Class StreamId

java.lang.Object
org.eclipse.jetty.quic.common.StreamId
public class StreamId extends Object

Stream id utilities.

A stream id is made of a progressive value and 2 least significant bits that indicate whether the stream is unidirectional (bit 1) and whether the stream is server-initiated (bit 0).

Furthermore, stream id are encoded using VarLenInt, which steals the 2 most significant bits, leaving 60 bits for the progressive value, whose max value is captured by constant MAX_PROGRESSIVE.

The encoded representation is therefore the following:


 6                                                              0
 3                                                              0
 XX------------------------------------------------------------US

 Legend:
 X : VarLenInt encoding bit
 U : uni/bi directional bit
 S : client/server bit
 - : progressive bit

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final long
    MAX_PROGRESSIVE
    The max value of the progressive part of a stream id.

  • Method Summary

    Modifier and Type
    Method
    Description
    static boolean
    exceedsMaxProgressive(long streamId)
    Tests whether the given stream id exceeds the max progressive value.
    static boolean
    isBidirectional(long streamId)
    Tests whether the given stream id is bidirectional.
    static boolean
    isLocal(long streamId, boolean client)
    Returns whether a stream id is local with respect to the given client parameter.
    static long
    newStreamId(long progressive, boolean bidirectional, boolean client)
    Generates and returns a new stream id, or -1 if the stream id cannot be generated.
    static long
    progressive(long streamId)
    Returns the progressive value of the stream id, that is progressive bits shifted by two bits to the right.
    static int
    type(long streamId)
    Returns the encoded stream type, that is the value of the two least significant bits of the stream id.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • MAX_PROGRESSIVE

      public static final long MAX_PROGRESSIVE

      The max value of the progressive part of a stream id.

      See Also:

  • Method Details

    • type

      public static int type(long streamId)

      Returns the encoded stream type, that is the value of the two least significant bits of the stream id.

      Returns:

      • 0 - for bidirectional client stream ids
      • 1 - for bidirectional server stream ids
      • 2 - for unidirectional client stream ids
      • 3 - for unidirectional server stream ids
      Parameters:
      streamId - the stream id to extract the type from
      Returns:
      the encoded stream type

    • progressive

      public static long progressive(long streamId)

      Returns the progressive value of the stream id, that is progressive bits shifted by two bits to the right.

      For example, for unidirectional client (type 0b10) stream id 0b10110 returns 0b101 == 5.

      Parameters:
      streamId - the stream id to extract the progressive from
      Returns:
      the progressive value of the stream id
      See Also:

    • exceedsMaxProgressive

      public static boolean exceedsMaxProgressive(long streamId)

      Tests whether the given stream id exceeds the max progressive value.

      Parameters:
      streamId - the stream id to test
      Returns:
      whether the stream id exceeds the max progressive value
      See Also:

    • isBidirectional

      public static boolean isBidirectional(long streamId)

      Tests whether the given stream id is bidirectional.

      Parameters:
      streamId - the stream id to test
      Returns:
      whether the stream id is bidirectional

    • newStreamId

      public static long newStreamId(long progressive, boolean bidirectional, boolean client)

      Generates and returns a new stream id, or -1 if the stream id cannot be generated.

      Stream ids are typically encoded via VarLenInt (which steals the 2 msb), and encode uni/bi directional and client/server (which steals the 2 lsb).

      Therefore the progressive number only has 60 bits available, or 260-1 values, from 0 to 1152921504606846975; trying to generate a stream id with a larger progressive value results in -1 to be returned by this method.

      Parameters:
      progressive - the stream id progressive number
      bidirectional - whether the stream is bidirectional
      client - whether the stream is client-initiated
      Returns:
      an encoded stream id, or -1 if the stream id cannot be generated

    • isLocal

      public static boolean isLocal(long streamId, boolean client)

      Returns whether a stream id is local with respect to the given client parameter.

      Parameters:
      streamId - the stream id to test
      client - the side asking for locality
      Returns:
      whether the stream id is local to the given side