change GetChainMessages api to include tipsets for validation

chain/exchange/client.go

@@ -217,6 +217,7 @@ func (c *client) processResponse(req *Request, res *Response) (*validatedRespons
 		}
 
 		if options.ValidateMessages {
+			// if the request includes target tipsets, validate against them
 			chain := make([]*BSTipSet, 0, resLength)
 			for i, resChain := range res.Chain {
 				next := &BSTipSet{
@@ -318,7 +319,10 @@ func (c *client) GetFullTipSet(ctx context.Context, peer peer.ID, tsk types.TipS
 }
 
 // GetChainMessages implements Client.GetChainMessages(). Refer to the godocs there.
-func (c *client) GetChainMessages(ctx context.Context, head *types.TipSet, length uint64) ([]*CompactedMessages, error) {
+func (c *client) GetChainMessages(ctx context.Context, tipsets []*types.TipSet) ([]*CompactedMessages, error) {
+	head := tipsets[0]
+	length := uint64(len(tipsets))
+
 	ctx, span := trace.StartSpan(ctx, "GetChainMessages")
 	if span.IsRecordingEvents() {
 		span.AddAttributes(
@@ -331,7 +335,8 @@ func (c *client) GetChainMessages(ctx context.Context, head *types.TipSet, lengt
 	req := &Request{
 		Head:    head.Cids(),
 		Length:  length,
-		Options: Messages,
+		Options: Messages | Validate,
+		TipSets: tipsets,
 	}
 
 	validRes, err := c.doRequest(ctx, req, nil)

chain/exchange/interfaces.go

@@ -32,10 +32,9 @@ type Client interface {
 	// or less.
 	GetBlocks(ctx context.Context, tsk types.TipSetKey, count int) ([]*types.TipSet, error)
 
-	// GetChainMessages fetches messages from the network, from the provided
+	// GetChainMessages fetches messages from the network, starting from the first provided tipset
-	// tipset *backwards*, returning the messages from as many tipsets as the
+	// and returning messages from as many tipsets as requested or less.
-	// count parameter, or less.
+	GetChainMessages(ctx context.Context, tipsets []*types.TipSet) ([]*CompactedMessages, error)
-	GetChainMessages(ctx context.Context, head *types.TipSet, length uint64) ([]*CompactedMessages, error)
 
 	// GetFullTipSet fetches a full tipset from a given peer. If successful,
 	// the fetched object contains block headers and all messages in full form.

chain/sync.go

@@ -1555,7 +1555,7 @@ func (syncer *Syncer) fetchMessages(ctx context.Context, headers []*types.TipSet
 			failed := false
 			for offset := 0; !failed && offset < nreq; {
 				nextI := j + offset
-				nextHeader := headers[nextI]
+				lastI := j + nreq
 
 				var requestErr error
 				var requestResult []*exchange.CompactedMessages
@@ -1566,7 +1566,7 @@ func (syncer *Syncer) fetchMessages(ctx context.Context, headers []*types.TipSet
 						log.Infof("fetching messages at %d", startOffset+nextI)
 					}
 
-					result, err := syncer.Exchange.GetChainMessages(ctx, nextHeader, uint64(nreq-offset))
+					result, err := syncer.Exchange.GetChainMessages(ctx, headers[nextI:lastI])
 					if err != nil {
 						requestErr = multierror.Append(requestErr, err)
 					} else {