Exemple #1
0
        /// <summary>read as a d-gaps list </summary>
        private void  ReadDgaps(IndexInput input, IState state)
        {
            size  = input.ReadInt(state);            // (re)read size
            count = input.ReadInt(state);            // read count
            bits  = new byte[(size >> 3) + 1];       // allocate bits
            int last = 0;
            int n    = Count();

            while (n > 0)
            {
                last      += input.ReadVInt(state);
                bits[last] = input.ReadByte(state);
                n         -= BYTE_COUNTS[bits[last] & 0xFF];
            }
        }
        private int CheckValidFormat(IndexInput in_Renamed, IState state)
        {
            int format = in_Renamed.ReadInt(state);

            if (format > FORMAT_CURRENT)
            {
                throw new CorruptIndexException("Incompatible format version: " + format + " expected " + FORMAT_CURRENT + " or less");
            }
            return(format);
        }
Exemple #3
0
        /// <summary>Constructs a bit vector from the file <c>name</c> in Directory
        /// <c>d</c>, as written by the <see cref="Write" /> method.
        /// </summary>
        public BitVector(Directory d, System.String name, IState state)
        {
            IndexInput input = d.OpenInput(name, state);

            try
            {
                size = input.ReadInt(state);                 // read size
                if (size == -1)
                {
                    ReadDgaps(input, state);
                }
                else
                {
                    ReadBits(input, state);
                }
            }
            finally
            {
                input.Close();
            }
        }
 /// <summary>
 /// Sole constructor. </summary>
 public MonotonicBlockPackedReader(IndexInput @in, int packedIntsVersion, int blockSize, long valueCount, bool direct)
 {
     this.ValueCount = valueCount;
     BlockShift = PackedInts.CheckBlockSize(blockSize, AbstractBlockPackedWriter.MIN_BLOCK_SIZE, AbstractBlockPackedWriter.MAX_BLOCK_SIZE);
     BlockMask = blockSize - 1;
     int numBlocks = PackedInts.NumBlocks(valueCount, blockSize);
     MinValues = new long[numBlocks];
     Averages = new float[numBlocks];
     SubReaders = new PackedInts.Reader[numBlocks];
     for (int i = 0; i < numBlocks; ++i)
     {
         MinValues[i] = @in.ReadVLong();
         Averages[i] = Number.IntBitsToFloat(@in.ReadInt());
         int bitsPerValue = @in.ReadVInt();
         if (bitsPerValue > 64)
         {
             throw new Exception("Corrupted");
         }
         if (bitsPerValue == 0)
         {
             SubReaders[i] = new PackedInts.NullReader(blockSize);
         }
         else
         {
             int size = (int)Math.Min(blockSize, valueCount - (long)i * blockSize);
             if (direct)
             {
                 long pointer = @in.FilePointer;
                 SubReaders[i] = PackedInts.GetDirectReaderNoHeader(@in, PackedInts.Format.PACKED, packedIntsVersion, size, bitsPerValue);
                 @in.Seek(pointer + PackedInts.Format.PACKED.ByteCount(packedIntsVersion, size, bitsPerValue));
             }
             else
             {
                 SubReaders[i] = PackedInts.GetReaderNoHeader(@in, PackedInts.Format.PACKED, packedIntsVersion, size, bitsPerValue);
             }
         }
     }
 }
        private BinaryEntry ReadBinaryEntry(IndexInput meta)
        {
            var entry = new BinaryEntry();
            entry.offset = meta.ReadLong();
            entry.numBytes = meta.ReadInt();
            entry.count = meta.ReadInt();
            entry.missingOffset = meta.ReadLong();
            if (entry.missingOffset != -1)
            {
                entry.missingBytes = meta.ReadLong();
            }
            else
            {
                entry.missingBytes = 0;
            }

            return entry;
        }
        private static NumericEntry ReadNumericEntry(IndexInput meta)
        {
            var entry = new NumericEntry { offset = meta.ReadLong(), count = meta.ReadInt(), missingOffset = meta.ReadLong() };
            if (entry.missingOffset != -1)
            {
                entry.missingBytes = meta.ReadLong();
            }
            else
            {
                entry.missingBytes = 0;
            }
            entry.byteWidth = meta.ReadByte();

            return entry;
        }
        internal SegmentTermEnum(IndexInput i, FieldInfos fis, bool isi, IState state)
        {
            input         = i;
            fieldInfos    = fis;
            isIndex       = isi;
            maxSkipLevels = 1;             // use single-level skip lists for formats > -3

            int firstInt = input.ReadInt(state);

            if (firstInt >= 0)
            {
                // original-format file, without explicit format version number
                format = 0;
                size   = firstInt;

                // back-compatible settings
                indexInterval = 128;
                skipInterval  = System.Int32.MaxValue;                // switch off skipTo optimization
            }
            else
            {
                // we have a format version number
                format = firstInt;

                // check that it is a format we can understand
                if (format < TermInfosWriter.FORMAT_CURRENT)
                {
                    throw new CorruptIndexException("Unknown format version:" + format + " expected " + TermInfosWriter.FORMAT_CURRENT + " or higher");
                }

                size = input.ReadLong(state);                 // read the size

                if (format == -1)
                {
                    if (!isIndex)
                    {
                        indexInterval        = input.ReadInt(state);
                        formatM1SkipInterval = input.ReadInt(state);
                    }
                    // switch off skipTo optimization for file format prior to 1.4rc2 in order to avoid a bug in
                    // skipTo implementation of these versions
                    skipInterval = System.Int32.MaxValue;
                }
                else
                {
                    indexInterval = input.ReadInt(state);
                    skipInterval  = input.ReadInt(state);
                    if (format <= TermInfosWriter.FORMAT)
                    {
                        // this new format introduces multi-level skipping
                        maxSkipLevels = input.ReadInt(state);
                    }
                }
                System.Diagnostics.Debug.Assert(indexInterval > 0, "indexInterval=" + indexInterval + " is negative; must be > 0");
                System.Diagnostics.Debug.Assert(skipInterval > 0, "skipInterval=" + skipInterval + " is negative; must be > 0");
            }
            if (format > TermInfosWriter.FORMAT_VERSION_UTF8_LENGTH_IN_BYTES)
            {
                termBuffer.SetPreUTF8Strings();
                scanBuffer.SetPreUTF8Strings();
                prevBuffer.SetPreUTF8Strings();
            }
        }
Exemple #8
0
        /// <summary>Returns a <see cref="Status" /> instance detailing
        /// the state of the index.
        ///
        /// </summary>
        /// <param name="onlySegments">list of specific segment names to check
        ///
        /// <p/>As this method checks every byte in the specified
        /// segments, on a large index it can take quite a long
        /// time to run.
        ///
        /// <p/><b>WARNING</b>: make sure
        /// you only call this when the index is not opened by any
        /// writer.
        /// </param>
        public virtual Status CheckIndex_Renamed_Method(List <string> onlySegments, IState state)
        {
            System.Globalization.NumberFormatInfo nf = System.Globalization.CultureInfo.CurrentCulture.NumberFormat;
            SegmentInfos sis    = new SegmentInfos();
            Status       result = new Status();

            result.dir = dir;
            try
            {
                sis.Read(dir, state);
            }
            catch (System.Exception t)
            {
                Msg("ERROR: could not read any segments file in directory");
                result.missingSegments = true;
                if (infoStream != null)
                {
                    infoStream.WriteLine(t.StackTrace);
                }
                return(result);
            }

            int        numSegments      = sis.Count;
            var        segmentsFileName = sis.GetCurrentSegmentFileName();
            IndexInput input            = null;

            try
            {
                input = dir.OpenInput(segmentsFileName, state);
            }
            catch (System.Exception t)
            {
                Msg("ERROR: could not open segments file in directory");
                if (infoStream != null)
                {
                    infoStream.WriteLine(t.StackTrace);
                }
                result.cantOpenSegments = true;
                return(result);
            }
            int format = 0;

            try
            {
                format = input.ReadInt(state);
            }
            catch (System.Exception t)
            {
                Msg("ERROR: could not read segment file version in directory");
                if (infoStream != null)
                {
                    infoStream.WriteLine(t.StackTrace);
                }
                result.missingSegmentVersion = true;
                return(result);
            }
            finally
            {
                if (input != null)
                {
                    input.Close();
                }
            }

            System.String sFormat = "";
            bool          skip    = false;

            if (format == SegmentInfos.FORMAT)
            {
                sFormat = "FORMAT [Lucene Pre-2.1]";
            }
            if (format == SegmentInfos.FORMAT_LOCKLESS)
            {
                sFormat = "FORMAT_LOCKLESS [Lucene 2.1]";
            }
            else if (format == SegmentInfos.FORMAT_SINGLE_NORM_FILE)
            {
                sFormat = "FORMAT_SINGLE_NORM_FILE [Lucene 2.2]";
            }
            else if (format == SegmentInfos.FORMAT_SHARED_DOC_STORE)
            {
                sFormat = "FORMAT_SHARED_DOC_STORE [Lucene 2.3]";
            }
            else
            {
                if (format == SegmentInfos.FORMAT_CHECKSUM)
                {
                    sFormat = "FORMAT_CHECKSUM [Lucene 2.4]";
                }
                else if (format == SegmentInfos.FORMAT_DEL_COUNT)
                {
                    sFormat = "FORMAT_DEL_COUNT [Lucene 2.4]";
                }
                else if (format == SegmentInfos.FORMAT_HAS_PROX)
                {
                    sFormat = "FORMAT_HAS_PROX [Lucene 2.4]";
                }
                else if (format == SegmentInfos.FORMAT_USER_DATA)
                {
                    sFormat = "FORMAT_USER_DATA [Lucene 2.9]";
                }
                else if (format == SegmentInfos.FORMAT_DIAGNOSTICS)
                {
                    sFormat = "FORMAT_DIAGNOSTICS [Lucene 2.9]";
                }
                else if (format < SegmentInfos.CURRENT_FORMAT)
                {
                    sFormat = "int=" + format + " [newer version of Lucene than this tool]";
                    skip    = true;
                }
                else
                {
                    sFormat = format + " [Lucene 1.3 or prior]";
                }
            }

            result.segmentsFileName = segmentsFileName;
            result.numSegments      = numSegments;
            result.segmentFormat    = sFormat;
            result.userData         = sis.UserData;
            System.String userDataString;
            if (sis.UserData.Count > 0)
            {
                userDataString = " userData=" + CollectionsHelper.CollectionToString(sis.UserData);
            }
            else
            {
                userDataString = "";
            }

            Msg("Segments file=" + segmentsFileName + " numSegments=" + numSegments + " version=" + sFormat + userDataString);

            if (onlySegments != null)
            {
                result.partial = true;
                if (infoStream != null)
                {
                    infoStream.Write("\nChecking only these segments:");
                }
                foreach (string s in onlySegments)
                {
                    if (infoStream != null)
                    {
                        infoStream.Write(" " + s);
                    }
                }
                result.segmentsChecked.AddRange(onlySegments);
                Msg(":");
            }

            if (skip)
            {
                Msg("\nERROR: this index appears to be created by a newer version of Lucene than this tool was compiled on; please re-compile this tool on the matching version of Lucene; exiting");
                result.toolOutOfDate = true;
                return(result);
            }


            result.newSegments = (SegmentInfos)sis.Clone();
            result.newSegments.Clear();

            for (int i = 0; i < numSegments; i++)
            {
                SegmentInfo info = sis.Info(i);
                if (onlySegments != null && !onlySegments.Contains(info.name))
                {
                    continue;
                }
                var segInfoStat = new Status.SegmentInfoStatus();
                result.segmentInfos.Add(segInfoStat);
                Msg("  " + (1 + i) + " of " + numSegments + ": name=" + info.name + " docCount=" + info.docCount);
                segInfoStat.name     = info.name;
                segInfoStat.docCount = info.docCount;

                int toLoseDocCount = info.docCount;

                SegmentReader reader = null;

                try
                {
                    Msg("    compound=" + info.GetUseCompoundFile(state));
                    segInfoStat.compound = info.GetUseCompoundFile(state);
                    Msg("    hasProx=" + info.HasProx);
                    segInfoStat.hasProx = info.HasProx;
                    Msg("    numFiles=" + info.Files(state).Count);
                    segInfoStat.numFiles = info.Files(state).Count;
                    Msg(System.String.Format(nf, "    size (MB)={0:f}", new System.Object[] { (info.SizeInBytes(state) / (1024.0 * 1024.0)) }));
                    segInfoStat.sizeMB = info.SizeInBytes(state) / (1024.0 * 1024.0);
                    IDictionary <string, string> diagnostics = info.Diagnostics;
                    segInfoStat.diagnostics = diagnostics;
                    if (diagnostics.Count > 0)
                    {
                        Msg("    diagnostics = " + CollectionsHelper.CollectionToString(diagnostics));
                    }

                    int docStoreOffset = info.DocStoreOffset;
                    if (docStoreOffset != -1)
                    {
                        Msg("    docStoreOffset=" + docStoreOffset);
                        segInfoStat.docStoreOffset = docStoreOffset;
                        Msg("    docStoreSegment=" + info.DocStoreSegment);
                        segInfoStat.docStoreSegment = info.DocStoreSegment;
                        Msg("    docStoreIsCompoundFile=" + info.DocStoreIsCompoundFile);
                        segInfoStat.docStoreCompoundFile = info.DocStoreIsCompoundFile;
                    }
                    System.String delFileName = info.GetDelFileName();
                    if (delFileName == null)
                    {
                        Msg("    no deletions");
                        segInfoStat.hasDeletions = false;
                    }
                    else
                    {
                        Msg("    has deletions [delFileName=" + delFileName + "]");
                        segInfoStat.hasDeletions      = true;
                        segInfoStat.deletionsFileName = delFileName;
                    }
                    if (infoStream != null)
                    {
                        infoStream.Write("    test: open reader.........");
                    }
                    reader = SegmentReader.Get(true, info, IndexReader.DEFAULT_TERMS_INDEX_DIVISOR, state);

                    segInfoStat.openReaderPassed = true;

                    int numDocs = reader.NumDocs();
                    toLoseDocCount = numDocs;
                    if (reader.HasDeletions)
                    {
                        if (reader.deletedDocs.Count() != info.GetDelCount(state))
                        {
                            throw new System.SystemException("delete count mismatch: info=" + info.GetDelCount(state) + " vs deletedDocs.count()=" + reader.deletedDocs.Count());
                        }
                        if (reader.deletedDocs.Count() > reader.MaxDoc)
                        {
                            throw new System.SystemException("too many deleted docs: MaxDoc=" + reader.MaxDoc + " vs deletedDocs.count()=" + reader.deletedDocs.Count());
                        }
                        if (info.docCount - numDocs != info.GetDelCount(state))
                        {
                            throw new System.SystemException("delete count mismatch: info=" + info.GetDelCount(state) + " vs reader=" + (info.docCount - numDocs));
                        }
                        segInfoStat.numDeleted = info.docCount - numDocs;
                        Msg("OK [" + (segInfoStat.numDeleted) + " deleted docs]");
                    }
                    else
                    {
                        if (info.GetDelCount(state) != 0)
                        {
                            throw new System.SystemException("delete count mismatch: info=" + info.GetDelCount(state) + " vs reader=" + (info.docCount - numDocs));
                        }
                        Msg("OK");
                    }
                    if (reader.MaxDoc != info.docCount)
                    {
                        throw new System.SystemException("SegmentReader.MaxDoc " + reader.MaxDoc + " != SegmentInfos.docCount " + info.docCount);
                    }

                    // Test getFieldNames()
                    if (infoStream != null)
                    {
                        infoStream.Write("    test: fields..............");
                    }
                    ICollection <string> fieldNames = reader.GetFieldNames(IndexReader.FieldOption.ALL);
                    Msg("OK [" + fieldNames.Count + " fields]");
                    segInfoStat.numFields = fieldNames.Count;

                    // Test Field Norms
                    segInfoStat.fieldNormStatus = TestFieldNorms(fieldNames, reader, state);

                    // Test the Term Index
                    segInfoStat.termIndexStatus = TestTermIndex(info, reader, state);

                    // Test Stored Fields
                    segInfoStat.storedFieldStatus = TestStoredFields(info, reader, nf, state);

                    // Test Term Vectors
                    segInfoStat.termVectorStatus = TestTermVectors(info, reader, nf, state);

                    // Rethrow the first exception we encountered
                    //  This will cause stats for failed segments to be incremented properly
                    if (segInfoStat.fieldNormStatus.error != null)
                    {
                        throw new SystemException("Field Norm test failed");
                    }
                    else if (segInfoStat.termIndexStatus.error != null)
                    {
                        throw new SystemException("Term Index test failed");
                    }
                    else if (segInfoStat.storedFieldStatus.error != null)
                    {
                        throw new SystemException("Stored Field test failed");
                    }
                    else if (segInfoStat.termVectorStatus.error != null)
                    {
                        throw new System.SystemException("Term Vector test failed");
                    }

                    Msg("");
                }
                catch (System.Exception t)
                {
                    Msg("FAILED");
                    const string comment = "fixIndex() would remove reference to this segment";
                    Msg("    WARNING: " + comment + "; full exception:");
                    if (infoStream != null)
                    {
                        infoStream.WriteLine(t.StackTrace);
                    }
                    Msg("");
                    result.totLoseDocCount += toLoseDocCount;
                    result.numBadSegments++;
                    continue;
                }
                finally
                {
                    if (reader != null)
                    {
                        reader.Close();
                    }
                }

                // Keeper
                result.newSegments.Add((SegmentInfo)info.Clone());
            }

            if (0 == result.numBadSegments)
            {
                result.clean = true;
                Msg("No problems were detected with this index.\n");
            }
            else
            {
                Msg("WARNING: " + result.numBadSegments + " broken segments (containing " + result.totLoseDocCount + " documents) detected");
            }

            return(result);
        }
Exemple #9
0
        /// <summary> Construct a new SegmentInfo instance by reading a
        /// previously saved SegmentInfo from input.
        ///
        /// </summary>
        /// <param name="dir">directory to load from
        /// </param>
        /// <param name="format">format of the segments info file
        /// </param>
        /// <param name="input">input handle to read segment info from
        /// </param>
        internal SegmentInfo(Directory dir, int format, IndexInput input, IState state)
        {
            this.dir = dir;
            name     = input.ReadString(state);
            docCount = input.ReadInt(state);
            if (format <= SegmentInfos.FORMAT_LOCKLESS)
            {
                delGen = input.ReadLong(state);
                if (format <= SegmentInfos.FORMAT_SHARED_DOC_STORE)
                {
                    docStoreOffset = input.ReadInt(state);
                    if (docStoreOffset != -1)
                    {
                        docStoreSegment        = input.ReadString(state);
                        docStoreIsCompoundFile = (1 == input.ReadByte(state));
                    }
                    else
                    {
                        docStoreSegment        = name;
                        docStoreIsCompoundFile = false;
                    }
                }
                else
                {
                    docStoreOffset         = -1;
                    docStoreSegment        = name;
                    docStoreIsCompoundFile = false;
                }
                if (format <= SegmentInfos.FORMAT_SINGLE_NORM_FILE)
                {
                    hasSingleNormFile = (1 == input.ReadByte(state));
                }
                else
                {
                    hasSingleNormFile = false;
                }
                int numNormGen = input.ReadInt(state);
                if (numNormGen == NO)
                {
                    normGen = null;
                }
                else
                {
                    normGen = new long[numNormGen];
                    for (int j = 0; j < numNormGen; j++)
                    {
                        normGen[j] = input.ReadLong(state);
                    }
                }
                isCompoundFile = (sbyte)input.ReadByte(state);
                preLockless    = (isCompoundFile == CHECK_DIR);
                if (format <= SegmentInfos.FORMAT_DEL_COUNT)
                {
                    delCount = input.ReadInt(state);
                    System.Diagnostics.Debug.Assert(delCount <= docCount);
                }
                else
                {
                    delCount = -1;
                }
                if (format <= SegmentInfos.FORMAT_HAS_PROX)
                {
                    hasProx = input.ReadByte(state) == 1;
                }
                else
                {
                    hasProx = true;
                }

                if (format <= SegmentInfos.FORMAT_DIAGNOSTICS)
                {
                    diagnostics = input.ReadStringStringMap(state);
                }
                else
                {
                    diagnostics = new Dictionary <string, string>();
                }
            }
            else
            {
                delGen                 = CHECK_DIR;
                normGen                = null;
                isCompoundFile         = (sbyte)(CHECK_DIR);
                preLockless            = true;
                hasSingleNormFile      = false;
                docStoreOffset         = -1;
                docStoreIsCompoundFile = false;
                docStoreSegment        = null;
                delCount               = -1;
                hasProx                = true;
                diagnostics            = new Dictionary <string, string>();
            }
        }
 protected internal VariableIntBlockIndexInput(IndexInput input)
 {
     this.input = input;
     maxBlockSize = input.ReadInt();
 }
Exemple #11
0
        private static void ValidateFooter(IndexInput @in)
        {
            int magic = @in.ReadInt();
            if (magic != FOOTER_MAGIC)
            {
                throw new System.IO.IOException("codec footer mismatch: actual footer=" + magic + " vs expected footer=" + FOOTER_MAGIC + " (resource: " + @in + ")");
            }

            int algorithmID = @in.ReadInt();
            if (algorithmID != 0)
            {
                throw new System.IO.IOException("codec footer mismatch: unknown algorithmID: " + algorithmID);
            }
        }
Exemple #12
0
 /// <summary>Read as a bit set </summary>
 private void  ReadBits(IndexInput input, IState state)
 {
     count = input.ReadInt(state);             // read count
     bits  = new byte[(size >> 3) + 1];        // allocate bits
     input.ReadBytes(bits, 0, bits.Length, state);
 }
Exemple #13
0
        internal FieldsReader(Directory d, System.String segment, FieldInfos fn, int readBufferSize, int docStoreOffset, int size, IState state)
        {
            bool success = false;

            isOriginal = true;
            try
            {
                fieldInfos = fn;

                cloneableFieldsStream = d.OpenInput(segment + "." + IndexFileNames.FIELDS_EXTENSION, readBufferSize, state);
                cloneableIndexStream  = d.OpenInput(segment + "." + IndexFileNames.FIELDS_INDEX_EXTENSION, readBufferSize, state);

                // First version of fdx did not include a format
                // header, but, the first int will always be 0 in that
                // case
                int firstInt = cloneableIndexStream.ReadInt(state);
                format = firstInt == 0 ? 0 : firstInt;

                if (format > FieldsWriter.FORMAT_CURRENT)
                {
                    throw new CorruptIndexException("Incompatible format version: " + format + " expected " + FieldsWriter.FORMAT_CURRENT + " or lower");
                }

                formatSize = format > FieldsWriter.FORMAT ? 4 : 0;

                if (format < FieldsWriter.FORMAT_VERSION_UTF8_LENGTH_IN_BYTES)
                {
                    cloneableFieldsStream.SetModifiedUTF8StringsMode();
                }

                fieldsStream = (IndexInput)cloneableFieldsStream.Clone(state);

                long indexSize = cloneableIndexStream.Length(state) - formatSize;

                if (docStoreOffset != -1)
                {
                    // We read only a slice out of this shared fields file
                    this.docStoreOffset = docStoreOffset;
                    this.size           = size;

                    // Verify the file is long enough to hold all of our
                    // docs
                    System.Diagnostics.Debug.Assert(((int)(indexSize / 8)) >= size + this.docStoreOffset, "indexSize=" + indexSize + " size=" + size + " docStoreOffset=" + docStoreOffset);
                }
                else
                {
                    this.docStoreOffset = 0;
                    this.size           = (int)(indexSize >> 3);
                }

                indexStream  = (IndexInput)cloneableIndexStream.Clone(state);
                numTotalDocs = (int)(indexSize >> 3);
                success      = true;
            }
            finally
            {
                // With lock-less commits, it's entirely possible (and
                // fine) to hit a FileNotFound exception above. In
                // this case, we want to explicitly close any subset
                // of things that were opened so that we don't have to
                // wait for a GC to do so.
                if (!success)
                {
                    Dispose();
                }
            }
        }
Exemple #14
0
            public System.Object Run(IndexCommit commit, IState state)
            {
                if (commit != null)
                {
                    if (directory != commit.Directory)
                    {
                        throw new System.IO.IOException("the specified commit does not match the specified Directory");
                    }
                    return(DoBody(commit.SegmentsFileName, state));
                }

                System.String segmentFileName   = null;
                long          lastGen           = -1;
                long          gen               = 0;
                int           genLookaheadCount = 0;

                System.IO.IOException exc = null;
                bool retry = false;

                int method = 0;

                // Loop until we succeed in calling doBody() without
                // hitting an IOException.  An IOException most likely
                // means a commit was in process and has finished, in
                // the time it took us to load the now-old infos files
                // (and segments files).  It's also possible it's a
                // true error (corrupt index).  To distinguish these,
                // on each retry we must see "forward progress" on
                // which generation we are trying to load.  If we
                // don't, then the original error is real and we throw
                // it.

                // We have three methods for determining the current
                // generation.  We try the first two in parallel, and
                // fall back to the third when necessary.

                while (true)
                {
                    if (0 == method)
                    {
                        // Method 1: list the directory and use the highest
                        // segments_N file.  This method works well as long
                        // as there is no stale caching on the directory
                        // contents (NOTE: NFS clients often have such stale
                        // caching):
                        System.String[] files = null;

                        long genA = -1;

                        files = directory.ListAll(state);

                        if (files != null)
                        {
                            genA = Lucene.Net.Index.SegmentInfos.GetCurrentSegmentGeneration(files);
                        }

                        Lucene.Net.Index.SegmentInfos.Message("directory listing genA=" + genA);

                        // Method 2: open segments.gen and read its
                        // contents.  Then we take the larger of the two
                        // gens.  This way, if either approach is hitting
                        // a stale cache (NFS) we have a better chance of
                        // getting the right generation.
                        long genB = -1;
                        for (int i = 0; i < Lucene.Net.Index.SegmentInfos.defaultGenFileRetryCount; i++)
                        {
                            IndexInput genInput = null;
                            try
                            {
                                genInput = directory.OpenInput(IndexFileNames.SEGMENTS_GEN, state);
                            }
                            catch (System.IO.FileNotFoundException e)
                            {
                                Lucene.Net.Index.SegmentInfos.Message("segments.gen open: FileNotFoundException " + e);
                                break;
                            }
                            catch (System.IO.IOException e)
                            {
                                Lucene.Net.Index.SegmentInfos.Message("segments.gen open: IOException " + e);
                            }

                            if (genInput != null)
                            {
                                try
                                {
                                    int version = genInput.ReadInt(state);
                                    if (version == Lucene.Net.Index.SegmentInfos.FORMAT_LOCKLESS)
                                    {
                                        long gen0 = genInput.ReadLong(state);
                                        long gen1 = genInput.ReadLong(state);
                                        Lucene.Net.Index.SegmentInfos.Message("fallback check: " + gen0 + "; " + gen1);
                                        if (gen0 == gen1)
                                        {
                                            // The file is consistent.
                                            genB = gen0;
                                            break;
                                        }
                                    }
                                }
                                catch (System.IO.IOException)
                                {
                                    // will retry
                                }
                                finally
                                {
                                    genInput.Close();
                                }
                            }

                            System.Threading.Thread.Sleep(new TimeSpan((System.Int64) 10000 * Lucene.Net.Index.SegmentInfos.defaultGenFileRetryPauseMsec));
                        }

                        Lucene.Net.Index.SegmentInfos.Message(IndexFileNames.SEGMENTS_GEN + " check: genB=" + genB);

                        // Pick the larger of the two gen's:
                        if (genA > genB)
                        {
                            gen = genA;
                        }
                        else
                        {
                            gen = genB;
                        }

                        if (gen == -1)
                        {
                            throw new System.IO.FileNotFoundException("no segments* file found in " + directory + ": files:" + string.Join(" ", files));
                        }
                    }

                    // Third method (fallback if first & second methods
                    // are not reliable): since both directory cache and
                    // file contents cache seem to be stale, just
                    // advance the generation.
                    if (1 == method || (0 == method && lastGen == gen && retry))
                    {
                        method = 1;

                        if (genLookaheadCount < Lucene.Net.Index.SegmentInfos.defaultGenLookaheadCount)
                        {
                            gen++;
                            genLookaheadCount++;
                            Lucene.Net.Index.SegmentInfos.Message("look ahead increment gen to " + gen);
                        }
                    }

                    if (lastGen == gen)
                    {
                        // This means we're about to try the same
                        // segments_N last tried.  This is allowed,
                        // exactly once, because writer could have been in
                        // the process of writing segments_N last time.

                        if (retry)
                        {
                            // OK, we've tried the same segments_N file
                            // twice in a row, so this must be a real
                            // error.  We throw the original exception we
                            // got.
                            throw exc;
                        }

                        retry = true;
                    }
                    else if (0 == method)
                    {
                        // Segment file has advanced since our last loop, so
                        // reset retry:
                        retry = false;
                    }

                    lastGen = gen;

                    segmentFileName = IndexFileNames.FileNameFromGeneration(IndexFileNames.SEGMENTS, "", gen);

                    try
                    {
                        System.Object v = DoBody(segmentFileName, state);
                        Lucene.Net.Index.SegmentInfos.Message("success on " + segmentFileName);

                        return(v);
                    }
                    catch (System.IO.IOException err)
                    {
                        // Save the original root cause:
                        if (exc == null)
                        {
                            exc = err;
                        }

                        Lucene.Net.Index.SegmentInfos.Message("primary Exception on '" + segmentFileName + "': " + err + "'; will retry: retry=" + retry + "; gen = " + gen);

                        if (!retry && gen > 1)
                        {
                            // This is our first time trying this segments
                            // file (because retry is false), and, there is
                            // possibly a segments_(N-1) (because gen > 1).
                            // So, check if the segments_(N-1) exists and
                            // try it if so:
                            System.String prevSegmentFileName = IndexFileNames.FileNameFromGeneration(IndexFileNames.SEGMENTS, "", gen - 1);

                            bool prevExists;
                            prevExists = directory.FileExists(prevSegmentFileName, state);

                            if (prevExists)
                            {
                                Lucene.Net.Index.SegmentInfos.Message("fallback to prior segment file '" + prevSegmentFileName + "'");
                                try
                                {
                                    System.Object v = DoBody(prevSegmentFileName, state);
                                    if (exc != null)
                                    {
                                        Lucene.Net.Index.SegmentInfos.Message("success on fallback " + prevSegmentFileName);
                                    }
                                    return(v);
                                }
                                catch (System.IO.IOException err2)
                                {
                                    Lucene.Net.Index.SegmentInfos.Message("secondary Exception on '" + prevSegmentFileName + "': " + err2 + "'; will retry");
                                }
                            }
                        }
                    }
                }
            }
 public override int ReadInt()
 {
     EnsureOpen();
     return(@delegate.ReadInt());
 }