对goroutine的“选择性”互斥

Question

I am new to Go and I would like to implement a custom mutual exclusion mechanism, where each application user can execute one goroutine at a time. To simplify, consider U1 and U2 as application users and F1(userId), F2(userId) and F3(userId) three different goroutines, which read/write records from a database that are related only to a given user. I would like that, if U1 calls (F1, F2, F3), (F2, F3) are not executed until F1 has ended, than F2 or F3 are executed (in calling order would be an optimal solution), lastly the remaining one is executed. U2 is not affected by U1 lock, but she is controlled by its own lock as described before. How would you implement this? Is there a built-in primitive? Thanks

Answer 1

You can use a buffered channel as a semaphore, and create such a channel per user. Then two goroutines related to the same user will only be able to do things after acquiring the semaphore (successfully writing to the channel).

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Resources on using Go channels as semaphores:

• Effective Go: https://golang.org/doc/effective_go.html#channels
• http://www.golangpatterns.info/concurrency/semaphores