## Uses of Class
org.apache.lucene.index.AtomicReader

- Packages that use AtomicReader
  Package | Description
  --- | ---
  org.apache.lucene.index | Code to maintain and access indices.
  org.apache.lucene.search | Code to search indices.

- - ### Uses of AtomicReader in org.apache.lucene.index

    Subclasses of AtomicReader in org.apache.lucene.index
    Modifier and Type | Class and Description
    --- | ---
    `class` | `FilterAtomicReader` A `FilterAtomicReader` contains another AtomicReader, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality.
    `class` | `ParallelAtomicReader` An `AtomicReader` which reads multiple, parallel indexes.
    `class` | `SegmentReader` IndexReader implementation over a single segment.
    `class` | `SlowCompositeReaderWrapper` This class forces a composite reader (eg a `MultiReader` or `DirectoryReader`) to emulate an atomic reader.

    Fields in org.apache.lucene.index declared as AtomicReader
    Modifier and Type | Field and Description
    --- | ---
    `protected AtomicReader` | FilterAtomicReader.`in` The underlying AtomicReader.

    Fields in org.apache.lucene.index with type parameters of type AtomicReader
    Modifier and Type | Field and Description
    --- | ---
    `List<AtomicReader>` | MergeState.`readers` Readers being merged.

    Methods in org.apache.lucene.index that return AtomicReader
    Modifier and Type | Method and Description
    --- | ---
    `AtomicReader` | AtomicReaderContext.`reader()`
    `static AtomicReader` | SlowCompositeReaderWrapper.`wrap(IndexReader reader)` This method is sugar for getting an `AtomicReader` from an `IndexReader` of any kind.

    Methods in org.apache.lucene.index with parameters of type AtomicReader
    Modifier and Type | Method and Description
    --- | ---
    `static MergeState.DocMap` | MergeState.DocMap.`build(AtomicReader reader)` Creates a `MergeState.DocMap` instance appropriate for this reader.
    `TermsEnum` | DocTermOrds.`getOrdTermsEnum(AtomicReader reader)` Returns a TermsEnum that implements ord.
    `static CheckIndex.Status.DocValuesStatus` | CheckIndex.`testDocValues(AtomicReader reader, PrintStream infoStream)` Test docvalues.
    `static CheckIndex.Status.FieldNormStatus` | CheckIndex.`testFieldNorms(AtomicReader reader, PrintStream infoStream)` Test field norms.
    `static CheckIndex.Status.TermIndexStatus` | CheckIndex.`testPostings(AtomicReader reader, PrintStream infoStream)` Test the term index.
    `static CheckIndex.Status.TermIndexStatus` | CheckIndex.`testPostings(AtomicReader reader, PrintStream infoStream, boolean verbose)` Test the term index.
    `static CheckIndex.Status.StoredFieldStatus` | CheckIndex.`testStoredFields(AtomicReader reader, PrintStream infoStream)` Test stored fields.
    `static CheckIndex.Status.TermVectorStatus` | CheckIndex.`testTermVectors(AtomicReader reader, PrintStream infoStream)` Test term vectors.
    `static CheckIndex.Status.TermVectorStatus` | CheckIndex.`testTermVectors(AtomicReader reader, PrintStream infoStream, boolean verbose, boolean crossCheckTermVectors)` Test term vectors.
    `protected void` | DocTermOrds.`uninvert(AtomicReader reader, Bits liveDocs, BytesRef termPrefix)` Call this only once (if you subclass!)
    `abstract void` | IndexWriter.IndexReaderWarmer.`warm(AtomicReader reader)` Invoked on the `AtomicReader` for the newly merged segment, before that segment is made visible to near-real-time readers.

    Constructors in org.apache.lucene.index with parameters of type AtomicReader
    Constructor and Description
    `DirectoryReader(Directory directory, AtomicReader[] segmentReaders)` Expert: Constructs a `DirectoryReader` on the given subReaders.
    `DocTermOrds(AtomicReader reader, Bits liveDocs, String field)` Inverts all terms
    `DocTermOrds(AtomicReader reader, Bits liveDocs, String field, BytesRef termPrefix)` Inverts only terms starting w/ prefix
    `DocTermOrds(AtomicReader reader, Bits liveDocs, String field, BytesRef termPrefix, int maxTermDocFreq)` Inverts only terms starting w/ prefix, and only terms whose docFreq (not taking deletions into account) is <= maxTermDocFreq
    `DocTermOrds(AtomicReader reader, Bits liveDocs, String field, BytesRef termPrefix, int maxTermDocFreq, int indexIntervalBits)` Inverts only terms starting w/ prefix, and only terms whose docFreq (not taking deletions into account) is <= maxTermDocFreq, with a custom indexing interval (default is every 128nd term).
    `FilterAtomicReader(AtomicReader in)` Construct a FilterAtomicReader based on the specified base reader.
    `ParallelAtomicReader(AtomicReader... readers)` Create a ParallelAtomicReader based on the provided readers; auto-closes the given readers on `IndexReader.close()`.
    `ParallelAtomicReader(boolean closeSubReaders, AtomicReader... readers)` Create a ParallelAtomicReader based on the provided readers.
    `ParallelAtomicReader(boolean closeSubReaders, AtomicReader[] readers, AtomicReader[] storedFieldsReaders)` Expert: create a ParallelAtomicReader based on the provided readers and storedFieldReaders; when a document is loaded, only storedFieldsReaders will be used.
    `ParallelAtomicReader(boolean closeSubReaders, AtomicReader[] readers, AtomicReader[] storedFieldsReaders)` Expert: create a ParallelAtomicReader based on the provided readers and storedFieldReaders; when a document is loaded, only storedFieldsReaders will be used.

  - ### Uses of AtomicReader in org.apache.lucene.search

    Methods in org.apache.lucene.search with parameters of type AtomicReader
    Modifier and Type | Method and Description
    --- | ---
    `protected DocIdSet` | CachingWrapperFilter.`docIdSetToCache(DocIdSet docIdSet, AtomicReader reader)` Provide the DocIdSet to be cached, using the DocIdSet provided by the wrapped Filter.
    `FieldCache.Bytes` | FieldCache.`getBytes(AtomicReader reader, String field, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as a single byte and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Bytes` | FieldCache.`getBytes(AtomicReader reader, String field, FieldCache.ByteParser parser, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as bytes and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `Bits` | FieldCache.`getDocsWithField(AtomicReader reader, String field)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` and returns a bit set at the size of `reader.maxDoc()`, with turned on bits for each docid that does have a value for this field.
    `SortedSetDocValues` | FieldCache.`getDocTermOrds(AtomicReader reader, String field)` Checks the internal cache for an appropriate entry, and if none is found, reads the term values in `field` and returns a `DocTermOrds` instance, providing a method to retrieve the terms (as ords) per document.
    `FieldCache.Doubles` | FieldCache.`getDoubles(AtomicReader reader, String field, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as integers and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Doubles` | FieldCache.`getDoubles(AtomicReader reader, String field, FieldCache.DoubleParser parser, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as doubles and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Floats` | FieldCache.`getFloats(AtomicReader reader, String field, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as floats and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Floats` | FieldCache.`getFloats(AtomicReader reader, String field, FieldCache.FloatParser parser, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as floats and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Ints` | FieldCache.`getInts(AtomicReader reader, String field, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as integers and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Ints` | FieldCache.`getInts(AtomicReader reader, String field, FieldCache.IntParser parser, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as integers and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Longs` | FieldCache.`getLongs(AtomicReader reader, String field, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as longs and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Longs` | FieldCache.`getLongs(AtomicReader reader, String field, FieldCache.LongParser parser, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as longs and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Shorts` | FieldCache.`getShorts(AtomicReader reader, String field, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as shorts and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `FieldCache.Shorts` | FieldCache.`getShorts(AtomicReader reader, String field, FieldCache.ShortParser parser, boolean setDocsWithField)` Checks the internal cache for an appropriate entry, and if none is found, reads the terms in `field` as shorts and returns an array of size `reader.maxDoc()` of the value each document has in the given field.
    `BinaryDocValues` | FieldCache.`getTerms(AtomicReader reader, String field)` Checks the internal cache for an appropriate entry, and if none is found, reads the term values in `field` and returns a `BinaryDocValues` instance, providing a method to retrieve the term (as a BytesRef) per document.
    `BinaryDocValues` | FieldCache.`getTerms(AtomicReader reader, String field, float acceptableOverheadRatio)` Expert: just like `FieldCache.getTerms(AtomicReader,String)`, but you can specify whether more RAM should be consumed in exchange for faster lookups (default is "true").
    `SortedDocValues` | FieldCache.`getTermsIndex(AtomicReader reader, String field)` Checks the internal cache for an appropriate entry, and if none is found, reads the term values in `field` and returns a `SortedDocValues` instance, providing methods to retrieve sort ordinals and terms (as a ByteRef) per document.
    `SortedDocValues` | FieldCache.`getTermsIndex(AtomicReader reader, String field, float acceptableOverheadRatio)` Expert: just like `FieldCache.getTermsIndex(AtomicReader,String)`, but you can specify whether more RAM should be consumed in exchange for faster lookups (default is "true").
    `void` | FieldCache.`purge(AtomicReader r)` Expert: drops all cache entries associated with this reader.

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