Package org.apache.pekko.http.impl.util

Class ByteStringOutputStream

java.lang.Object

java.io.OutputStream

org.apache.pekko.http.impl.util.ByteStringOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public final class ByteStringOutputStream
extends OutputStream

INTERNAL API

An OutputStream that buffers into a byte array like ByteArrayOutputStream but that hands the buffered data over as a pekko.util.ByteString without copying it, unlike ByteArrayOutputStream.toByteArray which always creates a copy, and whose writes are not synchronized: every user is a single stage that owns the stream, and the per-call monitor was a measurable share of the cost of encoding an HPACK header block.

After a hand-over the stream is empty again and can be reused for the next block of data.

Not thread-safe.

Derived from the ByteStringOutputStream in Apache Pekko gRPC (https://github.com/apache/pekko-grpc/pull/862).

Constructor Summary

Constructors

Constructor	Description
ByteStringOutputStream(int initialCapacity)

Method Summary

Modifier and Type	Method	Description
byte[]	array()	The array backing the buffered data.
int	reserve(int length)	Reserves length bytes at the end of the buffered data for the caller to fill in directly.
int	size()	The number of bytes written since the last hand-over.
org.apache.pekko.util.ByteString	takeByteString()	Hands the buffered data over as a ByteString and leaves the stream empty for the next block.
void	write(byte[] bytes, int offset, int length)
void	write(int b)

Methods inherited from class java.io.OutputStream

close, flush, nullOutputStream, write

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ByteStringOutputStream

public ByteStringOutputStream(int initialCapacity)

Method Details

array

public byte[] array()

The array backing the buffered data. Only valid until the next write, reserve or hand-over, any of which may replace it.

Returns:

(undocumented)

reserve

public int reserve(int length)

Reserves length bytes at the end of the buffered data for the caller to fill in directly.

Parameters:

length - (undocumented)

Returns:

the position in array() at which the reserved bytes start

size

public int size()

The number of bytes written since the last hand-over.

takeByteString

public org.apache.pekko.util.ByteString takeByteString()

Hands the buffered data over as a ByteString and leaves the stream empty for the next block.

When most of the buffer is used the ByteString wraps the array without copying and the stream starts a fresh array for the next block; when only a small part is used the data is copied so the ByteString does not retain a large, mostly unused array, and the stream keeps its array.

Returns:

(undocumented)

write

public void write(int b)

Specified by:

write in class OutputStream

write

public void write(byte[] bytes,
 int offset,
 int length)

Overrides:

write in class OutputStream