folly::detail::MMapAlloc Class Reference

#include <AtomicUnorderedMapUtils.h>

Public Member Functions
void *	allocate (size_t size)
void	deallocate (void *p, size_t size)

Private Member Functions
size_t	computeSize (size_t size)

Detailed Description

Definition at line 30 of file AtomicUnorderedMapUtils.h.

Member Function Documentation

void* folly::detail::MMapAlloc::allocate ( size_t  size )

inline

Definition at line 41 of file AtomicUnorderedMapUtils.h.

References computeSize(), and MAP_POPULATE.

                              {
    auto len = computeSize(size);

    int extraflags = 0;
#if defined(MAP_POPULATE)
    extraflags |= MAP_POPULATE;
#endif
    // MAP_HUGETLB is a perf win, but requires cooperation from the
    // deployment environment (and a change to computeSize()).
    void* mem = static_cast<void*>(mmap(
        nullptr,
        len,
        PROT_READ | PROT_WRITE,
        MAP_PRIVATE | MAP_ANONYMOUS | extraflags,
        -1,
        0));
    if (mem == reinterpret_cast<void*>(-1)) {
      throw std::system_error(errno, std::system_category());
    }
#if !defined(MAP_POPULATE) && defined(MADV_WILLNEED)
    madvise(mem, size, MADV_WILLNEED);
#endif

    return mem;
  }

size_t folly::detail::MMapAlloc::computeSize ( size_t  size )

inlineprivate

Definition at line 32 of file AtomicUnorderedMapUtils.h.

Referenced by allocate(), and deallocate().

                                  {
    long pagesize = sysconf(_SC_PAGESIZE);
    size_t mmapLength = ((size - 1) & ~(pagesize - 1)) + pagesize;
    assert(size <= mmapLength && mmapLength < size + pagesize);
    assert((mmapLength % pagesize) == 0);
    return mmapLength;
  }

void folly::detail::MMapAlloc::deallocate ( void *  p, size_t  size  )

inline

Definition at line 67 of file AtomicUnorderedMapUtils.h.

References computeSize().

                                        {
    auto len = computeSize(size);
    munmap(p, len);
  }

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The documentation for this class was generated from the following file:

• proxygen/folly/folly/detail/AtomicUnorderedMapUtils.h