jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1StringDedupQueue.cpp@595c0f60d50d (annotated)

src/share/vm/gc_implementation/g1/g1StringDedupQueue.cpp@595c0f60d50d (annotated)

src/share/vm/gc_implementation/g1/g1StringDedupQueue.cpp

Tue, 18 Mar 2014 19:07:22 +0100

author: pliden
date: Tue, 18 Mar 2014 19:07:22 +0100
changeset 6413: 595c0f60d50d
child 6690: 1772223a25a2
permissions: -rw-r--r--

8029075: String deduplication in G1
Summary: Implementation of JEP 192, http://openjdk.java.net/jeps/192
Reviewed-by: brutisso, tschatzl, coleenp

 /*
  * 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/g1StringDedupQueue.hpp"
 #include "memory/gcLocker.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "utilities/stack.inline.hpp"
 G1StringDedupQueue* G1StringDedupQueue::_queue = NULL;
 const size_t        G1StringDedupQueue::_max_size = 1000000; // Max number of elements per queue
 const size_t        G1StringDedupQueue::_max_cache_size = 0; // Max cache size per queue
 G1StringDedupQueue::G1StringDedupQueue() :
   _cursor(0),
   _empty(true),
   _dropped(0) {
   _nqueues = MAX2(ParallelGCThreads, (size_t)1);
   _queues = NEW_C_HEAP_ARRAY(G1StringDedupWorkerQueue, _nqueues, mtGC);
   for (size_t i = 0; i < _nqueues; i++) {
     new (_queues + i) G1StringDedupWorkerQueue(G1StringDedupWorkerQueue::default_segment_size(), _max_cache_size, _max_size);
   }
 }
 G1StringDedupQueue::~G1StringDedupQueue() {
   ShouldNotReachHere();
 }
 void G1StringDedupQueue::create() {
   assert(_queue == NULL, "One string deduplication queue allowed");
   _queue = new G1StringDedupQueue();
 }
 void G1StringDedupQueue::wait() {
   MonitorLockerEx ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);
   while (_queue->_empty) {
     ml.wait(Mutex::_no_safepoint_check_flag);
   }
 }
 void G1StringDedupQueue::push(uint worker_id, oop java_string) {
   assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
   assert(worker_id < _queue->_nqueues, "Invalid queue");
   // Push and notify waiter
   G1StringDedupWorkerQueue& worker_queue = _queue->_queues[worker_id];
   if (!worker_queue.is_full()) {
     worker_queue.push(java_string);
     if (_queue->_empty) {
       MonitorLockerEx ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag);
       if (_queue->_empty) {
         // Mark non-empty and notify waiter
         _queue->_empty = false;
         ml.notify();
       }
     }
   } else {
     // Queue is full, drop the string and update the statistics
     Atomic::inc_ptr(&_queue->_dropped);
   }
 }
 oop G1StringDedupQueue::pop() {
   assert(!SafepointSynchronize::is_at_safepoint(), "Must not be at safepoint");
   No_Safepoint_Verifier nsv;
   // Try all queues before giving up
   for (size_t tries = 0; tries < _queue->_nqueues; tries++) {
     // The cursor indicates where we left of last time
     G1StringDedupWorkerQueue* queue = &_queue->_queues[_queue->_cursor];
     while (!queue->is_empty()) {
       oop obj = queue->pop();
       // The oop we pop can be NULL if it was marked
       // dead. Just ignore those and pop the next oop.
       if (obj != NULL) {
         return obj;
       }
     }
     // Try next queue
     _queue->_cursor = (_queue->_cursor + 1) % _queue->_nqueues;
   }
   // Mark empty
   _queue->_empty = true;
   return NULL;
 }
 void G1StringDedupQueue::unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl) {
   // A worker thread first claims a queue, which ensures exclusive
   // access to that queue, then continues to process it.
   for (;;) {
     // Grab next queue to scan
     size_t queue = cl->claim_queue();
     if (queue >= _queue->_nqueues) {
       // End of queues
       break;
     }
     // Scan the queue
     unlink_or_oops_do(cl, queue);
   }
 }
 void G1StringDedupQueue::unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl, size_t queue) {
   assert(queue < _queue->_nqueues, "Invalid queue");
   StackIterator<oop, mtGC> iter(_queue->_queues[queue]);
   while (!iter.is_empty()) {
     oop* p = iter.next_addr();
     if (*p != NULL) {
       if (cl->is_alive(*p)) {
         cl->keep_alive(p);
       } else {
         // Clear dead reference
         *p = NULL;
       }
     }
   }
 }
 void G1StringDedupQueue::print_statistics(outputStream* st) {
   st->print_cr(
     "   [Queue]\n"
     "      [Dropped: "UINTX_FORMAT"]", _queue->_dropped);
 }
 void G1StringDedupQueue::verify() {
   for (size_t i = 0; i < _queue->_nqueues; i++) {
     StackIterator<oop, mtGC> iter(_queue->_queues[i]);
     while (!iter.is_empty()) {
       oop obj = iter.next();
       if (obj != NULL) {
         guarantee(Universe::heap()->is_in_reserved(obj), "Object must be on the heap");
         guarantee(!obj->is_forwarded(), "Object must not be forwarded");
         guarantee(java_lang_String::is_instance(obj), "Object must be a String");
       }
     }
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1StringDedupQueue.cpp@595c0f60d50d (annotated)

src/share/vm/gc_implementation/g1/g1StringDedupQueue.cpp