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82009c4220
Replace the `volatile int dirty` with a reference counter protected by a mutex when available. Solve the problem of when to call application's lock function by adding a volatile flag that indicates a share has been added to easy handles in its lifetime. That flag ever goes from FALSE to TRUE, so volatile might work (in the absence of a mutex). (The problem is that the lock/unlock functions need 2-3 `curl_share_setopt()` invocations to become usable and there is no way of telling if the third will ever happen. Calling the lock function before the 3rd setopt may crash the application.) When removing a share from an easy handle (or replacing it with another share), detach the easy connection on a share with a connection pool. When cleaning up a share, allow this even if it is still used in easy handles. It will be destroyed when the reference count drops to 0. Closes #20870
103 lines
3.1 KiB
C
103 lines
3.1 KiB
C
#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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#ifdef _WIN32
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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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#ifdef 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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#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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#define HAVE_BUILTIN_IA32_PAUSE
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#elif defined(__has_builtin) /* Keep this PP check separate from others */
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#if __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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#endif /* !__INTEL_COMPILER */
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static CURL_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 CURL_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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#elif defined(HAVE_THREADS_POSIX) && defined(HAVE_PTHREAD_H)
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#include <pthread.h>
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#define curl_simple_lock pthread_mutex_t
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#define CURL_SIMPLE_LOCK_INIT PTHREAD_MUTEX_INITIALIZER
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#define curl_simple_lock_lock(m) pthread_mutex_lock(m)
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#define curl_simple_lock_unlock(m) pthread_mutex_unlock(m)
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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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