You're absolutely right. (I wrote the simplified example a bit too fast and missed that in a few places https://go.dev/play/p/9fk_yt0vkHD)
To add the general motivation, I have a reactive UI tree and need to introduce concurrency (for when async data fetching is done and the data is reintroduced,, essentially mutating the tree). On Tuesday, July 5, 2022 at 4:13:01 PM UTC+2 Marvin Renich wrote: > * Brian Candler <b.ca...@pobox.com> [220705 09:48]: > > Have a public Set() that does the lock and then calls a private internal > > function, which assumes it's already running under the lock. > > https://go.dev/play/p/M1XuC8bxCxL > > > > On Tuesday, 5 July 2022 at 13:32:26 UTC+1 atd...@gmail.com wrote: > > > > > Hi, > > > > > > I have a tree datastructure where mutating some nodes *may *trigger a > > > mutation on some other tree nodes. > > > > > > This tree should be accessible by multiple goroutines but mutated by > only > > > one at a time. > > > > > > As such, I wanted to have a global lock on the tree such that > mutatiing > > > node methods should acquire this lock beforehand. > > > > > > But it seems to require for the mutex to be reentrant? > > > > > > I have tried to create a very simplified*** model to illustrate > > > https://go.dev/play/p/v37cbYQ1jSY > > > > > > (***) I know people might want to suggest for the Set method to use a > > > lockless variant when iterating over the linked nodes but in the real > code, > > > it iterates over user created callbacks instead and I don't think I > can > > > expect callbacks writers to juggle between the two kind of methods to > avoid > > > deadlocks. > > > > > > Any suggestion? > > > > > > > > Note also that for referencing a Node to be safe, you must do one of two > things: either use sync/atomic for all reads and writes of Num > (assuming the data in the tree is of a type that can be handled by > sync/atomic), or use sync.RWMutex instead of sync.Mutex, and use RLock > on reads and Lock on writes. > > If Node has more than one data field, e.g. {Name string; Age int; ...}, > you will have to go with the RWMutex option. > > ...Marvin > > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/94b3ef70-9431-4a8a-916d-034dd5822d01n%40googlegroups.com.
