lightning::util::anchor_channel_reserves

Function get_reserve_per_channel

Source 
pub fn get_reserve_per_channel(context: &AnchorChannelReserveContext) -> Amount
Expand description

Returns the amount that needs to be maintained as a reserve per anchor channel.

This reserve currently needs to be allocated as a disjoint set of at least 1 UTXO per channel, as claims are not yet aggregated across channels.

To only require 1 UTXO per channel, it is assumed that, on average, transactions are able to get confirmed within 1 block with ConfirmationTarget::UrgentOnChainSweep, or that only a portion of channels will go through unilateral closure at the same time, allowing UTXOs to be shared. Otherwise, multiple UTXOs would be needed per channel:

  • HTLC time-out transactions with different expiries cannot be aggregated. This could result in many individual transactions that need to be confirmed starting from different, but potentially sequential block heights.
  • If each transaction takes N blocks to confirm, at least N UTXOs per channel are needed to provide the necessary concurrency.

The returned amount includes the fee to spend a single UTXO of the type indicated by AnchorChannelReserveContext::taproot_wallet. Larger sets of UTXOs with more complex witnesses will need to include the corresponding fee required to spend them.