/// <summary> Read a particular segmentFileName. Note that this may
/// throw an IOException if a commit is in process.
///
/// </summary>
/// <param name="directory">-- directory containing the segments file
/// </param>
/// <param name="segmentFileName">-- segment file to load
/// </param>
/// <throws> CorruptIndexException if the index is corrupt </throws>
/// <throws> IOException if there is a low-level IO error </throws>
public void Read(Directory directory, System.String segmentFileName)
{
bool success = false;
// Clear any previous segments:
Clear();
var input = new ChecksumIndexInput(directory.OpenInput(segmentFileName));
generation = GenerationFromSegmentsFileName(segmentFileName);
lastGeneration = generation;
try
{
int format = input.ReadInt();
if (format < 0)
{
// file contains explicit format info
// check that it is a format we can understand
if (format < CURRENT_FORMAT)
{
throw new CorruptIndexException("Unknown format version: " + format);
}
version = input.ReadLong(); // read version
counter = input.ReadInt(); // read counter
}
else
{
// file is in old format without explicit format info
counter = format;
}
for (int i = input.ReadInt(); i > 0; i--)
{
// read segmentInfos
Add(new SegmentInfo(directory, format, input));
}
if (format >= 0)
{
// in old format the version number may be at the end of the file
if (input.FilePointer >= input.Length())
{
version = (DateTime.UtcNow.Ticks / TimeSpan.TicksPerMillisecond);
}
// old file format without version number
else
{
version = input.ReadLong(); // read version
}
}
if (format <= FORMAT_USER_DATA)
{
if (format <= FORMAT_DIAGNOSTICS)
{
userData = input.ReadStringStringMap();
}
else if (0 != input.ReadByte())
{
// TODO: Should be read-only map
userData = new HashMap <string, string> {
{ "userData", input.ReadString() }
};
}
else
{
// TODO: Should be empty read-only map
userData = new HashMap <string, string>();
}
}
else
{
// TODO: Should be empty read-only map
userData = new HashMap <string, string>();
}
if (format <= FORMAT_CHECKSUM)
{
long checksumNow = input.Checksum;
long checksumThen = input.ReadLong();
if (checksumNow != checksumThen)
{
throw new CorruptIndexException("checksum mismatch in segments file");
}
}
success = true;
}
finally
{
input.Close();
if (!success)
{
// Clear any segment infos we had loaded so we
// have a clean slate on retry:
Clear();
}
}
}