[MESOS-8727] JSON -> protobuf conversion in stout handles duplicated keys in a map incorrectly

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: stout
• Assignee: Unassigned
• Reporter: Qian Zhang
• Created: 23/Mar/18 03:32
• Updated: 26/Nov/19 21:10

Description

In Mesos code, we usually use the following two functions in stout to convert a JSON string to a protobuf message.

1. JSON::parse() to convert a JSON string to a JSON object (i.e., JSON::Object).
2. protobuf::parse() to convert the JSON object to a protobuf message.

In Google protobuf, there is a single function which can be used to achieve the same goal: JsonStringToMessage(). And based on the doc of Google protobuf, if there are duplicated keys in a map in a JSON string, the conversion to protobuf message may fail, i.e., if we use JsonStringToMessage to convert the following JSON string to a protobuf message, it will fail with an error like int32_to_string[0]: Repeated map key: '1' is already set. 

"int32_to_string": {
  "1": "value1",
  "1": "value2"
}

However, JSON::parse() and protobuf::parse() handles this case differently: they will succeed, and in the resulted protobuf message, we will see only one key-value pair "1": "value2", i.e., the first key-value pair is overwritten. We should have the same behavior with JsonStringToMessage.

NOTE: The asV1Protobuf copy needs to also be updated.

Issue Links

• relates to: MESOS-9896 Consider using protobuf provided json conversion facilities rather than custom ones.