lotus/chain/events/tscache.go
2019-09-18 15:32:21 +02:00

85 lines
1.9 KiB
Go

package events
import (
"context"
"golang.org/x/xerrors"
"github.com/filecoin-project/go-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()+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 {
return tsc.storage(context.TODO(), height, tsc.cache[tailH])
}
return tsc.cache[int(height-tailH+1)%len(tsc.cache)], nil
}
func (tsc *tipSetCache) best() *types.TipSet {
return tsc.cache[tsc.start]
}