[Java] Auto meta shared mode for type forward/backward compatibility #202
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This was referenced May 11, 2023
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chaokunyang
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## What does this PR do? This PR implements type meta encoding for java proposed in #1240 . The type meta encoding in xlang spec proposed in #1413 will be finished in another PR based on this PR. The spec has been updated too: type meta header ``` | 8 bytes meta header | meta size | variable bytes | variable bytes | variable bytes | +-------------------------------+-----------|--------------------+-------------------+----------------+ | 7 bytes hash + 1 bytes header | 1~2 bytes | current class meta | parent class meta | ... | ``` And the encoding for packge/class/field name has been updated to: ``` - Package name encoding(omitted when class is registered): - encoding algorithm: `UTF8/ALL_TO_LOWER_SPECIAL/LOWER_UPPER_DIGIT_SPECIAL` - Header: `6 bits size | 2 bits encoding flags`. The `6 bits size: 0~63` will be used to indicate size `0~62`, the value `63` the size need more byte to read, the encoding will encode `size - 62` as a varint next. - Class name encoding(omitted when class is registered): - encoding algorithm: `UTF8/LOWER_UPPER_DIGIT_SPECIAL/FIRST_TO_LOWER_SPECIAL/ALL_TO_LOWER_SPECIAL` - header: `6 bits size | 2 bits encoding flags`. The `6 bits size: 0~63` will be used to indicate size `1~64`, the value `63` the size need more byte to read, the encoding will encode `size - 63` as a varint next. - Field info: - header(8 bits): `3 bits size + 2 bits field name encoding + polymorphism flag + nullability flag + ref tracking flag`. Users can use annotation to provide those info. - 2 bits field name encoding: - encoding: `UTF8/ALL_TO_LOWER_SPECIAL/LOWER_UPPER_DIGIT_SPECIAL/TAG_ID` - If tag id is used, i.e. field name is written by an unsigned varint tag id. 2 bits encoding will be `11`. - size of field name: - The `3 bits size: 0~7` will be used to indicate length `1~7`, the value `6` the size read more bytes, the encoding will encode `size - 7` as a varint next. - If encoding is `TAG_ID`, then num_bytes of field name will be used to store tag id. - Field name: If type id is set, type id will be used instead. Otherwise meta string encoding length and data will be written instead. ``` ## Meta size Before this PR: ```java class org.apache.fury.benchmark.data.MediaContent 78 class org.apache.fury.benchmark.data.Media 208 class org.apache.fury.benchmark.data.Image 114 ``` With this PR: ```java class org.apache.fury.benchmark.data.MediaContent 53 class org.apache.fury.benchmark.data.Media 114 class org.apache.fury.benchmark.data.Image 68 ``` The size of class meta reduced by half, which is a great gain. The size can be reduded more if we introduce field name hash, but it's not related to this PR. We can discuss it in another PR. ## Related issues #1240 #203 #202 ## Does this PR introduce any user-facing change? <!-- If any user-facing interface changes, please [open an issue](https://github.com/apache/incubator-fury/issues/new/choose) describing the need to do so and update the document if necessary. --> - [ ] Does this PR introduce any public API change? - [ ] Does this PR introduce any binary protocol compatibility change? ## Benchmark <!-- When the PR has an impact on performance (if you don't know whether the PR will have an impact on performance, you can submit the PR first, and if it will have impact on performance, the code reviewer will explain it), be sure to attach a benchmark data here. -->
This was referenced May 29, 2024
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chaokunyang
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May 30, 2024
…lity (#1660) ## What does this PR do? This PR implements scoped meta share mode for type forward/backward compaibility ## Related issues #202 ## Does this PR introduce any user-facing change? <!-- If any user-facing interface changes, please [open an issue](https://github.com/apache/incubator-fury/issues/new/choose) describing the need to do so and update the document if necessary. --> - [ ] Does this PR introduce any public API change? - [ ] Does this PR introduce any binary protocol compatibility change? ## Benchmark Perf increased from `1900102.586` to `2430410.064` ``` Before: Benchmark (bufferType) (objectType) (references) Mode Cnt Score Error Units fury_deserialize array MEDIA_CONTENT false thrpt 10 2734151.212 ± 253921.628 ops/s fury_deserialize_compatible array MEDIA_CONTENT false thrpt 10 1900102.586 ± 62176.872 ops/s furymetashared_deserialize_compatible array MEDIA_CONTENT false thrpt 10 3011439.327 ± 260518.752 ops/s After: Benchmark (bufferType) (objectType) (references) Mode Cnt Score Error Units fury_deserialize array MEDIA_CONTENT false thrpt 10 2661186.814 ± 279377.198 ops/s fury_deserialize_compatible array MEDIA_CONTENT false thrpt 10 2430410.064 ± 164165.865 ops/s furymetashared_deserialize_compatible array MEDIA_CONTENT false thrpt 10 3098083.064 ± 259391.053 ops/s ``` Size decreased from **732 to 577**: ``` Before 2024-05-30 01:00:49 INFO FuryState:157 [fury_deserialize_compatible-jmh-worker-1] - ======> Fury | MEDIA_CONTENT | false | array | 732 | After 2024-05-30 12:57:00 INFO FuryState:157 [fury_deserialize_compatible-jmh-worker-1] - ======> Fury | MEDIA_CONTENT | false | array | 577 | ``` The
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Is your feature request related to a problem? Please describe.
We supported type forward/backward compatibility in #197, but as the issue said, the solution proposed in that issue will write class meta every time the object is serialized. If multiple objects of same time are serialized as a whole, the meta will be serialized multiple times, which is unneccessary.
We can use meta sharing to write meta only once in a serialization for an object graph. And the meta can be encoded to binary, so the actual meta writting will be just a memory copy, which is far more faster.
The issue #80 proposed meta share across serialization, which need the rpc or users to maintain the
MetaContext, which is inconvinient for users.Describe the solution you'd like
We can support auto meta sharing to reduce meta cost in every serialization. This will ensure multiple objects of same type write meta only once for space saving, and got better pperformance by memory copy meta binary.
Currently meta encoding is not compressed, this will be discussed in another issue.
Additional context
#80 #197
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