Add MySQL backend metadata (#3828)

FerretDB · Dec 11, 2023 · 1290378 · 1290378
1 parent c0eace0
commit 1290378
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diff --git a/.golangci.yml b/.golangci.yml
@@ -46,6 +46,8 @@ linters-settings:
           - "!**/internal/backends/sqlite/*.go"
           - "!**/internal/backends/postgresql/*.go"
           - "!**/internal/backends/postgresql/metadata/*.go"
+          - "!**/internal/backends/mysql/*.go"
+          - "!**/internal/backends/mysql/metadata/*.go"
           - "!**/internal/backends/hana/*.go"
         deny:
           - pkg: github.com/FerretDB/FerretDB/internal/handler/sjson

diff --git a/internal/backends/mysql/metadata/indexes.go b/internal/backends/mysql/metadata/indexes.go
@@ -0,0 +1,121 @@
+// Copyright 2021 FerretDB Inc.
+//
+// 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 metadata
+
+import (
+	"errors"
+
+	"github.com/FerretDB/FerretDB/internal/types"
+	"github.com/FerretDB/FerretDB/internal/util/iterator"
+	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
+	"github.com/FerretDB/FerretDB/internal/util/must"
+)
+
+// Indexes represents information about all indexes in a collection.
+type Indexes []IndexInfo
+
+// IndexInfo represents information about a single index.
+type IndexInfo struct {
+	Name   string
+	Index  string
+	Key    []IndexKeyPair
+	Unique bool
+}
+
+// IndexKeyPair consists of a field name and a sort order that are part of the index.
+type IndexKeyPair struct {
+	Field      string
+	Descending bool
+}
+
+// marshal returns [*types.Array] for indexes.
+func (indexes Indexes) marshal() *types.Array {
+	res := types.MakeArray(len(indexes))
+
+	for _, index := range indexes {
+		key := types.MakeDocument(len(index.Key))
+
+		for _, pair := range index.Key {
+			order := int32(1)
+			if pair.Descending {
+				order = int32(-1)
+			}
+
+			key.Set(pair.Field, order)
+		}
+
+		res.Append(must.NotFail(types.NewDocument(
+			"name", index.Name,
+			"index", index.Index,
+			"key", key,
+			"unique", index.Unique,
+		)))
+	}
+
+	return res
+}
+
+func (s *Indexes) unmarshal(a *types.Array) error {
+	res := make([]IndexInfo, a.Len())
+
+	iter := a.Iterator()
+	defer iter.Close()
+
+	for {
+		i, v, err := iter.Next()
+
+		if errors.Is(err, iterator.ErrIteratorDone) {
+			break
+		}
+
+		if err != nil {
+			return lazyerrors.Error(err)
+		}
+
+		index := v.(*types.Document)
+
+		keyDoc := must.NotFail(index.Get("key")).(*types.Document)
+		fields := keyDoc.Keys()
+		orders := keyDoc.Values()
+
+		key := make([]IndexKeyPair, keyDoc.Len())
+
+		for j, f := range fields {
+			descending := false
+			if orders[j].(int32) == -1 {
+				descending = true
+			}
+
+			key = append(key, IndexKeyPair{
+				Field:      f,
+				Descending: descending,
+			})
+		}
+
+		v, _ = index.Get("unique")
+		unique, _ := v.(bool)
+
+		res[i] = IndexInfo{
+			Name:   must.NotFail(index.Get("name")).(string),
+			Index:  must.NotFail(index.Get("index")).(string),
+			Key:    key,
+			Unique: unique,
+		}
+	}
+
+	*s = res
+
+	return nil
+}
diff --git a/internal/backends/mysql/metadata/metadata.go b/internal/backends/mysql/metadata/metadata.go
@@ -0,0 +1,132 @@
+// Copyright 2021 FerretDB Inc.
+//
+// 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 metadata provides access to databases and collections information.
+package metadata
+
+import (
+	"database/sql"
+	"database/sql/driver"
+
+	"github.com/FerretDB/FerretDB/internal/handler/sjson"
+	"github.com/FerretDB/FerretDB/internal/types"
+	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
+	"github.com/FerretDB/FerretDB/internal/util/must"
+)
+
+// Collection represents collection metadata.
+//
+// Collection value should be immutable to avoid data races.
+// Use [deepCopy] to replace whole value instead of modifying fields of existing value.
+type Collection struct {
+	Name            string
+	TableName       string
+	Indexes         Indexes
+	CappedSize      int64
+	CappedDocuments int64
+}
+
+// Capped returns true if collection is capped.
+func (c Collection) Capped() bool {
+	return c.CappedSize > 0
+}
+
+// Value implements driver.Valuer interface.
+func (c Collection) Value() (driver.Value, error) {
+	b, err := sjson.Marshal(c.marshal())
+	if err != nil {
+		return nil, lazyerrors.Error(err)
+	}
+
+	return b, nil
+}
+
+// Scan implements sql.Scanner interface.
+func (c *Collection) Scan(src any) error {
+	var doc *types.Document
+	var err error
+
+	switch src := src.(type) {
+	case nil:
+		*c = Collection{}
+		return nil
+	case []byte:
+		doc, err = sjson.Unmarshal(src)
+	case string:
+		doc, err = sjson.Unmarshal([]byte(src))
+	default:
+		panic("can't scan collection")
+	}
+
+	if err != nil {
+		return lazyerrors.Error(err)
+	}
+
+	if err = c.unmarshal(doc); err != nil {
+		return lazyerrors.Error(err)
+	}
+
+	return nil
+}
+
+// marshal returns the [*types.Document] for that collection.
+func (c *Collection) marshal() *types.Document {
+	return must.NotFail(types.NewDocument(
+		"_id", c.Name,
+		"table", c.TableName,
+		"indexes", c.Indexes.marshal(),
+		"cappedSize", c.CappedSize,
+		"cappedDocuments", c.CappedDocuments,
+	))
+}
+
+// unmarshal sets collection metadata from [*types.Document].
+func (c *Collection) unmarshal(doc *types.Document) error {
+	v, _ := doc.Get("_id")
+	c.Name, _ = v.(string)
+
+	if c.Name == "" {
+		return lazyerrors.New("collection name is empty")
+	}
+
+	v, _ = doc.Get("table")
+	c.TableName, _ = v.(string)
+
+	if c.TableName == "" {
+		return lazyerrors.New("table name is empty")
+	}
+
+	v, _ = doc.Get("indexes")
+	i, _ := v.(*types.Array)
+
+	if err := c.Indexes.unmarshal(i); err != nil {
+		return lazyerrors.Error(err)
+	}
+
+	if v, _ := doc.Get("cappedSize"); v != nil {
+		c.CappedSize = v.(int64)
+	}
+
+	if v, _ := doc.Get("cappedDocuments"); v != nil {
+		c.CappedSize = v.(int64)
+	}
+
+	return nil
+}
+
+// check interfaces
+var (
+	_ driver.Valuer = Collection{}
+	_ sql.Scanner   = (*Collection)(nil)
+)
diff --git a/internal/backends/mysql/metadata/pool/opendb.go b/internal/backends/mysql/metadata/pool/opendb.go
@@ -0,0 +1,68 @@
+// Copyright 2021 FerretDB Inc.
+//
+// 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 pool
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	_ "github.com/go-sql-driver/mysql" // register database/sql driver
+	"go.uber.org/zap"
+
+	"github.com/FerretDB/FerretDB/internal/util/fsql"
+	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
+	"github.com/FerretDB/FerretDB/internal/util/state"
+)
+
+// openDB creates a pool of connections to MySQL database
+// and check that it works (authentication passes, settings are okay).
+func openDB(uri string, l *zap.Logger, sp *state.Provider) (*fsql.DB, error) {
+	mysqlURL, err := parseURI(uri)
+	if err != nil {
+		return nil, lazyerrors.Error(err)
+	}
+
+	db, err := sql.Open("mysql", mysqlURL)
+	if err != nil {
+		return nil, lazyerrors.Error(err)
+	}
+
+	db.SetConnMaxIdleTime(1 * time.Minute)
+	db.SetMaxIdleConns(50)
+	db.SetMaxOpenConns(50)
+
+	if err = db.Ping(); err != nil {
+		_ = db.Close()
+		return nil, lazyerrors.Error(err)
+	}
+
+	// set backend version
+	if sp.Get().BackendVersion == "" {
+		err := sp.Update(func(s *state.State) {
+			s.BackendName = "MySQL"
+
+			row := db.QueryRowContext(context.Background(), `SELECT version()`)
+			if err := row.Scan(&s.BackendVersion); err != nil {
+				l.Error("mysql.metadata.pool.openDB: failed to query MySQL version", zap.Error(err))
+			}
+		})
+		if err != nil {
+			l.Error("mysql.metadata.pool.openDB: failed to query MySQL version", zap.Error(err))
+		}
+	}
+
+	return fsql.WrapDB(db, "", l), nil
+}