2.10 Two-Phase Implementation: TCC

1. What Is TCC?

• 2PC is a two-phase approach at the database layer, while TCC is a two-phase approach at the application layer.
• TCC:
  • Try: attempt to execute the transaction.
  • Confirm: confirm execution of the transaction.
  • Cancel: cancel execution of the transaction.
• In essence, it is also a two-phase transaction.
  • In the first phase, execute Try to perform business checks and reserve resources.
  • The second phase depends on the result of the first phase. If successful, execute Confirm to perform business confirmation; if it fails, execute Cancel to perform the opposite of Try, similar to a manual rollback.
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2. Why Is TCC Needed?

• TCC solves several shortcomings of 2PC:
  • Single-point problem: the business activity manager becomes multi-point.
  • Synchronous blocking: commit directly during Try, without needing to block and wait; Cancel…

3. Problems with TCC

• Code intrusion: developers need to manually write code to implement Try, Confirm, and Cancel.

4. Implementation

4.1. Seata

• seata/seata: Seata is an easy-to-use, high-performance, open source distributed transaction solution.

5. References

• If Someone Asks You About Distributed Transactions Again, Send Them This Article - Juejin
• Transactions - What Is the Difference Between TCC and 2PC? - SegmentFault
• What Is the Difference Between TCC and 2PC? - Zhihu