SharedAscendingPageAllocator

Constructors

this

this(size_t n)

Rounds the mapping size to the next multiple of the page size and calls the OS primitive responsible for creating memory mappings: mmap on POSIX and VirtualAlloc on Windows.

Members

Functions

alignedAllocate

void[] alignedAllocate(size_t n, uint a)

Rounds the allocation size to the next multiple of the page size. The allocation only reserves a range of virtual pages but the actual physical memory is allocated on demand, when accessing the memory.

allocate

void[] allocate(size_t n)

Rounds the allocation size to the next multiple of the page size. The allocation only reserves a range of virtual pages but the actual physical memory is allocated on demand, when accessing the memory.

deallocate

void deallocate(void[] b)

Decommit all physical memory associated with the buffer given as parameter, but keep the range of virtual addresses.

deallocateAll

bool deallocateAll()

Removes the memory mapping causing all physical memory to be decommited and the virtual address space to be reclaimed.

expand

bool expand(void[] b, size_t delta)

If the passed buffer is not the last allocation, then delta can be at most the number of bytes left on the last page. Otherwise, we can expand the last allocation until the end of the virtual address range.

getAvailableSize

size_t getAvailableSize()

Returns the available size for further allocations in bytes.

goodAllocSize

size_t goodAllocSize(size_t n)

Rounds the requested size to the next multiple of the page size.

owns

Ternary owns(void[] buf)

Returns Ternary.yes if the passed buffer is inside the range of virtual adresses. Does not guarantee that the passed buffer is still valid.

import core.memory : pageSize;
import core.thread : ThreadGroup;

enum numThreads = 100;
shared SharedAscendingPageAllocator a = SharedAscendingPageAllocator(pageSize * numThreads);

void fun()
{
    void[] b = a.allocate(pageSize);
    assert(b.length == pageSize);

    assert(a.deallocate(b));
}

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

• AscendingPageAllocator
• SharedAscendingPageAllocator