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60 lines
2.1 KiB
C
60 lines
2.1 KiB
C
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/* Copyright (C) 2008-2009 Sun Microsystems, Inc
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#ifndef PFS_GLOBAL_H
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#define PFS_GLOBAL_H
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/**
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@file storage/perfschema/pfs_global.h
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Miscellaneous global dependencies (declarations).
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*/
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extern bool pfs_initialized;
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void *pfs_malloc(size_t size, myf flags);
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#define PFS_MALLOC_ARRAY(n, T, f) \
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reinterpret_cast<T*> (pfs_malloc((n) * sizeof(T), (f)))
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void pfs_free(void *ptr);
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inline uint randomized_index(const void *ptr, uint max_size)
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{
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if (unlikely(max_size == 0))
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return 0;
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/*
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ptr is typically an aligned structure,
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so the last bits are not really random, but this has no effect.
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Apply a factor A*x to spread
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close values of ptr further apart (which helps with arrays),
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and to spread values way beyond a typical max_size.
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Then, apply a modulo to end within [0, max_size - 1].
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A is big prime numbers, to avoid resonating with max_size,
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to have a uniform distribution in [0, max_size - 1].
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The value of A is chosen so that index(ptr) and index(ptr + N) (for arrays)
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are likely to be not similar for typical values of max_size
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(50, 100, 1000, etc).
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In other words, (sizeof(T)*A % max_size) should not be a small number,
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to avoid that with 'T array[max_size]', index(array[i])
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and index(array[i + 1]) end up pointing in the same area in [0, max_size - 1].
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*/
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return static_cast<uint>
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(((reinterpret_cast<intptr> (ptr)) * 2166179) % max_size);
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}
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void pfs_print_error(const char *format, ...);
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#endif
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