lnd.xprv/chanacceptor/chainedacceptor.go

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package chanacceptor
import (
"sync"
"sync/atomic"
)
// ChainedAcceptor represents a conjunction of ChannelAcceptor results.
type ChainedAcceptor struct {
// acceptors is a map of ChannelAcceptors that will be evaluated when
// the ChainedAcceptor's Accept method is called.
acceptors map[uint64]ChannelAcceptor
acceptorsMtx sync.RWMutex
acceptorID uint64 // To be used atomically.
}
// NewChainedAcceptor initializes a ChainedAcceptor.
func NewChainedAcceptor() *ChainedAcceptor {
return &ChainedAcceptor{
acceptors: make(map[uint64]ChannelAcceptor),
}
}
// AddAcceptor adds a ChannelAcceptor to this ChainedAcceptor.
func (c *ChainedAcceptor) AddAcceptor(acceptor ChannelAcceptor) uint64 {
id := atomic.AddUint64(&c.acceptorID, 1)
c.acceptorsMtx.Lock()
c.acceptors[id] = acceptor
c.acceptorsMtx.Unlock()
// Return the id so that a caller can call RemoveAcceptor.
return id
}
// RemoveAcceptor removes a ChannelAcceptor from this ChainedAcceptor given
// an ID.
func (c *ChainedAcceptor) RemoveAcceptor(id uint64) {
c.acceptorsMtx.Lock()
delete(c.acceptors, id)
c.acceptorsMtx.Unlock()
}
// Accept evaluates the results of all ChannelAcceptors in the acceptors map
// and returns the conjunction of all these predicates.
//
// NOTE: Part of the ChannelAcceptor interface.
func (c *ChainedAcceptor) Accept(req *ChannelAcceptRequest) *ChannelAcceptResponse {
c.acceptorsMtx.RLock()
defer c.acceptorsMtx.RUnlock()
var finalResp ChannelAcceptResponse
for _, acceptor := range c.acceptors {
// Call our acceptor to determine whether we want to accept this
// channel.
acceptorResponse := acceptor.Accept(req)
// If we should reject the channel, we can just exit early. This
// has the effect of returning the error belonging to our first
// failed acceptor.
if acceptorResponse.RejectChannel() {
return acceptorResponse
}
// If we have accepted the channel, we need to set the other
// fields that were set in the response. However, since we are
// dealing with multiple responses, we need to make sure that we
// have not received inconsistent values (eg a csv delay of 1
// from one acceptor, and a delay of 120 from another). We
// set each value on our final response if it has not been set
// yet, and allow duplicate sets if the value is the same. If
// we cannot set a field, we return an error response.
var err error
finalResp, err = mergeResponse(finalResp, *acceptorResponse)
if err != nil {
log.Errorf("response for: %x has inconsistent values: %v",
req.OpenChanMsg.PendingChannelID, err)
return NewChannelAcceptResponse(
false, errChannelRejected, nil, 0, 0,
0, 0, 0, 0,
)
}
}
// If we have gone through all of our acceptors with no objections, we
// can return an acceptor with a nil error.
return &finalResp
}
// A compile-time constraint to ensure ChainedAcceptor implements the
// ChannelAcceptor interface.
var _ ChannelAcceptor = (*ChainedAcceptor)(nil)