waiter.go

package chain

import (
	"context"
	"fmt"

	"github.com/filecoin-project/go-address"
	"github.com/filecoin-project/go-state-types/abi"
	"github.com/filecoin-project/venus/pkg/constants"
	"github.com/filecoin-project/venus/pkg/vm"
	"github.com/filecoin-project/venus/venus-shared/types"
	"github.com/ipfs/go-cid"
	bstore "github.com/ipfs/go-ipfs-blockstore"
	cbor "github.com/ipfs/go-ipld-cbor"
	"github.com/pkg/errors"
)

type MsgLookup struct {
	Message   cid.Cid // Can be different than requested, in case it was replaced, but only gas values changed
	Receipt   types.MessageReceipt
	ReturnDec interface{}
	TipSet    types.TipSetKey
	Height    abi.ChainEpoch
}

// Abstracts over a store of blockchain state.
type waiterChainReader interface {
	GetHead() *types.TipSet
	GetTipSet(context.Context, types.TipSetKey) (*types.TipSet, error)
	LookupID(context.Context, *types.TipSet, address.Address) (address.Address, error)
	GetActorAt(context.Context, *types.TipSet, address.Address) (*types.Actor, error)
	GetTipSetReceiptsRoot(context.Context, *types.TipSet) (cid.Cid, error)
	SubHeadChanges(context.Context) chan []*types.HeadChange
}

type IStmgr interface {
	GetActorAt(context.Context, address.Address, *types.TipSet) (*types.Actor, error)
	RunStateTransition(context.Context, *types.TipSet, vm.ExecCallBack, bool) (root cid.Cid, receipts cid.Cid, err error)
}

// Waiter waits for a message to appear on chain.
type Waiter struct {
	chainReader     waiterChainReader
	messageProvider MessageProvider
	cst             cbor.IpldStore
	bs              bstore.Blockstore
	Stmgr           IStmgr
}

// WaitPredicate is a function that identifies a message and returns true when found.
type WaitPredicate func(msg *types.Message, msgCid cid.Cid) bool

// NewWaiter returns a new Waiter.
func NewWaiter(chainStore waiterChainReader, messages MessageProvider, bs bstore.Blockstore, cst cbor.IpldStore) *Waiter {
	return &Waiter{
		chainReader:     chainStore,
		cst:             cst,
		bs:              bs,
		messageProvider: messages,
	}
}

// Find searches the blockchain history (but doesn't wait).
func (w *Waiter) Find(ctx context.Context, msg types.ChainMsg, lookback abi.ChainEpoch, ts *types.TipSet, allowReplaced bool) (*types.ChainMessage, bool, error) {
	if ts == nil {
		ts = w.chainReader.GetHead()
	}

	return w.findMessage(ctx, ts, msg, lookback, allowReplaced)
}

// WaitPredicate invokes the callback when the passed predicate succeeds.
// See api description.
//
// Note: this method does too much -- the callback should just receive the tipset
// containing the message and the caller should pull the receipt out of the block
// if in fact that's what it wants to do, using something like receiptFromTipset.
// Something like receiptFromTipset is necessary because not every message in
// a block will have a receipt in the tipset: it might be a duplicate message.
// This method will always check for the message in the current head tipset.
// A lookback parameter > 1 will cause this method to check for the message in
// up to that many previous tipsets on the chain of the current head.
func (w *Waiter) WaitPredicate(ctx context.Context, msg types.ChainMsg, confidence uint64, lookback abi.ChainEpoch, allowReplaced bool) (*types.ChainMessage, error) {
	ch := w.chainReader.SubHeadChanges(ctx)
	chainMsg, found, err := w.waitForMessage(ctx, ch, msg, confidence, lookback, allowReplaced)
	if err != nil {
		return nil, err
	}
	if found {
		return chainMsg, nil
	}
	return nil, nil
}

// Wait uses WaitPredicate to invoke the callback when a message with the given cid appears on chain.
func (w *Waiter) Wait(ctx context.Context, msg types.ChainMsg, confidence uint64, lookbackLimit abi.ChainEpoch, allowReplaced bool) (*types.ChainMessage, error) {
	mid := msg.VMMessage().Cid()
	log.Infof("Calling Waiter.Wait CID: %s", mid.String())

	return w.WaitPredicate(ctx, msg, confidence, lookbackLimit, allowReplaced)
}

// findMessage looks for a matching in the chain and returns the message,
// block and receipt, when it is found. Returns the found message/block or nil
// if now block with the given CID exists in the chain.
// The lookback parameter is the number of tipsets in the past this method will check before giving up.
func (w *Waiter) findMessage(ctx context.Context, from *types.TipSet, m types.ChainMsg, lookback abi.ChainEpoch, allowReplaced bool) (*types.ChainMessage, bool, error) {
	limitHeight := from.Height() - lookback
	noLimit := lookback == constants.LookbackNoLimit

	cur := from
	curActor, err := w.Stmgr.GetActorAt(ctx, m.VMMessage().From, cur)
	if err != nil {
		return nil, false, fmt.Errorf("failed to load from actor")
	}

	mNonce := m.VMMessage().Nonce

	for {
		// If we've reached the genesis block, or we've reached the limit of
		// how far back to look
		if cur.Height() == 0 || !noLimit && cur.Height() <= limitHeight {
			// it ain't here!
			return nil, false, nil
		}

		select {
		case <-ctx.Done():
			return nil, false, nil
		default:
		}

		// we either have no messages from the sender, or the latest message we found has a lower nonce than the one being searched for,
		// either way, no reason to lookback, it ain't there
		if curActor == nil || curActor.Nonce == 0 || curActor.Nonce < mNonce {
			return nil, false, nil
		}

		pts, err := w.chainReader.GetTipSet(ctx, cur.Parents())
		if err != nil {
			return nil, false, fmt.Errorf("failed to load tipset during msg wait searchback: %w", err)
		}

		act, err := w.Stmgr.GetActorAt(ctx, m.VMMessage().From, pts)
		actorNoExist := errors.Is(err, types.ErrActorNotFound)
		if err != nil && !actorNoExist {
			return nil, false, fmt.Errorf("failed to load the actor: %w", err)
		}

		// check that between cur and parent tipset the nonce fell into range of our message
		if actorNoExist || (curActor.Nonce > mNonce && act.Nonce <= mNonce) {
			msg, found, err := w.receiptForTipset(ctx, cur, m, allowReplaced)
			if err != nil {
				log.Errorf("Waiter.Wait: %s", err)
				return nil, false, err
			}
			if found {
				return msg, true, nil
			}
		}

		cur = pts
		curActor = act
	}
}

// waitForMessage looks for a matching message in a channel of tipsets and returns
// the message, block and receipt, when it is found. Reads until the channel is
// closed or the context done. Returns the found message/block (or nil if the
// channel closed without finding it), whether it was found, or an error.
// notice matching mesage by message from and nonce. the return message may not be
// expected, because there maybe another message have the same from and nonce value
func (w *Waiter) waitForMessage(ctx context.Context, ch <-chan []*types.HeadChange, msg types.ChainMsg, confidence uint64, lookbackLimit abi.ChainEpoch, allowReplaced bool) (*types.ChainMessage, bool, error) {
	current, ok := <-ch
	if !ok {
		return nil, false, fmt.Errorf("SubHeadChanges stream was invalid")
	}
	// todo message wait
	if len(current) != 1 {
		return nil, false, fmt.Errorf("SubHeadChanges first entry should have been one item")
	}

	if current[0].Type != types.HCCurrent {
		return nil, false, fmt.Errorf("expected current head on SHC stream (got %s)", current[0].Type)
	}

	currentHead := current[0].Val
	chainMsg, found, err := w.receiptForTipset(ctx, currentHead, msg, allowReplaced)
	if err != nil {
		return nil, false, err
	}
	if found {
		return chainMsg, found, nil
	}

	var backRcp *types.ChainMessage
	backSearchWait := make(chan struct{})
	go func() {
		r, foundMsg, err := w.findMessage(ctx, currentHead, msg, lookbackLimit, allowReplaced)
		if err != nil {
			log.Warnf("failed to look back through chain for message: %w", err)
			return
		}
		if foundMsg {
			backRcp = r
			close(backSearchWait)
		}
	}()

	var candidateTS *types.TipSet
	var candidateRcp *types.ChainMessage
	heightOfHead := currentHead.Height()
	reverts := map[string]bool{}

	for {
		select {
		case notif, ok := <-ch:
			if !ok {
				return nil, false, err
			}
			for _, val := range notif {
				switch val.Type {
				case types.HCRevert:
					if val.Val.Equals(candidateTS) {
						candidateTS = nil
						candidateRcp = nil
					}
					if backSearchWait != nil {
						reverts[val.Val.Key().String()] = true
					}
				case types.HCApply:
					if candidateTS != nil && val.Val.Height() >= candidateTS.Height()+abi.ChainEpoch(confidence) {
						return candidateRcp, true, nil
					}

					r, foundMsg, err := w.receiptForTipset(ctx, val.Val, msg, allowReplaced)
					if err != nil {
						return nil, false, err
					}
					if r != nil {
						if confidence == 0 {
							return r, foundMsg, err
						}
						candidateTS = val.Val
						candidateRcp = r
					}
					heightOfHead = val.Val.Height()
				}
			}
		case <-backSearchWait:
			// check if we found the message in the chain and that is hasn't been reverted since we started searching
			if backRcp != nil && !reverts[backRcp.TS.Key().String()] {
				// if head is at or past confidence interval, return immediately
				if heightOfHead >= backRcp.TS.Height()+abi.ChainEpoch(confidence) {
					return backRcp, true, nil
				}

				// wait for confidence interval
				candidateTS = backRcp.TS
				candidateRcp = backRcp
			}
			reverts = nil
			backSearchWait = nil
		case <-ctx.Done():
			return nil, false, err
		}
	}
}

func (w *Waiter) receiptForTipset(ctx context.Context, ts *types.TipSet, msg types.ChainMsg, allowReplaced bool) (*types.ChainMessage, bool, error) {
	// The genesis block
	if ts.Height() == 0 {
		return nil, false, nil
	}

	pts, err := w.chainReader.GetTipSet(ctx, ts.Parents())
	if err != nil {
		return nil, false, err
	}
	blockMessageInfos, err := w.messageProvider.LoadTipSetMessage(ctx, pts)
	if err != nil {
		return nil, false, err
	}
	expectedMsg := msg.VMMessage()
	expectedCid := msg.Cid()
	expectedNonce := msg.VMMessage().Nonce
	expectedFrom := msg.VMMessage().From
	for _, bms := range blockMessageInfos {
		for _, msg := range append(bms.BlsMessages, bms.SecpkMessages...) {
			msgCid := msg.Cid()
			if msg.VMMessage().From == expectedFrom { // cheaper to just check origin first
				if msg.VMMessage().Nonce == expectedNonce {
					if !msg.VMMessage().EqualCall(expectedMsg) {
						// this is an entirely different message, fail
						return nil, false, fmt.Errorf("found message with equal nonce as the one we are looking for that is NOT a valid replacement message (F:%s n %d, TS: %s n%d)",
							expectedMsg.Cid(), expectedMsg.Nonce, msg.Cid(), msg.VMMessage().Nonce)
					}

					if msgCid != expectedCid {
						if !allowReplaced {
							log.Warnw("found message with equal nonce and call params but different CID",
								"wanted", expectedCid, "found", msgCid, "nonce", expectedNonce, "from", expectedFrom)
							return nil, false, fmt.Errorf("found message with equal nonce as the one we are looking for (F:%s n %d, TS: %s n%d)",
								expectedCid, expectedNonce, msgCid, msg.VMMessage().Nonce)
						}
					}

					recpt, err := w.receiptByIndex(ctx, pts, msgCid, blockMessageInfos)
					if err != nil {
						return nil, false, errors.Wrap(err, "error retrieving receipt from tipset")
					}
					return &types.ChainMessage{TS: ts, Message: msg, Block: bms.Block, Receipt: recpt}, true, nil
				}
			}
		}
	}

	return nil, false, nil
}

func (w *Waiter) receiptByIndex(ctx context.Context, ts *types.TipSet, targetCid cid.Cid, blockMsgs []types.BlockMessagesInfo) (*types.MessageReceipt, error) {
	var receiptCid cid.Cid
	var err error
	if _, receiptCid, err = w.Stmgr.RunStateTransition(ctx, ts, nil, false); err != nil {
		return nil, fmt.Errorf("RunStateTransition failed:%w", err)
	}

	receipts, err := w.messageProvider.LoadReceipts(ctx, receiptCid)
	if err != nil {
		return nil, err
	}

	receiptIndex := 0
	for _, blkInfo := range blockMsgs {
		// todo aggrate bls and secp msg to one msg
		for _, msg := range append(blkInfo.BlsMessages, blkInfo.SecpkMessages...) {
			if msg.Cid().Equals(targetCid) {
				if receiptIndex >= len(receipts) {
					return nil, errors.Errorf("could not find message receipt at index %d", receiptIndex)
				}
				return &receipts[receiptIndex], nil
			}
			receiptIndex++
		}
	}
	return nil, errors.Errorf("could not find message cid %s in dedupped messages", targetCid.String())
}