Fix NPE in KeyValue when the message payload is null

[vroyer]

Motivation

Fix a NullPointerException when decoding a KeyValue with a null message payload.

Modifications

Return a KeyValue(null, null) when data is null or empty.

Verifying this change

Add a unit test in org.apache.pulsar.common.schema.KeyValueTest

[eolivelli]

can we make this private ?

[eolivelli]

can you please explain how it can happen that we fall into these cases ?

I mean, probably data == null is possible in case of a message will NULL value, but I cannot think about a case in which the array may be of zero length.

probably in case of zero length array we should throw an IllegalArgumentException, because it is not possible that it is a valid value, as we are always writing the length of the key and the length of the value (with -1 as marker for nulls)

[vroyer]

It appends when key is SEPARATED and value is null, here is the KeyValueSchema.encode():

public byte[] encode(KeyValue<K, V> message) {
        if (keyValueEncodingType != null && keyValueEncodingType == KeyValueEncodingType.INLINE) {
            return KeyValue.encode(
                message.getKey(),
                keySchema,
                message.getValue(),
                valueSchema
            );
        } else {
            if (message.getValue() == null) {
                return null;
            }
            return valueSchema.encode(message.getValue());
        }
    }

[eolivelli]

@vroyer I still do not see how we can have a zero byte array from your example.

if we have keyValueEncodingType == KeyValueEncodingType.SEPARATED then we are not using the KeyValue encoding, but the value contains only the serialized version of the value (valueSchema.encode(message.getValue()) ).

this "decode" code should be used only when you read an KeyValueEncodingType.INLINE message, that contains both the key and the value inside the payload of the message:

• keylen
• key bytes
• valuelen
• value bytes

when you serialize a null KeyValue you can a null value
when you serialize a null key you see -1 as "keylen"
when you serialize a null value you see -1 as "valuelen"

there is no way to see a zero byte array

[vroyer]

Yes, #10089 is possibly the root cause. The KeyValue with a null value was decoded as INLINED, so this protection https://github.com/apache/pulsar/blob/master/pulsar-client/src/main/java/org/apache/pulsar/client/impl/schema/KeyValueSchema.java#L146 was not working as expected.

[eolivelli]

please remove this import

[eolivelli]

this import looks unused

[eolivelli]

this import looks unused

[eolivelli]

it looks like we can close this PR in favour of #10089

correct ?

[sijie]

Don't you need to test empty data array?

[sijie]

Don't you need to assert the key & value of this kv?

[eolivelli]

this patch is obsolete, we can close this PR