Package org.apache.hadoop.fs

Interface StreamCapabilities

All Known Implementing Classes:

BindingPathOutputCommitter, FSDataInputStream, FSDataOutputStream, HdfsDataInputStream, HdfsDataOutputStream, ManifestCommitter

@Public
@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.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static enum	StreamCapabilities.StreamCapability	Deprecated.

Field Summary

Fields

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

Method Summary

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

Field Details

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.

See Also:

• Constant Field Values

HSYNC

static final String HSYNC

Stream hsync capability implemented by Syncable.hsync().

See Also:

• Constant Field Values

READAHEAD

static final String READAHEAD

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

See Also:

• Constant Field Values

DROPBEHIND

static final String DROPBEHIND

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

See Also:

• Constant Field Values

UNBUFFER

static final String UNBUFFER

Stream unbuffer capability implemented by CanUnbuffer.unbuffer().

See Also:

• Constant Field Values

READBYTEBUFFER

static final String READBYTEBUFFER

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

See Also:

• Constant Field Values

PREADBYTEBUFFER

static final String PREADBYTEBUFFER

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

See Also:

• Constant Field Values

IOSTATISTICS

static final String IOSTATISTICS

IOStatisticsSource API.

See Also:

• Constant Field Values

VECTOREDIO

static final String VECTOREDIO

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

See Also:

• 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.

See Also:

• 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.

See Also:

• 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 Details

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.