kvserver: abstract away system config span usage in kv

Part of #67679. We'll hide config.SystemConfig behind the
spanconfig.StoreReader interface, and use that instead in the various
queues that need access to the system config span. In future PRs we'll
introduce a data structure that maintains a mapping between spans and
configs that implements this same interface. This will be powered by a
view of `system.span_configurations`, following the ideas described in
\#66348.

When we do make that switch, i.e. have KV consult the new thing for
splits, merges, GC and replication, instead of the gossip backed system
config span, ideally it'd be as easy as swapping the source. This PR
helps pave the way for just that.

In \#66348 we described how zonepb.ZoneConfigs going forward were going
to be an exclusively SQL-level construct. Consequently we purge[*] all
usages of it in KV, storing on each replica a roachpb.SpanConfig
instead.

[*]: The only remaining use is what powers our replication reports,
which does not extend well to multi-tenancy and needs replacing.

Release note: None

pkg/cli/debug.go

@@ -31,7 +31,6 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/base"
 	"github.com/cockroachdb/cockroach/pkg/cli/syncbench"
 	"github.com/cockroachdb/cockroach/pkg/config"
-	"github.com/cockroachdb/cockroach/pkg/config/zonepb"
 	"github.com/cockroachdb/cockroach/pkg/gossip"
 	"github.com/cockroachdb/cockroach/pkg/keys"
 	"github.com/cockroachdb/cockroach/pkg/kv/kvserver"
@@ -671,7 +670,7 @@ func runDebugGCCmd(cmd *cobra.Command, args []string) error {
 	defer stopper.Stop(context.Background())
 
 	var rangeID roachpb.RangeID
-	gcTTLInSeconds := int64((24 * time.Hour).Seconds())
+	gcTTL := 24 * time.Hour
 	intentAgeThreshold := gc.IntentAgeThreshold.Default()
 	intentBatchSize := gc.MaxIntentsPerCleanupBatch.Default()
 
@@ -682,10 +681,11 @@ func runDebugGCCmd(cmd *cobra.Command, args []string) error {
 		}
 	}
 	if len(args) > 2 {
-		var err error
-		if gcTTLInSeconds, err = parsePositiveInt(args[2]); err != nil {
+		gcTTLInSeconds, err := parsePositiveInt(args[2])
+		if err != nil {
 			return errors.Wrapf(err, "unable to parse %v as TTL", args[2])
 		}
+		gcTTL = time.Duration(gcTTLInSeconds) * time.Second
 	}
 	if len(args) > 1 {
 		var err error
@@ -735,14 +735,14 @@ func runDebugGCCmd(cmd *cobra.Command, args []string) error {
 	for _, desc := range descs {
 		snap := db.NewSnapshot()
 		defer snap.Close()
-		policy := zonepb.GCPolicy{TTLSeconds: int32(gcTTLInSeconds)}
 		now := hlc.Timestamp{WallTime: timeutil.Now().UnixNano()}
-		thresh := gc.CalculateThreshold(now, policy)
+		thresh := gc.CalculateThreshold(now, gcTTL)
 		info, err := gc.Run(
 			context.Background(),
 			&desc, snap,
-			now, thresh, gc.RunOptions{IntentAgeThreshold: intentAgeThreshold, MaxIntentsPerIntentCleanupBatch: intentBatchSize}, policy,
-			gc.NoopGCer{},
+			now, thresh,
+			gc.RunOptions{IntentAgeThreshold: intentAgeThreshold, MaxIntentsPerIntentCleanupBatch: intentBatchSize},
+			gcTTL, gc.NoopGCer{},
 			func(_ context.Context, _ []roachpb.Intent) error { return nil },
 			func(_ context.Context, _ *roachpb.Transaction) error { return nil },
 		)

pkg/config/system.go

@@ -294,6 +294,18 @@ func (s *SystemConfig) GetZoneConfigForKey(key roachpb.RKey) (*zonepb.ZoneConfig
 	return s.getZoneConfigForKey(DecodeKeyIntoZoneIDAndSuffix(key))
 }
 
+// GetSpanConfigForKey looks of the span config for the given key. It's part of
+// spanconfig.StoreReader interface.
+func (s *SystemConfig) GetSpanConfigForKey(
+	ctx context.Context, key roachpb.RKey,
+) (roachpb.SpanConfig, error) {
+	zone, err := s.GetZoneConfigForKey(key)
+	if err != nil {
+		return roachpb.SpanConfig{}, err
+	}
+	return zone.AsSpanConfig(), nil
+}
+
 // DecodeKeyIntoZoneIDAndSuffix figures out the zone that the key belongs to.
 func DecodeKeyIntoZoneIDAndSuffix(key roachpb.RKey) (id SystemTenantObjectID, keySuffix []byte) {
 	objectID, keySuffix, ok := DecodeSystemTenantObjectID(key)

pkg/config/system_test.go

@@ -542,6 +542,7 @@ func TestComputeSplitKeyTenantBoundaries(t *testing.T) {
 func TestGetZoneConfigForKey(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 
+	ctx := context.Background()
 	testCases := []struct {
 		key        roachpb.RKey
 		expectedID config.SystemTenantObjectID
@@ -612,11 +613,11 @@ func TestGetZoneConfigForKey(t *testing.T) {
 			_ *config.SystemConfig, id config.SystemTenantObjectID,
 		) (*zonepb.ZoneConfig, *zonepb.ZoneConfig, bool, error) {
 			objectID = id
-			return &zonepb.ZoneConfig{}, nil, false, nil
+			return cfg.DefaultZoneConfig, nil, false, nil
 		}
-		_, err := cfg.GetZoneConfigForKey(tc.key)
+		_, err := cfg.GetSpanConfigForKey(ctx, tc.key)
 		if err != nil {
-			t.Errorf("#%d: GetZoneConfigForKey(%v) got error: %v", tcNum, tc.key, err)
+			t.Errorf("#%d: GetSpanConfigForKey(%v) got error: %v", tcNum, tc.key, err)
 		}
 		if objectID != tc.expectedID {
 			t.Errorf("#%d: GetZoneConfigForKey(%v) got %d; want %d", tcNum, tc.key, objectID, tc.expectedID)

pkg/config/zonepb/zone.go

@@ -15,7 +15,6 @@ import (
 	"context"
 	"fmt"
 	"strings"
-	"time"
 
 	"github.com/cockroachdb/cockroach/pkg/base"
 	"github.com/cockroachdb/cockroach/pkg/keys"
@@ -206,20 +205,6 @@ func NewZoneConfig() *ZoneConfig {
 	}
 }
 
-// EmptyCompleteZoneConfig is the zone configuration where
-// all fields are set but set to their respective zero values.
-func EmptyCompleteZoneConfig() *ZoneConfig {
-	return &ZoneConfig{
-		NumReplicas:               proto.Int32(0),
-		NumVoters:                 proto.Int32(0),
-		RangeMinBytes:             proto.Int64(0),
-		RangeMaxBytes:             proto.Int64(0),
-		GC:                        &GCPolicy{TTLSeconds: 0},
-		InheritedConstraints:      true,
-		InheritedLeasePreferences: true,
-	}
-}
-
 // DefaultZoneConfig is the default zone configuration used when no custom
 // config has been specified.
 func DefaultZoneConfig() ZoneConfig {
@@ -977,37 +962,6 @@ func (z ZoneConfig) GetSubzoneForKeySuffix(keySuffix []byte) (*Subzone, int32) {
 	return nil, -1
 }
 
-// GetNumVoters returns the number of voting replicas for the given zone config.
-//
-// This method will panic if called on a ZoneConfig with an uninitialized
-// NumReplicas attribute.
-func (z *ZoneConfig) GetNumVoters() int32 {
-	if z.NumReplicas == nil {
-		panic("NumReplicas must not be nil")
-	}
-	if z.NumVoters != nil && *z.NumVoters != 0 {
-		return *z.NumVoters
-	}
-	return *z.NumReplicas
-}
-
-// GetNumNonVoters returns the number of non-voting replicas as defined in the
-// zone config.
-//
-// This method will panic if called on a ZoneConfig with an uninitialized
-// NumReplicas attribute.
-func (z *ZoneConfig) GetNumNonVoters() int32 {
-	if z.NumReplicas == nil {
-		panic("NumReplicas must not be nil")
-	}
-	if z.NumVoters != nil && *z.NumVoters != 0 {
-		return *z.NumReplicas - *z.NumVoters
-	}
-	// `num_voters` hasn't been explicitly configured. Every replica should be a
-	// voting replica.
-	return 0
-}
-
 // SetSubzone installs subzone into the ZoneConfig, overwriting any existing
 // subzone with the same IndexID and PartitionName.
 func (z *ZoneConfig) SetSubzone(subzone Subzone) {
@@ -1150,11 +1104,6 @@ func (c *Constraint) GetValue() string {
 	return c.Value
 }
 
-// TTL returns the implies TTL as a time.Duration.
-func (m *GCPolicy) TTL() time.Duration {
-	return time.Duration(m.TTLSeconds) * time.Second
-}
-
 // EnsureFullyHydrated returns an assertion error if the zone config is not
 // fully hydrated. A fully hydrated zone configuration must have all required
 // fields set, which are RangeMaxBytes, RangeMinBytes, GC, and NumReplicas.

pkg/kv/kvclient/kvcoord/split_test.go

@@ -19,7 +19,6 @@ import (
 	"time"
 
 	"github.com/cockroachdb/cockroach/pkg/config"
-	"github.com/cockroachdb/cockroach/pkg/config/zonepb"
 	"github.com/cockroachdb/cockroach/pkg/keys"
 	"github.com/cockroachdb/cockroach/pkg/kv"
 	"github.com/cockroachdb/cockroach/pkg/kv/kvserver"
@@ -32,7 +31,6 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/cockroach/pkg/util/randutil"
 	"github.com/cockroachdb/errors"
-	"github.com/gogo/protobuf/proto"
 )
 
 // startTestWriter creates a writer which initiates a sequence of
@@ -176,15 +174,15 @@ func TestRangeSplitsWithConcurrentTxns(t *testing.T) {
 func TestRangeSplitsWithWritePressure(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)
-	// Override default zone config.
-	cfg := zonepb.DefaultZoneConfigRef()
-	cfg.RangeMaxBytes = proto.Int64(1 << 18)
+	// Override default span config.
+	cfg := kvserver.TestingDefaultSpanConfig()
+	cfg.RangeMaxBytes = 1 << 18
 
 	// Manually create the local test cluster so that the split queue
 	// is not disabled (LocalTestCluster disables it by default).
 	s := &localtestcluster.LocalTestCluster{
 		Cfg: kvserver.StoreConfig{
-			DefaultZoneConfig: cfg,
+			DefaultSpanConfig: cfg,
 		},
 		StoreTestingKnobs: &kvserver.StoreTestingKnobs{
 			DisableScanner: true,