wip accessed-cids retention.

tvx/extract_msg.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"os"
 
@@ -51,7 +52,7 @@ var extractMsgCmd = &cli.Command{
 		&cli.StringFlag{
 			Name:        "state-retain",
 			Usage:       "state retention policy; values: 'accessed-cids' (default), 'accessed-actors'",
-			Value:       "accessed-actors",
+			Value:       "accessed-cids",
 			Destination: &extractMsgFlags.retain,
 		},
 	},
@@ -170,9 +171,11 @@ func runExtractMsg(c *cli.Context) error {
 	var (
 		preroot   cid.Cid
 		postroot  cid.Cid
+		carWriter func(w io.Writer) error
 	)
 
-	if extractMsgFlags.retain == "accessed-actors" {
+	switch retention := extractMsgFlags.retain; retention {
+	case "accessed-actors":
 		log.Printf("calculating accessed actors...")
 		// get actors accessed by message.
 		retain, err := g.GetAccessedActors(ctx, api, mcid)
@@ -192,6 +195,30 @@ func runExtractMsg(c *cli.Context) error {
 		if err != nil {
 			return fmt.Errorf("failed to execute message: %w", err)
 		}
+		carWriter = func(w io.Writer) error {
+			return g.WriteCAR(w, preroot, postroot)
+		}
+
+	case "accessed-cids":
+		log.Printf("using state retention: %s", retention)
+		tbs, ok := pst.Blockstore.(state.TracingBlockstore)
+		if !ok {
+			return fmt.Errorf("requested 'accessed-cids' state retention, but no tracing blockstore was present")
+		}
+		tbs.StartTracing()
+
+		preroot = execTs.ParentState()
+		_, postroot, err = driver.ExecuteMessage(pst.Blockstore, preroot, execTs.Height(), msg)
+		if err != nil {
+			return fmt.Errorf("failed to execute message: %w", err)
+		}
+		accessed := tbs.FinishTracing()
+		carWriter = func(w io.Writer) error {
+			return g.WriteCARIncluding(w, accessed, preroot, postroot)
+		}
+
+	default:
+		return fmt.Errorf("unknown state retention option: %s", retention)
 	}
 
 	msgBytes, err := msg.Serialize()
@@ -199,17 +226,11 @@ func runExtractMsg(c *cli.Context) error {
 		return err
 	}
 
-	// don't fetch additional content that wasn't accessed yet during car spidering / generation.
-	type onlineblockstore interface {
-		SetOnline(bool)
-	}
-	if ob, ok := pst.Blockstore.(onlineblockstore); ok {
-		ob.SetOnline(false)
-	}
-
-	out := new(bytes.Buffer)
-	gw := gzip.NewWriter(out)
-	if err := g.WriteCAR(gw, preroot, postroot); err != nil {
+	var (
+		out = new(bytes.Buffer)
+		gw  = gzip.NewWriter(out)
+	)
+	if err := carWriter(gw); err != nil {
 		return err
 	}
 	if err = gw.Flush(); err != nil {

tvx/state/store.go

@@ -58,18 +58,50 @@ type proxyingBlockstore struct {
 	ctx context.Context
 	api api.FullNode
 
-	online bool
-	lock   sync.RWMutex
+	lk      sync.RWMutex
+	tracing bool
+	traced  map[cid.Cid]struct{}
+
 	blockstore.Blockstore
 }
 
+type TracingBlockstore interface {
+	StartTracing()
+	FinishTracing() map[cid.Cid]struct{}
+}
+
+var _ TracingBlockstore = (*proxyingBlockstore)(nil)
+
+// StartTracing starts tracing the CIDs that are effectively fetched during the
+// processing of a message.
+func (pb *proxyingBlockstore) StartTracing() {
+	pb.lk.Lock()
+	pb.tracing = true
+	pb.traced = map[cid.Cid]struct{}{}
+	pb.lk.Unlock()
+}
+
+// FinishTracing finishes tracing accessed CIDs, and returns a map of the
+// CIDs that were traced.
+func (pb *proxyingBlockstore) FinishTracing() map[cid.Cid]struct{} {
+	pb.lk.Lock()
+	ret := pb.traced
+	pb.tracing = false
+	pb.traced = map[cid.Cid]struct{}{}
+	pb.lk.Unlock()
+	return ret
+}
+
 func (pb *proxyingBlockstore) Get(cid cid.Cid) (blocks.Block, error) {
-	pb.lock.RLock()
-	if block, err := pb.Blockstore.Get(cid); err == nil || !pb.online {
-		pb.lock.RUnlock()
+	pb.lk.RLock()
+	if pb.tracing {
+		pb.traced[cid] = struct{}{}
+	}
+	pb.lk.RUnlock()
+
+	if block, err := pb.Blockstore.Get(cid); err == nil {
 		return block, err
 	}
-	pb.lock.RUnlock()
 
 	log.Println(color.CyanString("fetching cid via rpc: %v", cid))
 	item, err := pb.api.ChainReadObj(pb.ctx, cid)
@@ -81,8 +113,6 @@ func (pb *proxyingBlockstore) Get(cid cid.Cid) (blocks.Block, error) {
 		return nil, err
 	}
 
-	pb.lock.Lock()
-	defer pb.lock.Unlock()
 	err = pb.Blockstore.Put(block)
 	if err != nil {
 		return nil, err
@@ -91,10 +121,6 @@ func (pb *proxyingBlockstore) Get(cid cid.Cid) (blocks.Block, error) {
 	return block, nil
 }
 
-func (pb *proxyingBlockstore) SetOnline(online bool) {
-	pb.online = online
-}
-
 // NewProxyingStores is a Stores that proxies get requests for unknown CIDs
 // to a Filecoin node, via the ChainReadObj RPC.
 func NewProxyingStores(ctx context.Context, api api.FullNode) *Stores {
@@ -103,7 +129,6 @@ func NewProxyingStores(ctx context.Context, api api.FullNode) *Stores {
 	bs := &proxyingBlockstore{
 		ctx:        ctx,
 		api:        api,
-		online:     true,
 		Blockstore: blockstore.NewBlockstore(ds),
 	}
 

tvx/state/surgeon.go

@@ -153,6 +153,24 @@ func (sg *Surgeon) WriteCAR(w io.Writer, roots ...cid.Cid) error {
 	return car.WriteCarWithWalker(sg.ctx, sg.stores.DAGService, roots, w, carWalkFn)
 }
 
+// WriteCARIncluding writes a CAR including only the CIDs that are listed in
+// the include set. This leads to an intentially sparse tree with dangling links.
+func (sg *Surgeon) WriteCARIncluding(w io.Writer, include map[cid.Cid]struct{}, roots ...cid.Cid) error {
+	carWalkFn := func(nd format.Node) (out []*format.Link, err error) {
+		for _, link := range nd.Links() {
+			if _, ok := include[link.Cid]; !ok {
+				continue
+			}
+			if link.Cid.Prefix().Codec == cid.FilCommitmentSealed || link.Cid.Prefix().Codec == cid.FilCommitmentUnsealed {
+				continue
+			}
+			out = append(out, link)
+		}
+		return out, nil
+	}
+	return car.WriteCarWithWalker(sg.ctx, sg.stores.DAGService, roots, w, carWalkFn)
+}
+
 // transplantActors plucks the state from the supplied actors at the given
 // tipset, and places it into the supplied state map.
 func (sg *Surgeon) transplantActors(src *state.StateTree, pluck []address.Address) (*state.StateTree, error) {