1aa6c4ab92
Fixing few macros that doesn't follows most basic safety conventions which is wrapping any usage of passed variable with parentheses and if written more than one command, then wrap it with do-while(0) (or parentheses).
159 lines
6.8 KiB
C
159 lines
6.8 KiB
C
/* This file implements atomic counters using c11 _Atomic, __atomic or __sync
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* macros if available, otherwise we will throw an error when compile.
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*
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* The exported interface is composed of three macros:
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*
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* atomicIncr(var,count) -- Increment the atomic counter
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* atomicGetIncr(var,oldvalue_var,count) -- Get and increment the atomic counter
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* atomicDecr(var,count) -- Decrement the atomic counter
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* atomicGet(var,dstvar) -- Fetch the atomic counter value
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* atomicSet(var,value) -- Set the atomic counter value
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* atomicGetWithSync(var,value) -- 'atomicGet' with inter-thread synchronization
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* atomicSetWithSync(var,value) -- 'atomicSet' with inter-thread synchronization
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*
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* Never use return value from the macros, instead use the AtomicGetIncr()
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* if you need to get the current value and increment it atomically, like
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* in the following example:
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*
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* long oldvalue;
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* atomicGetIncr(myvar,oldvalue,1);
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* doSomethingWith(oldvalue);
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*
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* ----------------------------------------------------------------------------
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*
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* Copyright (c) 2015, Salvatore Sanfilippo <antirez at gmail dot com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Redis nor the names of its contributors may be used
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* to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <pthread.h>
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#include "config.h"
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#ifndef __ATOMIC_VAR_H
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#define __ATOMIC_VAR_H
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/* Define redisAtomic for atomic variable. */
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#define redisAtomic
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/* To test Redis with Helgrind (a Valgrind tool) it is useful to define
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* the following macro, so that __sync macros are used: those can be detected
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* by Helgrind (even if they are less efficient) so that no false positive
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* is reported. */
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// #define __ATOMIC_VAR_FORCE_SYNC_MACROS
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/* There will be many false positives if we test Redis with Helgrind, since
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* Helgrind can't understand we have imposed ordering on the program, so
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* we use macros in helgrind.h to tell Helgrind inter-thread happens-before
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* relationship explicitly for avoiding false positives.
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*
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* For more details, please see: valgrind/helgrind.h and
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* https://www.valgrind.org/docs/manual/hg-manual.html#hg-manual.effective-use
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*
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* These macros take effect only when 'make helgrind', and you must first
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* install Valgrind in the default path configuration. */
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#ifdef __ATOMIC_VAR_FORCE_SYNC_MACROS
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#include <valgrind/helgrind.h>
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#else
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#define ANNOTATE_HAPPENS_BEFORE(v) ((void) v)
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#define ANNOTATE_HAPPENS_AFTER(v) ((void) v)
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#endif
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#if !defined(__ATOMIC_VAR_FORCE_SYNC_MACROS) && defined(__STDC_VERSION__) && \
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(__STDC_VERSION__ >= 201112L) && !defined(__STDC_NO_ATOMICS__)
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/* Use '_Atomic' keyword if the compiler supports. */
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#undef redisAtomic
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#define redisAtomic _Atomic
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/* Implementation using _Atomic in C11. */
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#include <stdatomic.h>
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#define atomicIncr(var,count) atomic_fetch_add_explicit(&var,(count),memory_order_relaxed)
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#define atomicGetIncr(var,oldvalue_var,count) do { \
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oldvalue_var = atomic_fetch_add_explicit(&var,(count),memory_order_relaxed); \
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} while(0)
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#define atomicDecr(var,count) atomic_fetch_sub_explicit(&var,(count),memory_order_relaxed)
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#define atomicGet(var,dstvar) do { \
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dstvar = atomic_load_explicit(&var,memory_order_relaxed); \
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} while(0)
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#define atomicSet(var,value) atomic_store_explicit(&var,value,memory_order_relaxed)
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#define atomicGetWithSync(var,dstvar) do { \
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dstvar = atomic_load_explicit(&var,memory_order_seq_cst); \
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} while(0)
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#define atomicSetWithSync(var,value) \
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atomic_store_explicit(&var,value,memory_order_seq_cst)
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#define REDIS_ATOMIC_API "c11-builtin"
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#elif !defined(__ATOMIC_VAR_FORCE_SYNC_MACROS) && \
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(!defined(__clang__) || !defined(__APPLE__) || __apple_build_version__ > 4210057) && \
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defined(__ATOMIC_RELAXED) && defined(__ATOMIC_SEQ_CST)
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/* Implementation using __atomic macros. */
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#define atomicIncr(var,count) __atomic_add_fetch(&var,(count),__ATOMIC_RELAXED)
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#define atomicGetIncr(var,oldvalue_var,count) do { \
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oldvalue_var = __atomic_fetch_add(&var,(count),__ATOMIC_RELAXED); \
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} while(0)
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#define atomicDecr(var,count) __atomic_sub_fetch(&var,(count),__ATOMIC_RELAXED)
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#define atomicGet(var,dstvar) do { \
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dstvar = __atomic_load_n(&var,__ATOMIC_RELAXED); \
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} while(0)
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#define atomicSet(var,value) __atomic_store_n(&var,value,__ATOMIC_RELAXED)
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#define atomicGetWithSync(var,dstvar) do { \
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dstvar = __atomic_load_n(&var,__ATOMIC_SEQ_CST); \
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} while(0)
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#define atomicSetWithSync(var,value) \
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__atomic_store_n(&var,value,__ATOMIC_SEQ_CST)
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#define REDIS_ATOMIC_API "atomic-builtin"
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#elif defined(HAVE_ATOMIC)
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/* Implementation using __sync macros. */
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#define atomicIncr(var,count) __sync_add_and_fetch(&var,(count))
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#define atomicGetIncr(var,oldvalue_var,count) do { \
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oldvalue_var = __sync_fetch_and_add(&var,(count)); \
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} while(0)
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#define atomicDecr(var,count) __sync_sub_and_fetch(&var,(count))
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#define atomicGet(var,dstvar) do { \
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dstvar = __sync_sub_and_fetch(&var,0); \
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} while(0)
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#define atomicSet(var,value) do { \
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while(!__sync_bool_compare_and_swap(&var,var,value)); \
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} while(0)
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/* Actually the builtin issues a full memory barrier by default. */
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#define atomicGetWithSync(var,dstvar) do { \
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dstvar = __sync_sub_and_fetch(&var,0,__sync_synchronize); \
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ANNOTATE_HAPPENS_AFTER(&var); \
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} while(0)
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#define atomicSetWithSync(var,value) do { \
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ANNOTATE_HAPPENS_BEFORE(&var); \
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while(!__sync_bool_compare_and_swap(&var,var,value,__sync_synchronize)); \
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} while(0)
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#define REDIS_ATOMIC_API "sync-builtin"
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#else
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#error "Unable to determine atomic operations for your platform"
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#endif
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#endif /* __ATOMIC_VAR_H */
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