Package org.apache.lucene.misc.store
Class DirectIODirectory
- java.lang.Object
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- org.apache.lucene.store.Directory
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- org.apache.lucene.store.FilterDirectory
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- org.apache.lucene.misc.store.DirectIODirectory
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- All Implemented Interfaces:
Closeable,AutoCloseable
public class DirectIODirectory extends FilterDirectory
ADirectoryimplementation for all Unixes and Windows that uses DIRECT I/O to bypass OS level IO caching during merging. For all other cases (searching, writing) we delegate to the provided Directory instance.See Overview for more details.
WARNING: this code is very new and quite easily could contain horrible bugs.
This directory passes Solr and Lucene tests on Linux, OS X, and Windows; other systems should work but have not been tested! Use at your own risk.
@throws UnsupportedOperationException if the operating system, file system or JDK does not support Direct I/O or a sufficient equivalent.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Field Summary
Fields Modifier and Type Field Description static intDEFAULT_MERGE_BUFFER_SIZEDefault buffer size before writing to disk (256 KB); larger means less IO load but more RAM and direct buffer storage space consumed during merging.static longDEFAULT_MIN_BYTES_DIRECTDefault min expected merge size before direct IO is used (10 MB):-
Fields inherited from class org.apache.lucene.store.FilterDirectory
in
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Constructor Summary
Constructors Constructor Description DirectIODirectory(FSDirectory delegate)Create a new DirectIODirectory for the named location.DirectIODirectory(FSDirectory delegate, int mergeBufferSize, long minBytesDirect)Create a new DirectIODirectory for the named location.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description voidclose()IndexOutputcreateOutput(String name, IOContext context)protected voidensureOpen()PathgetDirectory()IndexInputopenInput(String name, IOContext context)protected booleanuseDirectIO(String name, IOContext context, OptionalLong fileLength)Determines if direct IO should be used for a file.-
Methods inherited from class org.apache.lucene.store.FilterDirectory
createTempOutput, deleteFile, fileLength, getDelegate, getPendingDeletions, listAll, obtainLock, rename, sync, syncMetaData, toString, unwrap
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Methods inherited from class org.apache.lucene.store.Directory
copyFrom, getTempFileName, openChecksumInput
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Field Detail
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DEFAULT_MERGE_BUFFER_SIZE
public static final int DEFAULT_MERGE_BUFFER_SIZE
Default buffer size before writing to disk (256 KB); larger means less IO load but more RAM and direct buffer storage space consumed during merging.- See Also:
- Constant Field Values
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DEFAULT_MIN_BYTES_DIRECT
public static final long DEFAULT_MIN_BYTES_DIRECT
Default min expected merge size before direct IO is used (10 MB):- See Also:
- Constant Field Values
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Constructor Detail
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DirectIODirectory
public DirectIODirectory(FSDirectory delegate, int mergeBufferSize, long minBytesDirect) throws IOException
Create a new DirectIODirectory for the named location.- Parameters:
delegate- Directory for non-merges, also used as reference to file system path.mergeBufferSize- Size of buffer to use for merging.minBytesDirect- Merges, or files to be opened for reading, smaller than this will not use direct IO. SeeDEFAULT_MIN_BYTES_DIRECTanduseDirectIO(java.lang.String, org.apache.lucene.store.IOContext, java.util.OptionalLong).- Throws:
IOException- If there is a low-level I/O error
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DirectIODirectory
public DirectIODirectory(FSDirectory delegate) throws IOException
Create a new DirectIODirectory for the named location.- Parameters:
delegate- Directory for non-merges, also used as reference to file system path.- Throws:
IOException- If there is a low-level I/O error
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Method Detail
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getDirectory
public Path getDirectory()
- Returns:
- the underlying file system directory
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ensureOpen
protected void ensureOpen() throws AlreadyClosedException- Overrides:
ensureOpenin classFilterDirectory- Throws:
AlreadyClosedException
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useDirectIO
protected boolean useDirectIO(String name, IOContext context, OptionalLong fileLength)
Determines if direct IO should be used for a file. By default this tests if it is a merge context and if the merge or file length extends the minimum size (seeDEFAULT_MIN_BYTES_DIRECT). Subclasses may override method to enforce direct IO for specific file types.- Parameters:
name- file name (unused by default implementation)context- information about merge sizefileLength- if available, gives the file length. Will be empty when requesting anIndexOutput.- Returns:
trueif direct IO should be used;falseif input/output should be requested from delegate directory.
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openInput
public IndexInput openInput(String name, IOContext context) throws IOException
- Overrides:
openInputin classFilterDirectory- Throws:
IOException
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createOutput
public IndexOutput createOutput(String name, IOContext context) throws IOException
- Overrides:
createOutputin classFilterDirectory- Throws:
IOException
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close
public void close() throws IOException- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Overrides:
closein classFilterDirectory- Throws:
IOException
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