120 lines
4.1 KiB
Go
120 lines
4.1 KiB
Go
package dtmcli
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import (
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"context"
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"database/sql"
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"encoding/json"
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"fmt"
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"net/url"
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"github.com/gin-gonic/gin"
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)
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// BusiFunc type for busi func
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type BusiFunc func(db *sql.Tx) (interface{}, error)
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// TransInfo every branch info
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type TransInfo struct {
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TransType string
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Gid string
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BranchID string
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BranchType string
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}
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func (t *TransInfo) String() string {
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return fmt.Sprintf("transInfo: %s %s %s %s", t.TransType, t.Gid, t.BranchID, t.BranchType)
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}
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// MustGetTrans construct transaction info from request
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func MustGetTrans(c *gin.Context) *TransInfo {
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ti, err := TransInfoFromQuery(c.Request.URL.Query())
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e2p(err)
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return ti
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}
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// TransInfoFromQuery construct transaction info from request
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func TransInfoFromQuery(qs url.Values) (*TransInfo, error) {
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ti := &TransInfo{
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TransType: qs.Get("trans_type"),
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Gid: qs.Get("gid"),
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BranchID: qs.Get("branch_id"),
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BranchType: qs.Get("branch_type"),
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}
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if ti.TransType == "" || ti.Gid == "" || ti.BranchID == "" || ti.BranchType == "" {
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return nil, fmt.Errorf("invlid trans info: %v", ti)
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}
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return ti, nil
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}
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func insertBarrier(tx *sql.Tx, transType string, gid string, branchID string, branchType string, reason string) (int64, error) {
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if branchType == "" {
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return 0, nil
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}
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return StxExec(tx, "insert ignore into dtm_barrier.barrier(trans_type, gid, branch_id, branch_type, reason) values(?,?,?,?,?)", transType, gid, branchID, branchType, reason)
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}
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// ThroughBarrierCall 子事务屏障，详细介绍见 https://zhuanlan.zhihu.com/p/388444465
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// db: 本地数据库
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// transInfo: 事务信息
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// bisiCall: 业务函数，仅在必要时被调用
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// 返回值:
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// 如果正常调用，返回bisiCall的结果
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// 如果发生重复调用，则busiCall不会被重复调用，直接对保存在数据库中上一次的结果，进行unmarshal，通常是一个map[string]interface{}，直接作为http的resp
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// 如果发生悬挂，则busiCall不会被调用，直接返回错误 {"dtm_result": "FAILURE"}
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// 如果发生空补偿，则busiCall不会被调用，直接返回 {"dtm_result": "SUCCESS"}
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func ThroughBarrierCall(db *sql.DB, transInfo *TransInfo, busiCall BusiFunc) (res interface{}, rerr error) {
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tx, rerr := db.BeginTx(context.Background(), &sql.TxOptions{})
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if rerr != nil {
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return
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}
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defer func() {
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Logf("result is %v error is %v", res, rerr)
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if x := recover(); x != nil {
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tx.Rollback()
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panic(x)
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} else if rerr != nil {
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tx.Rollback()
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} else {
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tx.Commit()
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}
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}()
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ti := transInfo
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originType := map[string]string{
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"cancel": "try",
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"compensate": "action",
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}[ti.BranchType]
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originAffected, _ := insertBarrier(tx, ti.TransType, ti.Gid, ti.BranchID, originType, ti.BranchType)
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currentAffected, rerr := insertBarrier(tx, ti.TransType, ti.Gid, ti.BranchID, ti.BranchType, ti.BranchType)
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Logf("originAffected: %d currentAffected: %d", originAffected, currentAffected)
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if (ti.BranchType == "cancel" || ti.BranchType == "compensate") && originAffected > 0 { // 这个是空补偿，返回成功
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res = ResultSuccess
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return
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} else if currentAffected == 0 { // 插入不成功
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var result sql.NullString
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err := StxQueryRow(tx, "select result from dtm_barrier.barrier where trans_type=? and gid=? and branch_id=? and branch_type=? and reason=?",
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ti.TransType, ti.Gid, ti.BranchID, ti.BranchType, ti.BranchType).Scan(&result)
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if err == sql.ErrNoRows { // 这个是悬挂操作，返回失败，AP收到这个返回，会尽快回滚
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res = ResultFailure
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return
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}
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if err != nil {
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rerr = err
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return
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}
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if result.Valid { // 数据库里有上一次结果，返回上一次的结果
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rerr = json.Unmarshal([]byte(result.String), &res)
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return
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}
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// 数据库里没有上次的结果，属于重复空补偿，直接返回成功
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res = ResultSuccess
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return
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}
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res, rerr = busiCall(tx)
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if rerr == nil { // 正确返回了，需要将结果保存到数据库
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sval := MustMarshalString(res)
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_, rerr = StxExec(tx, "update dtm_barrier.barrier set result=? where trans_type=? and gid=? and branch_id=? and branch_type=?", sval,
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ti.TransType, ti.Gid, ti.BranchID, ti.BranchType)
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}
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return
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}
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