Add support for L1 distance in AKNN, custom scoring and painless scripting

[elb3k]

Feature request from this issue

nmslib 2.0.11 added efficient indexing for l1 and linf. So I added support for l1 spaceType and scoring. I did not add new scoring to knn whitelist as it needs review.

[codecov[bot]]

Codecov Report

Merging #310 (22d4662) into master (b34f930) will increase coverage by 0.10%. The diff coverage is 89.47%.

@@             Coverage Diff              @@
##             master     #310      +/-   ##
============================================
+ Coverage     80.51%   80.61%   +0.10%     
- Complexity      388      392       +4     
============================================
  Files            62       62              
  Lines          1468     1486      +18     
  Branches        130      133       +3     
============================================
+ Hits           1182     1198      +16     
- Misses          239      240       +1     
- Partials         47       48       +1     

Impacted Files	Coverage Δ	Complexity Δ
...oforelasticsearch/knn/index/util/KNNConstants.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
...asticsearch/knn/plugin/script/KNNScoringSpace.java	94.73% <75.00%> (-5.27%)	0.00 <0.00> (ø)
...endistroforelasticsearch/knn/index/SpaceTypes.java	100.00% <100.00%> (ø)	5.00 <0.00> (ø)
...arch/knn/plugin/script/KNNScoringSpaceFactory.java	90.90% <100.00%> (+2.02%)	5.00 <0.00> (+1.00)
...lasticsearch/knn/plugin/script/KNNScoringUtil.java	98.27% <100.00%> (+0.23%)	21.00 <3.00> (+3.00)

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[jmazanec15]

Hi @Elbek-Khoshimjonov, thanks for the PR! I will review this week,

[elb3k]

Hi @Elbek-Khoshimjonov, overall this change looks great! A couple minor comments:

1. Could you add L1 below here: https://github.com/opendistro-for-elasticsearch/k-NN/blob/master/src/main/java/com/amazon/opendistroforelasticsearch/knn/index/util/KNNConstants.java#L24
2. Could you add L1 here: https://github.com/opendistro-for-elasticsearch/k-NN/blob/master/src/main/java/com/amazon/opendistroforelasticsearch/knn/plugin/script/KNNScoringSpaceFactory.java#L32
3. Could you add a test similar to this one? https://github.com/opendistro-for-elasticsearch/k-NN/blob/master/src/test/java/com/amazon/opendistroforelasticsearch/knn/plugin/script/KNNScriptScoringIT.java#L48. This should fix test coverage failure.

Done!

[VijayanB]

can you add the corresponding method to below file like l2Squared? https://github.com/opendistro-for-elasticsearch/k-NN/blob/master/src/main/resources/com/amazon/opendistroforelasticsearch/knn/plugin/script/knn_whitelist.txt

Can you also corresponding tests here? https://github.com/opendistro-for-elasticsearch/k-NN/blob/master/src/test/java/com/amazon/opendistroforelasticsearch/knn/plugin/script/PainlessScriptScoringIT.java

[elb3k]

can you add the corresponding method to below file like l2Squared? https://github.com/opendistro-for-elasticsearch/k-NN/blob/master/src/main/resources/com/amazon/opendistroforelasticsearch/knn/plugin/script/knn_whitelist.txt

Can you also corresponding tests here? https://github.com/opendistro-for-elasticsearch/k-NN/blob/master/src/test/java/com/amazon/opendistroforelasticsearch/knn/plugin/script/PainlessScriptScoringIT.java

Done.

[VijayanB]

LGTM! Thanks for making changes!