Class IndexInput
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Cloneable
- Direct Known Subclasses:
BufferedIndexInput
,ByteBufferIndexInput
,ByteBuffersIndexInput
,ChecksumIndexInput
Directory
. A random-access input stream.
Used for all Lucene index input operations.
IndexInput
may only be used from one thread, because it is not thread safe (it keeps
internal state like file position). To allow multithreaded use, every IndexInput
instance
must be cloned before it is used in another thread. Subclasses must therefore implement clone()
, returning a new IndexInput
which operates on the same underlying resource, but
positioned independently.
Warning: Lucene never closes cloned IndexInput
s, it will only call close()
on the original object.
If you access the cloned IndexInput after closing the original object, any readXXX
methods will throw AlreadyClosedException
.
- See Also:
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Constructor Summary
ConstructorsModifierConstructorDescriptionprotected
IndexInput
(String resourceDescription) resourceDescription should be a non-null, opaque string describing this resource; it's returned fromtoString()
. -
Method Summary
Modifier and TypeMethodDescriptionclone()
Returns a clone of this stream.abstract void
close()
Closes the stream to further operations.abstract long
Returns the current position in this file, where the next read will occur.protected String
getFullSliceDescription
(String sliceDescription) Subclasses call this to get the String for resourceDescription of a slice of thisIndexInput
.abstract long
length()
The number of bytes in the file.randomAccessSlice
(long offset, long length) Creates a random-access slice of this index input, with the given offset and length.abstract void
seek
(long pos) Sets current position in this file, where the next read will occur.void
skipBytes
(long numBytes) Skip overnumBytes
bytes.abstract IndexInput
Creates a slice of this index input, with the given description, offset, and length.toString()
Methods inherited from class org.apache.lucene.store.DataInput
readByte, readBytes, readBytes, readFloats, readInt, readLong, readLongs, readMapOfStrings, readSetOfStrings, readShort, readString, readVInt, readVLong, readZInt, readZLong
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Constructor Details
-
IndexInput
resourceDescription should be a non-null, opaque string describing this resource; it's returned fromtoString()
.
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Method Details
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close
Closes the stream to further operations.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Throws:
IOException
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getFilePointer
public abstract long getFilePointer()Returns the current position in this file, where the next read will occur.- See Also:
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seek
Sets current position in this file, where the next read will occur. If this is beyond the end of the file then this will throwEOFException
and then the stream is in an undetermined state.- Throws:
IOException
- See Also:
-
skipBytes
Skip overnumBytes
bytes. This method may skip bytes in whatever way is most optimal, and may not have the same behavior as reading the skipped bytes. In general, negativenumBytes
are not supported.Behavior is functionally equivalent to seeking to
getFilePointer() + numBytes
.- Specified by:
skipBytes
in classDataInput
- Throws:
IOException
- See Also:
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length
public abstract long length()The number of bytes in the file. -
toString
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clone
Returns a clone of this stream.Clones of a stream access the same data, and are positioned at the same point as the stream they were cloned from.
Expert: Subclasses must ensure that clones may be positioned at different points in the input from each other and from the stream they were cloned from.
Warning: Lucene never closes cloned
IndexInput
s, it will only callclose()
on the original object.If you access the cloned IndexInput after closing the original object, any
readXXX
methods will throwAlreadyClosedException
.This method is NOT thread safe, so if the current
IndexInput
is being used by one thread whileclone
is called by another, disaster could strike. -
slice
public abstract IndexInput slice(String sliceDescription, long offset, long length) throws IOException Creates a slice of this index input, with the given description, offset, and length. The slice is sought to the beginning.- Throws:
IOException
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getFullSliceDescription
Subclasses call this to get the String for resourceDescription of a slice of thisIndexInput
. -
randomAccessSlice
Creates a random-access slice of this index input, with the given offset and length.The default implementation calls
slice(java.lang.String, long, long)
, and it doesn't support random access, it implements absolute reads as seek+read.- Throws:
IOException
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