internal static bool TryReservePages(Thread currentThread,
UIntPtr startPage,
UIntPtr pageCount,
PageType newType,
ref bool fCleanPages)
{
Trace.Log(Trace.Area.Page,
"TryReservePages start={0:x} count={1:x}",
__arglist(startPage, pageCount));
VTable.Deny(PageTable.IsUnusedPageType(newType));
VTable.Assert(pageCount > UIntPtr.Zero);
VTable.Deny(startPage != UIntPtr.Zero &&
PageTable.IsUnusedPage(startPage - 1) &&
PageTable.IsMyPage(startPage - 1));
UIntPtr endPage = startPage + pageCount;
UIntPtr index = startPage;
while (index < endPage &&
PageTable.IsUnusedPage(index) &&
PageTable.IsMyPage(index))
{
index++;
}
if (PageTable.IsUnallocatedPage(PageTable.Type(index)))
{
// We should try to extend the region of allocated pages
UIntPtr pagesNeeded = pageCount - (index - startPage);
UIntPtr bytesNeeded = PageTable.RegionSize(pagesNeeded);
UIntPtr allocSize = Util.Pad(bytesNeeded, heap_commit_size);
UIntPtr startAddr = PageTable.PageAddr(index);
bool gotMemory = false;
bool iflag = EnterMutex(currentThread);
try {
gotMemory =
MemoryManager.AllocateMemory(startAddr, allocSize);
if (gotMemory)
{
UIntPtr allocPages = PageTable.PageCount(allocSize);
MarkUnusedPages(/* avoid recursive locking */ null,
index, allocPages, true);
}
} finally {
LeaveMutex(currentThread, iflag);
}
if (gotMemory)
{
bool success =
TryReserveUnusedPages(currentThread, startPage,
pageCount, newType,
ref fCleanPages);
Trace.Log(Trace.Area.Page,
"TryReservePages success={0}",
__arglist(success));
return(success);
}
}
return(false);
}