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 /*

  * Copyright (c) 2014, 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.hpp"

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"

 #include "gc_implementation/g1/g1StringDedup.hpp"

 #include "gc_implementation/g1/g1StringDedupQueue.hpp"

 #include "gc_implementation/g1/g1StringDedupStat.hpp"

 #include "gc_implementation/g1/g1StringDedupTable.hpp"

 #include "gc_implementation/g1/g1StringDedupThread.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::stop();

 }

 bool G1StringDedup::is_candidate_from_mark(oop obj) {

   if (java_lang_String::is_instance(obj)) {

     bool from_young = G1CollectedHeap::heap()->heap_region_containing_raw(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(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);

 }

 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;

 public:

   G1StringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive,

                                   OopClosure* keep_alive,

                                   bool allow_resize_and_rehash) :

     AbstractGangTask("G1StringDedupUnlinkOrOopsDoTask"),

     _cl(is_alive, keep_alive, allow_resize_and_rehash) {

   }

   virtual void work(uint worker_id) {

     double queue_fixup_start = os::elapsedTime();

     G1StringDedupQueue::unlink_or_oops_do(&_cl);

     double table_fixup_start = os::elapsedTime();

     G1StringDedupTable::unlink_or_oops_do(&_cl, worker_id);

     double queue_fixup_time_ms = (table_fixup_start - queue_fixup_start) * 1000.0;

     double table_fixup_time_ms = (os::elapsedTime() - table_fixup_start) * 1000.0;

     G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();

     g1p->phase_times()->record_string_dedup_queue_fixup_worker_time(worker_id, queue_fixup_time_ms);

     g1p->phase_times()->record_string_dedup_table_fixup_worker_time(worker_id, table_fixup_time_ms);

   }

 };

 void G1StringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* keep_alive, bool allow_resize_and_rehash) {

   assert(is_enabled(), "String deduplication not enabled");

   G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();

   g1p->phase_times()->note_string_dedup_fixup_start();

   double fixup_start = os::elapsedTime();

   G1StringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash);

   if (G1CollectedHeap::use_parallel_gc_threads()) {

     G1CollectedHeap* g1h = G1CollectedHeap::heap();

     g1h->set_par_threads();

     g1h->workers()->run_task(&task);

     g1h->set_par_threads(0);

   } else {

     task.work(0);

   }

   double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;

   g1p->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);

   g1p->phase_times()->note_string_dedup_fixup_end();

 }

 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);

   }

 }