private IEnumerable <BsonDocument> GetList(uint pageID, string indexName, TransactionService transaction, Snapshot snapshot)
{
if (pageID == uint.MaxValue)
{
yield break;
}
var page = snapshot.GetPage <BasePage>(pageID);
while (page != null)
{
_collections.TryGetValue(page.ColID, out var collection);
yield return(new BsonDocument
{
["pageID"] = (int)page.PageID,
["pageType"] = page.PageType.ToString(),
["slot"] = (int)page.PageListSlot,
["collection"] = collection,
["index"] = indexName,
["freeBytes"] = page.FreeBytes,
["itemsCount"] = (int)page.ItemsCount
});
if (page.NextPageID == uint.MaxValue)
{
break;
}
transaction.Safepoint();
page = snapshot.GetPage <BasePage>(page.NextPageID);
}
}
/// <summary>
/// Get last _id index key from collection. Returns MinValue if collection are empty
/// </summary>
private async Task <BsonValue> GetLastId(Snapshot snapshot)
{
var pk = snapshot.CollectionPage.PK;
// get tail page and previous page
var tailPage = await snapshot.GetPage <IndexPage>(pk.Tail.PageID);
var node = tailPage.GetIndexNode(pk.Tail.Index);
var prevNode = node.Prev[0];
if (prevNode == pk.Head)
{
return(BsonValue.MinValue);
}
else
{
var lastPage = prevNode.PageID == tailPage.PageID ? tailPage : await snapshot.GetPage <IndexPage>(prevNode.PageID);
var lastNode = lastPage.GetIndexNode(prevNode.Index);
var lastKey = lastNode.Key;
return(lastKey);
}
}
/// <summary>
/// Get a node inside a page using PageAddress - Returns null if address IsEmpty
/// </summary>
public IndexNode GetNode(PageAddress address)
{
if (address.PageID == uint.MaxValue)
{
return(null);
}
var indexPage = _snapshot.GetPage <IndexPage>(address.PageID);
return(indexPage.GetIndexNode(address.Index));
}
/// <summary>
/// Get collection page instance (or create a new one)
/// </summary>
public void Get(string name, bool addIfNotExists, ref CollectionPage collectionPage)
{
// get collection pageID from header
var pageID = _header.GetCollectionPageID(name);
if (pageID != uint.MaxValue)
{
collectionPage = _snapshot.GetPage <CollectionPage>(pageID);
}
else if (addIfNotExists)
{
this.Add(name, ref collectionPage);
}
}
/// <summary>
/// Get collection page instance (or create a new one). Returns null if not found and not created
/// </summary>
public async Task <CollectionPage> Get(string name, bool addIfNotExists)
{
// get collection pageID from header
var pageID = _header.GetCollectionPageID(name);
if (pageID != uint.MaxValue)
{
return(await _snapshot.GetPage <CollectionPage>(pageID));
}
else if (addIfNotExists)
{
return(await this.Add(name));
}
return(null);
}
/// <summary>
/// Update document using same page position as reference
/// </summary>
public void Update(CollectionPage col, PageAddress blockAddress, BsonDocument doc)
{
var bytesLeft = doc.GetBytesCount(true);
if (bytesLeft > MAX_DOCUMENT_SIZE)
{
throw new LiteException(0, "Document size exceed {0} limit", MAX_DOCUMENT_SIZE);
}
DataBlock lastBlock = null;
var updateAddress = blockAddress;
IEnumerable <BufferSlice> source()
{
var bytesToCopy = 0;
while (bytesLeft > 0)
{
// if last block contains new block sequence, continue updating
if (updateAddress.IsEmpty == false)
{
var dataPage = _snapshot.GetPage <DataPage>(updateAddress.PageID);
var currentBlock = dataPage.GetBlock(updateAddress.Index);
// try get full page size content
bytesToCopy = Math.Min(bytesLeft, dataPage.FreeBytes + currentBlock.Buffer.Count);
// get current free slot linked list
var slot = BasePage.FreeIndexSlot(dataPage.FreeBytes);
var updateBlock = dataPage.UpdateBlock(currentBlock, bytesToCopy);
_snapshot.AddOrRemoveFreeList(dataPage, slot);
yield return(updateBlock.Buffer);
lastBlock = updateBlock;
// go to next address (if extits)
updateAddress = updateBlock.NextBlock;
}
else
{
bytesToCopy = Math.Min(bytesLeft, MAX_DATA_BYTES_PER_PAGE);
var dataPage = _snapshot.GetFreePage <DataPage>(bytesToCopy + DataBlock.DATA_BLOCK_FIXED_SIZE);
var insertBlock = dataPage.InsertBlock(bytesToCopy, true);
if (lastBlock != null)
{
lastBlock.SetNextBlock(insertBlock.Position);
}
yield return(insertBlock.Buffer);
lastBlock = insertBlock;
}
bytesLeft -= bytesToCopy;
}
// old document was bigger than current, must delete extend blocks
if (lastBlock.NextBlock.IsEmpty == false)
{
this.Delete(lastBlock.NextBlock);
}
}
// consume all source bytes to write BsonDocument direct into PageBuffer
// must be fastest as possible
using (var w = new BufferWriter(source()))
{
// already bytes count calculate at method start
w.WriteDocument(doc, false);
w.Consume();
}
}
/// <summary>
/// Update document using same page position as reference
/// </summary>
public async Task Update(CollectionPage col, PageAddress blockAddress, BsonDocument doc)
{
var bytesLeft = doc.GetBytesCount(true);
if (bytesLeft > MAX_DOCUMENT_SIZE)
{
throw new LiteException(0, "Document size exceed {0} limit", MAX_DOCUMENT_SIZE);
}
DataBlock lastBlock = null;
var updateAddress = blockAddress;
async IAsyncEnumerable <BufferSlice> source()
{
var bytesToCopy = 0;
while (bytesLeft > 0)
{
// if last block contains new block sequence, continue updating
if (updateAddress.IsEmpty == false)
{
var dataPage = await _snapshot.GetPage <DataPage>(updateAddress.PageID);
var currentBlock = dataPage.GetBlock(updateAddress.Index);
// try get full page size content (do not add DATA_BLOCK_FIXED_SIZE because will be added in UpdateBlock)
bytesToCopy = Math.Min(bytesLeft, dataPage.FreeBytes + currentBlock.Buffer.Count);
var updateBlock = dataPage.UpdateBlock(currentBlock, bytesToCopy);
await _snapshot.AddOrRemoveFreeDataList(dataPage);
yield return(updateBlock.Buffer);
lastBlock = updateBlock;
// go to next address (if exists)
updateAddress = updateBlock.NextBlock;
}
else
{
bytesToCopy = Math.Min(bytesLeft, MAX_DATA_BYTES_PER_PAGE);
var dataPage = await _snapshot.GetFreeDataPage(bytesToCopy + DataBlock.DATA_BLOCK_FIXED_SIZE);
var insertBlock = dataPage.InsertBlock(bytesToCopy, true);
if (lastBlock != null)
{
lastBlock.SetNextBlock(insertBlock.Position);
}
await _snapshot.AddOrRemoveFreeDataList(dataPage);
yield return(insertBlock.Buffer);
lastBlock = insertBlock;
}
bytesLeft -= bytesToCopy;
}
// old document was bigger than current, must delete extend blocks
if (lastBlock.NextBlock.IsEmpty == false)
{
var nextBlockAddress = lastBlock.NextBlock;
lastBlock.SetNextBlock(PageAddress.Empty);
await this.Delete(nextBlockAddress);
}
}
// consume all source bytes to write BsonDocument direct into PageBuffer
await using (var writer = await BufferWriterAsync.CreateAsync(source()))
{
// already bytes count calculate at method start
await writer.WriteDocument(doc, false);
await writer.Consume();
}
}
