152 lines
3.6 KiB
Go
152 lines
3.6 KiB
Go
package bcast
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import (
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"context"
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"encoding/binary"
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"fmt"
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"sync"
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"time"
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"github.com/filecoin-project/go-state-types/abi"
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"github.com/filecoin-project/lotus/chain/types"
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"github.com/ipfs/go-cid"
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"github.com/multiformats/go-multihash"
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)
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// TODO: Take const out of here and make them build params.
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const (
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DELAY = 6 * time.Second
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GC_SANITY_CHECK = 5
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GC_LOOKBACK = 2
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)
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type blksInfo struct {
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ctx context.Context
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cancel context.CancelFunc
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blks []cid.Cid
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}
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type bcastDict struct {
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// thread-safe map impl for the dictionary
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// sync.Map accepts `any` as keys and values.
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// To make it type safe and only support the right
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// types we use this auxiliary type.
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m *sync.Map
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}
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func (bd *bcastDict) load(key multihash.Multihash) (*blksInfo, bool) {
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v, ok := bd.m.Load(key.String())
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if !ok {
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return nil, ok
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}
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return v.(*blksInfo), ok
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}
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func (bd *bcastDict) store(key multihash.Multihash, d *blksInfo) {
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bd.m.Store(key.String(), d)
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}
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type ConsistentBCast struct {
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lk sync.Mutex
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delay time.Duration
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// FIXME: Make this a slice??? Less storage but needs indexing logic.
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m map[abi.ChainEpoch]*bcastDict
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}
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func newBcastDict(delay time.Duration) *bcastDict {
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return &bcastDict{new(sync.Map)}
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}
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// TODO: What if the VRFProof is already small?? We don´t need the CID. Useless computation.
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func BCastKey(bh *types.BlockHeader) (multihash.Multihash, error) {
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proof := bh.Ticket.VRFProof
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binary.PutVarint(proof, int64(bh.Height))
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return multihash.Sum(proof, multihash.SHA2_256, -1)
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}
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func NewConsistentBCast(delay time.Duration) *ConsistentBCast {
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return &ConsistentBCast{
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delay: delay,
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m: make(map[abi.ChainEpoch]*bcastDict),
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}
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}
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func cidExists(cids []cid.Cid, c cid.Cid) bool {
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for _, v := range cids {
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if v == c {
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return true
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}
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}
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return false
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}
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func (bInfo *blksInfo) eqErr() error {
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bInfo.cancel()
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return fmt.Errorf("equivocation error detected. Different block with the same ticket already seen")
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}
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func (cb *ConsistentBCast) RcvBlock(ctx context.Context, blk *types.BlockMsg) error {
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cb.lk.Lock()
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bcastDict, ok := cb.m[blk.Header.Height]
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if !ok {
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bcastDict = newBcastDict(cb.delay)
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cb.m[blk.Header.Height] = bcastDict
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}
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cb.lk.Unlock()
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key, err := BCastKey(blk.Header)
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if err != nil {
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return err
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}
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blkCid := blk.Cid()
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bInfo, ok := bcastDict.load(key)
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if ok {
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if len(bInfo.blks) > 1 {
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return bInfo.eqErr()
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}
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if !cidExists(bInfo.blks, blkCid) {
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bInfo.blks = append(bInfo.blks, blkCid)
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return bInfo.eqErr()
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}
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return nil
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}
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ctx, cancel := context.WithTimeout(ctx, cb.delay*time.Second)
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bcastDict.store(key, &blksInfo{ctx, cancel, []cid.Cid{blkCid}})
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return nil
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}
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func (cb *ConsistentBCast) WaitForDelivery(bh *types.BlockHeader) error {
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bcastDict := cb.m[bh.Height]
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key, err := BCastKey(bh)
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if err != nil {
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return err
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}
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bInfo, ok := bcastDict.load(key)
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if !ok {
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return fmt.Errorf("something went wrong, unknown block with Epoch + VRFProof (cid=%s) in consistent broadcast storage", key)
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}
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// Wait for the timeout
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<-bInfo.ctx.Done()
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if len(bInfo.blks) > 1 {
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return fmt.Errorf("equivocation detected for epoch %d. Two blocks being broadcast with same VRFProof", bh.Height)
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}
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return nil
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}
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func (cb *ConsistentBCast) GarbageCollect(currEpoch abi.ChainEpoch) {
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cb.lk.Lock()
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defer cb.lk.Unlock()
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// keep currEpoch-2 and delete a few more in the past
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// as a sanity-check
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// Garbage collection is triggered before block delivery,
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// and we use the sanity-check in case there were a few rounds
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// without delivery, and the garbage collection wasn't triggered
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// for a few epochs.
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for i := 0; i < GC_SANITY_CHECK; i++ {
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delete(cb.m, currEpoch-abi.ChainEpoch(2-i))
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}
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}
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