org.apache.hadoop.fs

Interface StreamCapabilities

All Known Implementing Classes:

BindingPathOutputCommitter, FSDataInputStream, FSDataOutputStream, HdfsDataInputStream, HdfsDataOutputStream, ManifestCommitter

@InterfaceAudience.Public
 @InterfaceStability.Evolving
public interface StreamCapabilities

Interface to query streams for supported capabilities. Capability strings must be in lower case. Constant strings are chosen over enums in order to allow other file systems to define their own capabilities.

Field Summary

Fields

Modifier and Type	Field and Description
static String	ABORTABLE_STREAM Stream abort() capability implemented by Abortable.abort().
static String	DROPBEHIND Stream setDropBehind capability implemented by CanSetDropBehind.setDropBehind(Boolean).
static String	HFLUSH Deprecated.
static String	HSYNC Stream hsync capability implemented by Syncable.hsync().
static String	IOSTATISTICS IOStatisticsSource API.
static String	IOSTATISTICS_CONTEXT Streams that support IOStatistics context and capture thread-level IOStatistics.
static String	PREADBYTEBUFFER Stream read(long, ByteBuffer) capability implemented by ByteBufferPositionedReadable.read(long, java.nio.ByteBuffer).
static String	READAHEAD Stream setReadahead capability implemented by CanSetReadahead.setReadahead(Long).
static String	READBYTEBUFFER Stream read(ByteBuffer) capability implemented by ByteBufferReadable.read(java.nio.ByteBuffer).
static String	UNBUFFER Stream unbuffer capability implemented by CanUnbuffer.unbuffer().
static String	VECTOREDIO Support for vectored IO api.
static String	VECTOREDIO_BUFFERS_SLICED Probe for vector IO implementation details: "fs.capability.vectoredio.sliced".

Method Summary

Modifier and Type	Method and Description
boolean	hasCapability(String capability) Query the stream for a specific capability.

Field Detail

HFLUSH

@Deprecated
static final String HFLUSH

Deprecated.

Stream hflush capability implemented by Syncable.hflush(). Use the HSYNC probe to check for the support of Syncable; it's that presence of hsync() which matters.

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Constant Field Values

HSYNC

static final String HSYNC

Stream hsync capability implemented by Syncable.hsync().

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Constant Field Values

READAHEAD

static final String READAHEAD

Stream setReadahead capability implemented by CanSetReadahead.setReadahead(Long).

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Constant Field Values

DROPBEHIND

static final String DROPBEHIND

Stream setDropBehind capability implemented by CanSetDropBehind.setDropBehind(Boolean).

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Constant Field Values

UNBUFFER

static final String UNBUFFER

Stream unbuffer capability implemented by CanUnbuffer.unbuffer().

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Constant Field Values

READBYTEBUFFER

static final String READBYTEBUFFER

Stream read(ByteBuffer) capability implemented by ByteBufferReadable.read(java.nio.ByteBuffer).

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Constant Field Values

PREADBYTEBUFFER

static final String PREADBYTEBUFFER

Stream read(long, ByteBuffer) capability implemented by ByteBufferPositionedReadable.read(long, java.nio.ByteBuffer).

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Constant Field Values

IOSTATISTICS

static final String IOSTATISTICS

IOStatisticsSource API.

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Constant Field Values

VECTOREDIO

static final String VECTOREDIO

Support for vectored IO api. See PositionedReadable#readVectored(List, IntFunction).

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Constant Field Values

VECTOREDIO_BUFFERS_SLICED

static final String VECTOREDIO_BUFFERS_SLICED

Probe for vector IO implementation details: "fs.capability.vectoredio.sliced". When performing vectored IO operations, are the buffers returned by readVectored() potentially sliced subsets of buffers allocated by the allocate() function passed in the read requests? If true, this means that the returned buffers may be sliced subsets of the allocated buffers.

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Constant Field Values

ABORTABLE_STREAM

static final String ABORTABLE_STREAM

Stream abort() capability implemented by Abortable.abort(). This matches the Path Capability CommonPathCapabilities.ABORTABLE_STREAM.

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Constant Field Values

IOSTATISTICS_CONTEXT

static final String IOSTATISTICS_CONTEXT

Streams that support IOStatistics context and capture thread-level IOStatistics.

See Also:

Constant Field Values

Method Detail

hasCapability

boolean hasCapability(String capability)

Query the stream for a specific capability.

Parameters:

capability - string to query the stream support for.

Returns:

True if the stream supports capability.