/// <summary>Merge files with the extensions added up to now.
/// All files with these extensions are combined sequentially into the
/// compound stream. After successful merge, the source files
/// are deleted.
/// </summary>
/// <throws> IllegalStateException if close() had been called before or </throws>
/// <summary> if no file has been added to this object
/// </summary>
public void Close()
{
if (merged)
{
throw new System.SystemException("Merge already performed");
}
if ((entries.Count == 0))
{
throw new System.SystemException("No entries to merge have been defined");
}
merged = true;
// open the compound stream
IndexOutput os = null;
try
{
os = directory.CreateOutput(fileName);
// Write the number of entries
os.WriteVInt(entries.Count);
// Write the directory with all offsets at 0.
// Remember the positions of directory entries so that we can
// adjust the offsets later
System.Collections.IEnumerator it = entries.GetEnumerator();
long totalSize = 0;
while (it.MoveNext())
{
FileEntry fe = (FileEntry)it.Current;
fe.directoryOffset = os.GetFilePointer();
os.WriteLong(0); // for now
os.WriteString(fe.file);
totalSize += directory.FileLength(fe.file);
}
// Pre-allocate size of file as optimization --
// this can potentially help IO performance as
// we write the file and also later during
// searching. It also uncovers a disk-full
// situation earlier and hopefully without
// actually filling disk to 100%:
long finalLength = totalSize + os.GetFilePointer();
os.SetLength(finalLength);
// Open the files and copy their data into the stream.
// Remember the locations of each file's data section.
byte[] buffer = new byte[16384];
it = entries.GetEnumerator();
while (it.MoveNext())
{
FileEntry fe = (FileEntry)it.Current;
fe.dataOffset = os.GetFilePointer();
CopyFile(fe, os, buffer);
}
// Write the data offsets into the directory of the compound stream
it = entries.GetEnumerator();
while (it.MoveNext())
{
FileEntry fe = (FileEntry)it.Current;
os.Seek(fe.directoryOffset);
os.WriteLong(fe.dataOffset);
}
System.Diagnostics.Debug.Assert(finalLength == os.Length());
// Close the output stream. Set the os to null before trying to
// close so that if an exception occurs during the close, the
// finally clause below will not attempt to close the stream
// the second time.
IndexOutput tmp = os;
os = null;
tmp.Close();
}
finally
{
if (os != null)
{
try
{
os.Close();
}
catch (System.IO.IOException e)
{
}
}
}
}