98 lines
2.8 KiB
Go
98 lines
2.8 KiB
Go
// Package orderstate 订单状态机：合法流转校验 + 乐观锁 + 审计日志（与状态修改在同一个事务里提交）。
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package orderstate
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import (
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"context"
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"errors"
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"fmt"
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"github.com/jackc/pgx/v5"
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"github.com/jackc/pgx/v5/pgxpool"
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)
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const Schema = `
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CREATE TABLE IF NOT EXISTS orders (
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id BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
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status TEXT NOT NULL DEFAULT 'pending',
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version INT NOT NULL DEFAULT 1,
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updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
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);
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CREATE TABLE IF NOT EXISTS order_events (
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id BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
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order_id BIGINT NOT NULL REFERENCES orders(id),
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from_status TEXT NOT NULL,
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to_status TEXT NOT NULL,
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actor TEXT NOT NULL,
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reason TEXT NOT NULL DEFAULT '',
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created_at TIMESTAMPTZ NOT NULL DEFAULT now()
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);`
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// 允许的状态流转：只有这里列出的才合法
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var transitions = map[string][]string{
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"pending": {"paid", "cancelled"},
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"paid": {"shipped", "refunding"},
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"shipped": {"completed"},
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"refunding": {"refunded", "paid"},
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}
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var (
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ErrIllegal = errors.New("不允许的状态流转")
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ErrConflict = errors.New("订单已被其他操作修改，请刷新后重试")
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ErrNotFound = errors.New("订单不存在")
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)
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func allowed(from, to string) bool {
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for _, s := range transitions[from] {
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if s == to {
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return true
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}
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}
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return false
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}
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type Order struct {
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ID int64
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Status string
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Version int
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}
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func Get(ctx context.Context, db *pgxpool.Pool, id int64) (Order, error) {
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var o Order
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err := db.QueryRow(ctx, `SELECT id, status, version FROM orders WHERE id = $1`, id).Scan(&o.ID, &o.Status, &o.Version)
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if errors.Is(err, pgx.ErrNoRows) {
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return o, ErrNotFound
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}
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return o, err
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}
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// Transition 把订单从 cur 状态改成 to。cur 是调用方读到的版本（乐观锁）。
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func Transition(ctx context.Context, db *pgxpool.Pool, cur Order, to, actor, reason string) (Order, error) {
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if !allowed(cur.Status, to) {
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return cur, fmt.Errorf("%s -> %s: %w", cur.Status, to, ErrIllegal)
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}
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tx, err := db.Begin(ctx)
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if err != nil {
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return cur, err
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}
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defer tx.Rollback(ctx) // 提交成功后再回滚是无害的
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tag, err := tx.Exec(ctx,
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`UPDATE orders SET status = $1, version = version + 1, updated_at = now()
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WHERE id = $2 AND status = $3 AND version = $4`, to, cur.ID, cur.Status, cur.Version)
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if err != nil {
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return cur, err
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}
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if tag.RowsAffected() == 0 {
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return cur, ErrConflict
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}
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if _, err := tx.Exec(ctx,
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`INSERT INTO order_events (order_id, from_status, to_status, actor, reason) VALUES ($1, $2, $3, $4, $5)`,
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cur.ID, cur.Status, to, actor, reason); err != nil {
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return cur, err
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}
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if err := tx.Commit(ctx); err != nil {
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return cur, err
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}
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return Order{ID: cur.ID, Status: to, Version: cur.Version + 1}, nil
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}
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