internal virtual void AddFreePageToFreelist(long pageRef)
{
object current;
FreePage freePage = new FreePage(pageRef);
do
{
current = FreelistHead;
if (current is AtomicInteger && (( AtomicInteger )current).get() > Pages.PageCount)
{
current = null;
}
freePage.Next = current;
} while (!CompareAndSetFreelistHead(current, freePage));
}
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
//ORIGINAL LINE: long grabFreeAndExclusivelyLockedPage(org.neo4j.io.pagecache.tracing.PageFaultEvent faultEvent) throws java.io.IOException
internal virtual long GrabFreeAndExclusivelyLockedPage(PageFaultEvent faultEvent)
{
// Review the comment on the freelist field before making changes to
// this part of the code.
// Whatever the case, we're going to the head-pointer of the freelist,
// and in doing so, we can discover a number of things.
// We can discover a MuninnPage object, in which case we can try to
// CAS the freelist pointer to the value of the MuninnPage.nextFree
// pointer, and if this succeeds then we've grabbed that page.
// We can discover a FreePage object, in which case we'll do a similar
// dance by attempting to CAS the freelist to the FreePage objects next
// pointer, and again, if we succeed then we've grabbed the MuninnPage
// given by the FreePage object.
// We can discover a null-pointer, in which case the freelist has just
// been emptied for whatever it contained before. New FreePage objects
// are eventually going to be added to the freelist, but we are not
// going to wait around for that to happen. If the freelist is empty,
// then we do our own eviction to get a free page.
// If we find a FreePage object on the freelist, then it is important
// to check and see if it is the shutdownSignal instance. If that's the
// case, then the page cache has been shut down, and we should throw an
// exception from our page fault routine.
object current;
for ( ;;)
{
AssertHealthy();
current = FreelistHead;
if (current == null)
{
UnparkEvictor();
long pageRef = CooperativelyEvict(faultEvent);
if (pageRef != 0)
{
return(pageRef);
}
}
else if (current is AtomicInteger)
{
int pageCount = Pages.PageCount;
AtomicInteger counter = ( AtomicInteger )current;
int pageId = counter.get();
if (pageId < pageCount && counter.compareAndSet(pageId, pageId + 1))
{
return(Pages.deref(pageId));
}
if (pageId >= pageCount)
{
CompareAndSetFreelistHead(current, null);
}
}
else if (current is FreePage)
{
FreePage freePage = ( FreePage )current;
if (freePage == _shutdownSignal)
{
throw new System.InvalidOperationException("The PageCache has been shut down.");
}
if (CompareAndSetFreelistHead(freePage, freePage.NextConflict))
{
return(freePage.PageRef);
}
}
}
}
