80 lines
2.0 KiB
Go
80 lines
2.0 KiB
Go
package events
|
|
|
|
import (
|
|
"golang.org/x/xerrors"
|
|
|
|
"github.com/filecoin-project/go-lotus/chain/types"
|
|
)
|
|
|
|
// tipSetCache implements a simple ring-buffer cache to keep track of recent
|
|
// tipsets
|
|
type tipSetCache struct {
|
|
cache []*types.TipSet
|
|
start int
|
|
len int
|
|
}
|
|
|
|
func newTSCache(cap int) *tipSetCache {
|
|
return &tipSetCache{
|
|
cache: make([]*types.TipSet, cap),
|
|
start: 0,
|
|
len: 0,
|
|
}
|
|
}
|
|
|
|
func (tsc *tipSetCache) add(ts *types.TipSet) error {
|
|
if tsc.len > 0 {
|
|
if tsc.cache[tsc.start].Height()+1 != ts.Height() {
|
|
return xerrors.Errorf("tipSetCache.add: expected new tipset height to be %d, was %d", tsc.cache[tsc.start].Height()+1, ts.Height())
|
|
}
|
|
}
|
|
|
|
tsc.start = (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 = (tsc.start - 1) % len(tsc.cache)
|
|
tsc.len--
|
|
return nil
|
|
}
|
|
|
|
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)
|
|
}
|
|
|
|
tailH := tsc.cache[(tsc.start-tsc.len+1)%len(tsc.cache)].Height()
|
|
|
|
if height < tailH {
|
|
// TODO: we can try to walk parents, but that shouldn't happen in
|
|
// practice, so it's probably not worth implementing
|
|
return nil, xerrors.Errorf("tipSetCache.get: requested tipset not in cache (req: %d, cache tail: %d)", height, tailH)
|
|
}
|
|
|
|
return tsc.cache[int(height-tailH+1)%len(tsc.cache)], nil
|
|
}
|
|
|
|
func (tsc *tipSetCache) best() *types.TipSet {
|
|
return tsc.cache[tsc.start]
|
|
}
|