Smart contract for "perpetual" staking pool(flexible rewards and time)?

Are there any existing smart contracts for staking pools? Are there any popular models?

It would be a bonus if the pool was perpetual, as in: it would run all the time and distribute the tokens to the holders at some formula + THAT you could keep depositing tokens(for rewards) into a pool and the pool would re-balance.

So instead of a pool where there is fixed amount of tokens and fixed expiration block(like pancakeswap), a pool keeps running and the tokens can keep getting deposited into a pool?