[core] user state db

[vivianjeng]

User can have his db to store related data
e.g.

data	type	description
attesterId	String	the attester ID
latestTransitionedEpoch	Int	the schema is created at which epoch
latestTransitionedIndex	Int	in this epoch, the index of the user in the state tree
provableData	Object	the data in the state tree
latestData	Object	the data in the current epoch

so the user doesn't have to search through all epochs

Unirep/packages/core/src/UserState.ts

Lines 284 to 299 in b51a3a4

	for (let x = signup?.epoch ?? 0; x <= toEpoch; x++) {
	allNullifiers.push(
	...[0, this.sync.settings.numEpochKeyNoncePerEpoch].map((v) =>
	genEpochKey(
	this.id.secret,
	attesterId,
	x,
	v,
	this.chainId
	).toString()
	)
	)
	}
	const sortedNullifiers = await this.sync.db.findMany('Nullifier', {
	where: {
	attesterId,

Details

original getData

epoch	data 1	data 2	data 3	data 4
0	0	0	1	0
1	0	0	0	1
2	1	0	0	0
3	0	1	0	0
...	...	...	...	...
total	1	1	1	1

proposed db

If there is no db, then use original getData to get the latest data

name	data
provable data	[1,1,1, 1]
latest transition epoch	3

new epoch original getData

epoch	data 1	data 2	data 3	data 4
0	0	0	1	0
1	0	0	0	1
2	1	0	0	0
3	0	1	0	0
4	1	1	1	1
...	...	...	...	...
total	2	2	2	2

new epoch proposed db

If there is a db, then new data is updated by
db.provableData = db.provableData + newData
[2,2,2,2] = [1,1,1,1] + [1,1,1,1]

name	data
provable data	[2,2,2, 2]
latest transition epoch	4