64 lines
2.4 KiB
C++
64 lines
2.4 KiB
C++
/*
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* Copyright (C) 2017-2019 Apple Inc. 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
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. 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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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "IsoTLSLayout.h"
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#include "IsoTLSEntry.h"
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namespace bmalloc {
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DEFINE_STATIC_PER_PROCESS_STORAGE(IsoTLSLayout);
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IsoTLSLayout::IsoTLSLayout(const LockHolder&)
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{
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}
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void IsoTLSLayout::add(IsoTLSEntry* entry)
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{
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static Mutex addingMutex;
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RELEASE_BASSERT(!entry->m_next);
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// IsoTLSLayout::head() does not take a lock. So we should emit memory fence to make sure that newly added entry is initialized when it is chained to this linked-list.
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// Emitting memory fence here is OK since this function is not frequently called.
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LockHolder locking(addingMutex);
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if (m_head) {
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RELEASE_BASSERT(m_tail);
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size_t offset = roundUpToMultipleOf(entry->alignment(), m_tail->extent());
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RELEASE_BASSERT(offset < UINT_MAX);
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entry->m_offset = offset;
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std::atomic_thread_fence(std::memory_order_seq_cst);
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m_tail->m_next = entry;
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m_tail = entry;
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} else {
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RELEASE_BASSERT(!m_tail);
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entry->m_offset = 0;
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std::atomic_thread_fence(std::memory_order_seq_cst);
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m_head = entry;
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m_tail = entry;
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}
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}
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} // namespace bmalloc
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