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## org.apache.lucene.index
Class SegmentInfos

    java.lang.Object
      org.apache.lucene.index.SegmentInfos

All Implemented Interfaces:
  Cloneable, Iterable<SegmentInfo>

    public final class SegmentInfos

extends Object
implements Cloneable, Iterable<SegmentInfo>

A collection of segmentInfo objects with methods for operating on those segments in relation to the file system.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary
`static class` | `SegmentInfos.FindSegmentsFile` Utility class for executing code that needs to do something with the current segments file.

Field Summary
`int` | `counter`
`static int` | `CURRENT_FORMAT`
`static int` | `FORMAT` The file format version, a negative number.
`static int` | `FORMAT_3_1` Each segment records the Lucene version that created it.
`static int` | `FORMAT_CHECKSUM` This format adds a checksum at the end of the file to ensure all bytes were successfully written.
`static int` | `FORMAT_DEL_COUNT` This format adds the deletion count for each segment.
`static int` | `FORMAT_DIAGNOSTICS` This format adds optional per-segment String diagnostics storage, and switches userData to Map
`static int` | `FORMAT_HAS_PROX` This format adds the boolean hasProx to record if any fields in the segment store prox information (ie, have omitTermFreqAndPositions==false)
`static int` | `FORMAT_HAS_VECTORS` Each segment records whether it has term vectors
`static int` | `FORMAT_LOCKLESS` This format adds details used for lockless commits.
`static int` | `FORMAT_MAXIMUM`
`static int` | `FORMAT_MINIMUM`
`static int` | `FORMAT_SHARED_DOC_STORE` This format allows multiple segments to share a single vectors and stored fields file.
`static int` | `FORMAT_SINGLE_NORM_FILE` This format adds a "hasSingleNormFile" flag into each segment info.
`static int` | `FORMAT_USER_DATA` This format adds optional commit userData (String) storage.

Constructor Summary
`SegmentInfos()`

Method Summary
`void` | `add(SegmentInfo si)`
`void` | `addAll(Iterable<SegmentInfo> sis)`
`List<SegmentInfo>` | `asList()` Returns all contained segments as an unmodifiable `List` view.
`Set<SegmentInfo>` | `asSet()` Returns all contained segments as an unmodifiable `Set` view.
`void` | `changed()` Call this before committing if changes have been made to the segments.
`void` | `clear()`
`Object` | `clone()` Returns a copy of this instance, also copying each SegmentInfo.
`boolean` | `contains(SegmentInfo si)`
`Collection<String>` | `files(Directory dir, boolean includeSegmentsFile)` Returns all file names referenced by SegmentInfo instances matching the provided Directory (ie files associated with any "external" segments are skipped).
`static long` | `generationFromSegmentsFileName(String fileName)` Parse the generation off the segments file name and return it.
`static int` | `getDefaultGenLookahedCount()`
`int` | `getFormat()`
`long` | `getGeneration()`
`static PrintStream` | `getInfoStream()`
`static long` | `getLastCommitGeneration(Directory directory)` Get the generation of the most recent commit to the index in this directory (N in the segments_N file).
`static long` | `getLastCommitGeneration(String[] files)` Get the generation of the most recent commit to the list of index files (N in the segments_N file).
`static String` | `getLastCommitSegmentsFileName(Directory directory)` Get the filename of the segments_N file for the most recent commit to the index in this Directory.
`static String` | `getLastCommitSegmentsFileName(String[] files)` Get the filename of the segments_N file for the most recent commit in the list of index files.
`long` | `getLastGeneration()`
`String` | `getNextSegmentFileName()` Get the next segments_N filename that will be written.
`String` | `getSegmentsFileName()` Get the segments_N filename in use by this segment infos.
`Map<String,String>` | `getUserData()`
`long` | `getVersion()` version number when this SegmentInfos was generated.
`int` | `indexOf(SegmentInfo si)`
`SegmentInfo` | `info(int i)`
`Iterator<SegmentInfo>` | `iterator()` Returns an unmodifiable `Iterator` of contained segments in order.
`void` | `pruneDeletedSegments()` Prunes any segment whose docs are all deleted.
`SegmentInfos` | `range(int first, int last)` Deprecated. use `asList().subList(first, last)` instead.
`void` | `read(Directory directory)` This version of read uses the retry logic (for lock-less commits) to find the right segments file to load.
`void` | `read(Directory directory, String segmentFileName)` Read a particular segmentFileName.
`static long` | `readCurrentVersion(Directory directory)` Deprecated. Load the SegmentInfos and then call `getVersion()`.
`void` | `remove(int index)`
`void` | `remove(SegmentInfo si)`
`static void` | `setDefaultGenLookaheadCount(int count)` Advanced: set how many times to try incrementing the gen when loading the segments file.
`void` | `setFormat(int format)`
`static void` | `setInfoStream(PrintStream infoStream)` If non-null, information about retries when loading the segments file will be printed to this.
`int` | `size()`
`String` | `toString(Directory directory)`
`int` | `totalDocCount()` Returns sum of all segment's docCounts.

Methods inherited from class java.lang.Object
`equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### FORMAT

    public static final int FORMAT

  The file format version, a negative number.

  See Also:
    Constant Field Values

### FORMAT_LOCKLESS

    public static final int FORMAT_LOCKLESS

  This format adds details used for lockless commits. It differs slightly from the previous format in that file names are never re-used (write once). Instead, each file is written to the next generation. For example, segments_1, segments_2, etc. This allows us to not use a commit lock. See file formats for details.

  See Also:
    Constant Field Values

### FORMAT_SINGLE_NORM_FILE

    public static final int FORMAT_SINGLE_NORM_FILE

  This format adds a "hasSingleNormFile" flag into each segment info. See LUCENE-756 for details.

  See Also:
    Constant Field Values

### FORMAT_SHARED_DOC_STORE

    public static final int FORMAT_SHARED_DOC_STORE

  This format allows multiple segments to share a single vectors and stored fields file.

  See Also:
    Constant Field Values

### FORMAT_CHECKSUM

    public static final int FORMAT_CHECKSUM

  This format adds a checksum at the end of the file to ensure all bytes were successfully written.

  See Also:
    Constant Field Values

### FORMAT_DEL_COUNT

    public static final int FORMAT_DEL_COUNT

  This format adds the deletion count for each segment. This way IndexWriter can efficiently report numDocs().

  See Also:
    Constant Field Values

### FORMAT_HAS_PROX

    public static final int FORMAT_HAS_PROX

  This format adds the boolean hasProx to record if any fields in the segment store prox information (ie, have omitTermFreqAndPositions==false)

  See Also:
    Constant Field Values

### FORMAT_USER_DATA

    public static final int FORMAT_USER_DATA

  This format adds optional commit userData (String) storage.

  See Also:
    Constant Field Values

### FORMAT_DIAGNOSTICS

    public static final int FORMAT_DIAGNOSTICS

  This format adds optional per-segment String diagnostics storage, and switches userData to Map

  See Also:
    Constant Field Values

### FORMAT_HAS_VECTORS

    public static final int FORMAT_HAS_VECTORS

  Each segment records whether it has term vectors

  See Also:
    Constant Field Values

### FORMAT_3_1

    public static final int FORMAT_3_1

  Each segment records the Lucene version that created it.

  See Also:
    Constant Field Values

### CURRENT_FORMAT

    public static final int CURRENT_FORMAT

See Also:
  Constant Field Values

### FORMAT_MINIMUM

    public static final int FORMAT_MINIMUM

See Also:
  Constant Field Values

### FORMAT_MAXIMUM

    public static final int FORMAT_MAXIMUM

See Also:
  Constant Field Values

### counter

    public int counter

Constructor Detail

### SegmentInfos

    public SegmentInfos()

Method Detail

### setFormat

    public void setFormat(int format)

### getFormat

    public int getFormat()

### info

    public SegmentInfo info(int i)

### getLastCommitGeneration

    public static long getLastCommitGeneration(String[] files)

  Get the generation of the most recent commit to the list of index files (N in the segments_N file).

  Parameters:
    `files` - -- array of file names to check

### getLastCommitGeneration

    public static long getLastCommitGeneration(Directory directory)
                                        throws IOException

  Get the generation of the most recent commit to the index in this directory (N in the segments_N file).

  Parameters:
    `directory` - -- directory to search for the latest segments_N file
  Throws:
    `IOException`

### getLastCommitSegmentsFileName

    public static String getLastCommitSegmentsFileName(String[] files)
                                                throws IOException

  Get the filename of the segments_N file for the most recent commit in the list of index files.

  Parameters:
    `files` - -- array of file names to check
  Throws:
    `IOException`

### getLastCommitSegmentsFileName

    public static String getLastCommitSegmentsFileName(Directory directory)
                                                throws IOException

  Get the filename of the segments_N file for the most recent commit to the index in this Directory.

  Parameters:
    `directory` - -- directory to search for the latest segments_N file
  Throws:
    `IOException`

### getSegmentsFileName

    public String getSegmentsFileName()

  Get the segments_N filename in use by this segment infos.

### generationFromSegmentsFileName

    public static long generationFromSegmentsFileName(String fileName)

  Parse the generation off the segments file name and return it.

### getNextSegmentFileName

    public String getNextSegmentFileName()

  Get the next segments_N filename that will be written.

### read

    public final void read(Directory directory,
                           String segmentFileName)
                    throws CorruptIndexException,
                           IOException

  Read a particular segmentFileName. Note that this may throw an IOException if a commit is in process.

  Parameters:
    `directory` - -- directory containing the segments file
    `segmentFileName` - -- segment file to load
  Throws:
    `CorruptIndexException` - if the index is corrupt
    `IOException` - if there is a low-level IO error

### read

    public final void read(Directory directory)
                    throws CorruptIndexException,
                           IOException

  This version of read uses the retry logic (for lock-less commits) to find the right segments file to load.

  Throws:
    `CorruptIndexException` - if the index is corrupt
    `IOException` - if there is a low-level IO error

### pruneDeletedSegments

    public void pruneDeletedSegments()
                              throws IOException

  Prunes any segment whose docs are all deleted.

  Throws:
    `IOException`

### clone

    public Object clone()

  Returns a copy of this instance, also copying each SegmentInfo.

  Overrides:
    `clone` in class `Object`

### getVersion

    public long getVersion()

  version number when this SegmentInfos was generated.

### getGeneration

    public long getGeneration()

### getLastGeneration

    public long getLastGeneration()

### readCurrentVersion

    @Deprecated
    public static long readCurrentVersion(Directory directory)
                                   throws CorruptIndexException,
                                          IOException

  Deprecated. Load the SegmentInfos and then call `getVersion()`.

  Current version number from segments file.

  Throws:
    `CorruptIndexException` - if the index is corrupt
    `IOException` - if there is a low-level IO error

### setInfoStream

    public static void setInfoStream(PrintStream infoStream)

  If non-null, information about retries when loading the segments file will be printed to this.

### setDefaultGenLookaheadCount

    public static void setDefaultGenLookaheadCount(int count)

  Advanced: set how many times to try incrementing the gen when loading the segments file. This only runs if the primary (listing directory) and secondary (opening segments.gen file) methods fail to find the segments file.

  WARNING: This API is experimental and might change in incompatible ways in the next release.

### getDefaultGenLookahedCount

    public static int getDefaultGenLookahedCount()

  See Also:
    `setDefaultGenLookaheadCount(int)`
  WARNING: This API is experimental and might change in incompatible ways in the next release.

### getInfoStream

    public static PrintStream getInfoStream()

  See Also:
    `setInfoStream(java.io.PrintStream)`

### range

    @Deprecated
    public SegmentInfos range(int first,
                                         int last)

  Deprecated. use `asList().subList(first, last)` instead.

  Returns a new SegmentInfos containing the SegmentInfo instances in the specified range first (inclusive) to last (exclusive), so total number of segments returned is last-first.

### files

    public Collection<String> files(Directory dir,
                                    boolean includeSegmentsFile)
                             throws IOException

  Returns all file names referenced by SegmentInfo instances matching the provided Directory (ie files associated with any "external" segments are skipped). The returned collection is recomputed on each invocation.

  Throws:
    `IOException`

### toString

    public String toString(Directory directory)

### getUserData

    public Map<String,String> getUserData()

### totalDocCount

    public int totalDocCount()

  Returns sum of all segment's docCounts. Note that this does not include deletions

### changed

    public void changed()

  Call this before committing if changes have been made to the segments.

### iterator

    public Iterator<SegmentInfo> iterator()

  Returns an unmodifiable `Iterator` of contained segments in order.

  Specified by:
    `iterator` in interface `Iterable<SegmentInfo>`

### asList

    public List<SegmentInfo> asList()

  Returns all contained segments as an unmodifiable `List` view.

### asSet

    public Set<SegmentInfo> asSet()

  Returns all contained segments as an unmodifiable `Set` view. The iterator is not sorted, use `List` view or `iterator()` to get all segments in order.

### size

    public int size()

### add

    public void add(SegmentInfo si)

### addAll

    public void addAll(Iterable<SegmentInfo> sis)

### clear

    public void clear()

### remove

    public void remove(SegmentInfo si)

### remove

    public void remove(int index)

### contains

    public boolean contains(SegmentInfo si)

### indexOf

    public int indexOf(SegmentInfo si)

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