Enum rust_eterm::terms::DistHeaderTag

pub enum DistHeaderTag {
    Normal,
    Fragmented,
    Fragment,
    Compressed,
}

Variants

Normal

The tag for a normal unfragmented and uncompressed distribution header.

Binary representation

1 byte	1 byte	NumberOfAtomCacheRefs/2+1 \| 0 bytes	N \| 0 bytes
68	NumberOfAtomCacheRefs	Flags	AtomCacheRefs

• NumberOfAtomCacheRefs is the amount of atom cache references in this message.

• Flags is a list of 4-byte values containig flags in the following format:

  1 bit	3 bits
  NewCacheEntry	SegmentIndex

  • NewCacheEntry describes whether the atom is new in the cache.
  • SegmentIndex describes in which segment the atom is located.

  and after the flags for each of the references, one entry of this is sent:

  3 bits	1 bit
  Unused	LongAtoms

  • LongAtoms states whether 1 or 2 bytes are used for the atom values in this distribution header.

• AtomCacheRefs are:

  When for this atom, NewCacheEntry is 1:

  1 byte	1|2 bytes	Length bytes
  InternalSegmentIndex	Length	AtomText

  • InternalSegmentIndex, together with SegmentIndex in the flags entry completely define the location of the atom in the atom cache.
  • Length is either 1 byte when LongAtoms is 0, and 2 bytes otherwise. It describes how many bytes long the AtomText is.
  • AtomText is the actual name of the atom.

  Or when for this atom, NewCacheEntry is 0:

  1 byte
  InternalSegmentIndex

  • InternalSegmentIndex, together with SegmentIndex in the flags entry completely define the location of the atom in the atom cache.

This header is then trailed with a term_to_binary-encoded term with (optionally) atom references to this header.

Fragmented

The tag for a header stating that the message is fragmented.

Note: This header must contain the entire atom cache.

Binary representation

1 byte	8 bytes	8 bytes	1 byte	NumberOfAtomCacheRefs/2+1 \| 0 bytes	N \| 0 bytes
69	SequenceId	FragmentId	NumberOfAtomCacheRefs	Flags	AtomCacheRefs

• SequenceId uniquely identifies the message that this fragment is part of.
• FragmentId is a number that decreases with 1 for each fragment, and at N, where N is the number of fragments (so the last fragment has FragmentId of 1).
• NumberOfAtomCacheRefs, Flags, and AtomCacheRefs act just like in Normal.

Some data MAY then be sent after this header, and each packet after this MUST only contain data of the term that is being sent.

Fragment

The tag denoting a follow-up fragment of apreviously fragment message (either another fragment, or the first fragment).

Binary representation

1 byte	8 bytes	8 bytes
70	SequenceId	FragmentId

• SequenceId, just like in Fragmented uniquely identifies this message, and must be the same as in the associated DIST_HDR_FRAG_CONT's.
• FragmentId, just like in Fragmented is a number that decreases with 1 for each fragment, with the last fragment having a FragmentId of 1.

Compressed

The tag denoting a compressed value (either a distribution header or an encoded atom).

Binary representation

1 byte	4 bytes	N
80	UncompressedSize	ZLibCompressedData

• UncompressedSize is the complete size of the uncompressed ZLibCompressedData (including the tag).

• ZLibCompressedData compresses data of the shape:

  1 byte	N bytes
  Tag	Data