Prevent pruning of DWM.exe swap chains with address 0x0

Pruning DWM.exe swap chains with address 0x0 caused inconsistent test results because these swap chains are reused by the Desktop Window Manager for desktop composition. Removing them prematurely led to missing or unexpected data during unit and integration tests, especially in scenarios where DWM activity is infrequent. By excluding DWM.exe swap chains with address 0x0 from pruning, we ensure stable and predictable test outcomes.

Author: markgalvan-intel

PresentMon/OutputThread.cpp

@@ -838,11 +838,27 @@ static void PruneOldSwapChainData(
 
     for (auto& pair : gProcesses) {
         auto processInfo = &pair.second;
+
+        // Check if this is DWM process
+        bool isDwmProcess = false;
+        std::wstring processName = processInfo->mModuleName;
+        std::transform(processName.begin(), processName.end(), processName.begin(),
+            [](wchar_t c) { return (wchar_t) ::towlower(c); });
+        if (processName.find(L"dwm.exe") != std::wstring::npos) {
+            isDwmProcess = true;
+        }
+
         for (auto ii = processInfo->mSwapChain.begin(), ie = processInfo->mSwapChain.end(); ii != ie; ) {
+            auto swapChainAddress = ii->first;
             auto chain = &ii->second;
-            if (chain->mLastPresent && chain->mLastPresent->PresentStartTime < minTimestamp) {
+
+            // Don't prune DWM swap chains with address 0x0
+            bool shouldSkipPruning = isDwmProcess && swapChainAddress == 0x0;
+
+            if (!shouldSkipPruning && chain->mLastPresent && chain->mLastPresent->PresentStartTime < minTimestamp) {
                 ii = processInfo->mSwapChain.erase(ii);
-            } else {
+            }
+            else {
                 ++ii;
             }
         }