| /* |
| * Copyright (c) 2001, 2019, 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 "jvm.h" |
| #include "gc/shared/collectedHeap.hpp" |
| #include "memory/allocation.inline.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/mutexLocker.hpp" |
| #include "runtime/safepoint.hpp" |
| #include "runtime/thread.hpp" |
| #include "runtime/threadSMR.hpp" |
| #include "runtime/vmThread.hpp" |
| #include "utilities/macros.hpp" |
| #include "gc/shenandoah/shenandoahHeap.inline.hpp" |
| #include "gc/shenandoah/shenandoahSATBMarkQueue.hpp" |
| #include "gc/shenandoah/shenandoahThreadLocalData.hpp" |
| |
| ShenandoahSATBMarkQueue::ShenandoahSATBMarkQueue(ShenandoahSATBMarkQueueSet* qset, bool permanent) : |
| // SATB queues are only active during marking cycles. We create |
| // them with their active field set to false. If a thread is |
| // created during a cycle and its SATB queue needs to be activated |
| // before the thread starts running, we'll need to set its active |
| // field to true. This is done in G1SBarrierSet::on_thread_attach(). |
| PtrQueue(qset, permanent, false /* active */) |
| { } |
| |
| void ShenandoahSATBMarkQueue::flush() { |
| // Filter now to possibly save work later. If filtering empties the |
| // buffer then flush_impl can deallocate the buffer. |
| filter(); |
| flush_impl(); |
| } |
| |
| // Return true if a SATB buffer entry refers to an object that |
| // requires marking. |
| // |
| // The entry must point into the Shenandoah heap. In particular, it must not |
| // be a NULL pointer. NULL pointers are pre-filtered and never |
| // inserted into a SATB buffer. |
| // |
| // An entry that is below the NTAMS pointer for the containing heap |
| // region requires marking. Such an entry must point to a valid object. |
| // |
| // An entry that is at least the NTAMS pointer for the containing heap |
| // region might be any of the following, none of which should be marked. |
| // |
| // * A reference to an object allocated since marking started. |
| // According to SATB, such objects are implicitly kept live and do |
| // not need to be dealt with via SATB buffer processing. |
| // |
| // * A reference to a young generation object. Young objects are |
| // handled separately and are not marked by concurrent marking. |
| // |
| // * A stale reference to a young generation object. If a young |
| // generation object reference is recorded and not filtered out |
| // before being moved by a young collection, the reference becomes |
| // stale. |
| // |
| // * A stale reference to an eagerly reclaimed humongous object. If a |
| // humongous object is recorded and then reclaimed, the reference |
| // becomes stale. |
| // |
| // The stale reference cases are implicitly handled by the NTAMS |
| // comparison. Because of the possibility of stale references, buffer |
| // processing must be somewhat circumspect and not assume entries |
| // in an unfiltered buffer refer to valid objects. |
| |
| inline bool retain_entry(const void* entry, ShenandoahHeap* heap) { |
| return heap->requires_marking(entry); |
| } |
| |
| // This method removes entries from a SATB buffer that will not be |
| // useful to the concurrent marking threads. Entries are retained if |
| // they require marking and are not already marked. Retained entries |
| // are compacted toward the top of the buffer. |
| |
| void ShenandoahSATBMarkQueue::filter() { |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| void** buf = _buf; |
| |
| if (buf == NULL) { |
| // nothing to do |
| return; |
| } |
| |
| // Two-fingered compaction toward the end. |
| void** src = &buf[index()]; |
| void** dst = &buf[capacity()]; |
| assert(src <= dst, "invariant"); |
| for ( ; src < dst; ++src) { |
| // Search low to high for an entry to keep. |
| void* entry = *src; |
| if (retain_entry(entry, heap)) { |
| // Found keeper. Search high to low for an entry to discard. |
| while (src < --dst) { |
| if (!retain_entry(*dst, heap)) { |
| *dst = entry; // Replace discard with keeper. |
| break; |
| } |
| } |
| // If discard search failed (src == dst), the outer loop will also end. |
| } |
| } |
| // dst points to the lowest retained entry, or the end of the buffer |
| // if all the entries were filtered out. |
| set_index(dst - buf); |
| } |
| |
| // This method will first apply the above filtering to the buffer. If |
| // post-filtering a large enough chunk of the buffer has been cleared |
| // we can re-use the buffer (instead of enqueueing it) and we can just |
| // allow the mutator to carry on executing using the same buffer |
| // instead of replacing it. |
| |
| bool ShenandoahSATBMarkQueue::should_enqueue_buffer() { |
| assert(_lock == NULL || _lock->owned_by_self(), |
| "we should have taken the lock before calling this"); |
| |
| // If G1SATBBufferEnqueueingThresholdPercent == 0 we could skip filtering. |
| |
| // This method should only be called if there is a non-NULL buffer |
| // that is full. |
| assert(index() == 0, "pre-condition"); |
| assert(_buf != NULL, "pre-condition"); |
| |
| filter(); |
| |
| size_t cap = capacity(); |
| size_t percent_used = ((cap - index()) * 100) / cap; |
| bool should_enqueue = percent_used > G1SATBBufferEnqueueingThresholdPercent; |
| return should_enqueue; |
| } |
| |
| void ShenandoahSATBMarkQueue::apply_closure_and_empty(ShenandoahSATBBufferClosure* cl) { |
| assert(SafepointSynchronize::is_at_safepoint(), |
| "SATB queues must only be processed at safepoints"); |
| if (_buf != NULL) { |
| cl->do_buffer(&_buf[index()], size()); |
| reset(); |
| } |
| } |
| |
| #ifndef PRODUCT |
| // Helpful for debugging |
| |
| static void print_satb_buffer(const char* name, |
| void** buf, |
| size_t index, |
| size_t capacity) { |
| tty->print_cr(" SATB BUFFER [%s] buf: " PTR_FORMAT " index: " SIZE_FORMAT |
| " capacity: " SIZE_FORMAT, |
| name, p2i(buf), index, capacity); |
| } |
| |
| void ShenandoahSATBMarkQueue::print(const char* name) { |
| print_satb_buffer(name, _buf, index(), capacity()); |
| } |
| |
| #endif // PRODUCT |
| |
| ShenandoahSATBMarkQueueSet::ShenandoahSATBMarkQueueSet() : |
| PtrQueueSet(), |
| _shared_satb_queue(this, true /* permanent */) { } |
| |
| void ShenandoahSATBMarkQueueSet::initialize(Monitor* cbl_mon, Mutex* fl_lock, |
| int process_completed_threshold, |
| Mutex* lock) { |
| PtrQueueSet::initialize(cbl_mon, fl_lock, process_completed_threshold, -1); |
| _shared_satb_queue.set_lock(lock); |
| } |
| |
| #ifdef ASSERT |
| void ShenandoahSATBMarkQueueSet::dump_active_states(bool expected_active) { |
| log_error(gc, verify)("Expected SATB active state: %s", expected_active ? "ACTIVE" : "INACTIVE"); |
| log_error(gc, verify)("Actual SATB active states:"); |
| log_error(gc, verify)(" Queue set: %s", is_active() ? "ACTIVE" : "INACTIVE"); |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { |
| log_error(gc, verify)(" Thread \"%s\" queue: %s", t->name(), satb_queue_for_thread(t).is_active() ? "ACTIVE" : "INACTIVE"); |
| } |
| log_error(gc, verify)(" Shared queue: %s", shared_satb_queue()->is_active() ? "ACTIVE" : "INACTIVE"); |
| } |
| |
| void ShenandoahSATBMarkQueueSet::verify_active_states(bool expected_active) { |
| // Verify queue set state |
| if (is_active() != expected_active) { |
| dump_active_states(expected_active); |
| guarantee(false, "SATB queue set has an unexpected active state"); |
| } |
| |
| // Verify thread queue states |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { |
| if (satb_queue_for_thread(t).is_active() != expected_active) { |
| dump_active_states(expected_active); |
| guarantee(false, "Thread SATB queue has an unexpected active state"); |
| } |
| } |
| |
| // Verify shared queue state |
| if (shared_satb_queue()->is_active() != expected_active) { |
| dump_active_states(expected_active); |
| guarantee(false, "Shared SATB queue has an unexpected active state"); |
| } |
| } |
| #endif // ASSERT |
| |
| void ShenandoahSATBMarkQueueSet::set_active_all_threads(bool active, bool expected_active) { |
| assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint."); |
| #ifdef ASSERT |
| verify_active_states(expected_active); |
| #endif // ASSERT |
| _all_active = active; |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { |
| satb_queue_for_thread(t).set_active(active); |
| } |
| shared_satb_queue()->set_active(active); |
| } |
| |
| void ShenandoahSATBMarkQueueSet::filter_thread_buffers() { |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { |
| satb_queue_for_thread(t).filter(); |
| } |
| shared_satb_queue()->filter(); |
| } |
| |
| bool ShenandoahSATBMarkQueueSet::apply_closure_to_completed_buffer(ShenandoahSATBBufferClosure* cl) { |
| BufferNode* nd = NULL; |
| { |
| MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); |
| if (_completed_buffers_head != NULL) { |
| nd = _completed_buffers_head; |
| _completed_buffers_head = nd->next(); |
| if (_completed_buffers_head == NULL) _completed_buffers_tail = NULL; |
| _n_completed_buffers--; |
| if (_n_completed_buffers == 0) _process_completed = false; |
| } |
| } |
| if (nd != NULL) { |
| void **buf = BufferNode::make_buffer_from_node(nd); |
| size_t index = nd->index(); |
| size_t size = buffer_size(); |
| assert(index <= size, "invariant"); |
| cl->do_buffer(buf + index, size - index); |
| deallocate_buffer(nd); |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| #ifndef PRODUCT |
| // Helpful for debugging |
| |
| #define SATB_PRINTER_BUFFER_SIZE 256 |
| |
| void ShenandoahSATBMarkQueueSet::print_all(const char* msg) { |
| char buffer[SATB_PRINTER_BUFFER_SIZE]; |
| assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint."); |
| |
| tty->cr(); |
| tty->print_cr("SATB BUFFERS [%s]", msg); |
| |
| BufferNode* nd = _completed_buffers_head; |
| int i = 0; |
| while (nd != NULL) { |
| void** buf = BufferNode::make_buffer_from_node(nd); |
| jio_snprintf(buffer, SATB_PRINTER_BUFFER_SIZE, "Enqueued: %d", i); |
| print_satb_buffer(buffer, buf, nd->index(), buffer_size()); |
| nd = nd->next(); |
| i += 1; |
| } |
| |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { |
| jio_snprintf(buffer, SATB_PRINTER_BUFFER_SIZE, "Thread: %s", t->name()); |
| satb_queue_for_thread(t).print(buffer); |
| } |
| |
| shared_satb_queue()->print("Shared"); |
| |
| tty->cr(); |
| } |
| #endif // PRODUCT |
| |
| void ShenandoahSATBMarkQueueSet::abandon_partial_marking() { |
| BufferNode* buffers_to_delete = NULL; |
| { |
| MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); |
| while (_completed_buffers_head != NULL) { |
| BufferNode* nd = _completed_buffers_head; |
| _completed_buffers_head = nd->next(); |
| nd->set_next(buffers_to_delete); |
| buffers_to_delete = nd; |
| } |
| _completed_buffers_tail = NULL; |
| _n_completed_buffers = 0; |
| DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked()); |
| } |
| while (buffers_to_delete != NULL) { |
| BufferNode* nd = buffers_to_delete; |
| buffers_to_delete = nd->next(); |
| deallocate_buffer(nd); |
| } |
| assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint."); |
| // So we can safely manipulate these queues. |
| for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) { |
| satb_queue_for_thread(t).reset(); |
| } |
| shared_satb_queue()->reset(); |
| } |
| |
| ShenandoahSATBMarkQueue& ShenandoahSATBMarkQueueSet::satb_queue_for_thread(Thread* t) { |
| return ShenandoahThreadLocalData::satb_mark_queue(t); |
| } |
| |