NO-ISSUE Code refactoring (#13)

Author: linxGnu

balancer.go

@@ -2,6 +2,7 @@ package mssqlx
 
 import (
 	"context"
+	"fmt"
 	"sync/atomic"
 	"time"
 )
@@ -22,7 +23,7 @@ type balancer struct {
 
 // new balancer and start health checkers
 func newBalancer(ctx context.Context, numHealthChecker int, numDbInstance int, isWsrep bool) *balancer {
-	if numHealthChecker <= 0 {
+	if numHealthChecker < 2 {
 		numHealthChecker = 2 // at least two checkers
 	}
 
@@ -71,55 +72,42 @@ func (c *balancer) get(shouldBalancing bool) *wrapper {
 }
 
 // failure make a db node become failure and auto health tracking
-func (c *balancer) failure(w *wrapper) {
+func (c *balancer) failure(w *wrapper, err error) {
 	if c.dbs.remove(w) { // remove this node
-		c.sendFailure(w)
-	}
-}
-
-func (c *balancer) sendFailure(w *wrapper) {
-	select {
-	case <-c.ctx.Done():
-		return
+		reportError(fmt.Sprintf("deactive connection:[%s] for health checking due to error", w.dsn), err)
 
-	case c.fail <- w: // give to health checker
+		select {
+		case <-c.ctx.Done():
+		case c.fail <- w:
+		}
 	}
 }
 
 // healthChecker daemon to check health of db connection
 func (c *balancer) healthChecker() {
-	doneCh := c.ctx.Done()
-
-	var db *wrapper
 	for {
 		select {
-		case <-doneCh:
+		case <-c.ctx.Done():
 			return
 
-		case db = <-c.fail:
+		case db := <-c.fail:
 			if ping(db) == nil && (!c.isWsrep || db.checkWsrepReady()) {
 				c.dbs.add(db)
 				continue
+			} else {
+				c.fail <- db
 			}
 
 			select {
-			case <-doneCh:
+			case <-c.ctx.Done():
 				return
 
 			case <-time.After(time.Duration(c.getHealthCheckPeriod()) * time.Millisecond):
 			}
-
-			select {
-			case <-doneCh:
-				return
-
-			case c.fail <- db:
-			}
 		}
 	}
 }
 
 func (c *balancer) destroy() {
-	c.dbs.clear()
 	c.cancel()
 }

dbList.go

@@ -0,0 +1,68 @@
+package mssqlx
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+type dbList struct {
+	lk           sync.RWMutex
+	list         []*wrapper
+	currentIndex uint32
+}
+
+func (b *dbList) current() (w *wrapper) {
+	b.lk.RLock()
+
+	if n := uint32(len(b.list)); n > 0 {
+		w = b.list[atomic.LoadUint32(&b.currentIndex)%n]
+	}
+
+	b.lk.RUnlock()
+
+	return
+}
+
+func (b *dbList) next() (w *wrapper) {
+	b.lk.RLock()
+
+	if n := uint32(len(b.list)); n > 0 {
+		w = b.list[atomic.AddUint32(&b.currentIndex, 1)%n]
+	}
+
+	b.lk.RUnlock()
+
+	return
+}
+
+func (b *dbList) add(w *wrapper) {
+	if w != nil {
+		b.lk.Lock()
+		b.list = append(b.list, w)
+		b.lk.Unlock()
+	}
+}
+
+func (b *dbList) remove(w *wrapper) (removed bool) {
+	if w != nil {
+		b.lk.Lock()
+
+		n := len(b.list)
+		for i := 0; i < n; i++ {
+			if b.list[i] == w { // found
+				removed = true
+
+				if i != n-1 {
+					b.list[i] = b.list[n-1]
+				}
+				b.list = b.list[:n-1]
+
+				break
+			}
+		}
+
+		b.lk.Unlock()
+	}
+
+	return
+}

db_wrapper.go

@@ -0,0 +1,35 @@
+package mssqlx
+
+import (
+	"github.com/jmoiron/sqlx"
+)
+
+type wrapper struct {
+	db  *sqlx.DB
+	dsn string
+}
+
+func (w *wrapper) checkWsrepReady() bool {
+	type wsrepVariable struct {
+		VariableName string `db:"Variable_name"`
+		Value        string `db:"Value"`
+	}
+
+	var v wsrepVariable
+
+	if err := w.db.Get(&v, "SHOW VARIABLES LIKE 'wsrep_on'"); err != nil {
+		reportError("SHOW VARIABLES LIKE 'wsrep_on'", err)
+		return false
+	}
+
+	if v.Value != "ON" {
+		return true
+	}
+
+	if err := w.db.Get(&v, "SHOW STATUS LIKE 'wsrep_ready'"); err != nil || v.Value != "ON" {
+		reportError("SHOW STATUS LIKE 'wsrep_ready'", err)
+		return false
+	}
+
+	return true
+}

errors.go

@@ -3,18 +3,22 @@ package mssqlx
 import (
 	"database/sql"
 	"database/sql/driver"
+	"errors"
 	"fmt"
 	"os"
 	"strings"
 	"time"
 
 	"github.com/go-sql-driver/mysql"
+	"github.com/lib/pq"
 )
 
 // check bad connection
 func isErrBadConn(err error) bool {
 	if err != nil {
-		if err == driver.ErrBadConn || err == sql.ErrConnDone || err == mysql.ErrInvalidConn {
+		if errors.Is(err, driver.ErrBadConn) ||
+			errors.Is(err, mysql.ErrInvalidConn) ||
+			errors.Is(err, pq.ErrChannelNotOpen) {
 			return true
 		}
 
@@ -42,7 +46,6 @@ func isErrCode(err error, code int) bool {
 	}
 
 	switch mErr := err.(type) {
-
 	case *mysql.MySQLError:
 		return mErr.Number == uint16(code)
 
@@ -52,16 +55,10 @@ func isErrCode(err error, code int) bool {
 	}
 }
 
-func parseError(w *wrapper, err error) error {
-	if err == nil {
-		return nil
-	}
-
-	if w != nil && ping(w) != nil {
-		return ErrNetwork
-	}
-
-	return err
+func isStdErr(err error) bool {
+	return errors.Is(err, sql.ErrNoRows) ||
+		errors.Is(err, sql.ErrTxDone) ||
+		errors.Is(err, sql.ErrConnDone)
 }
 
 func reportError(v string, err error) {

go.mod

@@ -1,11 +1,9 @@
 module github.com/linxGnu/mssqlx
 
 require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/go-sql-driver/mysql v1.6.0
+	github.com/hashicorp/go-multierror v1.1.1
 	github.com/jmoiron/sqlx v1.3.4
 	github.com/lib/pq v1.10.2
-	github.com/mattn/go-sqlite3 v1.14.7
 	github.com/stretchr/testify v1.7.0
-	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -1,24 +1,25 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-sql-driver/mysql v1.5.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
 github.com/go-sql-driver/mysql v1.6.0 h1:BCTh4TKNUYmOmMUcQ3IipzF5prigylS7XXjEkfCHuOE=
 github.com/go-sql-driver/mysql v1.6.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
+github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
+github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/jmoiron/sqlx v1.3.4 h1:wv+0IJZfL5z0uZoUjlpKgHkgaFSYD+r9CfrXjEXsO7w=
 github.com/jmoiron/sqlx v1.3.4/go.mod h1:2BljVx/86SuTyjE+aPYlHCTNvZrnJXghYGpNiXLBMCQ=
 github.com/lib/pq v1.2.0/go.mod h1:5WUZQaWbwv1U+lTReE5YruASi9Al49XbQIvNi/34Woo=
 github.com/lib/pq v1.10.2 h1:AqzbZs4ZoCBp+GtejcpCpcxM3zlSMx29dXbUSeVtJb8=
 github.com/lib/pq v1.10.2/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
+github.com/mattn/go-sqlite3 v1.14.6 h1:dNPt6NO46WmLVt2DLNpwczCmdV5boIZ6g/tlDrlRUbg=
 github.com/mattn/go-sqlite3 v1.14.6/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
-github.com/mattn/go-sqlite3 v1.14.7 h1:fxWBnXkxfM6sRiuH3bqJ4CfzZojMOLVc0UTsTglEghA=
-github.com/mattn/go-sqlite3 v1.14.7/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=