lotus/chain/blocksync/graphsync_client.go

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package blocksync
import (
"context"
"github.com/ipfs/go-cid"
"github.com/ipfs/go-datastore"
"github.com/ipfs/go-graphsync"
"github.com/ipld/go-ipld-prime"
"github.com/libp2p/go-libp2p-core/peer"
"golang.org/x/xerrors"
store "github.com/filecoin-project/lotus/chain/store"
"github.com/filecoin-project/lotus/chain/types"
cidlink "github.com/ipld/go-ipld-prime/linking/cid"
basicnode "github.com/ipld/go-ipld-prime/node/basic"
ipldselector "github.com/ipld/go-ipld-prime/traversal/selector"
selectorbuilder "github.com/ipld/go-ipld-prime/traversal/selector/builder"
)
const (
// AMT selector recursion. An AMT has arity of 8 so this gives allows
// us to retrieve trees with 8^10 (1,073,741,824) elements.
amtRecursionDepth = uint32(10)
// some constants for looking up tuple encoded struct fields
// field index of Parents field in a block header
blockIndexParentsField = 5
// field index of Messages field in a block header
blockIndexMessagesField = 10
// field index of AMT node in AMT head
amtHeadNodeFieldIndex = 2
// field index of links array AMT node
amtNodeLinksFieldIndex = 1
// field index of values array AMT node
amtNodeValuesFieldIndex = 2
// maximum depth per traversal
maxRequestLength = 50
)
var amtSelector selectorbuilder.SelectorSpec
func init() {
// builer for selectors
ssb := selectorbuilder.NewSelectorSpecBuilder(basicnode.Style.Any)
// amt selector -- needed to selector through a messages AMT
amtSelector = ssb.ExploreIndex(amtHeadNodeFieldIndex,
ssb.ExploreRecursive(ipldselector.RecursionLimitDepth(int(amtRecursionDepth)),
ssb.ExploreUnion(
ssb.ExploreIndex(amtNodeLinksFieldIndex,
ssb.ExploreAll(ssb.ExploreRecursiveEdge())),
ssb.ExploreIndex(amtNodeValuesFieldIndex,
ssb.ExploreAll(ssb.Matcher())))))
}
func selectorForRequest(req *BlockSyncRequest) ipld.Node {
// builer for selectors
ssb := selectorbuilder.NewSelectorSpecBuilder(basicnode.Style.Any)
bso := ParseBSOptions(req.Options)
if bso.IncludeMessages {
return ssb.ExploreRecursive(ipldselector.RecursionLimitDepth(int(req.RequestLength)),
ssb.ExploreIndex(blockIndexParentsField,
ssb.ExploreUnion(
ssb.ExploreAll(
ssb.ExploreIndex(blockIndexMessagesField,
ssb.ExploreRange(0, 2, amtSelector),
)),
ssb.ExploreIndex(0, ssb.ExploreRecursiveEdge()),
))).Node()
}
return ssb.ExploreRecursive(ipldselector.RecursionLimitDepth(int(req.RequestLength)), ssb.ExploreIndex(blockIndexParentsField,
ssb.ExploreUnion(
ssb.ExploreAll(
ssb.Matcher(),
),
ssb.ExploreIndex(0, ssb.ExploreRecursiveEdge()),
))).Node()
}
func firstTipsetSelector(req *BlockSyncRequest) ipld.Node {
// builer for selectors
ssb := selectorbuilder.NewSelectorSpecBuilder(basicnode.Style.Any)
bso := ParseBSOptions(req.Options)
if bso.IncludeMessages {
return ssb.ExploreIndex(blockIndexMessagesField,
ssb.ExploreRange(0, 2, amtSelector),
).Node()
}
return ssb.Matcher().Node()
}
func (bs *BlockSync) executeGsyncSelector(ctx context.Context, p peer.ID, root cid.Cid, sel ipld.Node) error {
extension := graphsync.ExtensionData{
Name: "chainsync",
Data: nil,
}
_, errs := bs.gsync.Request(ctx, p, cidlink.Link{Cid: root}, sel, extension)
for err := range errs {
return xerrors.Errorf("failed to complete graphsync request: %w", err)
}
return nil
}
// Fallback for interacting with other non-lotus nodes
func (bs *BlockSync) fetchBlocksGraphSync(ctx context.Context, p peer.ID, req *BlockSyncRequest) (*BlockSyncResponse, error) {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
immediateTsSelector := firstTipsetSelector(req)
// Do this because we can only request one root at a time
for _, r := range req.Start {
if err := bs.executeGsyncSelector(ctx, p, r, immediateTsSelector); err != nil {
return nil, err
}
}
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if req.RequestLength > maxRequestLength {
req.RequestLength = maxRequestLength
}
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sel := selectorForRequest(req)
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// execute the selector forreal
if err := bs.executeGsyncSelector(ctx, p, req.Start[0], sel); err != nil {
return nil, err
}
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// Now pull the data we fetched out of the chainstore (where it should now be persisted)
tempcs := store.NewChainStore(bs.bserv.Blockstore(), datastore.NewMapDatastore(), nil)
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opts := ParseBSOptions(req.Options)
tsk := types.NewTipSetKey(req.Start...)
chain, err := collectChainSegment(tempcs, tsk, req.RequestLength, opts)
if err != nil {
return nil, xerrors.Errorf("failed to load chain data from chainstore after successful graphsync response (start = %v): %w", req.Start, err)
}
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return &BlockSyncResponse{Chain: chain}, nil
}