Calculate new round active delegate list from memory and not from database

[fix]

Is your feature request related to a problem? Please describe.
Right now the calculation of the delegate list is made from database. This degrades performance because the wallets that have changed during last round should be synced with database before the calculation occurs. Using very costly upsert.

see the note https://github.com/ArkEcosystem/core/blob/blockchain_fix/packages/core-database-sequelize/lib/connection.js#L323

Describe the solution you'd like
The best way would be to to the calculation in wallet manager with a function calculateDelegateList(delegateMax = 51) inside https://github.com/ArkEcosystem/core/blob/blockchain_fix/packages/core-database/lib/wallet-manager.js#L16
consisting on 2 separate actions:

• updating each delegate wallets with balance of voters
• sorting top most voted delegate wallets.

and use it instead of the database calculation here https://github.com/ArkEcosystem/core/blob/blockchain_fix/packages/core-database/lib/interface.js#L71 instead of a database implementation

Describe alternatives you've considered
Even better would be to update the votes here https://github.com/ArkEcosystem/core/blob/blockchain_fix/packages/core-database/lib/wallet-manager.js inside the 4 functions:

• applyTransaction
• revertTransaction
• applyBlock
• revertBlock

in the end getting the delegate list would be as simple as sorting the most voted wallets

[faustbrian]

Can now be resolved by making use of https://github.com/ArkEcosystem/core/tree/develop/packages/core-storage