What does this PR do?

This changes the encoding of hashes from big-endian to little-endian when we are sending the stats to the DSM backend.

Its a relatively small change, but this broke how DSM worked in systems with multiple languages, as every other language uses little endian. This meant that context propagation did not work across languages, the javascript producer would produce a hash in hex format of 8 bytes, broadcast a checkpoint having converted the hash to big endian and the consumer would pull that hash from the message headers, convert it to little endian and the numbers would not match.

It was broken without a visual component for all queue technologies but in rabbitmq, it was also visually broken because of how rabbitmq associations work.

Tests

Before with rabbitmq

Kafka

which i can see when I look at the checkpoints:
test 4 which doesn't work, has the following checkpoints:

{
"key": {
"service": "nodejs-kafka-producer-test4-eric.firth",
"hash": 12593296123675988000,
"parentHash": 0,
"edgeType": "kafka",
"edgeDirection": "out",
"group": "",
"topic": "endian-fix-validation-topic-test4",
"eventType": "",
"exchange": ""
},
"value": {}
},
{
"key": {
"service": "python-kafka-consumer-test4-eric.firth",
"hash": 15170800266638707000,
"parentHash": 11403507064061660000,
"edgeType": "kafka",
"edgeDirection": "in",
"group": "my_group",
"topic": "endian-fix-validation-topic-test4",
"eventType": "",
"exchange": ""
},
"value": {}
}

as you can see the hash of the producer 12593296123675988000 is not the same as the parent hash of the consumer 11403507064061660000
where test5 which does gives the following checkpoints

{
"key": {
"service": "nodejs-kafka-producer-test5-eric.firth",
"hash": 7610290120735904000,
"parentHash": 0,
"edgeType": "kafka",
"edgeDirection": "out",
"group": "",
"topic": "endian-fix-validation-topic-test5",
"eventType": "",
"exchange": ""
},
"value": {}
},
{
"key": {
"service": "python-kafka-consumer-test5-eric.firth",
"hash": 17373314072852003000,
"parentHash": 7610290120735904000,
"edgeType": "kafka",
"edgeDirection": "in",
"group": "my_group",
"topic": "endian-fix-validation-topic-test5",
"eventType": "",
"exchange": ""
},
"value": {}
}

and in that. the hash of the producer and parent hash of the cnosumer do match (7610290120735904000)

Motivation

We received a bug report https://datadoghq.atlassian.net/browse/DSMS-98

Plugin Checklist

• Unit tests.
• Integration tests.
• Benchmarks.
• TypeScript definitions.
• TypeScript tests.
• API documentation.
• CI jobs/workflows.

Additional Notes