package events import ( "context" "golang.org/x/xerrors" "github.com/filecoin-project/lotus/chain/types" ) type tsByHFunc func(context.Context, uint64, *types.TipSet) (*types.TipSet, error) // tipSetCache implements a simple ring-buffer cache to keep track of recent // tipsets type tipSetCache struct { cache []*types.TipSet start int len int storage tsByHFunc } func newTSCache(cap int, storage tsByHFunc) *tipSetCache { return &tipSetCache{ cache: make([]*types.TipSet, cap), start: 0, len: 0, storage: storage, } } func (tsc *tipSetCache) add(ts *types.TipSet) error { if tsc.len > 0 { if tsc.cache[tsc.start].Height() >= ts.Height() { return xerrors.Errorf("tipSetCache.add: expected new tipset height to be at least %d, was %d", tsc.cache[tsc.start].Height()+1, ts.Height()) } } nextH := ts.Height() if tsc.len > 0 { nextH = tsc.cache[tsc.start].Height() + 1 } // fill null blocks for nextH != ts.Height() { tsc.start = normalModulo(tsc.start+1, len(tsc.cache)) tsc.cache[tsc.start] = nil if tsc.len < len(tsc.cache) { tsc.len++ } nextH++ } tsc.start = normalModulo(tsc.start+1, len(tsc.cache)) tsc.cache[tsc.start] = ts if tsc.len < len(tsc.cache) { tsc.len++ } return nil } func (tsc *tipSetCache) revert(ts *types.TipSet) error { if tsc.len == 0 { return xerrors.New("tipSetCache.revert: nothing to revert; cache is empty") } if !tsc.cache[tsc.start].Equals(ts) { return xerrors.New("tipSetCache.revert: revert tipset didn't match cache head") } tsc.cache[tsc.start] = nil tsc.start = normalModulo(tsc.start-1, len(tsc.cache)) tsc.len-- _ = tsc.revert(nil) // revert null block gap return nil } func (tsc *tipSetCache) getNonNull(height uint64) (*types.TipSet, error) { for { ts, err := tsc.get(height) if err != nil { return nil, err } if ts != nil { return ts, nil } height++ } } func (tsc *tipSetCache) get(height uint64) (*types.TipSet, error) { if tsc.len == 0 { return nil, xerrors.New("tipSetCache.get: cache is empty") } headH := tsc.cache[tsc.start].Height() if height > headH { return nil, xerrors.Errorf("tipSetCache.get: requested tipset not in cache (req: %d, cache head: %d)", height, headH) } clen := len(tsc.cache) var tail *types.TipSet for i := 1; i <= tsc.len; i++ { tail = tsc.cache[normalModulo(tsc.start-tsc.len+i, clen)] if tail != nil { break } } if height < tail.Height() { log.Warnf("tipSetCache.get: requested tipset not in cache, requesting from storage (h=%d; tail=%d)", height, tail.Height()) return tsc.storage(context.TODO(), height, tail) } return tsc.cache[normalModulo(tsc.start-int(headH-height), clen)], nil } func (tsc *tipSetCache) best() *types.TipSet { return tsc.cache[tsc.start] } func normalModulo(n, m int) int { return ((n % m) + m) % m }