80 lines
1.9 KiB
Go
80 lines
1.9 KiB
Go
package store
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import (
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"golang.org/x/xerrors"
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"github.com/filecoin-project/go-lotus/chain/types"
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)
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// tipSetCache implements a simple ring-buffer cache to keep track of recent
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// tipsets
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type tipSetCache struct {
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cache []*types.TipSet
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start int
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len int
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}
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func newTSCache(cap int) *tipSetCache {
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return &tipSetCache{
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cache: make([]*types.TipSet, cap),
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start: 0,
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len: 0,
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}
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}
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func (tsc *tipSetCache) add(ts *types.TipSet) error {
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if tsc.len > 0 {
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if tsc.cache[tsc.start].Height()+1 != ts.Height() {
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return xerrors.Errorf("tipSetCache.add: expected new tipset height to be %d, was %d", tsc.cache[tsc.start].Height()+1, ts.Height())
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}
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}
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tsc.start = (tsc.start + 1) % len(tsc.cache)
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tsc.cache[tsc.start] = ts
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if tsc.len < len(tsc.cache) {
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tsc.len++
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}
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return nil
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}
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func (tsc *tipSetCache) revert(ts *types.TipSet) error {
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if tsc.len == 0 {
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return xerrors.New("tipSetCache.revert: nothing to revert; cache is empty")
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}
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if !tsc.cache[tsc.start].Equals(ts) {
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return xerrors.New("tipSetCache.revert: revert tipset didn't match cache head")
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}
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tsc.cache[tsc.start] = nil
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tsc.start = (tsc.start - 1) % len(tsc.cache)
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tsc.len--
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return nil
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}
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func (tsc *tipSetCache) get(height uint64) (*types.TipSet, error) {
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if tsc.len == 0 {
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return nil, xerrors.New("tipSetCache.get: cache is empty")
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}
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headH := tsc.cache[tsc.start].Height()
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if height > headH {
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return nil, xerrors.Errorf("tipSetCache.get: requested tipset not in cache (req: %d, cache head: %d)", height, headH)
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}
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tailH := tsc.cache[(tsc.start-tsc.len+1)%len(tsc.cache)].Height()
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if height < tailH {
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// TODO: we can try to walk parents, but that shouldn't happen in
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// practice, so it's probably not worth implementing
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return nil, xerrors.Errorf("tipSetCache.get: requested tipset not in cache (req: %d, cache tail: %d)", height, tailH)
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}
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return tsc.cache[int(height-tailH+1)%len(tsc.cache)], nil
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}
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func (tsc *tipSetCache) best() *types.TipSet {
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return tsc.cache[tsc.start]
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}
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