| 25 | | The idea of the concurrency substrate is to provide a minimal set of primitives over which a variety of user-level concurrency libraries can be implemented. As such, the concurrency substrate must provide a way to create threads, a way to schedule them, and a synchronization mechanism in a multiprocessor context. Whereas, the Creation and maintenance of schedulers and concurrent data structures is the task of the concurrency library. |
| | 27 | The idea of the concurrency substrate is to provide a minimal set of primitives over which a variety of user-level concurrency libraries can be implemented. As such, the concurrency substrate must provide a way to create threads, a way to schedule them, and a synchronization mechanism in a multiprocessor context. Whereas, the Creation and maintenance of schedulers and concurrent data structures is the task of the concurrency library. Concurrency substrate resides at [source:libraries/base/LwConc/Substrate.hs@646ec91db34c4309555fd7dd3bfe3930a4c5c55f libraries/base/LwConc/Substrate.hs]. |
| | 28 | |
| | 29 | ==== PTM ==== |
| | 30 | |
| | 31 | The only synchronization mechanism exposed by the concurrency substrate is a primitive transactional memory (PTM). Locks and condition variables can be notoriously difficult to use, especially in an environment with user-level threads, where they tend to interfere with the scheduler. Moreover, they do not compose elegantly with lazy evaluation. PTM interface is shown below: |
| | 32 | |
| | 33 | {{{ |
| | 34 | data PTM a |
| | 35 | data PVar a |
| | 36 | instance Monad PTM |
| | 37 | |
| | 38 | |
| | 39 | }}} |
