pliden@6413: /*
pliden@6413:  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
pliden@6413:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
pliden@6413:  *
pliden@6413:  * This code is free software; you can redistribute it and/or modify it
pliden@6413:  * under the terms of the GNU General Public License version 2 only, as
pliden@6413:  * published by the Free Software Foundation.
pliden@6413:  *
pliden@6413:  * This code is distributed in the hope that it will be useful, but WITHOUT
pliden@6413:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
pliden@6413:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
pliden@6413:  * version 2 for more details (a copy is included in the LICENSE file that
pliden@6413:  * accompanied this code).
pliden@6413:  *
pliden@6413:  * You should have received a copy of the GNU General Public License version
pliden@6413:  * 2 along with this work; if not, write to the Free Software Foundation,
pliden@6413:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
pliden@6413:  *
pliden@6413:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
pliden@6413:  * or visit www.oracle.com if you need additional information or have any
pliden@6413:  * questions.
pliden@6413:  *
pliden@6413:  */
pliden@6413: 
pliden@6413: #include "precompiled.hpp"
pliden@6413: #include "classfile/javaClasses.hpp"
pliden@6413: #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
pliden@6413: #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
pliden@6413: #include "gc_implementation/g1/g1StringDedup.hpp"
pliden@6413: #include "gc_implementation/g1/g1StringDedupQueue.hpp"
pliden@6413: #include "gc_implementation/g1/g1StringDedupStat.hpp"
pliden@6413: #include "gc_implementation/g1/g1StringDedupTable.hpp"
pliden@6413: #include "gc_implementation/g1/g1StringDedupThread.hpp"
pliden@6413: 
pliden@6413: bool G1StringDedup::_enabled = false;
pliden@6413: 
pliden@6413: void G1StringDedup::initialize() {
pliden@6413:   assert(UseG1GC, "String deduplication only available with G1");
pliden@6413:   if (UseStringDeduplication) {
pliden@6413:     _enabled = true;
pliden@6413:     G1StringDedupQueue::create();
pliden@6413:     G1StringDedupTable::create();
pliden@6413:     G1StringDedupThread::create();
pliden@6413:   }
pliden@6413: }
pliden@6413: 
pliden@6690: void G1StringDedup::stop() {
pliden@6690:   assert(is_enabled(), "String deduplication not enabled");
pliden@6690:   G1StringDedupThread::stop();
pliden@6690: }
pliden@6690: 
pliden@6413: bool G1StringDedup::is_candidate_from_mark(oop obj) {
pliden@6413:   if (java_lang_String::is_instance(obj)) {
pliden@6413:     bool from_young = G1CollectedHeap::heap()->heap_region_containing_raw(obj)->is_young();
pliden@6413:     if (from_young && obj->age() < StringDeduplicationAgeThreshold) {
pliden@6413:       // Candidate found. String is being evacuated from young to old but has not
pliden@6413:       // reached the deduplication age threshold, i.e. has not previously been a
pliden@6413:       // candidate during its life in the young generation.
pliden@6413:       return true;
pliden@6413:     }
pliden@6413:   }
pliden@6413: 
pliden@6413:   // Not a candidate
pliden@6413:   return false;
pliden@6413: }
pliden@6413: 
pliden@6413: void G1StringDedup::enqueue_from_mark(oop java_string) {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   if (is_candidate_from_mark(java_string)) {
pliden@6413:     G1StringDedupQueue::push(0 /* worker_id */, java_string);
pliden@6413:   }
pliden@6413: }
pliden@6413: 
pliden@6413: bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) {
pliden@6413:   if (from_young && java_lang_String::is_instance(obj)) {
pliden@6413:     if (to_young && obj->age() == StringDeduplicationAgeThreshold) {
pliden@6413:       // Candidate found. String is being evacuated from young to young and just
pliden@6413:       // reached the deduplication age threshold.
pliden@6413:       return true;
pliden@6413:     }
pliden@6413:     if (!to_young && obj->age() < StringDeduplicationAgeThreshold) {
pliden@6413:       // Candidate found. String is being evacuated from young to old but has not
pliden@6413:       // reached the deduplication age threshold, i.e. has not previously been a
pliden@6413:       // candidate during its life in the young generation.
pliden@6413:       return true;
pliden@6413:     }
pliden@6413:   }
pliden@6413: 
pliden@6413:   // Not a candidate
pliden@6413:   return false;
pliden@6413: }
pliden@6413: 
pliden@6413: void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   if (is_candidate_from_evacuation(from_young, to_young, java_string)) {
pliden@6413:     G1StringDedupQueue::push(worker_id, java_string);
pliden@6413:   }
pliden@6413: }
pliden@6413: 
pliden@6413: void G1StringDedup::deduplicate(oop java_string) {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   G1StringDedupStat dummy; // Statistics from this path is never used
pliden@6413:   G1StringDedupTable::deduplicate(java_string, dummy);
pliden@6413: }
pliden@6413: 
pliden@6413: void G1StringDedup::oops_do(OopClosure* keep_alive) {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   unlink_or_oops_do(NULL, keep_alive);
pliden@6413: }
pliden@6413: 
pliden@6413: void G1StringDedup::unlink(BoolObjectClosure* is_alive) {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   // Don't allow a potential resize or rehash during unlink, as the unlink
pliden@6413:   // operation itself might remove enough entries to invalidate such a decision.
pliden@6413:   unlink_or_oops_do(is_alive, NULL, false /* allow_resize_and_rehash */);
pliden@6413: }
pliden@6413: 
pliden@6413: //
pliden@6413: // Task for parallel unlink_or_oops_do() operation on the deduplication queue
pliden@6413: // and table.
pliden@6413: //
pliden@6413: class G1StringDedupUnlinkOrOopsDoTask : public AbstractGangTask {
pliden@6413: private:
pliden@6413:   G1StringDedupUnlinkOrOopsDoClosure _cl;
pliden@6413: 
pliden@6413: public:
pliden@6413:   G1StringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive,
pliden@6413:                                   OopClosure* keep_alive,
pliden@6413:                                   bool allow_resize_and_rehash) :
pliden@6413:     AbstractGangTask("G1StringDedupUnlinkOrOopsDoTask"),
pliden@6413:     _cl(is_alive, keep_alive, allow_resize_and_rehash) {
pliden@6413:   }
pliden@6413: 
pliden@6413:   virtual void work(uint worker_id) {
pliden@6413:     double queue_fixup_start = os::elapsedTime();
pliden@6413:     G1StringDedupQueue::unlink_or_oops_do(&_cl);
pliden@6413: 
pliden@6413:     double table_fixup_start = os::elapsedTime();
pliden@6413:     G1StringDedupTable::unlink_or_oops_do(&_cl, worker_id);
pliden@6413: 
pliden@6413:     double queue_fixup_time_ms = (table_fixup_start - queue_fixup_start) * 1000.0;
pliden@6413:     double table_fixup_time_ms = (os::elapsedTime() - table_fixup_start) * 1000.0;
pliden@6413:     G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
pliden@6413:     g1p->phase_times()->record_string_dedup_queue_fixup_worker_time(worker_id, queue_fixup_time_ms);
pliden@6413:     g1p->phase_times()->record_string_dedup_table_fixup_worker_time(worker_id, table_fixup_time_ms);
pliden@6413:   }
pliden@6413: };
pliden@6413: 
pliden@6413: void G1StringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* keep_alive, bool allow_resize_and_rehash) {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
pliden@6413:   g1p->phase_times()->note_string_dedup_fixup_start();
pliden@6413:   double fixup_start = os::elapsedTime();
pliden@6413: 
pliden@6413:   G1StringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash);
pliden@6413:   if (G1CollectedHeap::use_parallel_gc_threads()) {
pliden@6413:     G1CollectedHeap* g1h = G1CollectedHeap::heap();
pliden@6413:     g1h->set_par_threads();
pliden@6413:     g1h->workers()->run_task(&task);
pliden@6413:     g1h->set_par_threads(0);
pliden@6413:   } else {
pliden@6413:     task.work(0);
pliden@6413:   }
pliden@6413: 
pliden@6413:   double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
pliden@6413:   g1p->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
pliden@6413:   g1p->phase_times()->note_string_dedup_fixup_end();
pliden@6413: }
pliden@6413: 
pliden@6413: void G1StringDedup::threads_do(ThreadClosure* tc) {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   tc->do_thread(G1StringDedupThread::thread());
pliden@6413: }
pliden@6413: 
pliden@6413: void G1StringDedup::print_worker_threads_on(outputStream* st) {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   G1StringDedupThread::thread()->print_on(st);
pliden@6413:   st->cr();
pliden@6413: }
pliden@6413: 
pliden@6413: void G1StringDedup::verify() {
pliden@6413:   assert(is_enabled(), "String deduplication not enabled");
pliden@6413:   G1StringDedupQueue::verify();
pliden@6413:   G1StringDedupTable::verify();
pliden@6413: }
pliden@6413: 
pliden@6413: G1StringDedupUnlinkOrOopsDoClosure::G1StringDedupUnlinkOrOopsDoClosure(BoolObjectClosure* is_alive,
pliden@6413:                                                                        OopClosure* keep_alive,
pliden@6413:                                                                        bool allow_resize_and_rehash) :
pliden@6413:   _is_alive(is_alive),
pliden@6413:   _keep_alive(keep_alive),
pliden@6413:   _resized_table(NULL),
pliden@6413:   _rehashed_table(NULL),
pliden@6413:   _next_queue(0),
pliden@6413:   _next_bucket(0) {
pliden@6413:   if (allow_resize_and_rehash) {
pliden@6413:     // If both resize and rehash is needed, only do resize. Rehash of
pliden@6413:     // the table will eventually happen if the situation persists.
pliden@6413:     _resized_table = G1StringDedupTable::prepare_resize();
pliden@6413:     if (!is_resizing()) {
pliden@6413:       _rehashed_table = G1StringDedupTable::prepare_rehash();
pliden@6413:     }
pliden@6413:   }
pliden@6413: }
pliden@6413: 
pliden@6413: G1StringDedupUnlinkOrOopsDoClosure::~G1StringDedupUnlinkOrOopsDoClosure() {
pliden@6413:   assert(!is_resizing() || !is_rehashing(), "Can not both resize and rehash");
pliden@6413:   if (is_resizing()) {
pliden@6413:     G1StringDedupTable::finish_resize(_resized_table);
pliden@6413:   } else if (is_rehashing()) {
pliden@6413:     G1StringDedupTable::finish_rehash(_rehashed_table);
pliden@6413:   }
pliden@6413: }