NLP will throw when no source for search result with compression

[XZhi]

Elasticsearch version: 2.1.1(2.x)

JVM version: 1.8.0_66-b17

OS version: Mac OS X 10.10.5

Description of the problem including expected versus actual behavior:
java.lang.NullPointerException will be thrown when converting search response to json if search hits without no source returned(just specify search field) and compress is enable, because the isCompressed method of LZFCompressor and DeflateCompressor will check the parameter 'bytes' is null or not before do uncompress operation.
Stacktrace can be referenced at log section.

Steps to reproduce:

1. Use SearchRequestBuilder.addField() to add search result field before execute search operation and it will not return source of document for search response hits.
2. Execute search operation.
3. Get the reference SearchResponse and use com.alibaba.fastjson.JSON.toJSONString() to convert it into json string, you will got NPE

Provide logs (if relevant):

java.lang.NullPointerException: null
at org.elasticsearch.common.compress.lzf.LZFCompressor.isCompressed(LZFCompressor.java:54) ~[elasticsearch-2.1.1.jar:2.1.1]
at org.elasticsearch.common.compress.CompressorFactory.compressor(CompressorFactory.java:74) ~[elasticsearch-2.1.1.jar:2.1.1]
at org.elasticsearch.common.compress.CompressorFactory.uncompressIfNeeded(CompressorFactory.java:118) ~[elasticsearch-2.1.1.jar:2.1.1]
at org.elasticsearch.search.internal.InternalSearchHit.sourceRef(InternalSearchHit.java:200) ~[elasticsearch-2.1.1.jar:2.1.1]
at org.elasticsearch.search.internal.InternalSearchHit.getSourceRef(InternalSearchHit.java:219) ~[elasticsearch-2.1.1.jar:2.1.1]
at Serializer_17.write1(Unknown Source) ~[na:na]
at Serializer_17.write(Unknown Source) ~[na:na]
at com.alibaba.fastjson.serializer.ArraySerializer.write(ArraySerializer.java:64) ~[fastjson-1.2.8.jar:na]
at com.alibaba.fastjson.serializer.JSONSerializer.writeWithFieldName(JSONSerializer.java:403) ~[fastjson-1.2.8.jar:na]
at Serializer_16.write1(Unknown Source) ~[na:na]
at Serializer_16.write(Unknown Source) ~[na:na]
at com.alibaba.fastjson.serializer.JSONSerializer.writeWithFieldName(JSONSerializer.java:403) ~[fastjson-1.2.8.jar:na]
at Serializer_14.write1(Unknown Source) ~[na:na]
at Serializer_14.write(Unknown Source) ~[na:na]
at com.alibaba.fastjson.serializer.JSONSerializer.writeWithFieldName(JSONSerializer.java:403) ~[fastjson-1.2.8.jar:na]
at Serializer_12.write1(Unknown Source) ~[na:na]
at Serializer_12.write(Unknown Source) ~[na:na]
at com.alibaba.fastjson.serializer.JSONSerializer.write(JSONSerializer.java:374) ~[fastjson-1.2.8.jar:na]
at com.alibaba.fastjson.JSON.toJSONString(JSON.java:394) ~[fastjson-1.2.8.jar:na]
at com.alibaba.fastjson.JSON.toJSONString(JSON.java:382) ~[fastjson-1.2.8.jar:na]

[clintongormley]

I think this has been fixed by #18957

Could you try your test on master and let us know if it is indeed fixed?

[XZhi]

Sorry for replying late.

I reviewed the changed code for #18957, but I don't think it is fixed in it.
The NPE is thrown by LZFCompressor or DeflateCompressor when _source is not returned and _source is not be disabled. I guess it will be fixed at LZFCompressor and DeflateCompressor from the stacktrace.

[neitomic]

I also met this issue. Function sourceRef() in class InternalSearchHit always throw NullPointerException when source is null.

Elasticsearch version: 2.4.0