95 lines
3.2 KiB
Go
95 lines
3.2 KiB
Go
package dtmcli
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import (
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"database/sql"
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"fmt"
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"net/url"
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)
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// BusiFunc type for busi func
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type BusiFunc func(db DB) error
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// BranchBarrier every branch info
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type BranchBarrier 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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BarrierID int
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}
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func (bb *BranchBarrier) String() string {
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return fmt.Sprintf("transInfo: %s %s %s %s", bb.TransType, bb.Gid, bb.BranchID, bb.BranchType)
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}
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// BarrierFromQuery construct transaction info from request
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func BarrierFromQuery(qs url.Values) (*BranchBarrier, error) {
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return BarrierFrom(qs.Get("trans_type"), qs.Get("gid"), qs.Get("branch_id"), qs.Get("branch_type"))
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}
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// BarrierFrom construct transaction info from request
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func BarrierFrom(transType, gid, branchID, branchType string) (*BranchBarrier, error) {
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ti := &BranchBarrier{
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TransType: transType,
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Gid: gid,
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BranchID: branchID,
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BranchType: branchType,
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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 Tx, transType string, gid string, branchID string, branchType string, barrierID 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 DBExec(tx, "insert ignore into dtm_barrier.barrier(trans_type, gid, branch_id, branch_type, barrier_id, reason) values(?,?,?,?,?,?)", transType, gid, branchID, branchType, barrierID, reason)
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}
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// Call 子事务屏障，详细介绍见 https://zhuanlan.zhihu.com/p/388444465
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// tx: 本地数据库的事务对象，允许子事务屏障进行事务操作
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// bisiCall: 业务函数，仅在必要时被调用
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func (bb *BranchBarrier) Call(tx Tx, busiCall BusiFunc) (rerr error) {
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bb.BarrierID = bb.BarrierID + 1
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bid := fmt.Sprintf("%02d", bb.BarrierID)
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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("barrier call error is %v", 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 := bb
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originType := map[string]string{
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BranchCancel: BranchTry,
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BranchCompensate: BranchAction,
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}[ti.BranchType]
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originAffected, _ := insertBarrier(tx, ti.TransType, ti.Gid, ti.BranchID, originType, bid, ti.BranchType)
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currentAffected, rerr := insertBarrier(tx, ti.TransType, ti.Gid, ti.BranchID, ti.BranchType, bid, ti.BranchType)
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Logf("originAffected: %d currentAffected: %d", originAffected, currentAffected)
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if (ti.BranchType == BranchCancel || ti.BranchType == BranchCompensate) && originAffected > 0 { // 这个是空补偿，返回成功
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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 := DBQueryRow(tx, "select 1 from dtm_barrier.barrier where trans_type=? and gid=? and branch_id=? and branch_type=? and barrier_id=? and reason=?",
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ti.TransType, ti.Gid, ti.BranchID, ti.BranchType, bid, ti.BranchType).Scan(&result)
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if err == sql.ErrNoRows { // 不是当前分支插入的，那么是cancel插入的，因此是悬挂操作，返回失败，AP收到这个返回，会尽快回滚
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rerr = ErrFailure
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return
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}
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rerr = err //幂等和空补偿，直接返回
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return
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}
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rerr = busiCall(tx)
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return
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}
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