[wip,dnm,dnr] migration: prototype lrm orchestrator

Release note: None

docs/generated/settings/settings.html

@@ -90,6 +90,6 @@
 <tr><td><code>trace.debug.enable</code></td><td>boolean</td><td><code>false</code></td><td>if set, traces for recent requests can be seen in the /debug page</td></tr>
 <tr><td><code>trace.lightstep.token</code></td><td>string</td><td><code></code></td><td>if set, traces go to Lightstep using this token</td></tr>
 <tr><td><code>trace.zipkin.collector</code></td><td>string</td><td><code></code></td><td>if set, traces go to the given Zipkin instance (example: '127.0.0.1:9411'); ignored if trace.lightstep.token is set</td></tr>
-<tr><td><code>version</code></td><td>custom validation</td><td><code>20.2-1</code></td><td>set the active cluster version in the format '<major>.<minor>'</td></tr>
+<tr><td><code>version</code></td><td>custom validation</td><td><code>20.2-2</code></td><td>set the active cluster version in the format '<major>.<minor>'</td></tr>
 </tbody>
 </table>

pkg/clusterversion/clusterversion.go

@@ -41,9 +41,9 @@ package clusterversion
 
 import (
 	"context"
-
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
 	"github.com/cockroachdb/cockroach/pkg/settings"
+	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
 	"github.com/cockroachdb/cockroach/pkg/util/syncutil"
 	"github.com/cockroachdb/redact"
 )
@@ -76,6 +76,11 @@ func SetBeforeChange(
 
 // Handle is a read-only view to the active cluster version and this binary's
 // version details.
+//
+// XXX: We'll want this same handle to exist going forward. Except underneath
+// the hood the "setting" of things doesn't happen through this StateMachine guy
+// anymore. It happens through the one RPC.
+// XXX: I'm unsure what the migration story _there_ looks like.
 type Handle interface {
 	// ActiveVersion returns the cluster's current active version: the minimum
 	// cluster version the caller may assume is in effect.
@@ -158,6 +163,32 @@ func MakeVersionHandle(sv *settings.Values) Handle {
 	return MakeVersionHandleWithOverride(sv, binaryVersion, binaryMinSupportedVersion)
 }
 
+type MutableRef struct {
+	handleImpl *handleImpl
+}
+
+func (r MutableRef) Set(ctx context.Context, v *roachpb.Version) error {
+	sv := r.handleImpl.sv
+	newV := *v
+	if err := version.validateSupportedVersionInner(ctx, newV, sv); err != nil {
+		return err
+	}
+
+	value := ClusterVersion{Version: newV}
+	encoded, err := protoutil.Marshal(&value)
+	if err != nil {
+		return err
+	}
+	version.SetInternal(sv, encoded)
+	return nil
+}
+
+func MakeMutableRef(handle Handle) MutableRef {
+	return MutableRef{
+		handleImpl: handle.(*handleImpl),
+	}
+}
+
 // MakeVersionHandleWithOverride returns a Handle that has its
 // binary and minimum supported versions initialized to the provided versions.
 //

pkg/clusterversion/cockroach_versions.go

@@ -78,6 +78,7 @@ const (
 	VersionHBAForNonTLS
 	Version20_2
 	VersionStart21_1
+	VersionLRMTable
 
 	// Add new versions here (step one of two).
 )
@@ -441,6 +442,11 @@ var versionsSingleton = keyedVersions([]keyedVersion{
 		Key:     VersionStart21_1,
 		Version: roachpb.Version{Major: 20, Minor: 2, Unstable: 1},
 	},
+	{
+		// XXX:
+		Key:     VersionLRMTable,
+		Version: roachpb.Version{Major: 20, Minor: 2, Unstable: 2},
+	},
 
 	// Add new versions here (step two of two).
 })

pkg/clusterversion/migration/migrations.go

@@ -0,0 +1,74 @@
+// Copyright 2020 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package migration
+
+import (
+	"context"
+	"github.com/cockroachdb/cockroach/pkg/roachpb"
+)
+
+var _ Migration = UnreplicatedTruncatedStateMigration
+var _ Migration = GenerationComparableMigration
+var _ Migration = SeparateRaftLogMigration
+var _ Migration = ReplicatedLockTableMigration
+var _ Migration = ReplicasKnowReplicaIDMigration
+
+func UnreplicatedTruncatedStateMigration(ctx context.Context, h *Helper) error {
+	if err := h.IterRangeDescriptors(func(descs ...roachpb.RangeDescriptor) error {
+		// Really AdminMigrate but it doesn't exist yet. It takes an argument
+		// determining the range version to migrate into. Unsure if that's a
+		// different kind of version or just `h.Version()`. I think I lean
+		// towards the latter.
+		_, err := h.db.Scan(ctx, descs[0].StartKey, descs[len(descs)-1].EndKey, -1)
+		return err
+	}); err != nil {
+		return err
+	}
+	if err := h.EveryNode(ctx, "forced-replicagc"); err != nil {
+		return err
+	}
+	return nil
+}
+
+func GenerationComparableMigration(ctx context.Context, h *Helper) error {
+	// Hmm now that I look at this again I think we can remove it just like that.
+	// No snapshots are in flight any more that don't respect the generational
+	// rules. Replicas get replicaGC'ed eagerly. (Once round of forced-replicagc
+	// somewhere is enough). Need to think this through more.
+	return nil
+}
+
+func SeparateRaftLogMigration(ctx context.Context, h *Helper) error {
+	// Impl will loop through all repls on the node and migrate them one by one
+	// (get raftMu, check if already copied, if not copy stuff, delete old stuff,
+	// release raftMu).
+	if err := h.EveryNode(ctx, "move-raft-logs"); err != nil {
+		return err
+	}
+	// TODO: sanity check that all are really using separate raft log now?
+	return nil
+}
+
+func ReplicatedLockTableMigration(ctx context.Context, h *Helper) error {
+	// Pretty vanilla Raft migration, see
+	// https://github.com/cockroachdb/cockroach/issues/41720#issuecomment-590817261
+	// also run forced-replicagc.
+	// Should probably bake the forced replicaGC and migrate command into a
+	// helper, there's never a reason not to run forced-replicaGC after a Migrate.
+	return nil
+}
+
+func ReplicasKnowReplicaIDMigration(ctx context.Context, h *Helper) error {
+	// Is a migration necessary here or are we already nuking them at startup anyway?
+	// Oh seems like it, so nothing to do here:
+	// https://github.com/cockroachdb/cockroach/blob/f0e751f00b7ba41f39dd83ddc8238011fa5b9c19/pkg/storage/store.go#L1347-L1350
+	return nil
+}