public void SpinLock()
{
// Check for a re-entrant lock.
if (threadLockedRecord == (RecordInfo *)Unsafe.AsPointer(ref this))
{
Debug.Assert(threadLockedRecordEntryCount > 0);
++threadLockedRecordEntryCount;
return;
}
// RecordInfo locking is intended for use in concurrent callbacks only (ConcurrentReader, ConcurrentWriter, InPlaceUpdater),
// so only the RecordInfo for that callback should be locked. A different RecordInfo being locked implies a missing Unlock.
Debug.Assert(threadLockedRecord == null);
Debug.Assert(threadLockedRecordEntryCount == 0);
while (true)
{
long expected_word = word;
if ((expected_word & kLatchBitMask) == 0)
{
var found_word = Interlocked.CompareExchange(ref word, expected_word | kLatchBitMask, expected_word);
if (found_word == expected_word)
{
threadLockedRecord = (RecordInfo *)Unsafe.AsPointer(ref this);
threadLockedRecordEntryCount = 1;
return;
}
}
Thread.Yield();
}
}
public static void WriteInfo(RecordInfo *info, int checkpointVersion, bool tombstone, bool invalidBit, long previousAddress)
{
info->word = default(long);
info->Tombstone = tombstone;
info->Invalid = invalidBit;
info->PreviousAddress = previousAddress;
info->Version = checkpointVersion;
info->access_data = 0;
}
public unsafe void RecordInfoLockTest()
{
for (var ii = 0; ii < 5; ++ii)
{
RecordInfo recordInfo = new RecordInfo();
RecordInfo *ri = &recordInfo;
XLockTest(() => ri->SpinLock(), () => ri->Unlock());
}
}
public void Unlock()
{
Debug.Assert(threadLockedRecord == (RecordInfo *)Unsafe.AsPointer(ref this));
if (threadLockedRecord == (RecordInfo *)Unsafe.AsPointer(ref this))
{
Debug.Assert(threadLockedRecordEntryCount > 0);
if (--threadLockedRecordEntryCount == 0)
{
word &= ~kLatchBitMask;
threadLockedRecord = null;
}
}
}
public unsafe void RecordInfoLockTest()
{
for (var ii = 0; ii < 5; ++ii)
{
RecordInfo recordInfo = new();
RecordInfo *ri = &recordInfo;
// We are not sealing in this test, so there is no need to check the return
XLockTest(() => ri->LockExclusive(), () => ri->UnlockExclusive());
SLockTest(() => ri->LockShared(), () => ri->UnlockShared());
XSLockTest(() => ri->LockExclusive(), () => ri->UnlockExclusive(), () => ri->LockShared(), () => ri->UnlockShared());
}
}
public static string ToString(RecordInfo *info)
{
return("RecordHeader Word = " + info->word);
}
