--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/ptrQueue.hpp Sat Aug 18 13:59:25 2018 -0400
@@ -0,0 +1,371 @@
+/*
+ * Copyright (c) 2001, 2018, 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_GC_SHARED_PTRQUEUE_HPP
+#define SHARE_GC_SHARED_PTRQUEUE_HPP
+
+#include "utilities/align.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 {
+ 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;
+
+ // The (byte) index at which an object was last enqueued. Starts at
+ // capacity_in_bytes (indicating an empty buffer) and goes towards zero.
+ // Value is always pointer-size aligned.
+ size_t _index;
+
+ // Size of the current buffer, in bytes.
+ // Value is always pointer-size aligned.
+ size_t _capacity_in_bytes;
+
+ static const size_t _element_size = sizeof(void*);
+
+ // Get the capacity, in bytes. The capacity must have been set.
+ size_t capacity_in_bytes() const {
+ assert(_capacity_in_bytes > 0, "capacity not set");
+ return _capacity_in_bytes;
+ }
+
+ void set_capacity(size_t entries) {
+ size_t byte_capacity = index_to_byte_index(entries);
+ assert(_capacity_in_bytes == 0 || _capacity_in_bytes == byte_capacity,
+ "changing capacity " SIZE_FORMAT " -> " SIZE_FORMAT,
+ _capacity_in_bytes, byte_capacity);
+ _capacity_in_bytes = byte_capacity;
+ }
+
+ static size_t byte_index_to_index(size_t ind) {
+ assert(is_aligned(ind, _element_size), "precondition");
+ return ind / _element_size;
+ }
+
+ static size_t index_to_byte_index(size_t ind) {
+ return ind * _element_size;
+ }
+
+protected:
+ // The buffer.
+ void** _buf;
+
+ size_t index() const {
+ return byte_index_to_index(_index);
+ }
+
+ void set_index(size_t new_index) {
+ size_t byte_index = index_to_byte_index(new_index);
+ assert(byte_index <= capacity_in_bytes(), "precondition");
+ _index = byte_index;
+ }
+
+ size_t capacity() const {
+ return byte_index_to_index(capacity_in_bytes());
+ }
+
+ // 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.
+ 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; }
+
+ // Forcibly set empty.
+ void reset() {
+ if (_buf != NULL) {
+ _index = capacity_in_bytes();
+ }
+ }
+
+ 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);
+
+ // Return the size of the in-use region.
+ size_t size() const {
+ size_t result = 0;
+ if (_buf != NULL) {
+ assert(_index <= capacity_in_bytes(), "Invariant");
+ result = byte_index_to_index(capacity_in_bytes() - _index);
+ }
+ return result;
+ }
+
+ bool is_empty() const {
+ return _buf == NULL || capacity_in_bytes() == _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) {
+ reset();
+ } else if (b && _buf != NULL) {
+ assert(index() == capacity(),
+ "invariant: queues are empty when activated.");
+ }
+ }
+
+ bool is_active() const { return _active; }
+
+ // 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(_element_size); }
+
+ 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 elements.
+ static BufferNode* allocate(size_t 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 {
+ // The size of all buffers in the set.
+ size_t _buffer_size;
+
+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;
+
+ 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 the buffer for a BufferNode of size buffer_size().
+ void** allocate_buffer();
+
+ // Return an empty buffer to the free list. The node is required
+ // to have been allocated with a size of buffer_size().
+ 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. Must have been set.
+ size_t buffer_size() const {
+ assert(_buffer_size > 0, "buffer size not set");
+ return _buffer_size;
+ }
+
+ // 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_GC_SHARED_PTRQUEUE_HPP