/// <summary>
/// Drop a collection - remove all data pages + indexes pages
/// </summary>
public void Drop(CollectionPage col)
{
// add all pages to delete
var pages = new HashSet <uint>();
// search for all data page and index page
foreach (var index in col.GetIndexes(true))
{
// get all nodes from index
var nodes = _indexer.FindAll(index, Query.Ascending);
foreach (var node in nodes)
{
// if is PK index, add dataPages
if (index.Slot == 0)
{
pages.Add(node.DataBlock.PageID);
// read datablock to check if there is any extended page
var block = _data.GetBlock(node.DataBlock);
if (block.ExtendPageID != uint.MaxValue)
{
_pager.DeletePage(block.ExtendPageID, true);
}
}
// memory checkpoint
_trans.CheckPoint();
// add index page to delete list page
pages.Add(node.Position.PageID);
}
// remove head+tail nodes in all indexes
pages.Add(index.HeadNode.PageID);
pages.Add(index.TailNode.PageID);
}
// and now, lets delete all this pages
foreach (var pageID in pages)
{
// delete page
_pager.DeletePage(pageID);
// memory checkpoint
_trans.CheckPoint();
}
// get header page to remove from collection list links
var header = _pager.GetPage <HeaderPage>(0);
header.CollectionPages.Remove(col.CollectionName);
// set header as dirty after remove
_pager.SetDirty(header);
_pager.DeletePage(col.PageID);
}
/// <summary>
/// Fetch documents from enumerator and add to buffer. If cache recycle, stop read to execute in another read
/// </summary>
public void Fetch(TransactionService trans, DataService data, BsonReader bsonReader)
{
// empty document buffer
Documents.Clear();
// while until must cache not recycle
while (trans.CheckPoint() == false)
{
// read next node
HasMore = _nodes.MoveNext();
// if finish, exit loop
if (HasMore == false)
{
return;
}
// if run ONLY under index, skip/limit before deserialize
if (_query.UseIndex && _query.UseFilter == false)
{
if (--_skip >= 0)
{
continue;
}
if (--_limit <= -1)
{
HasMore = false;
return;
}
}
// get current node
var node = _nodes.Current;
// read document from data block
var buffer = data.Read(node.DataBlock);
var doc = bsonReader.Deserialize(buffer).AsDocument;
// if need run in full scan, execute full scan and test return
if (_query.UseFilter)
{
// execute query condition here - if false, do not add on final results
if (_query.FilterDocument(doc) == false)
{
continue;
}
// implement skip/limit after deserialize in full scan
if (--_skip >= 0)
{
continue;
}
if (--_limit <= -1)
{
HasMore = false;
return;
}
}
// increment position cursor
_position++;
// avoid lock again just to check limit
if (_limit == 0)
{
HasMore = false;
}
Documents.Add(doc);
}
}
