// TODO: This should be part of buffer pool class.
// Ideally page manager shouldn't keep track of in memory-disk mappings.
private async Task RecordUsageAndEvict(ulong pageId, ITransaction tran)
{
ulong[] pageIdsToEvict = this.bufferPool.GetEvictionPolicy().RecordUsageAndEvict(pageId).ToArray();
foreach (ulong pageIdToEvict in pageIdsToEvict)
{
if (tran.AmIHoldingALock(pageIdToEvict, out LockTypeEnum heldLockType))
{
// If this page is needed for myself don't release the lock.
// Just ignore for now.
continue;
}
using (Releaser lckReleaser = await tran.AcquireLockWithCallerOwnership(pageIdToEvict, LockTypeEnum.Exclusive).ConfigureAwait(false))
{
logger.LogDebug($"Evicting page {pageIdToEvict}");
IPage pageToEvict = this.bufferPool.GetPage(pageIdToEvict);
// Somebody came before us and evicted the page.
if (pageToEvict == null)
{
continue;
}
await this.FlushPage(pageToEvict).ConfigureAwait(false);
bufferPool.EvictPage(pageToEvict.PageId(), pageToEvict.GetBufferPoolToken());
logger.LogDebug($"Page {pageIdToEvict} evicted from buffer pool and flushed to the disk.");
}
}
}
public async Task <IPage> AllocatePage(PageType pageType, ColumnInfo[] columnTypes, ulong prevPageId, ulong nextPageId, ulong pageId, ITransaction tran)
{
logger.LogDebug($"Allocating new page {pageId}");
IPage page;
using Releaser releaser = await tran.AcquireLockWithCallerOwnership(pageId, LockTypeEnum.Exclusive).ConfigureAwait(false);
(Memory <byte> memory, ulong token) = this.bufferPool.GetMemory();
page = pageType switch
{
PageType.StringPage => new StringOnlyPage(pageSize, pageId, prevPageId, nextPageId, tran),
PageType.MixedPage => new MixedPage(pageSize, pageId, columnTypes, prevPageId, nextPageId, memory, token, tran),
_ => throw new ArgumentException("Unknown page type")
};
Interlocked.Increment(ref this.pageCount);
if (prevPageId != PageManagerConstants.NullPageId)
{
tran.VerifyLock(prevPageId, LockTypeEnum.Exclusive);
IPage prevPage = await GetPage(prevPageId, tran, pageType, columnTypes).ConfigureAwait(false);
if (prevPage.NextPageId() != page.NextPageId())
{
throw new ArgumentException("Breaking the link");
}
// TODO: Set next page id needs to be logged as well...
prevPage.SetNextPageId(page.PageId());
}
if (nextPageId != PageManagerConstants.NullPageId)
{
IPage nextPage = await GetPage(nextPageId, tran, pageType, columnTypes).ConfigureAwait(false);
if (nextPage.PrevPageId() != page.PrevPageId())
{
throw new ArgumentException("breaking the link");
}
nextPage.SetPrevPageId(page.PageId());
}
await RecordUsageAndEvict(page.PageId(), tran).ConfigureAwait(false);
bufferPool.AddPage(page);
AddToAllocationMap(page);
return(page);
}