1// Copyright (c) 2005, Google Inc.
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are
6// met:
7//
8//     * Redistributions of source code must retain the above copyright
9// notice, this list of conditions and the following disclaimer.
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13// distribution.
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17//
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24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30// ---
31// Author: Sanjay Ghemawat
32//
33// Routine that uses sbrk/mmap to allocate memory from the system.
34// Useful for implementing malloc.
35
36#ifndef TCMALLOC_SYSTEM_ALLOC_H_
37#define TCMALLOC_SYSTEM_ALLOC_H_
38
39#include <config.h>
40#include <stddef.h>                     // for size_t
41
42class SysAllocator;
43
44// REQUIRES: "alignment" is a power of two or "0" to indicate default alignment
45//
46// Allocate and return "N" bytes of zeroed memory.
47//
48// If actual_bytes is NULL then the returned memory is exactly the
49// requested size.  If actual bytes is non-NULL then the allocator
50// may optionally return more bytes than asked for (i.e. return an
51// entire "huge" page if a huge page allocator is in use).
52//
53// The returned pointer is a multiple of "alignment" if non-zero. The
54// returned pointer will always be aligned suitably for holding a
55// void*, double, or size_t. In addition, if this platform defines
56// CACHELINE_ALIGNED, the return pointer will always be cacheline
57// aligned.
58//
59// Returns NULL when out of memory.
60extern void* TCMalloc_SystemAlloc(size_t bytes, size_t *actual_bytes,
61                                  size_t alignment = 0);
62
63// This call is a hint to the operating system that the pages
64// contained in the specified range of memory will not be used for a
65// while, and can be released for use by other processes or the OS.
66// Pages which are released in this way may be destroyed (zeroed) by
67// the OS.  The benefit of this function is that it frees memory for
68// use by the system, the cost is that the pages are faulted back into
69// the address space next time they are touched, which can impact
70// performance.  (Only pages fully covered by the memory region will
71// be released, partial pages will not.)
72extern void TCMalloc_SystemRelease(void* start, size_t length);
73
74// The current system allocator.
75extern PERFTOOLS_DLL_DECL SysAllocator* sys_alloc;
76
77#endif /* TCMALLOC_SYSTEM_ALLOC_H_ */
78