Thread-safe lock-free memory pool for managing large memory pages that are made up of many small Blocks.
Modulememory-pool-0.1.0.0Haskell2010
System.Memory.Pool
The goal of this Memory Pool is to provide the ability to allocate big chunks of memory that can fit many Blocks. Some memory allocators out there have a fairly large minimal size requirement, which would be wasteful if many chunks of small size (eg. 32 bytes) are needed at once. Memory pool will allocate one page at a time as more blocks is needed.
Currently there is no functionality for releasing unused pages. So, once a page is allocated, it will be re-used when more Blocks is needed, but it will not be GCed until the whole Pool is GCed.
- 2 types
- 5 values
- Packagememory-pool-0.1.0.0
- Exports7
- LanguageHaskell2010
- LicenceApache-2.0
- SourcePool.hs
Pool
2 declarationsvalue
initPool :: KnownNat n=> IntNumber of groups per page. Must be a posititve number, otherwise error. One group contains as many blocks as the operating system has bits. A 64bit architecture will have 64 blocks per group. For example, if program is compiled on a 64 bit OS and you know ahead of time the maximum number of blocks that will be allocated through out the program, then the optimal value for this argument will
maxBlockNum/64-> (forall a. Int -> ST s (ForeignPtr a))Mempool page allocator. Some allocated pages might be immediately discarded, therefore number of pages utilized will not necessesarely match the number of times this action will be called.
-> (Ptr (Block n) -> IO ())Finalizer to use for each block. It is an IO action because it will be executed by the Garbage Collector in a separate thread once the Block is no longer referenced.
-> ST s (Pool n s)
Initilizes the Pool that can be used for further allocation of ForeignPtr
Block n with grabNextBlock.
Block
3 declarationsThis is just a proxy type that carries information at the type level about the size of the block in bytes supported by a particular instance of a Pool. Use blockByteCount to get the byte size at the value level.
Number of bytes in a Block
Reserve a ForeignPtr of the blockByteCount size in the Pool. There is a default finalizer attached to the ForeignPtr that will run Block pointer finalizer and release that memory for re-use by other blocks allocated in the future. It is safe to add more Haskell finalizers with addForeignPtrConcFinalizer if necessary.
Helpers
2 declarationsUseful function for testing. Check how many pages have been allocated thus far.
Helper function that finds an index of the left-most bit that is not set.