-------------------------------------------- -- stm-chans 1.2.0 -------------------------------------------- The stm-chans package offers a collection of channel types, similar to Control.Concurrent.STM.TChan but with additional features. -------------------------------------------- -- Changes (since 1.0.0) -------------------------------------------- * (Version 1.1.0) Added tryWriteTBChan. * (Version 1.1.0) Added tryWriteTBMChan. * Some major performance improvements in TBChan and TBMChan, thanks to Thomas DuBuisson. In particular, these improvements reduce contention between readers and writers, improving throughput by up to 2--3 times when producers and consumers are running in separate OS threads. The cost for non-parallel programs is trivial (<1% worst-case running time, per Criterion). * Added estimateFreeSlotsTBChan, freeSlotsTBChan, estimateFreeSlotsTBMChan, and freeSlotsTBMChan. These functions return either the exact number or a lower-bound on the number of free slots available before the channels will block/retry. * Some other minor optimizations and code improvements. -------------------------------------------- -- Long description -------------------------------------------- In particular stm-chans offers these types: * Control.Concurrent.STM.TBChan: Bounded FIFO channels. When the channel is full, writers will block/retry. This ensures that the writers do not get too far ahead of the readers, which helps to make sure that memory and cpu resources are used responsibly. * Control.Concurrent.STM.TMChan: Closeable FIFO channels. This is like TChan (Maybe a) but with a monotonicity guarantee that once Nothing is returned all future reads will be Nothing as well. * Control.Concurrent.STM.TBMChan: Bounded Closeable FIFO channels. This combines the capabilities of TBChan and TMChan. In addition, the stm-chans package offers a (partial) compatibility layer for some recent API improvements to the stm package (see ticket #5104 [1]). These new functions include: * tryReadTChan :: TChan a -> STM (Maybe a) A version of readTChan which does not retry. Instead it returns Nothing if no value is available. * peekTChan :: TChan a -> STM a Get the next value from the TChan without removing it, retrying if the channel is empty. * tryPeekTChan :: TChan a -> STM (Maybe a) A version of peekTChan which does not retry. Instead it returns Nothing if no value is available. [1] http://hackage.haskell.org/trac/ghc/ticket/5104 -------------------------------------------- -- Links -------------------------------------------- Homepage: http://code.haskell.org/~wren/ Hackage: http://hackage.haskell.org/package/stm-chans Darcs: http://community.haskell.org/~wren/stm-chans Haddock (Darcs version): http://community.haskell.org/~wren/stm-chans/dist/doc/html/stm-chans -- Live well, ~wren