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执行时真实时钟与持久授权回读（撤销/过期即停并保留预备份）、写集合写前落盘、 租约与 attempt 身份、恢复队列与原发送身份分离、成功收尾必须释放维护后再登记终态。
37 lines
1.1 KiB
Go
37 lines
1.1 KiB
Go
package postgres
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import (
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"context"
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"errors"
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"time"
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)
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var ErrLibraryExecutionBusy = errors.New("target already has an active executor")
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func (s *Store) WithLibraryExecution(ctx context.Context, instance string, run func(context.Context, func(context.Context) error) error) error {
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if instance == "" {
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return errors.New("execution instance identity required")
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}
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// A lease expiry is not proof that the old writer has stopped. Keep a
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// shared PG advisory lock until the synchronous callback (including cleanup)
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// exits. No deferred unlock may run merely because ctx was cancelled.
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tx, err := s.db.Begin(ctx)
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if err != nil {
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return err
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}
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defer func() {
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cleanup, cancel := context.WithTimeout(context.WithoutCancel(ctx), 5*time.Second)
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defer cancel()
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_ = tx.Rollback(cleanup)
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}()
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var held bool
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if err = tx.QueryRow(ctx, `SELECT pg_try_advisory_xact_lock(hashtextextended($1,0))`, "library-execution:"+instance).Scan(&held); err != nil {
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return err
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}
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if !held {
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return ErrLibraryExecutionBusy
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}
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ping := func(probe context.Context) error { var one int; return tx.QueryRow(probe, `SELECT 1`).Scan(&one) }
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return run(ctx, ping)
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}
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