Clojure STM has 3 big unique features: Implements MVCC snapshot avoiding transactions restarts on read invalidation. Ensures references on read-writes provides a kind of manual control over resource acquisition order. Has explicit commute which reduces retries on commutative writes.
You can set up a worker thread to process all requests in a deterministic way, so nobody gets starved. This strategy would be reasonably efficient and immune to livelock. — yes, this is a horrible name createManagerFactory :: a -> IO ((IO a), IO (((a -> a) -> IO a))) IO a is an action … Read more
MVar can be empty used to implement synchronization patterns between threads allows one-way communication between threads can be faster than TVar in some cases TVar can not be empty atomic transactions “shared memory” between threads; can be used to implement, for example, a lookup cache from which multiple threads can read/write access is linear time … Read more
It’s not really a matter of locking, it’s about what the reference means: TVar is a mutable reference within STM, representing general shared state. You create it holding a value, you can read and write to it, etc. It’s very much akin to IORef or STRef (which are the same thing anyway). TMVar is a … Read more
I don’t know if it’s any help, but I tried to implement Iain’s suggestion and made a variant of mergeSources’ that stops as soon as any of the channels does: mergeSources’ :: (MonadIO m, MonadBaseControl IO m) => [Source (ResourceT m) a] — ^ The sources to merge. -> Int — ^ The bound of … Read more
I participated in the hobbyist development of the BitTorrent client in Haskell (named conjure). It uses STM quite heavily to coordinate different threads (1 per peer + 1 for storage management + 1 for overall management). Benefits: less locks, readable code. Speed was not an issue, at least not due to STM usage. Hope this … Read more