5b63ffd8b2
Use semaphore-based blocking and notifying, instead of Mutex. Reviewed-by: tschatzl, sangheki
66 lines
2.2 KiB
C++
66 lines
2.2 KiB
C++
/*
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* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_GC_G1_G1FREEIDSET_HPP
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#define SHARE_GC_G1_G1FREEIDSET_HPP
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#include "memory/allocation.hpp"
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#include "runtime/semaphore.hpp"
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#include "utilities/globalDefinitions.hpp"
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// Represents a set of small integer ids, from which elements can be
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// temporarily allocated for exclusive use. The ids are in a
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// contiguous range from 'start' to 'start + size'. Used to obtain a
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// distinct worker_id value for a mutator thread that doesn't normally
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// have such an id.
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class G1FreeIdSet : public CHeapObj<mtGC> {
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Semaphore _sem;
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uint* _next;
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uint _start;
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uint _size;
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uintx _head_index_mask;
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volatile uintx _head;
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uint head_index(uintx head) const;
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uintx make_head(uint index, uintx old_head) const;
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// Noncopyable.
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G1FreeIdSet(const G1FreeIdSet&);
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G1FreeIdSet& operator=(const G1FreeIdSet&);
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public:
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G1FreeIdSet(uint start, uint size);
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~G1FreeIdSet();
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// Returns an unclaimed parallel id (waiting for one to be released if
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// necessary). Must not safepoint while holding a claimed id.
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uint claim_par_id();
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void release_par_id(uint id);
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struct TestSupport; // For unit test access.
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};
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#endif // SHARE_GC_G1_G1FREEIDSET_HPP
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