Add cockroachdb quota manager driver

Signed-off-by: Juan Antonio Osorio <[email protected]>

.github/workflows/test.yaml

@@ -33,4 +33,4 @@ jobs:
         cache: true
 
     - name: Run tests
-      run: go test -v ./storage/crdb/...
+      run: go test -v ./storage/crdb/... ./quota/crdbqm/...

cmd/trillian_log_server/main.go

@@ -50,7 +50,8 @@ import (
 	_ "github.com/google/trillian/storage/crdb"
 	_ "github.com/google/trillian/storage/mysql"
 
-	// Load MySQL quota provider
+	// Load quota providers
+	_ "github.com/google/trillian/quota/crdbqm"
 	_ "github.com/google/trillian/quota/mysqlqm"
 )
 

cmd/trillian_log_signer/main.go

@@ -56,7 +56,8 @@ import (
 	_ "github.com/google/trillian/storage/crdb"
 	_ "github.com/google/trillian/storage/mysql"
 
-	// Load MySQL quota provider
+	// Load quota providers
+	_ "github.com/google/trillian/quota/crdbqm"
 	_ "github.com/google/trillian/quota/mysqlqm"
 )
 

quota/crdbqm/common_test.go

@@ -0,0 +1,50 @@
+// Copyright 2022 Trillian Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package crdbqm
+
+import (
+	"os"
+	"testing"
+
+	"github.com/cockroachdb/cockroach-go/v2/testserver"
+	"github.com/google/trillian/storage/testdb"
+	"k8s.io/klog/v2"
+)
+
+func TestMain(m *testing.M) {
+	ts, err := testserver.NewTestServer()
+	if err != nil {
+		klog.Errorf("Failed to start test server: %v", err)
+		os.Exit(1)
+	}
+	defer ts.Stop()
+
+	// reset the test server URL path. By default cockroach sets it
+	// to point to a default database, we don't want that.
+	dburl := ts.PGURL()
+	dburl.Path = "/"
+
+	// Set the environment variable for the test server
+	os.Setenv(testdb.CockroachDBURIEnv, dburl.String())
+
+	if !testdb.CockroachDBAvailable() {
+		klog.Errorf("CockroachDB not available, skipping all CockroachDB storage tests")
+		return
+	}
+
+	status := m.Run()
+
+	os.Exit(status)
+}

quota/crdbqm/crdb_quota.go

@@ -0,0 +1,100 @@
+// Copyright 2022 Trillian Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package crdbqm defines a CockroachDB-based quota.Manager implementation.
+package crdbqm
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+
+	"github.com/google/trillian/quota"
+)
+
+const (
+	// DefaultMaxUnsequenced is a suggested value for MaxUnsequencedRows.
+	// Note that this is a Global/Write quota suggestion, so it applies across trees.
+	DefaultMaxUnsequenced = 500000 // About 2h of non-stop signing at 70QPS.
+
+	// TODO(jaosorior): Come up with a more optimal solution for CRDB, as this is
+	// linear and too costly.
+	countFromUnsequencedTable = "SELECT COUNT(*) FROM Unsequenced"
+)
+
+// ErrTooManyUnsequencedRows is returned when tokens are requested but Unsequenced has grown
+// beyond the configured limit.
+var ErrTooManyUnsequencedRows = errors.New("too many unsequenced rows")
+
+// QuotaManager is a CockroachDB-based quota.Manager implementation.
+//
+// QuotaManager only implements Global/Write quotas, which is based on the number of Unsequenced
+// rows (to be exact, tokens = MaxUnsequencedRows - actualUnsequencedRows).
+// Other quotas are considered infinite.
+type QuotaManager struct {
+	DB                 *sql.DB
+	MaxUnsequencedRows int
+}
+
+// GetTokens implements quota.Manager.GetTokens.
+// It doesn't actually reserve or retrieve tokens, instead it allows access based on the number of
+// rows in the Unsequenced table.
+func (m *QuotaManager) GetTokens(ctx context.Context, numTokens int, specs []quota.Spec) error {
+	for _, spec := range specs {
+		if spec.Group != quota.Global || spec.Kind != quota.Write {
+			continue
+		}
+		// Only allow global writes if Unsequenced is under the expected limit
+		count, err := m.countUnsequenced(ctx)
+		if err != nil {
+			return err
+		}
+		if count+numTokens > m.MaxUnsequencedRows {
+			return ErrTooManyUnsequencedRows
+		}
+	}
+	return nil
+}
+
+// PutTokens implements quota.Manager.PutTokens.
+// It's a noop for QuotaManager.
+func (m *QuotaManager) PutTokens(ctx context.Context, numTokens int, specs []quota.Spec) error {
+	return nil
+}
+
+// ResetQuota implements quota.Manager.ResetQuota.
+// It's a noop for QuotaManager.
+func (m *QuotaManager) ResetQuota(ctx context.Context, specs []quota.Spec) error {
+	return nil
+}
+
+func (m *QuotaManager) countUnsequenced(ctx context.Context) (int, error) {
+	// table names are lowercase for some reason
+	rows, err := m.DB.QueryContext(ctx, countFromUnsequencedTable)
+	if err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+	if !rows.Next() {
+		return 0, errors.New("cursor has no rows after quota limit determination query")
+	}
+	var count int
+	if err := rows.Scan(&count); err != nil {
+		return 0, err
+	}
+	if rows.Next() {
+		return 0, errors.New("too many rows returned from quota limit determination query")
+	}
+	return count, nil
+}