/* * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2020 SAP SE. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. *
*/
// A simple single-linked list of chunks, used in MetaspaceArena to keep // a list of retired chunks, as well as in the ChunkHeaderPool to keep // a cache of unused chunk headers.
class MetachunkList {
Metachunk* _first;
IntCounter _num_chunks;
// Note: The chunks inside this list may be dead (->chunk header pool). // So, do not call c->word size on them or anything else which may not // work with dead chunks.
// Check that list does not contain the given chunk; Note that since that check // is expensive, it is subject to VerifyMetaspaceInterval.
DEBUG_ONLY(void verify_does_not_contain(const Metachunk* c) const;)
public:
MetachunkList() : _first(NULL), _num_chunks() {}
int count() const { return _num_chunks.get(); }
void add(Metachunk* c) {
DEBUG_ONLY(verify_does_not_contain(c);)
c->set_next(_first); if (_first) {
_first->set_prev(c);
}
_first = c;
_num_chunks.increment();
}
Metachunk* remove_first() { if (_first) {
Metachunk* c = _first;
_first = _first->next(); if (_first) {
_first->set_prev(NULL);
}
_num_chunks.decrement();
c->set_prev(NULL);
c->set_next(NULL); return c;
} return NULL;
}
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