| 1 | /***************************************************************************
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| 2 | * _ _ ____ _
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| 3 | * Project ___| | | | _ \| |
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| 4 | * / __| | | | |_) | |
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| 5 | * | (__| |_| | _ <| |___
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| 6 | * \___|\___/|_| \_\_____|
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| 7 | *
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| 8 | * Copyright (C) 1998 - 2022, Daniel Stenberg, <[email protected]>, et al.
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| 9 | *
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| 10 | * This software is licensed as described in the file COPYING, which
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| 11 | * you should have received as part of this distribution. The terms
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| 12 | * are also available at https://curl.se/docs/copyright.html.
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| 13 | *
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| 14 | * You may opt to use, copy, modify, merge, publish, distribute and/or sell
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| 15 | * copies of the Software, and permit persons to whom the Software is
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| 16 | * furnished to do so, under the terms of the COPYING file.
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| 17 | *
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| 18 | * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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| 19 | * KIND, either express or implied.
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| 20 | *
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| 21 | * SPDX-License-Identifier: curl
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| 22 | *
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| 23 | ***************************************************************************/
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| 24 |
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| 25 | #include "curl_setup.h"
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| 26 |
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| 27 | #define GLOBAL_INIT_IS_THREADSAFE
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| 28 |
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| 29 | #if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600
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| 30 |
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| 31 | #ifdef __MINGW32__
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| 32 | #ifndef __MINGW64_VERSION_MAJOR
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| 33 | #if (__MINGW32_MAJOR_VERSION < 5) || \
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| 34 | (__MINGW32_MAJOR_VERSION == 5 && __MINGW32_MINOR_VERSION == 0)
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| 35 | /* mingw >= 5.0.1 defines SRWLOCK, and slightly different from MS define */
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| 36 | typedef PVOID SRWLOCK, *PSRWLOCK;
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| 37 | #endif
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| 38 | #endif
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| 39 | #ifndef SRWLOCK_INIT
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| 40 | #define SRWLOCK_INIT NULL
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| 41 | #endif
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| 42 | #endif /* __MINGW32__ */
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| 43 |
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| 44 | #define curl_simple_lock SRWLOCK
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| 45 | #define CURL_SIMPLE_LOCK_INIT SRWLOCK_INIT
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| 46 |
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| 47 | #define curl_simple_lock_lock(m) AcquireSRWLockExclusive(m)
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| 48 | #define curl_simple_lock_unlock(m) ReleaseSRWLockExclusive(m)
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| 49 |
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| 50 | #elif defined(HAVE_ATOMIC) && defined(HAVE_STDATOMIC_H)
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| 51 | #include <stdatomic.h>
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| 52 | #if defined(HAVE_SCHED_YIELD)
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| 53 | #include <sched.h>
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| 54 | #endif
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| 55 |
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| 56 | #define curl_simple_lock atomic_int
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| 57 | #define CURL_SIMPLE_LOCK_INIT 0
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| 58 |
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| 59 | /* a clang-thing */
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| 60 | #ifndef __has_builtin
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| 61 | #define __has_builtin(x) 0
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| 62 | #endif
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| 63 |
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| 64 | #ifndef __INTEL_COMPILER
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| 65 | /* The Intel compiler tries to look like GCC *and* clang *and* lies in its
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| 66 | __has_builtin() function, so override it. */
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| 67 |
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| 68 | /* if GCC on i386/x86_64 or if the built-in is present */
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| 69 | #if ( (defined(__GNUC__) && !defined(__clang__)) && \
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| 70 | (defined(__i386__) || defined(__x86_64__))) || \
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| 71 | __has_builtin(__builtin_ia32_pause)
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| 72 | #define HAVE_BUILTIN_IA32_PAUSE
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| 73 | #endif
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| 74 |
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| 75 | #endif
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| 76 |
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| 77 | static inline void curl_simple_lock_lock(curl_simple_lock *lock)
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| 78 | {
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| 79 | for(;;) {
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| 80 | if(!atomic_exchange_explicit(lock, true, memory_order_acquire))
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| 81 | break;
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| 82 | /* Reduce cache coherency traffic */
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| 83 | while(atomic_load_explicit(lock, memory_order_relaxed)) {
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| 84 | /* Reduce load (not mandatory) */
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| 85 | #ifdef HAVE_BUILTIN_IA32_PAUSE
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| 86 | __builtin_ia32_pause();
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| 87 | #elif defined(__aarch64__)
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| 88 | __asm__ volatile("yield" ::: "memory");
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| 89 | #elif defined(HAVE_SCHED_YIELD)
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| 90 | sched_yield();
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| 91 | #endif
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| 92 | }
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| 93 | }
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| 94 | }
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| 95 |
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| 96 | static inline void curl_simple_lock_unlock(curl_simple_lock *lock)
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| 97 | {
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| 98 | atomic_store_explicit(lock, false, memory_order_release);
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| 99 | }
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| 100 |
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| 101 | #else
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| 102 |
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| 103 | #undef GLOBAL_INIT_IS_THREADSAFE
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| 104 |
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| 105 | #endif
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