public FileAndPages GetFile(string filename, int start, int pagesToLoad)
{
Api.JetSetCurrentIndex(session, Files, "by_name");
Api.MakeKey(session, Files, filename, Encoding.Unicode, MakeKeyGrbit.NewKey);
if (Api.TrySeek(session, Files, SeekGrbit.SeekEQ) == false)
throw new FileNotFoundException("Could not find file: " + filename);
var fileInformation = new FileAndPages
{
TotalSize = GetTotalSize(),
UploadedSize =
BitConverter.ToInt64(
Api.RetrieveColumn(session, Files, tableColumnsCache.FilesColumns["uploaded_size"]), 0),
Metadata = RetrieveMetadata(),
Name = filename,
Start = start
};
if (pagesToLoad > 0)
{
Api.JetSetCurrentIndex(session, Usage, "by_name_and_pos");
Api.MakeKey(session, Usage, filename, Encoding.Unicode, MakeKeyGrbit.NewKey);
Api.MakeKey(session, Usage, start, MakeKeyGrbit.None);
if (Api.TrySeek(session, Usage, SeekGrbit.SeekGE))
{
Api.MakeKey(session, Usage, filename, Encoding.Unicode, MakeKeyGrbit.NewKey);
Api.JetSetIndexRange(session, Usage, SetIndexRangeGrbit.RangeInclusive);
do
{
var name = Api.RetrieveColumnAsString(session, Usage, tableColumnsCache.UsageColumns["name"]);
if (name != filename)
continue;
fileInformation.Pages.Add(new PageInformation
{
Size =
Api.RetrieveColumnAsInt32(session, Usage, tableColumnsCache.UsageColumns["page_size"])
.Value,
Id =
Api.RetrieveColumnAsInt32(session, Usage, tableColumnsCache.UsageColumns["page_id"])
.Value
});
} while (Api.TryMoveNext(session, Usage) && fileInformation.Pages.Count < pagesToLoad);
}
}
return fileInformation;
}
private void MovePageFrame(long offset)
{
offset = Math.Min(Length, offset);
if (offset < currentPageFrameOffset || fileAndPages == null)
{
TransactionalStorage.Batch(accessor => fileAndPages = accessor.GetFile(Name, 0, PagesBatchSize));
currentPageFrameOffset = 0;
}
while (currentPageFrameOffset + CurrentPageFrameSize - 1 < offset)
{
var lastPageFrameSize = CurrentPageFrameSize;
var nextPageIndex = fileAndPages.Start + fileAndPages.Pages.Count;
TransactionalStorage.Batch(accessor => fileAndPages = accessor.GetFile(Name, nextPageIndex, PagesBatchSize));
if (fileAndPages.Pages.Count < 1)
{
fileAndPages.Start = 0;
break;
}
currentPageFrameOffset += lastPageFrameSize;
}
currentOffset = offset;
}