| /* |
| * Copyright (c) 2001, 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. |
| * |
| */ |
| |
| #ifndef SHARE_VM_GC_G1_PTRQUEUE_HPP |
| #define SHARE_VM_GC_G1_PTRQUEUE_HPP |
| |
| #include "memory/allocation.hpp" |
| #include "utilities/sizes.hpp" |
| |
| // There are various techniques that require threads to be able to log |
| // addresses. For example, a generational write barrier might log |
| // the addresses of modified old-generation objects. This type supports |
| // this operation. |
| |
| class BufferNode; |
| class PtrQueueSet; |
| class PtrQueue VALUE_OBJ_CLASS_SPEC { |
| friend class VMStructs; |
| |
| // Noncopyable - not defined. |
| PtrQueue(const PtrQueue&); |
| PtrQueue& operator=(const PtrQueue&); |
| |
| // The ptr queue set to which this queue belongs. |
| PtrQueueSet* const _qset; |
| |
| // Whether updates should be logged. |
| bool _active; |
| |
| // If true, the queue is permanent, and doesn't need to deallocate |
| // its buffer in the destructor (since that obtains a lock which may not |
| // be legally locked by then. |
| const bool _permanent; |
| |
| protected: |
| // The buffer. |
| void** _buf; |
| // The (byte) index at which an object was last enqueued. Starts at "_sz" |
| // (indicating an empty buffer) and goes towards zero. |
| size_t _index; |
| |
| // The (byte) size of the buffer. |
| size_t _sz; |
| |
| // If there is a lock associated with this buffer, this is that lock. |
| Mutex* _lock; |
| |
| PtrQueueSet* qset() { return _qset; } |
| bool is_permanent() const { return _permanent; } |
| |
| // Process queue entries and release resources, if not permanent. |
| void flush_impl(); |
| |
| // Initialize this queue to contain a null buffer, and be part of the |
| // given PtrQueueSet. |
| PtrQueue(PtrQueueSet* qset, bool permanent = false, bool active = false); |
| |
| // Requires queue flushed or permanent. |
| ~PtrQueue(); |
| |
| public: |
| |
| // Associate a lock with a ptr queue. |
| void set_lock(Mutex* lock) { _lock = lock; } |
| |
| void reset() { if (_buf != NULL) _index = _sz; } |
| |
| void enqueue(volatile void* ptr) { |
| enqueue((void*)(ptr)); |
| } |
| |
| // Enqueues the given "obj". |
| void enqueue(void* ptr) { |
| if (!_active) return; |
| else enqueue_known_active(ptr); |
| } |
| |
| // This method is called when we're doing the zero index handling |
| // and gives a chance to the queues to do any pre-enqueueing |
| // processing they might want to do on the buffer. It should return |
| // true if the buffer should be enqueued, or false if enough |
| // entries were cleared from it so that it can be re-used. It should |
| // not return false if the buffer is still full (otherwise we can |
| // get into an infinite loop). |
| virtual bool should_enqueue_buffer() { return true; } |
| void handle_zero_index(); |
| void locking_enqueue_completed_buffer(BufferNode* node); |
| |
| void enqueue_known_active(void* ptr); |
| |
| size_t size() { |
| assert(_sz >= _index, "Invariant."); |
| return _buf == NULL ? 0 : _sz - _index; |
| } |
| |
| bool is_empty() { |
| return _buf == NULL || _sz == _index; |
| } |
| |
| // Set the "active" property of the queue to "b". An enqueue to an |
| // inactive thread is a no-op. Setting a queue to inactive resets its |
| // log to the empty state. |
| void set_active(bool b) { |
| _active = b; |
| if (!b && _buf != NULL) { |
| _index = _sz; |
| } else if (b && _buf != NULL) { |
| assert(_index == _sz, "invariant: queues are empty when activated."); |
| } |
| } |
| |
| bool is_active() { return _active; } |
| |
| static size_t byte_index_to_index(size_t ind) { |
| assert((ind % sizeof(void*)) == 0, "Invariant."); |
| return ind / sizeof(void*); |
| } |
| |
| static size_t index_to_byte_index(size_t ind) { |
| return ind * sizeof(void*); |
| } |
| |
| // To support compiler. |
| |
| protected: |
| template<typename Derived> |
| static ByteSize byte_offset_of_index() { |
| return byte_offset_of(Derived, _index); |
| } |
| |
| static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); } |
| |
| template<typename Derived> |
| static ByteSize byte_offset_of_buf() { |
| return byte_offset_of(Derived, _buf); |
| } |
| |
| static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); } |
| |
| template<typename Derived> |
| static ByteSize byte_offset_of_active() { |
| return byte_offset_of(Derived, _active); |
| } |
| |
| static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); } |
| |
| }; |
| |
| class BufferNode { |
| size_t _index; |
| BufferNode* _next; |
| void* _buffer[1]; // Pseudo flexible array member. |
| |
| BufferNode() : _index(0), _next(NULL) { } |
| ~BufferNode() { } |
| |
| static size_t buffer_offset() { |
| return offset_of(BufferNode, _buffer); |
| } |
| |
| public: |
| BufferNode* next() const { return _next; } |
| void set_next(BufferNode* n) { _next = n; } |
| size_t index() const { return _index; } |
| void set_index(size_t i) { _index = i; } |
| |
| // Allocate a new BufferNode with the "buffer" having size bytes. |
| static BufferNode* allocate(size_t byte_size); |
| |
| // Free a BufferNode. |
| static void deallocate(BufferNode* node); |
| |
| // Return the BufferNode containing the buffer, after setting its index. |
| static BufferNode* make_node_from_buffer(void** buffer, size_t index) { |
| BufferNode* node = |
| reinterpret_cast<BufferNode*>( |
| reinterpret_cast<char*>(buffer) - buffer_offset()); |
| node->set_index(index); |
| return node; |
| } |
| |
| // Return the buffer for node. |
| static void** make_buffer_from_node(BufferNode *node) { |
| // &_buffer[0] might lead to index out of bounds warnings. |
| return reinterpret_cast<void**>( |
| reinterpret_cast<char*>(node) + buffer_offset()); |
| } |
| }; |
| |
| // A PtrQueueSet represents resources common to a set of pointer queues. |
| // In particular, the individual queues allocate buffers from this shared |
| // set, and return completed buffers to the set. |
| // All these variables are are protected by the TLOQ_CBL_mon. XXX ??? |
| class PtrQueueSet VALUE_OBJ_CLASS_SPEC { |
| protected: |
| Monitor* _cbl_mon; // Protects the fields below. |
| BufferNode* _completed_buffers_head; |
| BufferNode* _completed_buffers_tail; |
| size_t _n_completed_buffers; |
| int _process_completed_threshold; |
| volatile bool _process_completed; |
| |
| // This (and the interpretation of the first element as a "next" |
| // pointer) are protected by the TLOQ_FL_lock. |
| Mutex* _fl_lock; |
| BufferNode* _buf_free_list; |
| size_t _buf_free_list_sz; |
| // Queue set can share a freelist. The _fl_owner variable |
| // specifies the owner. It is set to "this" by default. |
| PtrQueueSet* _fl_owner; |
| |
| // The size of all buffers in the set. |
| size_t _sz; |
| |
| bool _all_active; |
| |
| // If true, notify_all on _cbl_mon when the threshold is reached. |
| bool _notify_when_complete; |
| |
| // Maximum number of elements allowed on completed queue: after that, |
| // enqueuer does the work itself. Zero indicates no maximum. |
| int _max_completed_queue; |
| size_t _completed_queue_padding; |
| |
| size_t completed_buffers_list_length(); |
| void assert_completed_buffer_list_len_correct_locked(); |
| void assert_completed_buffer_list_len_correct(); |
| |
| protected: |
| // A mutator thread does the the work of processing a buffer. |
| // Returns "true" iff the work is complete (and the buffer may be |
| // deallocated). |
| virtual bool mut_process_buffer(BufferNode* node) { |
| ShouldNotReachHere(); |
| return false; |
| } |
| |
| // Create an empty ptr queue set. |
| PtrQueueSet(bool notify_when_complete = false); |
| ~PtrQueueSet(); |
| |
| // Because of init-order concerns, we can't pass these as constructor |
| // arguments. |
| void initialize(Monitor* cbl_mon, |
| Mutex* fl_lock, |
| int process_completed_threshold, |
| int max_completed_queue, |
| PtrQueueSet *fl_owner = NULL); |
| |
| public: |
| |
| // Return an empty array of size _sz (required to be non-zero). |
| void** allocate_buffer(); |
| |
| // Return an empty buffer to the free list. The "buf" argument is |
| // required to be a pointer to the head of an array of length "_sz". |
| void deallocate_buffer(BufferNode* node); |
| |
| // Declares that "buf" is a complete buffer. |
| void enqueue_complete_buffer(BufferNode* node); |
| |
| // To be invoked by the mutator. |
| bool process_or_enqueue_complete_buffer(BufferNode* node); |
| |
| bool completed_buffers_exist_dirty() { |
| return _n_completed_buffers > 0; |
| } |
| |
| bool process_completed_buffers() { return _process_completed; } |
| void set_process_completed(bool x) { _process_completed = x; } |
| |
| bool is_active() { return _all_active; } |
| |
| // Set the buffer size. Should be called before any "enqueue" operation |
| // can be called. And should only be called once. |
| void set_buffer_size(size_t sz); |
| |
| // Get the buffer size. |
| size_t buffer_size() { return _sz; } |
| |
| // Get/Set the number of completed buffers that triggers log processing. |
| void set_process_completed_threshold(int sz) { _process_completed_threshold = sz; } |
| int process_completed_threshold() const { return _process_completed_threshold; } |
| |
| // Must only be called at a safe point. Indicates that the buffer free |
| // list size may be reduced, if that is deemed desirable. |
| void reduce_free_list(); |
| |
| size_t completed_buffers_num() { return _n_completed_buffers; } |
| |
| void merge_bufferlists(PtrQueueSet* src); |
| |
| void set_max_completed_queue(int m) { _max_completed_queue = m; } |
| int max_completed_queue() { return _max_completed_queue; } |
| |
| void set_completed_queue_padding(size_t padding) { _completed_queue_padding = padding; } |
| size_t completed_queue_padding() { return _completed_queue_padding; } |
| |
| // Notify the consumer if the number of buffers crossed the threshold |
| void notify_if_necessary(); |
| }; |
| |
| #endif // SHARE_VM_GC_G1_PTRQUEUE_HPP |