ded551e199
This allows safer lock-free reads to be done on lists that never shrink in size. The main use-case for this is to allow servers to be added to a service without locking the service each time a new session is created. Synchronizing the memory before adding new components into a list guarantees that if a session reads from the list and sees the new list item, the memory pointed by the item is valid.
40 lines
906 B
C
40 lines
906 B
C
/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl.
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*
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* Change Date: 2019-07-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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/**
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* @file atomic.c - Implementation of atomic operations for MaxScale
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*
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* @verbatim
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* Revision History
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*
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* Date Who Description
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* 10/06/13 Mark Riddoch Initial implementation
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*
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* @endverbatim
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*/
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int
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atomic_add(int *variable, int value)
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{
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#ifdef __GNUC__
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return (int) __sync_fetch_and_add (variable, value);
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#else
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asm volatile(
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"lock; xaddl %%eax, %2;"
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:"=a" (value)
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: "a" (value), "m" (*variable)
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: "memory" );
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return value;
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#endif
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}
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