Min. Cost Flow does not take into account fees when computing a flow
with liquidity constraints.
This is a work-around solution that reduces the amount on every route to
respect the liquidity bound. The deficity in the delivered amount is
solved by running MCF once again.
Changes:
1. the function `flow_complete` allocates amounts to send over the set of routes
computed by the MCF algorithm, but it does not allocate more than liquidity
bound of the route. For this reason `minflow` returns a set of routes that
satisfy the liquidity bounds but it is not guaranteed that the total payment
reaches the destination therefore there could a deficit in the delivery:
`deficit = amount_to_deliver - delivering`.
2. in the function `add_payflows` after `minflow` returns a set of routes we
call `flows_fit_amount` that tries to a allocate the `deficit` in the routes
that the MCF have computed.
3. if the resulting flows pass all payment constraints then we update
`amount_to_deliver = amount_to_deliver - delivering`, and the loop
repeats as long as `amount_to_deliver` is not zero.
In other words, the excess amount, beyond the liquidity bound,
in the routes is removed and then we try to allocate it
into known routes, otherwise we do a whole MCF again just for the
remaining amount.
Fixes issue #6599
We will get localmods from gossmods_from_listpeerchannels in the next commit,
so we need to save routehints to add to that later.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The main function here is payment_reconsider:
* Each payment has a list of pay_flow.
* This is populated in try_paying(), calling add_payflows & sendpay_new_flows.
* When we get a notification, we resolve a pay_flow using one of the pay_flow_failedxxx
or pay_flow_succeeded functions.
* They call payment_reconsider() which cleans up finished flows decides what to do:
often calling try_paying again.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
There are a few fields in `struct renepay` which are genuinely
transient, but it makes the code much harder to follow than simply
having a single structure.
More cleanups will follow, but this is the minimal set.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The general pattern for xxx_new is that it should populate all
fields, for encapsulation and so you never can have a half-formed
object.
This means a fair bit of work for now, but it pays off in the next
patch.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
You cannot refresh the gossmap with localmods applied, nor apply localmods
when others have applied localmods in the same process.
There are optimizations we could do, but for now always apply/unapply before
querying gossmap.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
- adopt "const <type> *"convention
- remove use_shadow option for some pyln tests
- show prob. information of flows into paynotes
- show prob. of success of entire payment flow in paynotes
- minflow: We were not releasing the memory of flow arrays when replacing
them with a new canditate.
- use memleak_scan_obj in memleak_check
- replace u64 with size_t
Signed-off-by: Lagrang3 <eduardo.quintana@pm.me>
- remove internal gheap checks
- add check for arc_t.chanidx overflow
- remove outdated comments
- check the delta flow bounds before augmenting along a path
- get_flow_paths uses a dynamic tal array instead of a list.
- fix a unit test that depended on the order of returned flows
- fix bug: lightnind doesn't like if I reuse the partid of a failed
flow, therefore use a higher partid than any of the previous attempts.
- plugin_err instead of LOG_BROKEN if sendpay fails and we cannot get a
an error code.
- fix wrong comments.
- remove the background timer.
- This is a bugfix. Previous to this the MCF network was built using the
knowledge of the min and max liquidity but it didn't take into account
pending HTLCs.
- Also remove the min_prob_success option but hardcode a 90% value.
Removing some options that are not relevant to the user, they're kept
for developer mode only:
- base_fee_penalty
- min_prob_success
- prob_cost_factor
- remove heap.h, not used
Signed-off-by: Lagrang3 <eduardo.quintana@pm.me>
Lagrang3
Lagrang3
Rusty Russell