| /* |
| * 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.hpp" |
| #include "gc/g1/g1StringDedup.hpp" |
| #include "gc/g1/g1StringDedupQueue.hpp" |
| #include "gc/shared/gcLocker.hpp" |
| #include "logging/log.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/atomic.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), |
| _cancel(false), |
| _empty(true), |
| _dropped(0) { |
| _nqueues = ParallelGCThreads; |
| _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 && !_queue->_cancel) { |
| ml.wait(Mutex::_no_safepoint_check_flag); |
| } |
| } |
| |
| void G1StringDedupQueue::cancel_wait() { |
| MonitorLockerEx ml(StringDedupQueue_lock, Mutex::_no_safepoint_check_flag); |
| _queue->_cancel = true; |
| ml.notify(); |
| } |
| |
| 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"); |
| NoSafepointVerifier 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() { |
| log_debug(gc, stringdedup)(" Queue"); |
| log_debug(gc, stringdedup)(" 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(G1CollectedHeap::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"); |
| } |
| } |
| } |
| } |