799142bf74
libitm/ * beginend.cc (GTM::gtm_thread::begin_transaction): Add comment. (GTM::gtm_thread::try_commit): Changed memory order. * config/linux/alpha/futex_bits.h (sys_futex0): Take atomic int as parameter. * config/linux/x86/futex_bits.h (sys_futex0): Same. * config/linux/sh/futex_bits.h (sys_futex0): Same. * config/linux/futex_bits.h (sys_futex0): Same. * config/linux/futex.cc (futex_wait, futex_wake): Same. * config/linux/futex.h (futex_wait, futex_wake): Same. * config/linux/rwlock.h (gtm_rwlock::writers, gtm_rwlock::writer_readers, gtm_rwlock::readers): Change to atomic ints. * config/linux/rwlock.cc (gtm_rwlock::read_lock, gtm_rwlock::write_lock_generic, gtm_rwlock::read_unlock, gtm_rwlock::write_unlock): Fix memory orders and fences. * config/posix/rwlock.cc (gtm_rwlock::read_lock, gtm_rwlock::write_lock_generic, gtm_rwlock::read_unlock, gtm_rwlock::write_unlock): Same. * config/linux/rwlock.h (gtm_rwlock::summary): Change to atomic int. * method-gl.cc (gl_mg::init, gl_wt_dispatch::memtransfer_static, gl_wt_dispatch::memset_static, gl_wt_dispatch::begin_or_restart): Add comments. (gl_wt_dispatch::pre_write, gl_wt_dispatch::validate, gl_wt_dispatch::load, gl_wt_dispatch::store, gl_wt_dispatch::try_commit, gl_wt_dispatch::rollback): Fix memory orders and fences. Add comments. From-SVN: r182674
68 lines
2.2 KiB
C++
68 lines
2.2 KiB
C++
/* Copyright (C) 2011 Free Software Foundation, Inc.
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Contributed by Torvald Riegel <triegel@redhat.com>.
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This file is part of the GNU Transactional Memory Library (libitm).
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Libitm is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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Libitm is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef GTM_RWLOCK_H
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#define GTM_RWLOCK_H
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#include "local_atomic"
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#include "common.h"
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namespace GTM HIDDEN {
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struct gtm_thread;
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// This datastructure is the blocking, futex-based version of the Dekker-style
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// reader-writer lock used to provide mutual exclusion between active and
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// serial transactions.
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// See libitm's documentation for further details.
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//
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// In this implementation, writers are given highest priority access but
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// read-to-write upgrades do not have a higher priority than writers.
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class gtm_rwlock
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{
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// TODO Put futexes on different cachelines?
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std::atomic<int> writers; // Writers' futex.
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std::atomic<int> writer_readers;// A confirmed writer waits here for readers.
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std::atomic<int> readers; // Readers wait here for writers (iff true).
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public:
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gtm_rwlock() : writers(0), writer_readers(0), readers(0) {};
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void read_lock (gtm_thread *tx);
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void read_unlock (gtm_thread *tx);
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void write_lock ();
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void write_unlock ();
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bool write_upgrade (gtm_thread *tx);
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protected:
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bool write_lock_generic (gtm_thread *tx);
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};
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} // namespace GTM
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#endif // GTM_RWLOCK_H
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