aoqi@0: /*
aoqi@0:  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "precompiled.hpp"
aoqi@0: #include "gc_implementation/g1/ptrQueue.hpp"
aoqi@0: #include "memory/allocation.hpp"
aoqi@0: #include "memory/allocation.inline.hpp"
aoqi@0: #include "runtime/mutex.hpp"
aoqi@0: #include "runtime/mutexLocker.hpp"
aoqi@0: #include "runtime/thread.inline.hpp"
aoqi@0: 
aoqi@0: PtrQueue::PtrQueue(PtrQueueSet* qset, bool perm, bool active) :
aoqi@0:   _qset(qset), _buf(NULL), _index(0), _active(active),
aoqi@0:   _perm(perm), _lock(NULL)
aoqi@0: {}
aoqi@0: 
aoqi@0: void PtrQueue::flush() {
aoqi@0:   if (!_perm && _buf != NULL) {
aoqi@0:     if (_index == _sz) {
aoqi@0:       // No work to do.
aoqi@0:       qset()->deallocate_buffer(_buf);
aoqi@0:     } else {
aoqi@0:       // We must NULL out the unused entries, then enqueue.
aoqi@0:       for (size_t i = 0; i < _index; i += oopSize) {
aoqi@0:         _buf[byte_index_to_index((int)i)] = NULL;
aoqi@0:       }
aoqi@0:       qset()->enqueue_complete_buffer(_buf);
aoqi@0:     }
aoqi@0:     _buf = NULL;
aoqi@0:     _index = 0;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: void PtrQueue::enqueue_known_active(void* ptr) {
aoqi@0:   assert(0 <= _index && _index <= _sz, "Invariant.");
aoqi@0:   assert(_index == 0 || _buf != NULL, "invariant");
aoqi@0: 
aoqi@0:   while (_index == 0) {
aoqi@0:     handle_zero_index();
aoqi@0:   }
aoqi@0: 
aoqi@0:   assert(_index > 0, "postcondition");
aoqi@0:   _index -= oopSize;
aoqi@0:   _buf[byte_index_to_index((int)_index)] = ptr;
aoqi@0:   assert(0 <= _index && _index <= _sz, "Invariant.");
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueue::locking_enqueue_completed_buffer(void** buf) {
aoqi@0:   assert(_lock->owned_by_self(), "Required.");
aoqi@0: 
aoqi@0:   // We have to unlock _lock (which may be Shared_DirtyCardQ_lock) before
aoqi@0:   // we acquire DirtyCardQ_CBL_mon inside enqeue_complete_buffer as they
aoqi@0:   // have the same rank and we may get the "possible deadlock" message
aoqi@0:   _lock->unlock();
aoqi@0: 
aoqi@0:   qset()->enqueue_complete_buffer(buf);
aoqi@0:   // We must relock only because the caller will unlock, for the normal
aoqi@0:   // case.
aoqi@0:   _lock->lock_without_safepoint_check();
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: PtrQueueSet::PtrQueueSet(bool notify_when_complete) :
aoqi@0:   _max_completed_queue(0),
aoqi@0:   _cbl_mon(NULL), _fl_lock(NULL),
aoqi@0:   _notify_when_complete(notify_when_complete),
aoqi@0:   _sz(0),
aoqi@0:   _completed_buffers_head(NULL),
aoqi@0:   _completed_buffers_tail(NULL),
aoqi@0:   _n_completed_buffers(0),
aoqi@0:   _process_completed_threshold(0), _process_completed(false),
aoqi@0:   _buf_free_list(NULL), _buf_free_list_sz(0)
aoqi@0: {
aoqi@0:   _fl_owner = this;
aoqi@0: }
aoqi@0: 
aoqi@0: void** PtrQueueSet::allocate_buffer() {
aoqi@0:   assert(_sz > 0, "Didn't set a buffer size.");
aoqi@0:   MutexLockerEx x(_fl_owner->_fl_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:   if (_fl_owner->_buf_free_list != NULL) {
aoqi@0:     void** res = BufferNode::make_buffer_from_node(_fl_owner->_buf_free_list);
aoqi@0:     _fl_owner->_buf_free_list = _fl_owner->_buf_free_list->next();
aoqi@0:     _fl_owner->_buf_free_list_sz--;
aoqi@0:     return res;
aoqi@0:   } else {
aoqi@0:     // Allocate space for the BufferNode in front of the buffer.
aoqi@0:     char *b =  NEW_C_HEAP_ARRAY(char, _sz + BufferNode::aligned_size(), mtGC);
aoqi@0:     return BufferNode::make_buffer_from_block(b);
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueueSet::deallocate_buffer(void** buf) {
aoqi@0:   assert(_sz > 0, "Didn't set a buffer size.");
aoqi@0:   MutexLockerEx x(_fl_owner->_fl_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:   BufferNode *node = BufferNode::make_node_from_buffer(buf);
aoqi@0:   node->set_next(_fl_owner->_buf_free_list);
aoqi@0:   _fl_owner->_buf_free_list = node;
aoqi@0:   _fl_owner->_buf_free_list_sz++;
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueueSet::reduce_free_list() {
aoqi@0:   assert(_fl_owner == this, "Free list reduction is allowed only for the owner");
aoqi@0:   // For now we'll adopt the strategy of deleting half.
aoqi@0:   MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:   size_t n = _buf_free_list_sz / 2;
aoqi@0:   while (n > 0) {
aoqi@0:     assert(_buf_free_list != NULL, "_buf_free_list_sz must be wrong.");
aoqi@0:     void* b = BufferNode::make_block_from_node(_buf_free_list);
aoqi@0:     _buf_free_list = _buf_free_list->next();
aoqi@0:     FREE_C_HEAP_ARRAY(char, b, mtGC);
aoqi@0:     _buf_free_list_sz --;
aoqi@0:     n--;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueue::handle_zero_index() {
aoqi@0:   assert(_index == 0, "Precondition.");
aoqi@0: 
aoqi@0:   // This thread records the full buffer and allocates a new one (while
aoqi@0:   // holding the lock if there is one).
aoqi@0:   if (_buf != NULL) {
aoqi@0:     if (!should_enqueue_buffer()) {
aoqi@0:       assert(_index > 0, "the buffer can only be re-used if it's not full");
aoqi@0:       return;
aoqi@0:     }
aoqi@0: 
aoqi@0:     if (_lock) {
aoqi@0:       assert(_lock->owned_by_self(), "Required.");
aoqi@0: 
aoqi@0:       // The current PtrQ may be the shared dirty card queue and
aoqi@0:       // may be being manipulated by more than one worker thread
aoqi@0:       // during a pause. Since the enqueuing of the completed
aoqi@0:       // buffer unlocks the Shared_DirtyCardQ_lock more than one
aoqi@0:       // worker thread can 'race' on reading the shared queue attributes
aoqi@0:       // (_buf and _index) and multiple threads can call into this
aoqi@0:       // routine for the same buffer. This will cause the completed
aoqi@0:       // buffer to be added to the CBL multiple times.
aoqi@0: 
aoqi@0:       // We "claim" the current buffer by caching value of _buf in
aoqi@0:       // a local and clearing the field while holding _lock. When
aoqi@0:       // _lock is released (while enqueueing the completed buffer)
aoqi@0:       // the thread that acquires _lock will skip this code,
aoqi@0:       // preventing the subsequent the multiple enqueue, and
aoqi@0:       // install a newly allocated buffer below.
aoqi@0: 
aoqi@0:       void** buf = _buf;   // local pointer to completed buffer
aoqi@0:       _buf = NULL;         // clear shared _buf field
aoqi@0: 
aoqi@0:       locking_enqueue_completed_buffer(buf);  // enqueue completed buffer
aoqi@0: 
aoqi@0:       // While the current thread was enqueuing the buffer another thread
aoqi@0:       // may have a allocated a new buffer and inserted it into this pointer
aoqi@0:       // queue. If that happens then we just return so that the current
aoqi@0:       // thread doesn't overwrite the buffer allocated by the other thread
aoqi@0:       // and potentially losing some dirtied cards.
aoqi@0: 
aoqi@0:       if (_buf != NULL) return;
aoqi@0:     } else {
aoqi@0:       if (qset()->process_or_enqueue_complete_buffer(_buf)) {
aoqi@0:         // Recycle the buffer. No allocation.
aoqi@0:         _sz = qset()->buffer_size();
aoqi@0:         _index = _sz;
aoqi@0:         return;
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0:   // Reallocate the buffer
aoqi@0:   _buf = qset()->allocate_buffer();
aoqi@0:   _sz = qset()->buffer_size();
aoqi@0:   _index = _sz;
aoqi@0:   assert(0 <= _index && _index <= _sz, "Invariant.");
aoqi@0: }
aoqi@0: 
aoqi@0: bool PtrQueueSet::process_or_enqueue_complete_buffer(void** buf) {
aoqi@0:   if (Thread::current()->is_Java_thread()) {
aoqi@0:     // We don't lock. It is fine to be epsilon-precise here.
aoqi@0:     if (_max_completed_queue == 0 || _max_completed_queue > 0 &&
aoqi@0:         _n_completed_buffers >= _max_completed_queue + _completed_queue_padding) {
aoqi@0:       bool b = mut_process_buffer(buf);
aoqi@0:       if (b) {
aoqi@0:         // True here means that the buffer hasn't been deallocated and the caller may reuse it.
aoqi@0:         return true;
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0:   // The buffer will be enqueued. The caller will have to get a new one.
aoqi@0:   enqueue_complete_buffer(buf);
aoqi@0:   return false;
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueueSet::enqueue_complete_buffer(void** buf, size_t index) {
aoqi@0:   MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
aoqi@0:   BufferNode* cbn = BufferNode::new_from_buffer(buf);
aoqi@0:   cbn->set_index(index);
aoqi@0:   if (_completed_buffers_tail == NULL) {
aoqi@0:     assert(_completed_buffers_head == NULL, "Well-formedness");
aoqi@0:     _completed_buffers_head = cbn;
aoqi@0:     _completed_buffers_tail = cbn;
aoqi@0:   } else {
aoqi@0:     _completed_buffers_tail->set_next(cbn);
aoqi@0:     _completed_buffers_tail = cbn;
aoqi@0:   }
aoqi@0:   _n_completed_buffers++;
aoqi@0: 
aoqi@0:   if (!_process_completed && _process_completed_threshold >= 0 &&
aoqi@0:       _n_completed_buffers >= _process_completed_threshold) {
aoqi@0:     _process_completed = true;
aoqi@0:     if (_notify_when_complete)
aoqi@0:       _cbl_mon->notify();
aoqi@0:   }
aoqi@0:   debug_only(assert_completed_buffer_list_len_correct_locked());
aoqi@0: }
aoqi@0: 
aoqi@0: int PtrQueueSet::completed_buffers_list_length() {
aoqi@0:   int n = 0;
aoqi@0:   BufferNode* cbn = _completed_buffers_head;
aoqi@0:   while (cbn != NULL) {
aoqi@0:     n++;
aoqi@0:     cbn = cbn->next();
aoqi@0:   }
aoqi@0:   return n;
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueueSet::assert_completed_buffer_list_len_correct() {
aoqi@0:   MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
aoqi@0:   assert_completed_buffer_list_len_correct_locked();
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueueSet::assert_completed_buffer_list_len_correct_locked() {
aoqi@0:   guarantee(completed_buffers_list_length() ==  _n_completed_buffers,
aoqi@0:             "Completed buffer length is wrong.");
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueueSet::set_buffer_size(size_t sz) {
aoqi@0:   assert(_sz == 0 && sz > 0, "Should be called only once.");
aoqi@0:   _sz = sz * oopSize;
aoqi@0: }
aoqi@0: 
aoqi@0: // Merge lists of buffers. Notify the processing threads.
aoqi@0: // The source queue is emptied as a result. The queues
aoqi@0: // must share the monitor.
aoqi@0: void PtrQueueSet::merge_bufferlists(PtrQueueSet *src) {
aoqi@0:   assert(_cbl_mon == src->_cbl_mon, "Should share the same lock");
aoqi@0:   MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
aoqi@0:   if (_completed_buffers_tail == NULL) {
aoqi@0:     assert(_completed_buffers_head == NULL, "Well-formedness");
aoqi@0:     _completed_buffers_head = src->_completed_buffers_head;
aoqi@0:     _completed_buffers_tail = src->_completed_buffers_tail;
aoqi@0:   } else {
aoqi@0:     assert(_completed_buffers_head != NULL, "Well formedness");
aoqi@0:     if (src->_completed_buffers_head != NULL) {
aoqi@0:       _completed_buffers_tail->set_next(src->_completed_buffers_head);
aoqi@0:       _completed_buffers_tail = src->_completed_buffers_tail;
aoqi@0:     }
aoqi@0:   }
aoqi@0:   _n_completed_buffers += src->_n_completed_buffers;
aoqi@0: 
aoqi@0:   src->_n_completed_buffers = 0;
aoqi@0:   src->_completed_buffers_head = NULL;
aoqi@0:   src->_completed_buffers_tail = NULL;
aoqi@0: 
aoqi@0:   assert(_completed_buffers_head == NULL && _completed_buffers_tail == NULL ||
aoqi@0:          _completed_buffers_head != NULL && _completed_buffers_tail != NULL,
aoqi@0:          "Sanity");
aoqi@0: }
aoqi@0: 
aoqi@0: void PtrQueueSet::notify_if_necessary() {
aoqi@0:   MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
aoqi@0:   if (_n_completed_buffers >= _process_completed_threshold || _max_completed_queue == 0) {
aoqi@0:     _process_completed = true;
aoqi@0:     if (_notify_when_complete)
aoqi@0:       _cbl_mon->notify();
aoqi@0:   }
aoqi@0: }