lotus/cmd/lotus-sim/simulation/block.go

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package simulation
import (
"context"
"crypto/sha256"
"encoding/binary"
"time"
"github.com/filecoin-project/lotus/build"
"github.com/filecoin-project/lotus/chain/types"
"golang.org/x/xerrors"
)
const beaconPrefix = "mockbeacon:"
// nextBeaconEntries returns a fake beacon entries for the next block.
func (sim *Simulation) nextBeaconEntries() []types.BeaconEntry {
parentBeacons := sim.head.Blocks()[0].BeaconEntries
lastBeacon := parentBeacons[len(parentBeacons)-1]
beaconRound := lastBeacon.Round + 1
buf := make([]byte, len(beaconPrefix)+8)
copy(buf, beaconPrefix)
binary.BigEndian.PutUint64(buf[len(beaconPrefix):], beaconRound)
beaconRand := sha256.Sum256(buf)
return []types.BeaconEntry{{
Round: beaconRound,
Data: beaconRand[:],
}}
}
// nextTicket returns a fake ticket for the next block.
func (sim *Simulation) nextTicket() *types.Ticket {
newProof := sha256.Sum256(sim.head.MinTicket().VRFProof)
return &types.Ticket{
VRFProof: newProof[:],
}
}
// makeTipSet generates and executes the next tipset from the given messages. This method:
//
// 1. Stores the given messages in the Chainstore.
// 2. Creates and persists a single block mined by the same miner as the parent.
// 3. Creates a tipset from this block and executes it.
// 4. Returns the resulting tipset.
//
// This method does _not_ mutate local state (although it does add blocks to the datastore).
func (sim *Simulation) makeTipSet(ctx context.Context, messages []*types.Message) (*types.TipSet, error) {
parentTs := sim.head
parentState, parentRec, err := sim.StateManager.TipSetState(ctx, parentTs)
if err != nil {
return nil, xerrors.Errorf("failed to compute parent tipset: %w", err)
}
msgsCid, err := sim.storeMessages(ctx, messages)
if err != nil {
return nil, xerrors.Errorf("failed to store block messages: %w", err)
}
uts := parentTs.MinTimestamp() + build.BlockDelaySecs
blks := []*types.BlockHeader{{
Miner: parentTs.MinTicketBlock().Miner, // keep reusing the same miner.
Ticket: sim.nextTicket(),
BeaconEntries: sim.nextBeaconEntries(),
Parents: parentTs.Cids(),
Height: parentTs.Height() + 1,
ParentStateRoot: parentState,
ParentMessageReceipts: parentRec,
Messages: msgsCid,
ParentBaseFee: baseFee,
Timestamp: uts,
ElectionProof: &types.ElectionProof{WinCount: 1},
}}
err = sim.Chainstore.PersistBlockHeaders(blks...)
if err != nil {
return nil, xerrors.Errorf("failed to persist block headers: %w", err)
}
newTipSet, err := types.NewTipSet(blks)
if err != nil {
return nil, xerrors.Errorf("failed to create new tipset: %w", err)
}
now := time.Now()
_, _, err = sim.StateManager.TipSetState(ctx, newTipSet)
if err != nil {
return nil, xerrors.Errorf("failed to compute new tipset: %w", err)
}
duration := time.Since(now)
log.Infow("computed tipset", "duration", duration, "height", newTipSet.Height())
return newTipSet, nil
}