add database pkg (#8)

* add database pkg

go.mod

@@ -2,18 +2,28 @@ module github.com/bilibili/Kratos
 
 require (
 	github.com/BurntSushi/toml v0.3.1
+	github.com/aristanetworks/goarista v0.0.0-20190325233358-a123909ec740 // indirect
+	github.com/cznic/b v0.0.0-20181122101859-a26611c4d92d // indirect
+	github.com/cznic/mathutil v0.0.0-20181122101859-297441e03548 // indirect
+	github.com/cznic/strutil v0.0.0-20181122101858-275e90344537 // indirect
 	github.com/fatih/color v1.7.0
 	github.com/fsnotify/fsnotify v1.4.7
 	github.com/go-playground/locales v0.12.1 // indirect
 	github.com/go-playground/universal-translator v0.16.0 // indirect
+	github.com/go-sql-driver/mysql v1.4.1
 	github.com/gogo/protobuf v1.2.0
 	github.com/golang/protobuf v1.2.0
 	github.com/kr/pty v1.1.4
 	github.com/leodido/go-urn v1.1.0 // indirect
 	github.com/pkg/errors v0.8.1
 	github.com/prometheus/client_golang v0.9.2
+	github.com/remyoudompheng/bigfft v0.0.0-20190321074620-2f0d2b0e0001 // indirect
+	github.com/samuel/go-zookeeper v0.0.0-20180130194729-c4fab1ac1bec // indirect
+	github.com/sirupsen/logrus v1.4.1 // indirect
 	github.com/stretchr/testify v1.3.0
+	github.com/tsuna/gohbase v0.0.0-20190201102810-d3184c1526df
 	github.com/urfave/cli v1.20.0
+	golang.org/x/time v0.0.0-20190308202827-9d24e82272b4 // indirect
 	google.golang.org/grpc v1.18.0
 	gopkg.in/AlecAivazis/survey.v1 v1.8.2
 	gopkg.in/go-playground/assert.v1 v1.2.1 // indirect

pkg/database/hbase/README.md

@@ -0,0 +1,44 @@
+### database/hbase
+
+### 项目简介
+
+Hbase Client，进行封装加入了链路追踪和统计。
+
+### usage
+```go
+package main
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/bilibili/Kratos/pkg/database/hbase"
+)
+
+func main() {
+	config := &hbase.Config{Zookeeper: &hbase.ZKConfig{Addrs: []string{"localhost"}}}
+	client := hbase.NewClient(config)
+
+	values := map[string]map[string][]byte{"name": {"firstname": []byte("hello"), "lastname": []byte("world")}}
+	ctx := context.Background()
+
+	_, err := client.PutStr(ctx, "user", "user1", values)
+	if err != nil {
+		panic(err)
+	}
+
+	result, err := client.GetStr(ctx, "user", "user1")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("%v", result)
+}
+```
+
+##### 编译环境
+
+> 请只用golang v1.8.x以上版本编译执行。
+
+##### 依赖包
+
+> 1.[gohbase](https://github.com/tsuna/gohbase)

pkg/database/hbase/config.go

@@ -0,0 +1,23 @@
+package hbase
+
+import (
+	xtime "github.com/bilibili/Kratos/pkg/time"
+)
+
+// ZKConfig Server&Client settings.
+type ZKConfig struct {
+	Root    string
+	Addrs   []string
+	Timeout xtime.Duration
+}
+
+// Config hbase config
+type Config struct {
+	Zookeeper           *ZKConfig
+	RPCQueueSize        int
+	FlushInterval       xtime.Duration
+	EffectiveUser       string
+	RegionLookupTimeout xtime.Duration
+	RegionReadTimeout   xtime.Duration
+	TestRowKey          string
+}

pkg/database/hbase/hbase.go

@@ -0,0 +1,297 @@
+package hbase
+
+import (
+	"context"
+	"io"
+	"strings"
+	"time"
+
+	"github.com/tsuna/gohbase"
+	"github.com/tsuna/gohbase/hrpc"
+
+	"github.com/bilibili/Kratos/pkg/log"
+)
+
+// HookFunc hook function call before every method and hook return function will call after finish.
+type HookFunc func(ctx context.Context, call hrpc.Call, customName string) func(err error)
+
+// Client hbase client.
+type Client struct {
+	hc     gohbase.Client
+	addr   string
+	config *Config
+	hooks  []HookFunc
+}
+
+// AddHook add hook function.
+func (c *Client) AddHook(hookFn HookFunc) {
+	c.hooks = append(c.hooks, hookFn)
+}
+
+func (c *Client) invokeHook(ctx context.Context, call hrpc.Call, customName string) func(error) {
+	finishHooks := make([]func(error), 0, len(c.hooks))
+	for _, fn := range c.hooks {
+		finishHooks = append(finishHooks, fn(ctx, call, customName))
+	}
+	return func(err error) {
+		for _, fn := range finishHooks {
+			fn(err)
+		}
+	}
+}
+
+// NewClient new a hbase client.
+func NewClient(config *Config, options ...gohbase.Option) *Client {
+	rawcli := NewRawClient(config, options...)
+	rawcli.AddHook(NewSlowLogHook(250 * time.Millisecond))
+	rawcli.AddHook(MetricsHook(nil))
+	rawcli.AddHook(TraceHook("database/hbase", strings.Join(config.Zookeeper.Addrs, ",")))
+	return rawcli
+}
+
+// NewRawClient new a hbase client without prometheus metrics and dapper trace hook.
+func NewRawClient(config *Config, options ...gohbase.Option) *Client {
+	zkquorum := strings.Join(config.Zookeeper.Addrs, ",")
+	if config.Zookeeper.Root != "" {
+		options = append(options, gohbase.ZookeeperRoot(config.Zookeeper.Root))
+	}
+	if config.Zookeeper.Timeout != 0 {
+		options = append(options, gohbase.ZookeeperTimeout(time.Duration(config.Zookeeper.Timeout)))
+	}
+
+	if config.RPCQueueSize != 0 {
+		log.Warn("RPCQueueSize configuration be ignored")
+	}
+	// force RpcQueueSize = 1, don't change it !!! it has reason  (゜-゜)つロ
+	options = append(options, gohbase.RpcQueueSize(1))
+
+	if config.FlushInterval != 0 {
+		options = append(options, gohbase.FlushInterval(time.Duration(config.FlushInterval)))
+	}
+	if config.EffectiveUser != "" {
+		options = append(options, gohbase.EffectiveUser(config.EffectiveUser))
+	}
+	if config.RegionLookupTimeout != 0 {
+		options = append(options, gohbase.RegionLookupTimeout(time.Duration(config.RegionLookupTimeout)))
+	}
+	if config.RegionReadTimeout != 0 {
+		options = append(options, gohbase.RegionReadTimeout(time.Duration(config.RegionReadTimeout)))
+	}
+	hc := gohbase.NewClient(zkquorum, options...)
+	return &Client{
+		hc:     hc,
+		addr:   zkquorum,
+		config: config,
+	}
+}
+
+// ScanAll do scan command and return all result
+// NOTE: if err != nil the results is safe for range operate even not result found
+func (c *Client) ScanAll(ctx context.Context, table []byte, options ...func(hrpc.Call) error) (results []*hrpc.Result, err error) {
+	cursor, err := c.Scan(ctx, table, options...)
+	if err != nil {
+		return nil, err
+	}
+	for {
+		result, err := cursor.Next()
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, err
+		}
+		results = append(results, result)
+	}
+	return results, nil
+}
+
+type scanTrace struct {
+	hrpc.Scanner
+	finishHook func(error)
+}
+
+func (s *scanTrace) Next() (*hrpc.Result, error) {
+	result, err := s.Scanner.Next()
+	if err != nil {
+		s.finishHook(err)
+	}
+	return result, err
+}
+
+func (s *scanTrace) Close() error {
+	err := s.Scanner.Close()
+	s.finishHook(err)
+	return err
+}
+
+// Scan do a scan command.
+func (c *Client) Scan(ctx context.Context, table []byte, options ...func(hrpc.Call) error) (scanner hrpc.Scanner, err error) {
+	var scan *hrpc.Scan
+	scan, err = hrpc.NewScan(ctx, table, options...)
+	if err != nil {
+		return nil, err
+	}
+	st := &scanTrace{}
+	st.finishHook = c.invokeHook(ctx, scan, "Scan")
+	st.Scanner = c.hc.Scan(scan)
+	return st, nil
+}
+
+// ScanStr scan string
+func (c *Client) ScanStr(ctx context.Context, table string, options ...func(hrpc.Call) error) (hrpc.Scanner, error) {
+	return c.Scan(ctx, []byte(table), options...)
+}
+
+// ScanStrAll scan string
+// NOTE: if err != nil the results is safe for range operate even not result found
+func (c *Client) ScanStrAll(ctx context.Context, table string, options ...func(hrpc.Call) error) ([]*hrpc.Result, error) {
+	return c.ScanAll(ctx, []byte(table), options...)
+}
+
+// ScanRange get a scanner for the given table and key range.
+// The range is half-open, i.e. [startRow; stopRow[ -- stopRow is not
+// included in the range.
+func (c *Client) ScanRange(ctx context.Context, table, startRow, stopRow []byte, options ...func(hrpc.Call) error) (scanner hrpc.Scanner, err error) {
+	var scan *hrpc.Scan
+	scan, err = hrpc.NewScanRange(ctx, table, startRow, stopRow, options...)
+	if err != nil {
+		return nil, err
+	}
+	st := &scanTrace{}
+	st.finishHook = c.invokeHook(ctx, scan, "ScanRange")
+	st.Scanner = c.hc.Scan(scan)
+	return st, nil
+}
+
+// ScanRangeStr get a scanner for the given table and key range.
+// The range is half-open, i.e. [startRow; stopRow[ -- stopRow is not
+// included in the range.
+func (c *Client) ScanRangeStr(ctx context.Context, table, startRow, stopRow string, options ...func(hrpc.Call) error) (hrpc.Scanner, error) {
+	return c.ScanRange(ctx, []byte(table), []byte(startRow), []byte(stopRow), options...)
+}
+
+// Get get result for the given table and row key.
+// NOTE: if err != nil then result != nil, if result not exists result.Cells length is 0
+func (c *Client) Get(ctx context.Context, table, key []byte, options ...func(hrpc.Call) error) (result *hrpc.Result, err error) {
+	var get *hrpc.Get
+	get, err = hrpc.NewGet(ctx, table, key, options...)
+	if err != nil {
+		return nil, err
+	}
+
+	finishHook := c.invokeHook(ctx, get, "GET")
+	result, err = c.hc.Get(get)
+	finishHook(err)
+	return
+}
+
+// GetStr do a get command.
+// NOTE: if err != nil then result != nil, if result not exists result.Cells length is 0
+func (c *Client) GetStr(ctx context.Context, table, key string, options ...func(hrpc.Call) error) (result *hrpc.Result, err error) {
+	return c.Get(ctx, []byte(table), []byte(key), options...)
+}
+
+// PutStr insert the given family-column-values in the given row key of the given table.
+func (c *Client) PutStr(ctx context.Context, table string, key string, values map[string]map[string][]byte, options ...func(hrpc.Call) error) (*hrpc.Result, error) {
+	put, err := hrpc.NewPutStr(ctx, table, key, values, options...)
+	if err != nil {
+		return nil, err
+	}
+
+	finishHook := c.invokeHook(ctx, put, "PUT")
+	result, err := c.hc.Put(put)
+	finishHook(err)
+	return result, err
+}
+
+// Delete is used to perform Delete operations on a single row.
+// To delete entire row, values should be nil.
+//
+// To delete specific families, qualifiers map should be nil:
+//  map[string]map[string][]byte{
+//		"cf1": nil,
+//		"cf2": nil,
+//  }
+//
+// To delete specific qualifiers:
+//  map[string]map[string][]byte{
+//      "cf": map[string][]byte{
+//			"q1": nil,
+//			"q2": nil,
+//		},
+//  }
+//
+// To delete all versions before and at a timestamp, pass hrpc.Timestamp() option.
+// By default all versions will be removed.
+//
+// To delete only a specific version at a timestamp, pass hrpc.DeleteOneVersion() option
+// along with a timestamp. For delete specific qualifiers request, if timestamp is not
+// passed, only the latest version will be removed. For delete specific families request,
+// the timestamp should be passed or it will have no effect as it's an expensive
+// operation to perform.
+func (c *Client) Delete(ctx context.Context, table string, key string, values map[string]map[string][]byte, options ...func(hrpc.Call) error) (*hrpc.Result, error) {
+	del, err := hrpc.NewDelStr(ctx, table, key, values, options...)
+	if err != nil {
+		return nil, err
+	}
+
+	finishHook := c.invokeHook(ctx, del, "Delete")
+	result, err := c.hc.Delete(del)
+	finishHook(err)
+	return result, err
+}
+
+// Append do a append command.
+func (c *Client) Append(ctx context.Context, table string, key string, values map[string]map[string][]byte, options ...func(hrpc.Call) error) (*hrpc.Result, error) {
+	appd, err := hrpc.NewAppStr(ctx, table, key, values, options...)
+	if err != nil {
+		return nil, err
+	}
+
+	finishHook := c.invokeHook(ctx, appd, "Append")
+	result, err := c.hc.Append(appd)
+	finishHook(err)
+	return result, err
+}
+
+// Increment the given values in HBase under the given table and key.
+func (c *Client) Increment(ctx context.Context, table string, key string, values map[string]map[string][]byte, options ...func(hrpc.Call) error) (int64, error) {
+	increment, err := hrpc.NewIncStr(ctx, table, key, values, options...)
+	if err != nil {
+		return 0, err
+	}
+	finishHook := c.invokeHook(ctx, increment, "Increment")
+	result, err := c.hc.Increment(increment)
+	finishHook(err)
+	return result, err
+}
+
+// IncrementSingle increment the given value by amount in HBase under the given table, key, family and qualifier.
+func (c *Client) IncrementSingle(ctx context.Context, table string, key string, family string, qualifier string, amount int64, options ...func(hrpc.Call) error) (int64, error) {
+	increment, err := hrpc.NewIncStrSingle(ctx, table, key, family, qualifier, amount, options...)
+	if err != nil {
+		return 0, err
+	}
+
+	finishHook := c.invokeHook(ctx, increment, "IncrementSingle")
+	result, err := c.hc.Increment(increment)
+	finishHook(err)
+	return result, err
+}
+
+// Ping ping.
+func (c *Client) Ping(ctx context.Context) (err error) {
+	testRowKey := "test"
+	if c.config.TestRowKey != "" {
+		testRowKey = c.config.TestRowKey
+	}
+	values := map[string]map[string][]byte{"test": map[string][]byte{"test": []byte("test")}}
+	_, err = c.PutStr(ctx, "test", testRowKey, values)
+	return
+}
+
+// Close close client.
+func (c *Client) Close() error {
+	c.hc.Close()
+	return nil
+}

pkg/database/hbase/metrics.go

@@ -0,0 +1,48 @@
+package hbase
+
+import (
+	"context"
+	"io"
+	"time"
+
+	"github.com/tsuna/gohbase"
+	"github.com/tsuna/gohbase/hrpc"
+
+	"github.com/bilibili/Kratos/pkg/stat"
+)
+
+func codeFromErr(err error) string {
+	code := "unknown_error"
+	switch err {
+	case gohbase.ErrClientClosed:
+		code = "client_closed"
+	case gohbase.ErrConnotFindRegion:
+		code = "connot_find_region"
+	case gohbase.TableNotFound:
+		code = "table_not_found"
+	case gohbase.ErrRegionUnavailable:
+		code = "region_unavailable"
+	}
+	return code
+}
+
+// MetricsHook if stats is nil use stat.DB as default.
+func MetricsHook(stats stat.Stat) HookFunc {
+	if stats == nil {
+		stats = stat.DB
+	}
+	return func(ctx context.Context, call hrpc.Call, customName string) func(err error) {
+		now := time.Now()
+		if customName == "" {
+			customName = call.Name()
+		}
+		method := "hbase:" + customName
+		return func(err error) {
+			durationMs := int64(time.Since(now) / time.Millisecond)
+			stats.Timing(method, durationMs)
+			if err != nil && err != io.EOF {
+				stats.Incr(method, codeFromErr(err))
+			}
+		}
+	}
+}

pkg/database/hbase/slowlog.go

@@ -0,0 +1,24 @@
+package hbase
+
+import (
+	"context"
+	"time"
+
+	"github.com/tsuna/gohbase/hrpc"
+
+	"github.com/bilibili/Kratos/pkg/log"
+)
+
+// NewSlowLogHook log slow operation.
+func NewSlowLogHook(threshold time.Duration) HookFunc {
+	return func(ctx context.Context, call hrpc.Call, customName string) func(err error) {
+		start := time.Now()
+		return func(error) {
+			duration := time.Since(start)
+			if duration < threshold {
+				return
+			}
+			log.Warn("hbase slow log: %s %s %s time: %s", customName, call.Table(), call.Key(), duration)
+		}
+	}
+}

pkg/database/hbase/trace.go

@@ -0,0 +1,40 @@
+package hbase
+
+import (
+	"context"
+	"io"
+
+	"github.com/tsuna/gohbase/hrpc"
+
+	"github.com/bilibili/Kratos/pkg/net/trace"
+)
+
+// TraceHook create new hbase trace hook.
+func TraceHook(component, instance string) HookFunc {
+	var internalTags []trace.Tag
+	internalTags = append(internalTags, trace.TagString(trace.TagComponent, component))
+	internalTags = append(internalTags, trace.TagString(trace.TagDBInstance, instance))
+	internalTags = append(internalTags, trace.TagString(trace.TagPeerService, "hbase"))
+	internalTags = append(internalTags, trace.TagString(trace.TagSpanKind, "client"))
+	return func(ctx context.Context, call hrpc.Call, customName string) func(err error) {
+		noop := func(error) {}
+		root, ok := trace.FromContext(ctx)
+		if !ok {
+			return noop
+		}
+		if customName == "" {
+			customName = call.Name()
+		}
+		span := root.Fork("", "Hbase:"+customName)
+		span.SetTag(internalTags...)
+		statement := string(call.Table()) + " " + string(call.Key())
+		span.SetTag(trace.TagString(trace.TagDBStatement, statement))
+		return func(err error) {
+			if err == io.EOF {
+				// reset error for trace.
+				err = nil
+			}
+			span.Finish(&err)
+		}
+	}
+}

pkg/database/sql/README.md

@@ -0,0 +1,12 @@
+#### database/sql
+
+##### 项目简介
+MySQL数据库驱动，进行封装加入了链路追踪和统计。
+
+如果需要SQL级别的超时管理 可以在业务代码里面使用context.WithDeadline实现 推荐超时配置放到application.toml里面 方便热加载
+
+##### 编译环境
+> 请只用golang v1.8.x以上版本编译执行。
+
+##### 依赖包
+> 1.[Go-MySQL-Driver](https://github.com/go-sql-driver/mysql)

pkg/database/sql/mysql.go

@@ -0,0 +1,40 @@
+package sql
+
+import (
+	"github.com/bilibili/Kratos/pkg/log"
+	"github.com/bilibili/Kratos/pkg/net/netutil/breaker"
+	"github.com/bilibili/Kratos/pkg/stat"
+	"github.com/bilibili/Kratos/pkg/time"
+
+	// database driver
+	_ "github.com/go-sql-driver/mysql"
+)
+
+var stats = stat.DB
+
+// Config mysql config.
+type Config struct {
+	Addr         string          // for trace
+	DSN          string          // write data source name.
+	ReadDSN      []string        // read data source name.
+	Active       int             // pool
+	Idle         int             // pool
+	IdleTimeout  time.Duration   // connect max life time.
+	QueryTimeout time.Duration   // query sql timeout
+	ExecTimeout  time.Duration   // execute sql timeout
+	TranTimeout  time.Duration   // transaction sql timeout
+	Breaker      *breaker.Config // breaker
+}
+
+// NewMySQL new db and retry connection when has error.
+func NewMySQL(c *Config) (db *DB) {
+	if c.QueryTimeout == 0 || c.ExecTimeout == 0 || c.TranTimeout == 0 {
+		panic("mysql must be set query/execute/transction timeout")
+	}
+	db, err := Open(c)
+	if err != nil {
+		log.Error("open mysql error(%v)", err)
+		panic(err)
+	}
+	return
+}

pkg/database/sql/sql.go

@@ -0,0 +1,678 @@
+package sql
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+	"sync/atomic"
+	"time"
+
+	"github.com/bilibili/Kratos/pkg/ecode"
+	"github.com/bilibili/Kratos/pkg/log"
+	"github.com/bilibili/Kratos/pkg/net/netutil/breaker"
+	"github.com/bilibili/Kratos/pkg/net/trace"
+
+	"github.com/pkg/errors"
+)
+
+const (
+	_family          = "sql_client"
+	_slowLogDuration = time.Millisecond * 250
+)
+
+var (
+	// ErrStmtNil prepared stmt error
+	ErrStmtNil = errors.New("sql: prepare failed and stmt nil")
+	// ErrNoMaster is returned by Master when call master multiple times.
+	ErrNoMaster = errors.New("sql: no master instance")
+	// ErrNoRows is returned by Scan when QueryRow doesn't return a row.
+	// In such a case, QueryRow returns a placeholder *Row value that defers
+	// this error until a Scan.
+	ErrNoRows = sql.ErrNoRows
+	// ErrTxDone transaction done.
+	ErrTxDone = sql.ErrTxDone
+)
+
+// DB database.
+type DB struct {
+	write  *conn
+	read   []*conn
+	idx    int64
+	master *DB
+}
+
+// conn database connection
+type conn struct {
+	*sql.DB
+	breaker breaker.Breaker
+	conf    *Config
+}
+
+// Tx transaction.
+type Tx struct {
+	db     *conn
+	tx     *sql.Tx
+	t      trace.Trace
+	c      context.Context
+	cancel func()
+}
+
+// Row row.
+type Row struct {
+	err error
+	*sql.Row
+	db     *conn
+	query  string
+	args   []interface{}
+	t      trace.Trace
+	cancel func()
+}
+
+// Scan copies the columns from the matched row into the values pointed at by dest.
+func (r *Row) Scan(dest ...interface{}) (err error) {
+	defer slowLog(fmt.Sprintf("Scan query(%s) args(%+v)", r.query, r.args), time.Now())
+	if r.t != nil {
+		defer r.t.Finish(&err)
+	}
+	if r.err != nil {
+		err = r.err
+	} else if r.Row == nil {
+		err = ErrStmtNil
+	}
+	if err != nil {
+		return
+	}
+	err = r.Row.Scan(dest...)
+	if r.cancel != nil {
+		r.cancel()
+	}
+	r.db.onBreaker(&err)
+	if err != ErrNoRows {
+		err = errors.Wrapf(err, "query %s args %+v", r.query, r.args)
+	}
+	return
+}
+
+// Rows rows.
+type Rows struct {
+	*sql.Rows
+	cancel func()
+}
+
+// Close closes the Rows, preventing further enumeration. If Next is called
+// and returns false and there are no further result sets,
+// the Rows are closed automatically and it will suffice to check the
+// result of Err. Close is idempotent and does not affect the result of Err.
+func (rs *Rows) Close() (err error) {
+	err = errors.WithStack(rs.Rows.Close())
+	if rs.cancel != nil {
+		rs.cancel()
+	}
+	return
+}
+
+// Stmt prepared stmt.
+type Stmt struct {
+	db    *conn
+	tx    bool
+	query string
+	stmt  atomic.Value
+	t     trace.Trace
+}
+
+// Open opens a database specified by its database driver name and a
+// driver-specific data source name, usually consisting of at least a database
+// name and connection information.
+func Open(c *Config) (*DB, error) {
+	db := new(DB)
+	d, err := connect(c, c.DSN)
+	if err != nil {
+		return nil, err
+	}
+	brkGroup := breaker.NewGroup(c.Breaker)
+	brk := brkGroup.Get(c.Addr)
+	w := &conn{DB: d, breaker: brk, conf: c}
+	rs := make([]*conn, 0, len(c.ReadDSN))
+	for _, rd := range c.ReadDSN {
+		d, err := connect(c, rd)
+		if err != nil {
+			return nil, err
+		}
+		brk := brkGroup.Get(parseDSNAddr(rd))
+		r := &conn{DB: d, breaker: brk, conf: c}
+		rs = append(rs, r)
+	}
+	db.write = w
+	db.read = rs
+	db.master = &DB{write: db.write}
+	return db, nil
+}
+
+func connect(c *Config, dataSourceName string) (*sql.DB, error) {
+	d, err := sql.Open("mysql", dataSourceName)
+	if err != nil {
+		err = errors.WithStack(err)
+		return nil, err
+	}
+	d.SetMaxOpenConns(c.Active)
+	d.SetMaxIdleConns(c.Idle)
+	d.SetConnMaxLifetime(time.Duration(c.IdleTimeout))
+	return d, nil
+}
+
+// Begin starts a transaction. The isolation level is dependent on the driver.
+func (db *DB) Begin(c context.Context) (tx *Tx, err error) {
+	return db.write.begin(c)
+}
+
+// Exec executes a query without returning any rows.
+// The args are for any placeholder parameters in the query.
+func (db *DB) Exec(c context.Context, query string, args ...interface{}) (res sql.Result, err error) {
+	return db.write.exec(c, query, args...)
+}
+
+// Prepare creates a prepared statement for later queries or executions.
+// Multiple queries or executions may be run concurrently from the returned
+// statement. The caller must call the statement's Close method when the
+// statement is no longer needed.
+func (db *DB) Prepare(query string) (*Stmt, error) {
+	return db.write.prepare(query)
+}
+
+// Prepared creates a prepared statement for later queries or executions.
+// Multiple queries or executions may be run concurrently from the returned
+// statement. The caller must call the statement's Close method when the
+// statement is no longer needed.
+func (db *DB) Prepared(query string) (stmt *Stmt) {
+	return db.write.prepared(query)
+}
+
+// Query executes a query that returns rows, typically a SELECT. The args are
+// for any placeholder parameters in the query.
+func (db *DB) Query(c context.Context, query string, args ...interface{}) (rows *Rows, err error) {
+	idx := db.readIndex()
+	for i := range db.read {
+		if rows, err = db.read[(idx+i)%len(db.read)].query(c, query, args...); !ecode.ServiceUnavailable.Equal(err) {
+			return
+		}
+	}
+	return db.write.query(c, query, args...)
+}
+
+// QueryRow executes a query that is expected to return at most one row.
+// QueryRow always returns a non-nil value. Errors are deferred until Row's
+// Scan method is called.
+func (db *DB) QueryRow(c context.Context, query string, args ...interface{}) *Row {
+	idx := db.readIndex()
+	for i := range db.read {
+		if row := db.read[(idx+i)%len(db.read)].queryRow(c, query, args...); !ecode.ServiceUnavailable.Equal(row.err) {
+			return row
+		}
+	}
+	return db.write.queryRow(c, query, args...)
+}
+
+func (db *DB) readIndex() int {
+	if len(db.read) == 0 {
+		return 0
+	}
+	v := atomic.AddInt64(&db.idx, 1)
+	return int(v) % len(db.read)
+}
+
+// Close closes the write and read database, releasing any open resources.
+func (db *DB) Close() (err error) {
+	if e := db.write.Close(); e != nil {
+		err = errors.WithStack(e)
+	}
+	for _, rd := range db.read {
+		if e := rd.Close(); e != nil {
+			err = errors.WithStack(e)
+		}
+	}
+	return
+}
+
+// Ping verifies a connection to the database is still alive, establishing a
+// connection if necessary.
+func (db *DB) Ping(c context.Context) (err error) {
+	if err = db.write.ping(c); err != nil {
+		return
+	}
+	for _, rd := range db.read {
+		if err = rd.ping(c); err != nil {
+			return
+		}
+	}
+	return
+}
+
+// Master return *DB instance direct use master conn
+// use this *DB instance only when you have some reason need to get result without any delay.
+func (db *DB) Master() *DB {
+	if db.master == nil {
+		panic(ErrNoMaster)
+	}
+	return db.master
+}
+
+func (db *conn) onBreaker(err *error) {
+	if err != nil && *err != nil && *err != sql.ErrNoRows && *err != sql.ErrTxDone {
+		db.breaker.MarkFailed()
+	} else {
+		db.breaker.MarkSuccess()
+	}
+}
+
+func (db *conn) begin(c context.Context) (tx *Tx, err error) {
+	now := time.Now()
+	defer slowLog("Begin", now)
+	t, ok := trace.FromContext(c)
+	if ok {
+		t = t.Fork(_family, "begin")
+		t.SetTag(trace.String(trace.TagAddress, db.conf.Addr), trace.String(trace.TagComment, ""))
+		defer func() {
+			if err != nil {
+				t.Finish(&err)
+			}
+		}()
+	}
+	if err = db.breaker.Allow(); err != nil {
+		stats.Incr("mysql:begin", "breaker")
+		return
+	}
+	_, c, cancel := db.conf.TranTimeout.Shrink(c)
+	rtx, err := db.BeginTx(c, nil)
+	stats.Timing("mysql:begin", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.WithStack(err)
+		cancel()
+		return
+	}
+	tx = &Tx{tx: rtx, t: t, db: db, c: c, cancel: cancel}
+	return
+}
+
+func (db *conn) exec(c context.Context, query string, args ...interface{}) (res sql.Result, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Exec query(%s) args(%+v)", query, args), now)
+	if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "exec")
+		t.SetTag(trace.String(trace.TagAddress, db.conf.Addr), trace.String(trace.TagComment, query))
+		defer t.Finish(&err)
+	}
+	if err = db.breaker.Allow(); err != nil {
+		stats.Incr("mysql:exec", "breaker")
+		return
+	}
+	_, c, cancel := db.conf.ExecTimeout.Shrink(c)
+	res, err = db.ExecContext(c, query, args...)
+	cancel()
+	db.onBreaker(&err)
+	stats.Timing("mysql:exec", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "exec:%s, args:%+v", query, args)
+	}
+	return
+}
+
+func (db *conn) ping(c context.Context) (err error) {
+	now := time.Now()
+	defer slowLog("Ping", now)
+	if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "ping")
+		t.SetTag(trace.String(trace.TagAddress, db.conf.Addr), trace.String(trace.TagComment, ""))
+		defer t.Finish(&err)
+	}
+	if err = db.breaker.Allow(); err != nil {
+		stats.Incr("mysql:ping", "breaker")
+		return
+	}
+	_, c, cancel := db.conf.ExecTimeout.Shrink(c)
+	err = db.PingContext(c)
+	cancel()
+	db.onBreaker(&err)
+	stats.Timing("mysql:ping", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.WithStack(err)
+	}
+	return
+}
+
+func (db *conn) prepare(query string) (*Stmt, error) {
+	defer slowLog(fmt.Sprintf("Prepare query(%s)", query), time.Now())
+	stmt, err := db.Prepare(query)
+	if err != nil {
+		err = errors.Wrapf(err, "prepare %s", query)
+		return nil, err
+	}
+	st := &Stmt{query: query, db: db}
+	st.stmt.Store(stmt)
+	return st, nil
+}
+
+func (db *conn) prepared(query string) (stmt *Stmt) {
+	defer slowLog(fmt.Sprintf("Prepared query(%s)", query), time.Now())
+	stmt = &Stmt{query: query, db: db}
+	s, err := db.Prepare(query)
+	if err == nil {
+		stmt.stmt.Store(s)
+		return
+	}
+	go func() {
+		for {
+			s, err := db.Prepare(query)
+			if err != nil {
+				time.Sleep(time.Second)
+				continue
+			}
+			stmt.stmt.Store(s)
+			return
+		}
+	}()
+	return
+}
+
+func (db *conn) query(c context.Context, query string, args ...interface{}) (rows *Rows, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Query query(%s) args(%+v)", query, args), now)
+	if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "query")
+		t.SetTag(trace.String(trace.TagAddress, db.conf.Addr), trace.String(trace.TagComment, query))
+		defer t.Finish(&err)
+	}
+	if err = db.breaker.Allow(); err != nil {
+		stats.Incr("mysql:query", "breaker")
+		return
+	}
+	_, c, cancel := db.conf.QueryTimeout.Shrink(c)
+	rs, err := db.DB.QueryContext(c, query, args...)
+	db.onBreaker(&err)
+	stats.Timing("mysql:query", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "query:%s, args:%+v", query, args)
+		cancel()
+		return
+	}
+	rows = &Rows{Rows: rs, cancel: cancel}
+	return
+}
+
+func (db *conn) queryRow(c context.Context, query string, args ...interface{}) *Row {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("QueryRow query(%s) args(%+v)", query, args), now)
+	t, ok := trace.FromContext(c)
+	if ok {
+		t = t.Fork(_family, "queryrow")
+		t.SetTag(trace.String(trace.TagAddress, db.conf.Addr), trace.String(trace.TagComment, query))
+	}
+	if err := db.breaker.Allow(); err != nil {
+		stats.Incr("mysql:queryrow", "breaker")
+		return &Row{db: db, t: t, err: err}
+	}
+	_, c, cancel := db.conf.QueryTimeout.Shrink(c)
+	r := db.DB.QueryRowContext(c, query, args...)
+	stats.Timing("mysql:queryrow", int64(time.Since(now)/time.Millisecond))
+	return &Row{db: db, Row: r, query: query, args: args, t: t, cancel: cancel}
+}
+
+// Close closes the statement.
+func (s *Stmt) Close() (err error) {
+	if s == nil {
+		err = ErrStmtNil
+		return
+	}
+	stmt, ok := s.stmt.Load().(*sql.Stmt)
+	if ok {
+		err = errors.WithStack(stmt.Close())
+	}
+	return
+}
+
+// Exec executes a prepared statement with the given arguments and returns a
+// Result summarizing the effect of the statement.
+func (s *Stmt) Exec(c context.Context, args ...interface{}) (res sql.Result, err error) {
+	if s == nil {
+		err = ErrStmtNil
+		return
+	}
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Exec query(%s) args(%+v)", s.query, args), now)
+	if s.tx {
+		if s.t != nil {
+			s.t.SetTag(trace.String(trace.TagAnnotation, s.query))
+		}
+	} else if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "exec")
+		t.SetTag(trace.String(trace.TagAddress, s.db.conf.Addr), trace.String(trace.TagComment, s.query))
+		defer t.Finish(&err)
+	}
+	if err = s.db.breaker.Allow(); err != nil {
+		stats.Incr("mysql:stmt:exec", "breaker")
+		return
+	}
+	stmt, ok := s.stmt.Load().(*sql.Stmt)
+	if !ok {
+		err = ErrStmtNil
+		return
+	}
+	_, c, cancel := s.db.conf.ExecTimeout.Shrink(c)
+	res, err = stmt.ExecContext(c, args...)
+	cancel()
+	s.db.onBreaker(&err)
+	stats.Timing("mysql:stmt:exec", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "exec:%s, args:%+v", s.query, args)
+	}
+	return
+}
+
+// Query executes a prepared query statement with the given arguments and
+// returns the query results as a *Rows.
+func (s *Stmt) Query(c context.Context, args ...interface{}) (rows *Rows, err error) {
+	if s == nil {
+		err = ErrStmtNil
+		return
+	}
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Query query(%s) args(%+v)", s.query, args), now)
+	if s.tx {
+		if s.t != nil {
+			s.t.SetTag(trace.String(trace.TagAnnotation, s.query))
+		}
+	} else if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "query")
+		t.SetTag(trace.String(trace.TagAddress, s.db.conf.Addr), trace.String(trace.TagComment, s.query))
+		defer t.Finish(&err)
+	}
+	if err = s.db.breaker.Allow(); err != nil {
+		stats.Incr("mysql:stmt:query", "breaker")
+		return
+	}
+	stmt, ok := s.stmt.Load().(*sql.Stmt)
+	if !ok {
+		err = ErrStmtNil
+		return
+	}
+	_, c, cancel := s.db.conf.QueryTimeout.Shrink(c)
+	rs, err := stmt.QueryContext(c, args...)
+	s.db.onBreaker(&err)
+	stats.Timing("mysql:stmt:query", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "query:%s, args:%+v", s.query, args)
+		cancel()
+		return
+	}
+	rows = &Rows{Rows: rs, cancel: cancel}
+	return
+}
+
+// QueryRow executes a prepared query statement with the given arguments.
+// If an error occurs during the execution of the statement, that error will
+// be returned by a call to Scan on the returned *Row, which is always non-nil.
+// If the query selects no rows, the *Row's Scan will return ErrNoRows.
+// Otherwise, the *Row's Scan scans the first selected row and discards the rest.
+func (s *Stmt) QueryRow(c context.Context, args ...interface{}) (row *Row) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("QueryRow query(%s) args(%+v)", s.query, args), now)
+	row = &Row{db: s.db, query: s.query, args: args}
+	if s == nil {
+		row.err = ErrStmtNil
+		return
+	}
+	if s.tx {
+		if s.t != nil {
+			s.t.SetTag(trace.String(trace.TagAnnotation, s.query))
+		}
+	} else if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "queryrow")
+		t.SetTag(trace.String(trace.TagAddress, s.db.conf.Addr), trace.String(trace.TagComment, s.query))
+		row.t = t
+	}
+	if row.err = s.db.breaker.Allow(); row.err != nil {
+		stats.Incr("mysql:stmt:queryrow", "breaker")
+		return
+	}
+	stmt, ok := s.stmt.Load().(*sql.Stmt)
+	if !ok {
+		return
+	}
+	_, c, cancel := s.db.conf.QueryTimeout.Shrink(c)
+	row.Row = stmt.QueryRowContext(c, args...)
+	row.cancel = cancel
+	stats.Timing("mysql:stmt:queryrow", int64(time.Since(now)/time.Millisecond))
+	return
+}
+
+// Commit commits the transaction.
+func (tx *Tx) Commit() (err error) {
+	err = tx.tx.Commit()
+	tx.cancel()
+	tx.db.onBreaker(&err)
+	if tx.t != nil {
+		tx.t.Finish(&err)
+	}
+	if err != nil {
+		err = errors.WithStack(err)
+	}
+	return
+}
+
+// Rollback aborts the transaction.
+func (tx *Tx) Rollback() (err error) {
+	err = tx.tx.Rollback()
+	tx.cancel()
+	tx.db.onBreaker(&err)
+	if tx.t != nil {
+		tx.t.Finish(&err)
+	}
+	if err != nil {
+		err = errors.WithStack(err)
+	}
+	return
+}
+
+// Exec executes a query that doesn't return rows. For example: an INSERT and
+// UPDATE.
+func (tx *Tx) Exec(query string, args ...interface{}) (res sql.Result, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Exec query(%s) args(%+v)", query, args), now)
+	if tx.t != nil {
+		tx.t.SetTag(trace.String(trace.TagAnnotation, fmt.Sprintf("exec %s", query)))
+	}
+	res, err = tx.tx.ExecContext(tx.c, query, args...)
+	stats.Timing("mysql:tx:exec", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "exec:%s, args:%+v", query, args)
+	}
+	return
+}
+
+// Query executes a query that returns rows, typically a SELECT.
+func (tx *Tx) Query(query string, args ...interface{}) (rows *Rows, err error) {
+	if tx.t != nil {
+		tx.t.SetTag(trace.String(trace.TagAnnotation, fmt.Sprintf("query %s", query)))
+	}
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Query query(%s) args(%+v)", query, args), now)
+	defer func() {
+		stats.Timing("mysql:tx:query", int64(time.Since(now)/time.Millisecond))
+	}()
+	rs, err := tx.tx.QueryContext(tx.c, query, args...)
+	if err == nil {
+		rows = &Rows{Rows: rs}
+	} else {
+		err = errors.Wrapf(err, "query:%s, args:%+v", query, args)
+	}
+	return
+}
+
+// QueryRow executes a query that is expected to return at most one row.
+// QueryRow always returns a non-nil value. Errors are deferred until Row's
+// Scan method is called.
+func (tx *Tx) QueryRow(query string, args ...interface{}) *Row {
+	if tx.t != nil {
+		tx.t.SetTag(trace.String(trace.TagAnnotation, fmt.Sprintf("queryrow %s", query)))
+	}
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("QueryRow query(%s) args(%+v)", query, args), now)
+	defer func() {
+		stats.Timing("mysql:tx:queryrow", int64(time.Since(now)/time.Millisecond))
+	}()
+	r := tx.tx.QueryRowContext(tx.c, query, args...)
+	return &Row{Row: r, db: tx.db, query: query, args: args}
+}
+
+// Stmt returns a transaction-specific prepared statement from an existing statement.
+func (tx *Tx) Stmt(stmt *Stmt) *Stmt {
+	as, ok := stmt.stmt.Load().(*sql.Stmt)
+	if !ok {
+		return nil
+	}
+	ts := tx.tx.StmtContext(tx.c, as)
+	st := &Stmt{query: stmt.query, tx: true, t: tx.t, db: tx.db}
+	st.stmt.Store(ts)
+	return st
+}
+
+// Prepare creates a prepared statement for use within a transaction.
+// The returned statement operates within the transaction and can no longer be
+// used once the transaction has been committed or rolled back.
+// To use an existing prepared statement on this transaction, see Tx.Stmt.
+func (tx *Tx) Prepare(query string) (*Stmt, error) {
+	if tx.t != nil {
+		tx.t.SetTag(trace.String(trace.TagAnnotation, fmt.Sprintf("prepare %s", query)))
+	}
+	defer slowLog(fmt.Sprintf("Prepare query(%s)", query), time.Now())
+	stmt, err := tx.tx.Prepare(query)
+	if err != nil {
+		err = errors.Wrapf(err, "prepare %s", query)
+		return nil, err
+	}
+	st := &Stmt{query: query, tx: true, t: tx.t, db: tx.db}
+	st.stmt.Store(stmt)
+	return st, nil
+}
+
+// parseDSNAddr parse dsn name and return addr.
+func parseDSNAddr(dsn string) (addr string) {
+	if dsn == "" {
+		return
+	}
+	part0 := strings.Split(dsn, "@")
+	if len(part0) > 1 {
+		part1 := strings.Split(part0[1], "?")
+		if len(part1) > 0 {
+			addr = part1[0]
+		}
+	}
+	return
+}
+
+func slowLog(statement string, now time.Time) {
+	du := time.Since(now)
+	if du > _slowLogDuration {
+		log.Warn("%s slow log statement: %s time: %v", _family, statement, du)
+	}
+}

pkg/database/tidb/README.md

@@ -0,0 +1,17 @@
+#### database/tidb
+
+##### 项目简介
+TiDB数据库驱动 对mysql驱动进行封装
+
+##### 功能
+1. 支持discovery服务发现 多节点直连
+2. 支持通过lvs单一地址连接
+3. 支持prepare绑定多个节点
+4. 支持动态增减节点负载均衡
+5. 日志区分运行节点
+
+##### 编译环境
+> 请只用golang v1.8.x以上版本编译执行。
+
+##### 依赖包
+> 1.[Go-MySQL-Driver](https://github.com/go-sql-driver/mysql)

pkg/database/tidb/discovery.go

@@ -0,0 +1,58 @@
+package tidb
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/bilibili/Kratos/pkg/conf/env"
+	"github.com/bilibili/Kratos/pkg/log"
+	"github.com/bilibili/Kratos/pkg/naming"
+	"github.com/bilibili/Kratos/pkg/naming/discovery"
+)
+
+var _schema = "tidb://"
+
+func (db *DB) nodeList() (nodes []string) {
+	var (
+		insInfo *naming.InstancesInfo
+		insMap map[string][]*naming.Instance
+		ins    []*naming.Instance
+		ok     bool
+	)
+	if insInfo, ok = db.dis.Fetch(context.Background()); !ok {
+		return
+	}
+	insMap = insInfo.Instances
+	if ins, ok = insMap[env.Zone]; !ok || len(ins) == 0 {
+		return
+	}
+	for _, in := range ins {
+		for _, addr := range in.Addrs {
+			if strings.HasPrefix(addr, _schema) {
+				addr = strings.Replace(addr, _schema, "", -1)
+				nodes = append(nodes, addr)
+			}
+		}
+	}
+	log.Info("tidb get %s instances(%v)", db.appid, nodes)
+	return
+}
+
+func (db *DB) disc() (nodes []string) {
+	db.dis = discovery.Build(db.appid)
+	e := db.dis.Watch()
+	select {
+	case <-e:
+		nodes = db.nodeList()
+	case <-time.After(10 * time.Second):
+		panic("tidb init discovery err")
+	}
+	if len(nodes) == 0 {
+		panic(fmt.Sprintf("tidb %s no instance", db.appid))
+	}
+	go db.nodeproc(e)
+	log.Info("init tidb discvoery info successfully")
+	return
+}

pkg/database/tidb/node_proc.go

@@ -0,0 +1,82 @@
+package tidb
+
+import (
+	"time"
+
+	"github.com/bilibili/Kratos/pkg/log"
+)
+
+func (db *DB) nodeproc(e <-chan struct{}) {
+	if db.dis == nil {
+		return
+	}
+	for {
+		<-e
+		nodes := db.nodeList()
+		if len(nodes) == 0 {
+			continue
+		}
+		cm := make(map[string]*conn)
+		var conns []*conn
+		for _, conn := range db.conns {
+			cm[conn.addr] = conn
+		}
+		for _, node := range nodes {
+			if cm[node] != nil {
+				conns = append(conns, cm[node])
+				continue
+			}
+			c, err := db.connectDSN(genDSN(db.conf.DSN, node))
+			if err == nil {
+				conns = append(conns, c)
+			} else {
+				log.Error("tidb: connect addr: %s err: %+v", node, err)
+			}
+		}
+		if len(conns) == 0 {
+			log.Error("tidb: no nodes ignore event")
+			continue
+		}
+		oldConns := db.conns
+		db.mutex.Lock()
+		db.conns = conns
+		db.mutex.Unlock()
+		log.Info("tidb: new nodes: %v", nodes)
+		var removedConn []*conn
+		for _, conn := range oldConns {
+			var exist bool
+			for _, c := range conns {
+				if c.addr == conn.addr {
+					exist = true
+					break
+				}
+			}
+			if !exist {
+				removedConn = append(removedConn, conn)
+			}
+		}
+		go db.closeConns(removedConn)
+	}
+}
+
+func (db *DB) closeConns(conns []*conn) {
+	if len(conns) == 0 {
+		return
+	}
+	du := db.conf.QueryTimeout
+	if db.conf.ExecTimeout > du {
+		du = db.conf.ExecTimeout
+	}
+	if db.conf.TranTimeout > du {
+		du = db.conf.TranTimeout
+	}
+	time.Sleep(time.Duration(du))
+	for _, conn := range conns {
+		err := conn.Close()
+		if err != nil {
+			log.Error("tidb: close removed conn: %s err: %v", conn.addr, err)
+		} else {
+			log.Info("tidb: close removed conn: %s", conn.addr)
+		}
+	}
+}

pkg/database/tidb/sql.go

@@ -0,0 +1,739 @@
+package tidb
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/bilibili/Kratos/pkg/log"
+	"github.com/bilibili/Kratos/pkg/naming"
+	"github.com/bilibili/Kratos/pkg/net/netutil/breaker"
+	"github.com/bilibili/Kratos/pkg/net/trace"
+
+	"github.com/go-sql-driver/mysql"
+	"github.com/pkg/errors"
+)
+
+const (
+	_family          = "tidb_client"
+	_slowLogDuration = time.Millisecond * 250
+)
+
+var (
+	// ErrStmtNil prepared stmt error
+	ErrStmtNil = errors.New("sql: prepare failed and stmt nil")
+	// ErrNoRows is returned by Scan when QueryRow doesn't return a row.
+	// In such a case, QueryRow returns a placeholder *Row value that defers
+	// this error until a Scan.
+	ErrNoRows = sql.ErrNoRows
+	// ErrTxDone transaction done.
+	ErrTxDone = sql.ErrTxDone
+)
+
+// DB database.
+type DB struct {
+	conf         *Config
+	conns        []*conn
+	idx          int64
+	dis          naming.Resolver
+	appid        string
+	mutex        sync.RWMutex
+	breakerGroup *breaker.Group
+}
+
+// conn database connection
+type conn struct {
+	*sql.DB
+	breaker breaker.Breaker
+	conf    *Config
+	addr    string
+}
+
+// Tx transaction.
+type Tx struct {
+	db     *conn
+	tx     *sql.Tx
+	t      trace.Trace
+	c      context.Context
+	cancel func()
+}
+
+// Row row.
+type Row struct {
+	err error
+	*sql.Row
+	db     *conn
+	query  string
+	args   []interface{}
+	t      trace.Trace
+	cancel func()
+}
+
+// Scan copies the columns from the matched row into the values pointed at by dest.
+func (r *Row) Scan(dest ...interface{}) (err error) {
+	defer slowLog(fmt.Sprintf("Scan addr: %s query(%s) args(%+v)", r.db.addr, r.query, r.args), time.Now())
+	if r.t != nil {
+		defer r.t.Finish(&err)
+	}
+	if r.err != nil {
+		err = r.err
+	} else if r.Row == nil {
+		err = ErrStmtNil
+	}
+	if err != nil {
+		return
+	}
+	err = r.Row.Scan(dest...)
+	if r.cancel != nil {
+		r.cancel()
+	}
+	r.db.onBreaker(&err)
+	if err != ErrNoRows {
+		err = errors.Wrapf(err, "addr: %s, query %s args %+v", r.db.addr, r.query, r.args)
+	}
+	return
+}
+
+// Rows rows.
+type Rows struct {
+	*sql.Rows
+	cancel func()
+}
+
+// Close closes the Rows, preventing further enumeration. If Next is called
+// and returns false and there are no further result sets,
+// the Rows are closed automatically and it will suffice to check the
+// result of Err. Close is idempotent and does not affect the result of Err.
+func (rs *Rows) Close() (err error) {
+	err = errors.WithStack(rs.Rows.Close())
+	if rs.cancel != nil {
+		rs.cancel()
+	}
+	return
+}
+
+// Stmt prepared stmt.
+type Stmt struct {
+	db    *conn
+	tx    bool
+	query string
+	stmt  atomic.Value
+	t     trace.Trace
+}
+
+// Stmts random prepared stmt.
+type Stmts struct {
+	query string
+	sts   map[string]*Stmt
+	mu    sync.RWMutex
+	db    *DB
+}
+
+// Open opens a database specified by its database driver name and a
+// driver-specific data source name, usually consisting of at least a database
+// name and connection information.
+func Open(c *Config) (db *DB, err error) {
+	db = &DB{conf: c, breakerGroup: breaker.NewGroup(c.Breaker)}
+	cfg, err := mysql.ParseDSN(c.DSN)
+	if err != nil {
+		return
+	}
+	var dsns []string
+	if cfg.Net == "discovery" {
+		db.appid = cfg.Addr
+		for _, addr := range db.disc() {
+			dsns = append(dsns, genDSN(c.DSN, addr))
+		}
+	} else {
+		dsns = append(dsns, c.DSN)
+	}
+
+	cs := make([]*conn, 0, len(dsns))
+	for _, dsn := range dsns {
+		r, err := db.connectDSN(dsn)
+		if err != nil {
+			return db, err
+		}
+		cs = append(cs, r)
+	}
+	db.conns = cs
+	return
+}
+
+func (db *DB) connectDSN(dsn string) (c *conn, err error) {
+	d, err := connect(db.conf, dsn)
+	if err != nil {
+		return
+	}
+	addr := parseDSNAddr(dsn)
+	brk := db.breakerGroup.Get(addr)
+	c = &conn{DB: d, breaker: brk, conf: db.conf, addr: addr}
+	return
+}
+
+func connect(c *Config, dataSourceName string) (*sql.DB, error) {
+	d, err := sql.Open("mysql", dataSourceName)
+	if err != nil {
+		err = errors.WithStack(err)
+		return nil, err
+	}
+	d.SetMaxOpenConns(c.Active)
+	d.SetMaxIdleConns(c.Idle)
+	d.SetConnMaxLifetime(time.Duration(c.IdleTimeout))
+	return d, nil
+}
+
+func (db *DB) conn() (c *conn) {
+	db.mutex.RLock()
+	c = db.conns[db.index()]
+	db.mutex.RUnlock()
+	return
+}
+
+// Begin starts a transaction. The isolation level is dependent on the driver.
+func (db *DB) Begin(c context.Context) (tx *Tx, err error) {
+	return db.conn().begin(c)
+}
+
+// Exec executes a query without returning any rows.
+// The args are for any placeholder parameters in the query.
+func (db *DB) Exec(c context.Context, query string, args ...interface{}) (res sql.Result, err error) {
+	return db.conn().exec(c, query, args...)
+}
+
+// Prepare creates a prepared statement for later queries or executions.
+// Multiple queries or executions may be run concurrently from the returned
+// statement. The caller must call the statement's Close method when the
+// statement is no longer needed.
+func (db *DB) Prepare(query string) (*Stmt, error) {
+	return db.conn().prepare(query)
+}
+
+// Prepared creates a prepared statement for later queries or executions.
+// Multiple queries or executions may be run concurrently from the returned
+// statement. The caller must call the statement's Close method when the
+// statement is no longer needed.
+func (db *DB) Prepared(query string) (s *Stmts) {
+	s = &Stmts{query: query, sts: make(map[string]*Stmt), db: db}
+	for _, c := range db.conns {
+		st := c.prepared(query)
+		s.mu.Lock()
+		s.sts[c.addr] = st
+		s.mu.Unlock()
+	}
+	return
+}
+
+// Query executes a query that returns rows, typically a SELECT. The args are
+// for any placeholder parameters in the query.
+func (db *DB) Query(c context.Context, query string, args ...interface{}) (rows *Rows, err error) {
+	return db.conn().query(c, query, args...)
+}
+
+// QueryRow executes a query that is expected to return at most one row.
+// QueryRow always returns a non-nil value. Errors are deferred until Row's
+// Scan method is called.
+func (db *DB) QueryRow(c context.Context, query string, args ...interface{}) *Row {
+	return db.conn().queryRow(c, query, args...)
+}
+
+func (db *DB) index() int {
+	if len(db.conns) == 1 {
+		return 0
+	}
+	v := atomic.AddInt64(&db.idx, 1)
+	return int(v) % len(db.conns)
+}
+
+// Close closes the databases, releasing any open resources.
+func (db *DB) Close() (err error) {
+	db.mutex.RLock()
+	defer db.mutex.RUnlock()
+	for _, d := range db.conns {
+		if e := d.Close(); e != nil {
+			err = errors.WithStack(e)
+		}
+	}
+	return
+}
+
+// Ping verifies a connection to the database is still alive, establishing a
+// connection if necessary.
+func (db *DB) Ping(c context.Context) (err error) {
+	if err = db.conn().ping(c); err != nil {
+		return
+	}
+	return
+}
+
+func (db *conn) onBreaker(err *error) {
+	if err != nil && *err != nil && *err != sql.ErrNoRows && *err != sql.ErrTxDone {
+		db.breaker.MarkFailed()
+	} else {
+		db.breaker.MarkSuccess()
+	}
+}
+
+func (db *conn) begin(c context.Context) (tx *Tx, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Begin addr: %s", db.addr), now)
+	t, ok := trace.FromContext(c)
+	if ok {
+		t = t.Fork(_family, "begin")
+		t.SetTag(trace.String(trace.TagAddress, db.addr), trace.String(trace.TagComment, ""))
+		defer func() {
+			if err != nil {
+				t.Finish(&err)
+			}
+		}()
+	}
+	if err = db.breaker.Allow(); err != nil {
+		stats.Incr("tidb:begin", "breaker")
+		return
+	}
+	_, c, cancel := db.conf.TranTimeout.Shrink(c)
+	rtx, err := db.BeginTx(c, nil)
+	stats.Timing("tidb:begin", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.WithStack(err)
+		cancel()
+		return
+	}
+	tx = &Tx{tx: rtx, t: t, db: db, c: c, cancel: cancel}
+	return
+}
+
+func (db *conn) exec(c context.Context, query string, args ...interface{}) (res sql.Result, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Exec addr: %s query(%s) args(%+v)", db.addr, query, args), now)
+	if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "exec")
+		t.SetTag(trace.String(trace.TagAddress, db.addr), trace.String(trace.TagComment, query))
+		defer t.Finish(&err)
+	}
+	if err = db.breaker.Allow(); err != nil {
+		stats.Incr("tidb:exec", "breaker")
+		return
+	}
+	_, c, cancel := db.conf.ExecTimeout.Shrink(c)
+	res, err = db.ExecContext(c, query, args...)
+	cancel()
+	db.onBreaker(&err)
+	stats.Timing("tidb:exec", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "addr: %s exec:%s, args:%+v", db.addr, query, args)
+	}
+	return
+}
+
+func (db *conn) ping(c context.Context) (err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Ping addr: %s", db.addr), now)
+	if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "ping")
+		t.SetTag(trace.String(trace.TagAddress, db.addr), trace.String(trace.TagComment, ""))
+		defer t.Finish(&err)
+	}
+	if err = db.breaker.Allow(); err != nil {
+		stats.Incr("tidb:ping", "breaker")
+		return
+	}
+	_, c, cancel := db.conf.ExecTimeout.Shrink(c)
+	err = db.PingContext(c)
+	cancel()
+	db.onBreaker(&err)
+	stats.Timing("tidb:ping", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.WithStack(err)
+	}
+	return
+}
+
+func (db *conn) prepare(query string) (*Stmt, error) {
+	defer slowLog(fmt.Sprintf("Prepare addr: %s query(%s)", db.addr, query), time.Now())
+	stmt, err := db.Prepare(query)
+	if err != nil {
+		err = errors.Wrapf(err, "addr: %s prepare %s", db.addr, query)
+		return nil, err
+	}
+	st := &Stmt{query: query, db: db}
+	st.stmt.Store(stmt)
+	return st, nil
+}
+
+func (db *conn) prepared(query string) (stmt *Stmt) {
+	defer slowLog(fmt.Sprintf("Prepared addr: %s query(%s)", db.addr, query), time.Now())
+	stmt = &Stmt{query: query, db: db}
+	s, err := db.Prepare(query)
+	if err == nil {
+		stmt.stmt.Store(s)
+		return
+	}
+	return
+}
+
+func (db *conn) query(c context.Context, query string, args ...interface{}) (rows *Rows, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Query addr: %s query(%s) args(%+v)", db.addr, query, args), now)
+	if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "query")
+		t.SetTag(trace.String(trace.TagAddress, db.addr), trace.String(trace.TagComment, query))
+		defer t.Finish(&err)
+	}
+	if err = db.breaker.Allow(); err != nil {
+		stats.Incr("tidb:query", "breaker")
+		return
+	}
+	_, c, cancel := db.conf.QueryTimeout.Shrink(c)
+	rs, err := db.DB.QueryContext(c, query, args...)
+	db.onBreaker(&err)
+	stats.Timing("tidb:query", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "addr: %s, query:%s, args:%+v", db.addr, query, args)
+		cancel()
+		return
+	}
+	rows = &Rows{Rows: rs, cancel: cancel}
+	return
+}
+
+func (db *conn) queryRow(c context.Context, query string, args ...interface{}) *Row {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("QueryRow addr: %s query(%s) args(%+v)", db.addr, query, args), now)
+	t, ok := trace.FromContext(c)
+	if ok {
+		t = t.Fork(_family, "queryrow")
+		t.SetTag(trace.String(trace.TagAddress, db.addr), trace.String(trace.TagComment, query))
+	}
+	if err := db.breaker.Allow(); err != nil {
+		stats.Incr("tidb:queryrow", "breaker")
+		return &Row{db: db, t: t, err: err}
+	}
+	_, c, cancel := db.conf.QueryTimeout.Shrink(c)
+	r := db.DB.QueryRowContext(c, query, args...)
+	stats.Timing("tidb:queryrow", int64(time.Since(now)/time.Millisecond))
+	return &Row{db: db, Row: r, query: query, args: args, t: t, cancel: cancel}
+}
+
+// Close closes the statement.
+func (s *Stmt) Close() (err error) {
+	stmt, ok := s.stmt.Load().(*sql.Stmt)
+	if ok {
+		err = errors.WithStack(stmt.Close())
+	}
+	return
+}
+
+func (s *Stmt) prepare() (st *sql.Stmt) {
+	var ok bool
+	if st, ok = s.stmt.Load().(*sql.Stmt); ok {
+		return
+	}
+	var err error
+	if st, err = s.db.Prepare(s.query); err == nil {
+		s.stmt.Store(st)
+	}
+	return
+}
+
+// Exec executes a prepared statement with the given arguments and returns a
+// Result summarizing the effect of the statement.
+func (s *Stmt) Exec(c context.Context, args ...interface{}) (res sql.Result, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Exec addr: %s query(%s) args(%+v)", s.db.addr, s.query, args), now)
+	if s.tx {
+		if s.t != nil {
+			s.t.SetTag(trace.String(trace.TagAnnotation, s.query))
+		}
+	} else if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "exec")
+		t.SetTag(trace.String(trace.TagAddress, s.db.addr), trace.String(trace.TagComment, s.query))
+		defer t.Finish(&err)
+	}
+	if err = s.db.breaker.Allow(); err != nil {
+		stats.Incr("tidb:stmt:exec", "breaker")
+		return
+	}
+	stmt := s.prepare()
+	if stmt == nil {
+		err = ErrStmtNil
+		return
+	}
+	_, c, cancel := s.db.conf.ExecTimeout.Shrink(c)
+	res, err = stmt.ExecContext(c, args...)
+	cancel()
+	s.db.onBreaker(&err)
+	stats.Timing("tidb:stmt:exec", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "addr: %s exec:%s, args:%+v", s.db.addr, s.query, args)
+	}
+	return
+}
+
+// Query executes a prepared query statement with the given arguments and
+// returns the query results as a *Rows.
+func (s *Stmt) Query(c context.Context, args ...interface{}) (rows *Rows, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Query addr: %s query(%s) args(%+v)", s.db.addr, s.query, args), now)
+	if s.tx {
+		if s.t != nil {
+			s.t.SetTag(trace.String(trace.TagAnnotation, s.query))
+		}
+	} else if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "query")
+		t.SetTag(trace.String(trace.TagAddress, s.db.addr), trace.String(trace.TagComment, s.query))
+		defer t.Finish(&err)
+	}
+	if err = s.db.breaker.Allow(); err != nil {
+		stats.Incr("tidb:stmt:query", "breaker")
+		return
+	}
+	stmt := s.prepare()
+	if stmt == nil {
+		err = ErrStmtNil
+		return
+	}
+	_, c, cancel := s.db.conf.QueryTimeout.Shrink(c)
+	rs, err := stmt.QueryContext(c, args...)
+	s.db.onBreaker(&err)
+	stats.Timing("tidb:stmt:query", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "addr: %s, query:%s, args:%+v", s.db.addr, s.query, args)
+		cancel()
+		return
+	}
+	rows = &Rows{Rows: rs, cancel: cancel}
+	return
+}
+
+// QueryRow executes a prepared query statement with the given arguments.
+// If an error occurs during the execution of the statement, that error will
+// be returned by a call to Scan on the returned *Row, which is always non-nil.
+// If the query selects no rows, the *Row's Scan will return ErrNoRows.
+// Otherwise, the *Row's Scan scans the first selected row and discards the rest.
+func (s *Stmt) QueryRow(c context.Context, args ...interface{}) (row *Row) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("QueryRow addr: %s query(%s) args(%+v)", s.db.addr, s.query, args), now)
+	row = &Row{db: s.db, query: s.query, args: args}
+	if s.tx {
+		if s.t != nil {
+			s.t.SetTag(trace.String(trace.TagAnnotation, s.query))
+		}
+	} else if t, ok := trace.FromContext(c); ok {
+		t = t.Fork(_family, "queryrow")
+		t.SetTag(trace.String(trace.TagAddress, s.db.addr), trace.String(trace.TagComment, s.query))
+		row.t = t
+	}
+	if row.err = s.db.breaker.Allow(); row.err != nil {
+		stats.Incr("tidb:stmt:queryrow", "breaker")
+		return
+	}
+	stmt := s.prepare()
+	if stmt == nil {
+		return
+	}
+	_, c, cancel := s.db.conf.QueryTimeout.Shrink(c)
+	row.Row = stmt.QueryRowContext(c, args...)
+	row.cancel = cancel
+	stats.Timing("tidb:stmt:queryrow", int64(time.Since(now)/time.Millisecond))
+	return
+}
+
+func (s *Stmts) prepare(conn *conn) (st *Stmt) {
+	if conn == nil {
+		conn = s.db.conn()
+	}
+	s.mu.RLock()
+	st = s.sts[conn.addr]
+	s.mu.RUnlock()
+	if st == nil {
+		st = conn.prepared(s.query)
+		s.mu.Lock()
+		s.sts[conn.addr] = st
+		s.mu.Unlock()
+	}
+	return
+}
+
+// Exec executes a prepared statement with the given arguments and returns a
+// Result summarizing the effect of the statement.
+func (s *Stmts) Exec(c context.Context, args ...interface{}) (res sql.Result, err error) {
+	return s.prepare(nil).Exec(c, args...)
+}
+
+// Query executes a prepared query statement with the given arguments and
+// returns the query results as a *Rows.
+func (s *Stmts) Query(c context.Context, args ...interface{}) (rows *Rows, err error) {
+	return s.prepare(nil).Query(c, args...)
+}
+
+// QueryRow executes a prepared query statement with the given arguments.
+// If an error occurs during the execution of the statement, that error will
+// be returned by a call to Scan on the returned *Row, which is always non-nil.
+// If the query selects no rows, the *Row's Scan will return ErrNoRows.
+// Otherwise, the *Row's Scan scans the first selected row and discards the rest.
+func (s *Stmts) QueryRow(c context.Context, args ...interface{}) (row *Row) {
+	return s.prepare(nil).QueryRow(c, args...)
+}
+
+// Close closes the statement.
+func (s *Stmts) Close() (err error) {
+	for _, st := range s.sts {
+		if err = errors.WithStack(st.Close()); err != nil {
+			return
+		}
+	}
+	return
+}
+
+// Commit commits the transaction.
+func (tx *Tx) Commit() (err error) {
+	err = tx.tx.Commit()
+	tx.cancel()
+	tx.db.onBreaker(&err)
+	if tx.t != nil {
+		tx.t.Finish(&err)
+	}
+	if err != nil {
+		err = errors.WithStack(err)
+	}
+	return
+}
+
+// Rollback aborts the transaction.
+func (tx *Tx) Rollback() (err error) {
+	err = tx.tx.Rollback()
+	tx.cancel()
+	tx.db.onBreaker(&err)
+	if tx.t != nil {
+		tx.t.Finish(&err)
+	}
+	if err != nil {
+		err = errors.WithStack(err)
+	}
+	return
+}
+
+// Exec executes a query that doesn't return rows. For example: an INSERT and
+// UPDATE.
+func (tx *Tx) Exec(query string, args ...interface{}) (res sql.Result, err error) {
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Exec addr: %s query(%s) args(%+v)", tx.db.addr, query, args), now)
+	if tx.t != nil {
+		tx.t.SetTag(trace.String(trace.TagAnnotation, fmt.Sprintf("exec %s", query)))
+	}
+	res, err = tx.tx.ExecContext(tx.c, query, args...)
+	stats.Timing("tidb:tx:exec", int64(time.Since(now)/time.Millisecond))
+	if err != nil {
+		err = errors.Wrapf(err, "addr: %s exec:%s, args:%+v", tx.db.addr, query, args)
+	}
+	return
+}
+
+// Query executes a query that returns rows, typically a SELECT.
+func (tx *Tx) Query(query string, args ...interface{}) (rows *Rows, err error) {
+	if tx.t != nil {
+		tx.t.SetTag(trace.String(trace.TagAnnotation, fmt.Sprintf("query %s", query)))
+	}
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("Query addr: %s query(%s) args(%+v)", tx.db.addr, query, args), now)
+	defer func() {
+		stats.Timing("tidb:tx:query", int64(time.Since(now)/time.Millisecond))
+	}()
+	rs, err := tx.tx.QueryContext(tx.c, query, args...)
+	if err == nil {
+		rows = &Rows{Rows: rs}
+	} else {
+		err = errors.Wrapf(err, "addr: %s, query:%s, args:%+v", tx.db.addr, query, args)
+	}
+	return
+}
+
+// QueryRow executes a query that is expected to return at most one row.
+// QueryRow always returns a non-nil value. Errors are deferred until Row's
+// Scan method is called.
+func (tx *Tx) QueryRow(query string, args ...interface{}) *Row {
+	if tx.t != nil {
+		tx.t.SetTag(trace.String(trace.TagAnnotation, fmt.Sprintf("queryrow %s", query)))
+	}
+	now := time.Now()
+	defer slowLog(fmt.Sprintf("QueryRow addr: %s query(%s) args(%+v)", tx.db.addr, query, args), now)
+	defer func() {
+		stats.Timing("tidb:tx:queryrow", int64(time.Since(now)/time.Millisecond))
+	}()
+	r := tx.tx.QueryRowContext(tx.c, query, args...)
+	return &Row{Row: r, db: tx.db, query: query, args: args}
+}
+
+// Stmt returns a transaction-specific prepared statement from an existing statement.
+func (tx *Tx) Stmt(stmt *Stmt) *Stmt {
+	if stmt == nil {
+		return nil
+	}
+	as, ok := stmt.stmt.Load().(*sql.Stmt)
+	if !ok {
+		return nil
+	}
+	ts := tx.tx.StmtContext(tx.c, as)
+	st := &Stmt{query: stmt.query, tx: true, t: tx.t, db: tx.db}
+	st.stmt.Store(ts)
+	return st
+}
+
+// Stmts returns a transaction-specific prepared statement from an existing statement.
+func (tx *Tx) Stmts(stmt *Stmts) *Stmt {
+	return tx.Stmt(stmt.prepare(tx.db))
+}
+
+// Prepare creates a prepared statement for use within a transaction.
+// The returned statement operates within the transaction and can no longer be
+// used once the transaction has been committed or rolled back.
+// To use an existing prepared statement on this transaction, see Tx.Stmt.
+func (tx *Tx) Prepare(query string) (*Stmt, error) {
+	if tx.t != nil {
+		tx.t.SetTag(trace.String(trace.TagAnnotation, fmt.Sprintf("prepare %s", query)))
+	}
+	defer slowLog(fmt.Sprintf("Prepare addr: %s query(%s)", tx.db.addr, query), time.Now())
+	stmt, err := tx.tx.Prepare(query)
+	if err != nil {
+		err = errors.Wrapf(err, "addr: %s prepare %s", tx.db.addr, query)
+		return nil, err
+	}
+	st := &Stmt{query: query, tx: true, t: tx.t, db: tx.db}
+	st.stmt.Store(stmt)
+	return st, nil
+}
+
+// parseDSNAddr parse dsn name and return addr.
+func parseDSNAddr(dsn string) (addr string) {
+	if dsn == "" {
+		return
+	}
+	cfg, err := mysql.ParseDSN(dsn)
+	if err != nil {
+		return
+	}
+	addr = cfg.Addr
+	return
+}
+
+func genDSN(dsn, addr string) (res string) {
+	cfg, err := mysql.ParseDSN(dsn)
+	if err != nil {
+		return
+	}
+	cfg.Addr = addr
+	cfg.Net = "tcp"
+	res = cfg.FormatDSN()
+	return
+}
+
+func slowLog(statement string, now time.Time) {
+	du := time.Since(now)
+	if du > _slowLogDuration {
+		log.Warn("%s slow log statement: %s time: %v", _family, statement, du)
+	}
+}

pkg/database/tidb/tidb.go

@@ -0,0 +1,38 @@
+package tidb
+
+import (
+	"github.com/bilibili/Kratos/pkg/log"
+	"github.com/bilibili/Kratos/pkg/net/netutil/breaker"
+	"github.com/bilibili/Kratos/pkg/stat"
+	"github.com/bilibili/Kratos/pkg/time"
+
+	// database driver
+	_ "github.com/go-sql-driver/mysql"
+)
+
+var stats = stat.DB
+
+// Config mysql config.
+type Config struct {
+	DSN          string          // dsn
+	Active       int             // pool
+	Idle         int             // pool
+	IdleTimeout  time.Duration   // connect max life time.
+	QueryTimeout time.Duration   // query sql timeout
+	ExecTimeout  time.Duration   // execute sql timeout
+	TranTimeout  time.Duration   // transaction sql timeout
+	Breaker      *breaker.Config // breaker
+}
+
+// NewTiDB new db and retry connection when has error.
+func NewTiDB(c *Config) (db *DB) {
+	if c.QueryTimeout == 0 || c.ExecTimeout == 0 || c.TranTimeout == 0 {
+		panic("tidb must be set query/execute/transction timeout")
+	}
+	db, err := Open(c)
+	if err != nil {
+		log.Error("open tidb error(%v)", err)
+		panic(err)
+	}
+	return
+}