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/*
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* Copyright (c) 2014, 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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#include "precompiled.hpp"
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#include "classfile/javaClasses.hpp"
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#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
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#include "gc_implementation/g1/g1GCPhaseTimes.hpp"
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#include "gc_implementation/g1/g1StringDedup.hpp"
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#include "gc_implementation/g1/g1StringDedupQueue.hpp"
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#include "gc_implementation/g1/g1StringDedupStat.hpp"
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#include "gc_implementation/g1/g1StringDedupTable.hpp"
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#include "gc_implementation/g1/g1StringDedupThread.hpp"
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bool G1StringDedup::_enabled = false;
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void G1StringDedup::initialize() {
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assert(UseG1GC, "String deduplication only available with G1");
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if (UseStringDeduplication) {
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_enabled = true;
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G1StringDedupQueue::create();
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G1StringDedupTable::create();
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G1StringDedupThread::create();
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}
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}
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bool G1StringDedup::is_candidate_from_mark(oop obj) {
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if (java_lang_String::is_instance(obj)) {
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bool from_young = G1CollectedHeap::heap()->heap_region_containing_raw(obj)->is_young();
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if (from_young && obj->age() < StringDeduplicationAgeThreshold) {
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// Candidate found. String is being evacuated from young to old but has not
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// reached the deduplication age threshold, i.e. has not previously been a
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// candidate during its life in the young generation.
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return true;
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}
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}
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// Not a candidate
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return false;
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}
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void G1StringDedup::enqueue_from_mark(oop java_string) {
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assert(is_enabled(), "String deduplication not enabled");
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if (is_candidate_from_mark(java_string)) {
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G1StringDedupQueue::push(0 /* worker_id */, java_string);
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}
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}
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bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) {
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if (from_young && java_lang_String::is_instance(obj)) {
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if (to_young && obj->age() == StringDeduplicationAgeThreshold) {
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// Candidate found. String is being evacuated from young to young and just
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// reached the deduplication age threshold.
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return true;
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}
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if (!to_young && obj->age() < StringDeduplicationAgeThreshold) {
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// Candidate found. String is being evacuated from young to old but has not
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// reached the deduplication age threshold, i.e. has not previously been a
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// candidate during its life in the young generation.
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return true;
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}
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}
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// Not a candidate
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return false;
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}
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void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) {
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assert(is_enabled(), "String deduplication not enabled");
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if (is_candidate_from_evacuation(from_young, to_young, java_string)) {
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G1StringDedupQueue::push(worker_id, java_string);
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}
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}
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void G1StringDedup::deduplicate(oop java_string) {
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assert(is_enabled(), "String deduplication not enabled");
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G1StringDedupStat dummy; // Statistics from this path is never used
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G1StringDedupTable::deduplicate(java_string, dummy);
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}
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void G1StringDedup::oops_do(OopClosure* keep_alive) {
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assert(is_enabled(), "String deduplication not enabled");
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unlink_or_oops_do(NULL, keep_alive);
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}
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void G1StringDedup::unlink(BoolObjectClosure* is_alive) {
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assert(is_enabled(), "String deduplication not enabled");
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// Don't allow a potential resize or rehash during unlink, as the unlink
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// operation itself might remove enough entries to invalidate such a decision.
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unlink_or_oops_do(is_alive, NULL, false /* allow_resize_and_rehash */);
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}
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//
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// Task for parallel unlink_or_oops_do() operation on the deduplication queue
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// and table.
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//
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class G1StringDedupUnlinkOrOopsDoTask : public AbstractGangTask {
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private:
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G1StringDedupUnlinkOrOopsDoClosure _cl;
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public:
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G1StringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive,
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OopClosure* keep_alive,
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bool allow_resize_and_rehash) :
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AbstractGangTask("G1StringDedupUnlinkOrOopsDoTask"),
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_cl(is_alive, keep_alive, allow_resize_and_rehash) {
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}
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virtual void work(uint worker_id) {
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double queue_fixup_start = os::elapsedTime();
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G1StringDedupQueue::unlink_or_oops_do(&_cl);
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double table_fixup_start = os::elapsedTime();
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G1StringDedupTable::unlink_or_oops_do(&_cl, worker_id);
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double queue_fixup_time_ms = (table_fixup_start - queue_fixup_start) * 1000.0;
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double table_fixup_time_ms = (os::elapsedTime() - table_fixup_start) * 1000.0;
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G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
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g1p->phase_times()->record_string_dedup_queue_fixup_worker_time(worker_id, queue_fixup_time_ms);
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g1p->phase_times()->record_string_dedup_table_fixup_worker_time(worker_id, table_fixup_time_ms);
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}
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};
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void G1StringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* keep_alive, bool allow_resize_and_rehash) {
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assert(is_enabled(), "String deduplication not enabled");
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G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
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g1p->phase_times()->note_string_dedup_fixup_start();
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double fixup_start = os::elapsedTime();
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G1StringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash);
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if (G1CollectedHeap::use_parallel_gc_threads()) {
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G1CollectedHeap* g1h = G1CollectedHeap::heap();
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g1h->set_par_threads();
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g1h->workers()->run_task(&task);
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g1h->set_par_threads(0);
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} else {
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task.work(0);
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}
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double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
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g1p->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
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g1p->phase_times()->note_string_dedup_fixup_end();
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}
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void G1StringDedup::threads_do(ThreadClosure* tc) {
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assert(is_enabled(), "String deduplication not enabled");
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tc->do_thread(G1StringDedupThread::thread());
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}
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void G1StringDedup::print_worker_threads_on(outputStream* st) {
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assert(is_enabled(), "String deduplication not enabled");
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G1StringDedupThread::thread()->print_on(st);
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st->cr();
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}
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void G1StringDedup::verify() {
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assert(is_enabled(), "String deduplication not enabled");
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G1StringDedupQueue::verify();
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G1StringDedupTable::verify();
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}
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G1StringDedupUnlinkOrOopsDoClosure::G1StringDedupUnlinkOrOopsDoClosure(BoolObjectClosure* is_alive,
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OopClosure* keep_alive,
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bool allow_resize_and_rehash) :
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_is_alive(is_alive),
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_keep_alive(keep_alive),
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_resized_table(NULL),
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_rehashed_table(NULL),
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_next_queue(0),
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_next_bucket(0) {
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if (allow_resize_and_rehash) {
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// If both resize and rehash is needed, only do resize. Rehash of
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// the table will eventually happen if the situation persists.
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_resized_table = G1StringDedupTable::prepare_resize();
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if (!is_resizing()) {
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_rehashed_table = G1StringDedupTable::prepare_rehash();
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}
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}
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}
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G1StringDedupUnlinkOrOopsDoClosure::~G1StringDedupUnlinkOrOopsDoClosure() {
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assert(!is_resizing() || !is_rehashing(), "Can not both resize and rehash");
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if (is_resizing()) {
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G1StringDedupTable::finish_resize(_resized_table);
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} else if (is_rehashing()) {
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G1StringDedupTable::finish_rehash(_rehashed_table);
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}
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}
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