/// <summary>
/// Copy database do another disk
/// </summary>
public int Shrink()
{
lock (_locker)
{
// lock and clear cache - no changes during shrink
_disk.Lock();
_cache.Clear();
// create a temporary disk
var tempDisk = _disk.GetTempDisk();
// get initial disk size
var header = _pager.GetPage <HeaderPage>(0);
var diff = 0;
// create temp engine instance to copy all documents
using (var tempEngine = new DbEngine(tempDisk, new Logger()))
{
// read all collections
foreach (var col in _collections.GetAll())
{
// first copy all indexes
foreach (var index in col.GetIndexes(false))
{
tempEngine.EnsureIndex(col.CollectionName, index.Field, index.Options);
}
// then, read all documents and copy to new engine
var nodes = _indexer.FindAll(col.PK, Query.Ascending);
tempEngine.Insert(col.CollectionName,
nodes.Select(node => BsonSerializer.Deserialize(_data.Read(node.DataBlock, true).Buffer)));
}
// get final header from temp engine
var tempHeader = tempEngine._pager.GetPage <HeaderPage>(0, true);
// copy info from initial header to final header
tempHeader.ChangeID = header.ChangeID;
// lets create journal file before re-write
for (uint pageID = 0; pageID <= header.LastPageID; pageID++)
{
_disk.WriteJournal(pageID, _disk.ReadPage(pageID));
}
// commit journal + shrink data file
_disk.SetLength((tempHeader.LastPageID + 1) * BasePage.PAGE_SIZE);
// lets re-write all pages copying from new database
for (uint pageID = 0; pageID <= tempHeader.LastPageID; pageID++)
{
_disk.WritePage(pageID, tempDisk.ReadPage(pageID));
}
// now delete journal
_disk.DeleteJournal();
// get diff from initial and final last pageID
diff = (int)((header.LastPageID - tempHeader.LastPageID) * BasePage.PAGE_SIZE);
}
// unlock disk and ckar cache to continue
_disk.Unlock();
_cache.Clear();
// delete temporary disk
_disk.DeleteTempDisk();
return(diff);
}
}
internal LiteFileStorage(DbEngine engine)
{
_engine = engine;
}
