Cosmos-sdk: Genesis Protobuf Migration

[aaronc]

Context

• with protobuf, we now have a new JSON format which we want to support
• streaming genesis is desirable because of large imports and exports from mature zones
• with the migration to Any, the same structs can support both amino and protobuf JSON

Roadmap

• [x] #6717 https://github.com/cosmos/cosmos-sdk/pull/6734 #6860 migrate x/genutil to new TxConfig
• [x] Ensure all module GenesisState structs properly support both amino and proto JSON (this usually will involve migrating interfaces to Any and generating GenesisState from a .proto file)
  
  
  
  • [x] (https://github.com/cosmos/cosmos-sdk/pull/6880) x/auth @blushi
  
  
  • [x] (#6835) x/bank @atheeshp
  
  
  • [x] (#6835) x/crisis @atheeshp
  
  
  • [x] (#6867) x/capability @atheeshp
  
  
  • [x] (#6835) x/distribution @atheeshp
  
  
  • [x] (#6864) x/evidence @blushi
  
  
  • [x] (#6835) x/mint @atheeshp
  
  
  • [x] (#6867) x/genutil @atheeshp
  
  
  • [x] (#6866) x/gov @sahith-narahari
  
  
  • [x] (#6881) x/slashing @atheeshp
  
  
  • [x] (#6835) x/staking @atheeshp
  
  
  • [x] (#6878) x/ibc @atheeshp
  
  
  • [x] (#6866) x/ibc-transfer @sahith-narahari
  
  
• [ ] enable proto JSON in simapp

/cc @alexanderbez @clevinson

[alpe]

GenTX decoding from genesis is very critical as well as it is required to run a node. DeliverGenTxs is still amino.

[clevinson]

Being worked on here by @alpe : https://github.com/alpe/cosmos-sdk/tree/genesis_demo/genesisdemo

[marbar3778]

will part of this also depend on tendermint genesis work or is it orthogonal? I am starting to delve into the tendermint side of JSON encoding

[aaronc]

will part of this also depend on tendermint genesis work or is it orthogonal? I am starting to delve into the tendermint side of JSON encoding

@marbar3778 Can you share some details/link about this?

[aaronc]

With #6147, we now have an easy pathway to support both Amino and Proto JSON, so I've updated this issue to include a task in this issue for adding flags to start and export to choose which JSON format to use.

[aaronc]

Also I've thought about how to approach streaming JSON based on some things @alpe has shared and just want to document the approach I have in mind. (I don't think we need to get to this quite yet.)

Here are the constraints I see:

• streaming JSON should be opt-in on a module by module basis and isn't blocking for v0.39 (unless there are resource issues doing the hub export)
• looking at our current genesis code, the order of operations is pretty important
• in order to support streaming properly, we need to be able to choose which elements in an object get parsed first

I think we can solve this with the following approach:

• allow either a genesis.json file as now, or a genesis/ folder
• arrays which are large and intended to be streamed can like in their own JSON files, i.e. staking.delegations could live in genesis/staking/delegations.json
• root.json in the genesis/ folder contains all definitions that are not in the separate files. Anything which is in a separate file should be omitted from root.json

The API for this might look something like:

type ObjectReader interface {
    // reads the named field from the object into the ptr
    ReadObject(name string, ptr interface{}) error
    // opens a stream reader for the array at the named field
    // this will open a separate file from the disk if it exists to support massive arrays
    // (i.e. `delegations.json` for the field `delegations`)
    StreamArray(name string) ArrayStreamer
}

type ArrayStreamer interface {
    ReadNext(ptr interface{}) error
    HaveMore() bool
}

Using gogo jsonpb, there is already an UnmarshalNext method we can leverage: https://godoc.org/github.com/gogo/protobuf/jsonpb#Unmarshaler.UnmarshalNext

[marbar3778]

Can you share some details/link about this?

we are discussing and started a small doc here: https://docs.google.com/document/d/1RzF9qvr-a6oYbmKdhHJ_lYLIUbxozTFfsJCwJzAqXkY/edit#heading=h.n4jqb5mvv9mq

and have a issue here: https://github.com/tendermint/tendermint/issues/4828

cc @aaronc

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[fedekunze]

should we get started with the .proto files? or is it blocked by something else?

[aaronc]

There is still a question in my mind of whether we need streaming genesis for stargate. For ibc it’s likely not needed yet (because there isn’t a huge amount of live data on the hub). So migrating the current GenesisState to proto files is probably okay. However, the streaming genesis is l believe the future proof way to go for large import/exports. This is likely something we should discuss in our SDK call Friday.

[aaronc]

@anilCSE and @sahith-narahari are going to export data from Cosmos Hub 3 so that we have a sense of how large the genesis import/export is. Then we can assess the best path forward.

[dokwon]

What are the performance benefits from streaming JSON?

We've explored storing genesis state as a binary (we have 1.7M accounts and state is getting bloated) and only present genesis.json for readability purposes.

[YunSuk-Yeo]

Terra will release cosmwasm before Stargate, so the state size is going much lager. In this aspect, we need streaming feature to avoid out of memory situation.

As @dokwon mentioned, It can be level db store like binary format.

[anilCSE]

@anilCSE and @sahith-narahari are going to export data from Cosmos Hub 3 so that we have a sense of how large the genesis import/export is. Then we can assess the best path forward.

Hub's exported state is ~52M in size, we might not need streaming genesis for stargate. We can address that later may be.

[aaronc]

Thanks @anilCSE.

So sounds like it's more of an issue for Terra possibly. @YunSuk-Yeo do you know the actual size of the exported Terra genesis.json file?

[dokwon]

@aaronc Our exported genstate for Columbus-3 (December last year) was around 500M. Assuming filesize growth is linear to account number growth that would imply a Columbus-4 genstate fillesize of > 1GB. The first block took a good 2 minutes for the fastest validators to process, and a lot longer for most others.

While I understand that the Hub would not have similar issues, think the SDK development should reflect needs of client chains that see sizable use.

[aaronc]

@dokwon @YunSuk-Yeo unfortunately we won't have the time to complete streaming genesis for the 0.40 release - there is just too much on our backlog. I have, however, created an issue specifically for this (#6936) and tagged it for the 0.41 release.