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// bdlma_heapbypassallocator.cpp -*-C++-*-
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// ----------------------------------------------------------------------------
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// NOTICE
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//
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// This component is not up to date with current BDE coding standards, and
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// should not be used as an example for new development.
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// ----------------------------------------------------------------------------
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#include <bdlma_heapbypassallocator.h>
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#include <bsls_ident.h>
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BSLS_IDENT_RCSID(bdlma_heapbypassallocator_cpp,"$Id$ $CSID$")
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#include <bsls_assert.h>
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#include <bsls_alignmentutil.h>
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#include <bsls_platform.h>
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#include <bsl_algorithm.h>
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#ifdef BSLS_PLATFORM_OS_WINDOWS
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#include <windows.h>
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#elif defined(BSLS_PLATFORM_OS_UNIX)
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#include <unistd.h>
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#include <sys/mman.h>
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#endif
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namespace BloombergLP {
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namespace bdlma {
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// ========================================
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// struct HeapBypassAllocator::BufferHeader
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// ========================================
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struct HeapBypassAllocator::BufferHeader {
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// This struct defines a link in a linked list of buffers allocated by
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// 'class HeapBypassAllocator'. Each buffer header is located at the
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// beginning of the buffer it describes, and contains the size (in bytes)
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// of the buffer.
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BufferHeader *d_nextBuffer; // pointer to linked list of buffers
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// allocated after this one
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bsls::Types::size_type d_size; // size (in bytes) of this buffer
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};
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} // close package namespace
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// --------------------------
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// bdlma::HeapBypassAllocator
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// --------------------------
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// PRIVATE CLASS METHODS
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#if defined(BSLS_PLATFORM_OS_UNIX)
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namespace bdlma {
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char *HeapBypassAllocator::map(bsls::Types::size_type size)
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{
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// Note that passing 'MAP_ANONYMOUS' and a null file descriptor tells
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// 'mmap' to use a special system file to map to.
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char *address = (char *)mmap(0, // 'mmap' chooses what address to which
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// to map the memory
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size,
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PROT_READ | PROT_WRITE,
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#ifdef BSLS_PLATFORM_OS_DARWIN
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MAP_ANON | MAP_PRIVATE,
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#else
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MAP_ANONYMOUS | MAP_PRIVATE,
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#endif
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-1, // null file descriptor
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0);
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return (MAP_FAILED == address ? 0 : address);
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}
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void HeapBypassAllocator::unmap(void *address, bsls::Types::size_type size) {
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// On some platforms, munmap takes a 'char *', on others, a 'void *'.
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munmap((char *)address, size);
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}
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} // close package namespace
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#elif defined(BSLS_PLATFORM_OS_WINDOWS)
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namespace bdlma {
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char *HeapBypassAllocator::map(bsls::Types::size_type size)
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{
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char *address =
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(char *)VirtualAlloc(0, // 'VirtualAlloc' chooses what address to
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// which to map the memory
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size,
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MEM_COMMIT | MEM_RESERVE,
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PAGE_READWRITE);
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return NULL == address ? 0 : address;
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}
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