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Struct std.experimental.allocator.building_blocks.aligned_block_list.SharedAlignedBlockList

SharedAlignedBlockList is the threadsafe version of AlignedBlockList. The Allocator template parameter must refer a shared allocator. Also, ParentAllocator must be a shared allocator, supporting alignedAllocate.

struct SharedAlignedBlockList(Allocator, ParentAllocator, ulong theAlignment = 1 << 21) ;

Methods

NameDescription
allocate (n) Returns a chunk of memory of size n It finds the first node in the AlignedBlockNode list which has available memory, and moves it to the front of the list.
deallocate (b) Deallocates the buffer b given as parameter. Deallocations take place in constant time, regardless of the number of nodes in the list. b.ptr is rounded down to the nearest multiple of the alignment to quickly find the corresponding AlignedBlockNode.
owns (b) Returns Ternary.yes if the buffer belongs to the parent allocator and Ternary.no otherwise.

Parameters

NameDescription
Allocator the shared allocator which is used to manage each node; it must have a constructor which receives ubyte[] and it must not have any parent allocators, except for the NullAllocator
ParentAllocator each node draws memory from the parent allocator; it must be shared and support alignedAllocate
theAlignment alignment of each block and at the same time length of each node

Example

import std.experimental.allocator.building_blocks.region : SharedBorrowedRegion;
import std.experimental.allocator.building_blocks.ascending_page_allocator : SharedAscendingPageAllocator;
import std.experimental.allocator.building_blocks.null_allocator : NullAllocator;
import core.thread : ThreadGroup;

enum numThreads = 8;
enum size = 2048;
enum maxIter = 10;

/*
In this example we use 'SharedAlignedBlockList' together with
'SharedBorrowedRegion', in order to create a fast, thread-safe allocator.
*/
alias SuperAllocator = SharedAlignedBlockList!(
        SharedBorrowedRegion!(1),
        SharedAscendingPageAllocator,
        4096);

SuperAllocator a;
// The 'SuperAllocator' will draw memory from a 'SharedAscendingPageAllocator'
a.parent = SharedAscendingPageAllocator(4096 * 1024);

// Launch 'numThreads', each performing allocations
void fun()
{
    foreach (i; 0 .. maxIter)
    {
        void[] b = a.allocate(size);
        writeln(b.length); // size
    }
}

auto tg = new ThreadGroup;
foreach (i; 0 .. numThreads)
{
    tg.create(&fun);
}
tg.joinAll();

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