83 lines
2.4 KiB
Go
83 lines
2.4 KiB
Go
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package wtclient
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import (
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"container/list"
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"sync"
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"github.com/lightningnetwork/lnd/watchtower/wtdb"
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)
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// TowerCandidateIterator provides an abstraction for iterating through possible
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// watchtower addresses when attempting to create a new session.
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type TowerCandidateIterator interface {
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// Reset clears any internal iterator state, making previously taken
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// candidates available as long as they remain in the set.
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Reset() error
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// Next returns the next candidate tower. The iterator is not required
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// to return results in any particular order. If no more candidates are
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// available, ErrTowerCandidatesExhausted is returned.
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Next() (*wtdb.Tower, error)
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}
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// towerListIterator is a linked-list backed TowerCandidateIterator.
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type towerListIterator struct {
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mu sync.Mutex
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candidates *list.List
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nextCandidate *list.Element
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}
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// Compile-time constraint to ensure *towerListIterator implements the
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// TowerCandidateIterator interface.
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var _ TowerCandidateIterator = (*towerListIterator)(nil)
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// newTowerListIterator initializes a new towerListIterator from a variadic list
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// of lnwire.NetAddresses.
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func newTowerListIterator(candidates ...*wtdb.Tower) *towerListIterator {
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iter := &towerListIterator{
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candidates: list.New(),
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}
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for _, candidate := range candidates {
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iter.candidates.PushBack(candidate)
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}
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iter.Reset()
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return iter
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}
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// Reset clears the iterators state, and makes the address at the front of the
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// list the next item to be returned..
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func (t *towerListIterator) Reset() error {
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t.mu.Lock()
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defer t.mu.Unlock()
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// Reset the next candidate to the front of the linked-list.
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t.nextCandidate = t.candidates.Front()
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return nil
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}
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// Next returns the next candidate tower. This iterator will always return
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// candidates in the order given when the iterator was instantiated. If no more
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// candidates are available, ErrTowerCandidatesExhausted is returned.
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func (t *towerListIterator) Next() (*wtdb.Tower, error) {
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t.mu.Lock()
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defer t.mu.Unlock()
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// If the next candidate is nil, we've exhausted the list.
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if t.nextCandidate == nil {
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return nil, ErrTowerCandidatesExhausted
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}
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// Propose the tower at the front of the list.
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tower := t.nextCandidate.Value.(*wtdb.Tower)
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// Set the next candidate to the subsequent element.
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t.nextCandidate = t.nextCandidate.Next()
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return tower, nil
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}
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// TODO(conner): implement graph-backed candidate iterator for public towers.
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