/// <summary> Trys to acquire the WriteLock on this directory.
/// this method is only valid if this IndexReader is directory owner.
///
/// </summary>
/// <throws> IOException If WriteLock cannot be acquired. </throws>
private void AquireWriteLock()
{
if (stale)
{
throw new System.IO.IOException("IndexReader out of date and no longer valid for delete, undelete, or setNorm operations");
}
if (this.writeLock == null)
{
Lock writeLock = directory.MakeLock(IndexWriter.WRITE_LOCK_NAME);
if (!writeLock.Obtain(IndexWriter.WRITE_LOCK_TIMEOUT))
// obtain write lock
{
throw new System.IO.IOException("Index locked for write: " + writeLock);
}
this.writeLock = writeLock;
// we have to check whether index has changed since this reader was opened.
// if so, this reader is no longer valid for deletion
if (SegmentInfos.ReadCurrentVersion(directory) > segmentInfos.GetVersion())
{
stale = true;
this.writeLock.Release();
this.writeLock = null;
throw new System.IO.IOException("IndexReader out of date and no longer valid for delete, undelete, or setNorm operations");
}
}
}
/// <summary> Current version number from segments file.</summary>
public static long ReadCurrentVersion(Directory directory)
{
InputStream input = directory.OpenFile("segments");
int format = 0;
long version = 0;
try
{
format = input.ReadInt();
if (format < 0)
{
if (format < FORMAT)
{
throw new System.IO.IOException("Unknown format version: " + format);
}
version = input.ReadLong(); // read version
}
}
finally
{
input.Close();
}
if (format < 0)
{
return(version);
}
// We cannot be sure about the format of the file.
// Therefore we have to read the whole file and cannot simply seek to the version entry.
SegmentInfos sis = new SegmentInfos();
sis.Read(directory);
return(sis.GetVersion());
}
/// <summary> Current version number from segments file.</summary>
public static long ReadCurrentVersion(Directory directory)
{
InputStream input = directory.OpenFile("segments");
int format = 0;
long version = 0;
try
{
format = input.ReadInt();
if (format < 0)
{
if (format < FORMAT)
throw new System.IO.IOException("Unknown format version: " + format);
version = input.ReadLong(); // read version
}
}
finally
{
input.Close();
}
if (format < 0)
return version;
// We cannot be sure about the format of the file.
// Therefore we have to read the whole file and cannot simply seek to the version entry.
SegmentInfos sis = new SegmentInfos();
sis.Read(directory);
return sis.GetVersion();
}
