Module: Datadog::OpenFeature::Hooks::SpanEnrichmentHook::Codec

Defined in:
lib/datadog/open_feature/hooks/span_enrichment_hook/codec.rb

Overview

Encoding/crypto helpers implementing the fixed cross-SDK wire format.

Constant Summary collapse

LOW_7_BITS_MASK =

ULEB128 stores 7 bits per byte; the high bit flags that more bytes follow.

0x7F
CONTINUATION_BIT = 
0x80

Class Method Summary collapse

Class Method Details

.encode_delta_varint(serial_ids) ⇒ Object

Encode a Set of serial ids as base64(ULEB128 delta-varint). Empty set -> empty string (the caller omits the tag).



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# File 'lib/datadog/open_feature/hooks/span_enrichment_hook/codec.rb', line 34

def encode_delta_varint(serial_ids)
  sorted = serial_ids.to_a.sort
  return "" if sorted.empty?

  bytes = (+"").b
  prev = 0
  sorted.each do |id|
    bytes << encode_varint(id - prev)
    prev = id
  end
  # `pack('m0')` is RFC 4648 base64 with no newlines (== strict_encode64)
  # and needs no `base64` gem, which stopped being a default gem in Ruby 3.4.
  [bytes].pack("m0")
end

.encode_varint(value) ⇒ Object

The bytes buffer built below MUST be binary (ASCII-8BIT): String#<< with an Integer on a UTF-8 string appends a Unicode codepoint, so any byte >= 0x80 would be re-encoded as a 2-byte UTF-8 sequence and corrupt the varint (e.g. serial 2312 -> bytes 88 12, but UTF-8 would emit C2 88 12 = 296002 on decode). (+'').b gives a mutable binary string.



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# File 'lib/datadog/open_feature/hooks/span_enrichment_hook/codec.rb', line 22

def encode_varint(value)
  bytes = (+"").b
  while value > LOW_7_BITS_MASK
    bytes << ((value & LOW_7_BITS_MASK) | CONTINUATION_BIT)
    value >>= 7
  end
  bytes << (value & LOW_7_BITS_MASK)
  bytes
end

.hash_targeting_key(targeting_key) ⇒ Object

Lowercase hex SHA256 of the targeting key: it is hashed before emission so raw user identifiers never leave the process.



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# File 'lib/datadog/open_feature/hooks/span_enrichment_hook/codec.rb', line 51

def hash_targeting_key(targeting_key)
  Digest::SHA256.hexdigest(targeting_key)
end