103 lines
2.9 KiB
C
103 lines
2.9 KiB
C
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#ifndef HEADER_CURL_EASY_LOCK_H
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#define HEADER_CURL_EASY_LOCK_H
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/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at https://curl.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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* SPDX-License-Identifier: curl
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*
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***************************************************************************/
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#include "curl_setup.h"
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#define GLOBAL_INIT_IS_THREADSAFE
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#if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600
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#ifdef __MINGW32__
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#ifndef SRWLOCK_INIT
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#define SRWLOCK_INIT NULL
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#endif
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#endif /* __MINGW32__ */
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#define curl_simple_lock SRWLOCK
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#define CURL_SIMPLE_LOCK_INIT SRWLOCK_INIT
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#define curl_simple_lock_lock(m) AcquireSRWLockExclusive(m)
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#define curl_simple_lock_unlock(m) ReleaseSRWLockExclusive(m)
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#elif defined(HAVE_ATOMIC) && defined(HAVE_STDATOMIC_H)
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#include <stdatomic.h>
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#if defined(HAVE_SCHED_YIELD)
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#include <sched.h>
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#endif
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#define curl_simple_lock atomic_int
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#define CURL_SIMPLE_LOCK_INIT 0
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/* a clang-thing */
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#ifndef __has_builtin
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#define __has_builtin(x) 0
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#endif
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#ifndef __INTEL_COMPILER
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/* The Intel compiler tries to look like GCC *and* clang *and* lies in its
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__has_builtin() function, so override it. */
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/* if GCC on i386/x86_64 or if the built-in is present */
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#if ( (defined(__GNUC__) && !defined(__clang__)) && \
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(defined(__i386__) || defined(__x86_64__))) || \
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__has_builtin(__builtin_ia32_pause)
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#define HAVE_BUILTIN_IA32_PAUSE
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#endif
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#endif
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static inline void curl_simple_lock_lock(curl_simple_lock *lock)
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{
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for(;;) {
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if(!atomic_exchange_explicit(lock, true, memory_order_acquire))
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break;
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/* Reduce cache coherency traffic */
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while(atomic_load_explicit(lock, memory_order_relaxed)) {
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/* Reduce load (not mandatory) */
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#ifdef HAVE_BUILTIN_IA32_PAUSE
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__builtin_ia32_pause();
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#elif defined(__aarch64__)
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__asm__ volatile("yield" ::: "memory");
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#elif defined(HAVE_SCHED_YIELD)
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sched_yield();
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#endif
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}
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}
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}
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static inline void curl_simple_lock_unlock(curl_simple_lock *lock)
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{
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atomic_store_explicit(lock, false, memory_order_release);
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}
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#else
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#undef GLOBAL_INIT_IS_THREADSAFE
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#endif
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#endif /* HEADER_CURL_EASY_LOCK_H */
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