUNCH;
+
         signaled.reserve(lsList.size());
 
         if (!bAny)
@@ -180,43 +199,73 @@ namespace Aurora::IO::Loop
         else
         {
             bool bTimedout {};
-            AuList<AuSPtr<Loop::ILoopSource>> next;
             AuList<AuSPtr<Loop::ILoopSource>> signalTemp;
 
-            for (const auto &pSource : lsList)
+            auto lsList2 = lsList;
+            bool bAnyFound {};
+
+            auto DoTheThing = [&]()
             {
-                if (pSource->GetType() == ELoopSource::eSourceMutex ||
-                    pSource->GetType() == ELoopSource::eSourceSemaphore ||
-                    pSource->GetType() == ELoopSource::eSourceEvent)
+                for (auto itr = lsList2.begin();
+                     itr != lsList2.end();
+                     )
                 {
-                    if (pSource->IsSignaled())
+                    auto pSource = *itr;
+
+                    if (pSource->GetType() == ELoopSource::eSourceMutex ||
+                        pSource->GetType() == ELoopSource::eSourceSemaphore ||
+                        pSource->GetType() == ELoopSource::eSourceEvent)
                     {
-                        signalTemp.push_back(pSource);
+                        auto pSourceEx = AuDynamicCast<Loop::ILoopSourceEx>(pSource);
+                        
+                        bAnyFound = true;
+
+                        if ((pSourceEx && pSourceEx->IsSignaledNoSpinIfUserland()) ||
+                            (!pSourceEx && pSource->IsSignaled()))
+                        {
+                            signalTemp.push_back(pSource);
+                            itr = lsList2.erase(itr);
+                        }
+                        else
+                        {
+                            itr++;
+                        }
                     }
                     else
                     {
-                        next.push_back(pSource);
+                        itr++;
                     }
                 }
-                else
+            };
+
+            if (gRuntimeConfig.threadingConfig.bPlatformIsSMPProcessorOptimized)
+            {
+                AuThreadPrimitives::DoTryIf([&]()
                 {
-                    next.push_back(pSource);
-                }
+                    DoTheThing();
+                    return lsList2.size() != lsList.size() || 
+                        !bAnyFound;
+                });
             }
 
-            if (next.size())
+            if (bAnyFound || !gRuntimeConfig.threadingConfig.bPlatformIsSMPProcessorOptimized)
+            {
+                DoTheThing();
+            }
+
+            if (lsList2.size())
             {
                 if (signalTemp.size())
                 {
                     uTimeoutMS = 1;
                 }
             #if defined(AURORA_IS_MODERNNT_DERIVED)
-                signaled = WaitMultipleOrObjects(next, uTimeoutMS);
+                signaled = WaitMultipleOrObjects(lsList2, uTimeoutMS);
                 bTimedout = uTimeoutMS ?
                     Time::SteadyClockNS() >= uTimeoutEnd :
                     false;
             #else
-                signaled = WaitMultipleOrObjectsFallback(next, uTimeoutMS, bTimedout);
+                signaled = WaitMultipleOrObjectsFallback(lsList2, uTimeoutMS, bTimedout);
             #endif
             }