| /* |
| * Copyright (c) 2014, 2016, Oracle and/or its affiliates. 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. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "classfile/javaClasses.inline.hpp" |
| #include "gc/g1/g1CollectedHeap.inline.hpp" |
| #include "gc/g1/g1GCPhaseTimes.hpp" |
| #include "gc/g1/g1StringDedup.hpp" |
| #include "gc/g1/g1StringDedupQueue.hpp" |
| #include "gc/g1/g1StringDedupStat.hpp" |
| #include "gc/g1/g1StringDedupTable.hpp" |
| #include "gc/g1/g1StringDedupThread.hpp" |
| #include "runtime/atomic.inline.hpp" |
| |
| bool G1StringDedup::_enabled = false; |
| |
| void G1StringDedup::initialize() { |
| assert(UseG1GC, "String deduplication only available with G1"); |
| if (UseStringDeduplication) { |
| _enabled = true; |
| G1StringDedupQueue::create(); |
| G1StringDedupTable::create(); |
| G1StringDedupThread::create(); |
| } |
| } |
| |
| void G1StringDedup::stop() { |
| assert(is_enabled(), "String deduplication not enabled"); |
| G1StringDedupThread::thread()->stop(); |
| } |
| |
| bool G1StringDedup::is_candidate_from_mark(oop obj) { |
| if (java_lang_String::is_instance_inlined(obj)) { |
| bool from_young = G1CollectedHeap::heap()->heap_region_containing(obj)->is_young(); |
| if (from_young && obj->age() < StringDeduplicationAgeThreshold) { |
| // Candidate found. String is being evacuated from young to old but has not |
| // reached the deduplication age threshold, i.e. has not previously been a |
| // candidate during its life in the young generation. |
| return true; |
| } |
| } |
| |
| // Not a candidate |
| return false; |
| } |
| |
| void G1StringDedup::enqueue_from_mark(oop java_string) { |
| assert(is_enabled(), "String deduplication not enabled"); |
| if (is_candidate_from_mark(java_string)) { |
| G1StringDedupQueue::push(0 /* worker_id */, java_string); |
| } |
| } |
| |
| bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) { |
| if (from_young && java_lang_String::is_instance_inlined(obj)) { |
| if (to_young && obj->age() == StringDeduplicationAgeThreshold) { |
| // Candidate found. String is being evacuated from young to young and just |
| // reached the deduplication age threshold. |
| return true; |
| } |
| if (!to_young && obj->age() < StringDeduplicationAgeThreshold) { |
| // Candidate found. String is being evacuated from young to old but has not |
| // reached the deduplication age threshold, i.e. has not previously been a |
| // candidate during its life in the young generation. |
| return true; |
| } |
| } |
| |
| // Not a candidate |
| return false; |
| } |
| |
| void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) { |
| assert(is_enabled(), "String deduplication not enabled"); |
| if (is_candidate_from_evacuation(from_young, to_young, java_string)) { |
| G1StringDedupQueue::push(worker_id, java_string); |
| } |
| } |
| |
| void G1StringDedup::deduplicate(oop java_string) { |
| assert(is_enabled(), "String deduplication not enabled"); |
| G1StringDedupStat dummy; // Statistics from this path is never used |
| G1StringDedupTable::deduplicate(java_string, dummy); |
| } |
| |
| void G1StringDedup::oops_do(OopClosure* keep_alive) { |
| assert(is_enabled(), "String deduplication not enabled"); |
| unlink_or_oops_do(NULL, keep_alive, true /* allow_resize_and_rehash */); |
| } |
| |
| void G1StringDedup::unlink(BoolObjectClosure* is_alive) { |
| assert(is_enabled(), "String deduplication not enabled"); |
| // Don't allow a potential resize or rehash during unlink, as the unlink |
| // operation itself might remove enough entries to invalidate such a decision. |
| unlink_or_oops_do(is_alive, NULL, false /* allow_resize_and_rehash */); |
| } |
| |
| // |
| // Task for parallel unlink_or_oops_do() operation on the deduplication queue |
| // and table. |
| // |
| class G1StringDedupUnlinkOrOopsDoTask : public AbstractGangTask { |
| private: |
| G1StringDedupUnlinkOrOopsDoClosure _cl; |
| G1GCPhaseTimes* _phase_times; |
| |
| public: |
| G1StringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive, |
| OopClosure* keep_alive, |
| bool allow_resize_and_rehash, |
| G1GCPhaseTimes* phase_times) : |
| AbstractGangTask("G1StringDedupUnlinkOrOopsDoTask"), |
| _cl(is_alive, keep_alive, allow_resize_and_rehash), _phase_times(phase_times) { } |
| |
| virtual void work(uint worker_id) { |
| { |
| G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); |
| G1StringDedupQueue::unlink_or_oops_do(&_cl); |
| } |
| { |
| G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); |
| G1StringDedupTable::unlink_or_oops_do(&_cl, worker_id); |
| } |
| } |
| }; |
| |
| void G1StringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive, |
| OopClosure* keep_alive, |
| bool allow_resize_and_rehash, |
| G1GCPhaseTimes* phase_times) { |
| assert(is_enabled(), "String deduplication not enabled"); |
| |
| G1StringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash, phase_times); |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| g1h->workers()->run_task(&task); |
| } |
| |
| void G1StringDedup::threads_do(ThreadClosure* tc) { |
| assert(is_enabled(), "String deduplication not enabled"); |
| tc->do_thread(G1StringDedupThread::thread()); |
| } |
| |
| void G1StringDedup::print_worker_threads_on(outputStream* st) { |
| assert(is_enabled(), "String deduplication not enabled"); |
| G1StringDedupThread::thread()->print_on(st); |
| st->cr(); |
| } |
| |
| void G1StringDedup::verify() { |
| assert(is_enabled(), "String deduplication not enabled"); |
| G1StringDedupQueue::verify(); |
| G1StringDedupTable::verify(); |
| } |
| |
| G1StringDedupUnlinkOrOopsDoClosure::G1StringDedupUnlinkOrOopsDoClosure(BoolObjectClosure* is_alive, |
| OopClosure* keep_alive, |
| bool allow_resize_and_rehash) : |
| _is_alive(is_alive), |
| _keep_alive(keep_alive), |
| _resized_table(NULL), |
| _rehashed_table(NULL), |
| _next_queue(0), |
| _next_bucket(0) { |
| if (allow_resize_and_rehash) { |
| // If both resize and rehash is needed, only do resize. Rehash of |
| // the table will eventually happen if the situation persists. |
| _resized_table = G1StringDedupTable::prepare_resize(); |
| if (!is_resizing()) { |
| _rehashed_table = G1StringDedupTable::prepare_rehash(); |
| } |
| } |
| } |
| |
| G1StringDedupUnlinkOrOopsDoClosure::~G1StringDedupUnlinkOrOopsDoClosure() { |
| assert(!is_resizing() || !is_rehashing(), "Can not both resize and rehash"); |
| if (is_resizing()) { |
| G1StringDedupTable::finish_resize(_resized_table); |
| } else if (is_rehashing()) { |
| G1StringDedupTable::finish_rehash(_rehashed_table); |
| } |
| } |
| |
| // Atomically claims the next available queue for exclusive access by |
| // the current thread. Returns the queue number of the claimed queue. |
| size_t G1StringDedupUnlinkOrOopsDoClosure::claim_queue() { |
| return (size_t)Atomic::add_ptr(1, &_next_queue) - 1; |
| } |
| |
| // Atomically claims the next available table partition for exclusive |
| // access by the current thread. Returns the table bucket number where |
| // the claimed partition starts. |
| size_t G1StringDedupUnlinkOrOopsDoClosure::claim_table_partition(size_t partition_size) { |
| return (size_t)Atomic::add_ptr(partition_size, &_next_bucket) - partition_size; |
| } |