In this commit, we attempt to fix a bug that's possible within the
Start() method of the ChainArbiter. We pass the channel pointer directly
into the newActiveChannelArbitrator function causing it to close over
the loop variable. We later use the channel point directly to send
messages to other sub-systems. It's possible that we actually have the
shadowed loop variable and will send an incorrect message. Defensively,
we now re-bind the loop variable in order to ensure we point to the
proper channel.
This commit adds a test for the case where the ChannelArbitrator fails
to broadcast its commitment during a force close because of
ErrDoubleSpend. We test that in this case it will still wait for a
commitment getting confirmed in-chain, then resolve.
This commit adds the new function closure option ContractBreach to the
ChainArbitrator config, a closure that is again used by the ChainWatcher
to reliably handoff a breach event to the breachArbiter.
This commit changes how the ChainWatcher notifies the breachArbiter
about a channel breach. Instead of assuming the breachArbiter is among
the clients subscibing to channel events, it will call a new method
contractBreach(), and assume the breachArbiter has reliably gotten the
breach info when this method returns with a non-nil error.
Since the breachArbiter was the only sybsystem having a sync chain
subsciption, we also remove the (now) unused syncDispatch option.
This move the log message "channel marked pending-closed" to the point
where the channel actually has been marked pending closed, instead of
before the database transaction has been done.
This commit removes the for loop in the closeObserver, as it wasn't
serving any purpose. After receiving a spend notification we would
return, breaking out of the loop. When getting a quit signal we would
also return, making the loop only do one iteration in any case.
This commit makes clients subscribing to channel events that are marked
"sync dispatch" _not_ being deleted from the list of clients when they
call Cancel(). Instead a go routine will be launched that will send an
error on every read of the ProcessACK channel.
This fixes a race in handing off the breach info while lnd was shutting
down. The breach arbiter could end up being shut down (and calling
Cancel()) before while the ChainWatcher was in the process of
dispatching a breach. Since the breach arbiter no longer was among the
registered clients at this point, the ChainWatcher would assume the
breach was handed off successfully, and mark the channel as pending
closed. When lnd now was restarted, the breach arbiter would not know
about the breach, and the ChainWatcher wouldn't attempt to re-dispatch,
as it was already marked as pending closed.
This commit adds MVP unit tests for the following scenarios in the
ChannelArbitrator:
1) A cooperative close is confirmed.
2) A remote force close is confirmed.
3) A local force close is requested and confirmed.
4) A local force close is requested, but a remote force close gets
confirmed.
This commit changes the ChainWatcher to only send a chain event in case
the various spends are _confirmed_ on-chain, not only seen on the
network.
A consequence of this is that we now give the ChainWatcher the
responsibility of marking the channel closed when the closing tx is
confirmed, instead of the ChannelArbitrator.
This commit changes the channel arbitrator state machine to only care
about commitment transactions that are being confirmed on-chain
according to the chain_watcher. This is meant to handles the cases where
we would broadcast our commitment, expecting it to get confirmed, but
instead a competing transaction was confirmed.
This commit readies the ChannelArbitrator state machine for the change
that will make the ChainWatcher only notify on confirmed commitments.
The state machine has gotten a new state, StateCommitmentBroadcasted,
which we'll transition to after we have broadcasted our own commitment.
From this state we'll go to the StateContractClosed state regardless of
which commitment the ChainWatcher notifies about, unifying the contract
resolution betweee the local and remote force close.
This commit adds a new method dispatchLocalClose, which will be called
in case our commitment is detected to spend the funding transaction. In
this case LocalUnilateralCloseInfo will be sent on the
LocalUnilateralClosure channel to all subscribers.
The UnilateralClosure channel is renamed to RemoteUnilateralClosure for
consistency.
This commit removes a short circuit checking if the contract resolver
after a unilateral close is empty. After removing this, the state
machine will advance the state from StateDefault->ContractClosed, in
which the stateCallback will be called, logging the state needed to
advance. Since this logged state is empty, the state machine will go
directly to StateFullyResolved, which will trigger the
MarkChannelResolved call. This means the behaviour is kept.
This commit adds a missing return to the resolveContract method, that
will ensure the goroutine exits if the ChannelArbitrator shuts down.
This fixes a potential deadlock during the integration tests.
We also promote some of the logs to Debug from Trace.
In this commit, we fix a long standing bug where at times a co-op
channel closure wouldn't be properly marked as fully closed in the
database. The culprit was a re-occurring code flaw we've seen many times
in the codebase: a closure variable that closes over a loop iterator
variable. Before this instance, I assumed that this could only pop up
when goroutines bind to the loop iterator within a closure. However,
this instance is the exact same issue, but within a regular closure that
has _delayed_ execution. As the closure doesn't execute until long after
the loop has finished executing, it may still be holding onto the _last_
item the loop iterator variable was assigned to.
The fix for this issue is very simple: re-assign the channel point
before creating the closure. Without this fix, we would go to call
db.MarkChanFullyClosed on a channel that may not have yet actually be in
the pending close state, causing all executions to fail.
Fixes#1054.
Fixes#1056.
Fixes#1075.
This commit renames ForceCloseSummary to LocalForceCloseSummary, and
adds a new method NewLocalForceCloseSummary that can be used to derive a
LocalForceCloseSummary if our commitment transaction gets confirmed
in-chain. It is meant to accompany the NewUnilateralCloseSummary method,
which is used for the same purpose in the event of a remote commitment
being seen in-chain.
This commit mitigates a problem within the ChannelArbitrator, where
after a restart we would start up in the state StateBroadcastCommit but
fail to broadcast out commitment because a conflicting transaction (most
likely our own commitment) was already broadcast. A more complete fix
for this case will be added later, but this commit let the
ChannelArbitrator continue, trying to close out the channel.
