Windows: Make file delete/rename retry configurable

Several CMake operations need to replace files in rapid succession.
This commonly fails on Windows due to filesystem lock behavior so
we have retry loops.  No matter how many times we retry or how long
we delay there will inevitably be someone with an environment that
needs more.  Make the retry count and delay configurable in the
Windows Registry keys:

 {HKCU,HKLM}/Software/Kitware/CMake/Config

in DWORD values

 FilesystemRetryCount = Number of tries
 FilesystemRetryDelay = Delay in milliseconds between tries

Leave the feature undocumented for now to see how it goes.

1 files changed, 42 insertions, 4 deletions

diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 41c7509..ff05975 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -864,6 +864,44 @@ bool cmSystemTools::CopyFileIfDifferent(const char* source,
 }
 
 //----------------------------------------------------------------------------
+#ifdef _WIN32
+cmSystemTools::WindowsFileRetry cmSystemTools::GetWindowsFileRetry()
+{
+  static WindowsFileRetry retry = {0,0};
+  if(!retry.Count)
+    {
+    unsigned int data[2] = {0,0};
+    HKEY const keys[2] = {HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE};
+    wchar_t const* const values[2] = {L"FilesystemRetryCount",
+                                      L"FilesystemRetryDelay"};
+    for(int k=0; k < 2; ++k)
+      {
+      HKEY hKey;
+      if(RegOpenKeyExW(keys[k], L"Software\\Kitware\\CMake\\Config",
+                       0, KEY_QUERY_VALUE, &hKey) == ERROR_SUCCESS)
+        {
+        for(int v=0; v < 2; ++v)
+          {
+          DWORD dwData, dwType, dwSize = 4;
+          if(!data[v] &&
+             RegQueryValueExW(hKey, values[v], 0, &dwType, (BYTE *)&dwData,
+                              &dwSize) == ERROR_SUCCESS &&
+             dwType == REG_DWORD && dwSize == 4)
+            {
+            data[v] = static_cast<unsigned int>(dwData);
+            }
+          }
+        RegCloseKey(hKey);
+        }
+      }
+    retry.Count = data[0]? data[0] : 5;
+    retry.Delay = data[1]? data[1] : 500;
+    }
+  return retry;
+}
+#endif
+
+//----------------------------------------------------------------------------
 bool cmSystemTools::RenameFile(const char* oldname, const char* newname)
 {
 #ifdef _WIN32
@@ -874,10 +912,10 @@ bool cmSystemTools::RenameFile(const char* oldname, const char* newname)
      fails then remove the read-only attribute from any existing destination.
      Try multiple times since we may be racing against another process
      creating/opening the destination file just before our MoveFileEx.  */
-  int tries = 5;
+  WindowsFileRetry retry = cmSystemTools::GetWindowsFileRetry();
   while(!MoveFileExW(cmsys::Encoding::ToWide(oldname).c_str(),
                      cmsys::Encoding::ToWide(newname).c_str(),
-                     MOVEFILE_REPLACE_EXISTING) && --tries)
+                     MOVEFILE_REPLACE_EXISTING) && --retry.Count)
     {
     // Try again only if failure was due to access permissions.
     if(GetLastError() != ERROR_ACCESS_DENIED)
@@ -896,10 +934,10 @@ bool cmSystemTools::RenameFile(const char* oldname, const char* newname)
     else
       {
       // The file may be temporarily in use so wait a bit.
-      cmSystemTools::Delay(100);
+      cmSystemTools::Delay(retry.Delay);
       }
     }
-  return tries > 0;
+  return retry.Count > 0;
 #else
   /* On UNIX we have an OS-provided call to do this atomically.  */
   return rename(oldname, newname) == 0;