feat: add simple migration nv27 (#386)

* feat: add simple migration nv27

* Run gofmt

Author: TippyFlitsUK

builtin/v17/migration/system.go

@@ -0,0 +1,40 @@
+package migration
+
+import (
+	"context"
+
+	system14 "github.com/filecoin-project/go-state-types/builtin/v14/system"
+
+	"github.com/filecoin-project/go-state-types/migration"
+
+	"github.com/ipfs/go-cid"
+	cbor "github.com/ipfs/go-ipld-cbor"
+)
+
+// System Actor migrator
+type systemActorMigrator struct {
+	OutCodeCID   cid.Cid
+	ManifestData cid.Cid
+}
+
+func (m systemActorMigrator) MigratedCodeCID() cid.Cid {
+	return m.OutCodeCID
+}
+
+func (m systemActorMigrator) MigrateState(ctx context.Context, store cbor.IpldStore, in migration.ActorMigrationInput) (*migration.ActorMigrationResult, error) {
+	// The ManifestData itself is already in the blockstore
+	state := system14.State{BuiltinActors: m.ManifestData}
+	stateHead, err := store.Put(ctx, &state)
+	if err != nil {
+		return nil, err
+	}
+
+	return &migration.ActorMigrationResult{
+		NewCodeCID: m.OutCodeCID,
+		NewHead:    stateHead,
+	}, nil
+}
+
+func (m systemActorMigrator) Deferred() bool {
+	return false
+}

builtin/v17/migration/top.go

@@ -0,0 +1,104 @@
+package migration
+
+import (
+	"context"
+
+	adt14 "github.com/filecoin-project/go-state-types/builtin/v14/util/adt"
+
+	system13 "github.com/filecoin-project/go-state-types/builtin/v13/system"
+
+	"github.com/filecoin-project/go-state-types/abi"
+	"github.com/filecoin-project/go-state-types/builtin"
+	"github.com/filecoin-project/go-state-types/manifest"
+	"github.com/filecoin-project/go-state-types/migration"
+
+	"github.com/ipfs/go-cid"
+	cbor "github.com/ipfs/go-ipld-cbor"
+	"golang.org/x/xerrors"
+)
+
+// MigrateStateTree Migrates the filecoin state tree starting from the global state tree and upgrading all actor state.
+// The store must support concurrent writes (even if the configured worker count is 1).
+func MigrateStateTree(ctx context.Context, store cbor.IpldStore, newManifestCID cid.Cid, actorsRootIn cid.Cid, priorEpoch abi.ChainEpoch, cfg migration.Config, log migration.Logger, cache migration.MigrationCache) (cid.Cid, error) {
+	if cfg.MaxWorkers <= 0 {
+		return cid.Undef, xerrors.Errorf("invalid migration config with %d workers", cfg.MaxWorkers)
+	}
+
+	adtStore := adt14.WrapStore(ctx, store)
+
+	// Load input and output state trees
+	actorsIn, err := builtin.LoadTree(adtStore, actorsRootIn)
+	if err != nil {
+		return cid.Undef, xerrors.Errorf("loading state tree: %w", err)
+	}
+
+	// load old manifest data
+	systemActor, ok, err := actorsIn.GetActorV5(builtin.SystemActorAddr)
+	if err != nil {
+		return cid.Undef, xerrors.Errorf("failed to get system actor: %w", err)
+	}
+
+	if !ok {
+		return cid.Undef, xerrors.New("didn't find system actor")
+	}
+
+	var systemState system13.State
+	if err := store.Get(ctx, systemActor.Head, &systemState); err != nil {
+		return cid.Undef, xerrors.Errorf("failed to get system actor state: %w", err)
+	}
+
+	var oldManifestData manifest.ManifestData
+	if err := store.Get(ctx, systemState.BuiltinActors, &oldManifestData); err != nil {
+		return cid.Undef, xerrors.Errorf("failed to get old manifest data: %w", err)
+	}
+
+	// load new manifest
+	var newManifest manifest.Manifest
+	if err := adtStore.Get(ctx, newManifestCID, &newManifest); err != nil {
+		return cid.Undef, xerrors.Errorf("error reading actor manifest: %w", err)
+	}
+
+	if err := newManifest.Load(ctx, adtStore); err != nil {
+		return cid.Undef, xerrors.Errorf("error loading actor manifest: %w", err)
+	}
+
+	// Maps prior version code CIDs to migration functions.
+	migrations := make(map[cid.Cid]migration.ActorMigration)
+	// Set of prior version code CIDs for actors to defer during iteration, for explicit migration afterwards.
+	deferredCodeIDs := make(map[cid.Cid]struct{})
+
+	for _, oldEntry := range oldManifestData.Entries {
+		newCodeCID, ok := newManifest.Get(oldEntry.Name)
+		if !ok {
+			return cid.Undef, xerrors.Errorf("code cid for %s actor not found in new manifest", oldEntry.Name)
+		}
+		migrations[oldEntry.Code] = migration.CachedMigration(cache, migration.CodeMigrator{OutCodeCID: newCodeCID})
+	}
+
+	// migrations that migrate both code and state, override entries in `migrations`
+
+	// The System Actor
+
+	newSystemCodeCID, ok := newManifest.Get(manifest.SystemKey)
+	if !ok {
+		return cid.Undef, xerrors.Errorf("code cid for system actor not found in new manifest")
+	}
+
+	migrations[systemActor.Code] = systemActorMigrator{OutCodeCID: newSystemCodeCID, ManifestData: newManifest.Data}
+
+	if len(migrations)+len(deferredCodeIDs) != len(oldManifestData.Entries) {
+		return cid.Undef, xerrors.Errorf("incomplete migration specification with %d code CIDs, need %d", len(migrations)+len(deferredCodeIDs), len(oldManifestData.Entries))
+	}
+
+	actorsOut, err := migration.RunMigration(ctx, cfg, cache, store, log, actorsIn, migrations)
+	if err != nil {
+		return cid.Undef, xerrors.Errorf("failed to run migration: %w", err)
+	}
+
+	outCid, err := actorsOut.Flush()
+	if err != nil {
+		return cid.Undef, xerrors.Errorf("failed to flush actorsOut: %w", err)
+	}
+
+	return outCid, nil
+}