--- /dev/null
+/* concurrentset.vala
+ *
+ * Copyright (C) 2012 Maciej Piechotka
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+
+ * This library 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
+ * Lesser General Public License for more details.
+
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Author:
+ * Maciej Piechotka <uzytkownik2@gmail.com>
+ */
+
+/**
+ * A skip-linked list. This implementation is based on
+ * [[http://www.cse.yorku.ca/~ruppert/Mikhail.pdf|Mikhail Fomitchev Master Thesis]].
+ *
+ * Many threads are allowed to operate on the same structure as well as modification
+ * of structure during iteration is allowed. However the change may not be immidiatly
+ * visible to other threads.
+ */
+public class Gee.ConcurrentSet<G> : AbstractCollection<G> {
+ public ConcurrentSet (owned CompareDataFunc<G>? compare_func = null) {
+ if (compare_func == null) {
+ compare_func = Functions.get_compare_func_for (typeof (G));
+ }
+ _cmp = compare_func;
+ }
+
+ ~ConcurrentSet () {
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ _head = null;
+ }
+
+ public override int size { get { return GLib.AtomicInt.get (ref _size); } }
+
+ public override bool read_only { get { return false; } }
+
+ public override Gee.Iterator<G> iterator () {
+ return new Iterator<G> (this, _head);
+ }
+
+ public override bool contains (G key) {
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ Tower<G> prev = _head;
+ return Tower.search<G> (_cmp, key, ref prev, null);
+ }
+
+ public override bool add (G key) {
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ //FIXME: Synchronization
+ Rand *rnd = rand.get ();
+ if (rnd == null) {
+ rand.set (rnd = new Rand ());
+ }
+ uint32 rand_int = rnd->int_range (0, int32.MAX);
+ uint8 height = 1 + (uint8)GLib.Bit.nth_lsf (~rand_int, -1);
+ Tower<G> prev = _head;
+ if (Tower.search<G> (_cmp, key, ref prev, null, height - 1)) {
+ return false;
+ }
+ Tower<G>? result = Tower.insert<G> (_cmp, ref prev, key, height - 1);
+ if (result != null) {
+ GLib.AtomicInt.inc (ref _size);
+ }
+ return result != null;
+ }
+
+ public override bool remove (G item) {
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ bool result = Tower.remove_key<G> (_cmp, _head, item);
+ if (result) {
+ GLib.AtomicInt.dec_and_test (ref _size);
+ }
+ return result;
+ }
+
+ public override void clear () {
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ Tower<G>? first;
+ while ((first = _head.get_next (0)) != null) {
+ remove (first._data);
+ }
+ }
+
+#if DEBUG
+ public void dump () {
+ for (int i = _MAX_HEIGHT - 1; i >= 0; i--) {
+ bool printed = false;
+ Tower<G>? curr = _head;
+ State state;
+ while ((curr = curr.get_succ (out state, (uint8)i)) != null) {
+ if (!printed) {
+ stderr.printf("Level %d\n", i);
+ printed = true;
+ }
+ stderr.printf(" Node %p%s - %s\n", curr, state == State.NONE ? "" : state == State.MARKED ? " (MARKED)" : " (FLAGGED)", (string)curr._data);
+ }
+ }
+ }
+#endif
+
+ private int _size = 0;
+ private Tower<G> _head = new Tower<G>.head ();
+ private CompareDataFunc<G>? _cmp;
+ private static const int _MAX_HEIGHT = 31;
+ private static Private rand = new Private((ptr) => {
+ Rand *rnd = (Rand *)ptr;
+ delete rnd;
+ });
+
+ private class Iterator<G> : Object, Traversable<G>, Gee.Iterator<G> {
+ public Iterator (ConcurrentSet cset, Tower<G> head) {
+ _curr = head;
+ _set = cset;
+ assert (_curr != null);
+ }
+
+ public Iterator.pointing (ConcurrentSet cset, Tower<G>[] prev, Tower<G> curr) {
+ for (int i = 0; i < _MAX_HEIGHT; i++) {
+ _prev[i] = prev[i];
+ }
+ _curr = curr;
+ _set = cset;
+ assert (_curr != null);
+ }
+
+ public new bool foreach (ForallFunc<G> f) {
+ assert (_curr != null);
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ if (_prev != null && !_removed) {
+ if (!f (_curr._data)) {
+ assert (_curr != null);
+ return false;
+ }
+ }
+ Tower<G> new_prev = _prev[0];
+ Tower<G>? new_curr = _curr;
+ while (Tower.proceed<G> (_set._cmp, ref new_prev, ref new_curr, 0)) {
+ assert (_curr != null);
+ if (!f (_curr._data)) {
+ assert (_curr != null);
+ return false;
+ }
+ if (!_removed) {
+ //FIXME: Help mark/delete on the way
+ _prev[0] = (owned)new_prev;
+ int prev_height = GLib.AtomicInt.get(ref _prev[0]._height);
+ for (int i = 1; i < prev_height; i++) {
+ _prev[i] = _prev[0];
+ }
+ }
+ _curr = (owned)new_curr;
+ _removed = false;
+ }
+ assert (_curr != null);
+ return true;
+ }
+
+ public bool next () {
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ Tower<G> new_prev = _prev[0];
+ Tower<G>? new_curr = _curr;
+ bool success = Tower.proceed<G> (_set._cmp, ref new_prev, ref new_curr, 0);
+ if (success) {
+ if (!_removed) {
+ //FIXME: Help mark/delete on the way
+ _prev[0] = (owned)new_prev;
+ int prev_height = GLib.AtomicInt.get(ref _prev[0]._height);
+ for (int i = 1; i < prev_height; i++) {
+ _prev[i] = _prev[0];
+ }
+ }
+ _curr = (owned)new_curr;
+ _removed = false;
+ }
+ assert (_curr != null);
+ return success;
+ }
+
+ public bool has_next () {
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ Tower<G> prev = _prev[0];
+ Tower<G>? curr = _curr;
+ return Tower.proceed<G> (_set._cmp, ref prev, ref curr, 0);
+ }
+
+ public new G get () {
+ assert (valid);
+ return _curr._data;
+ }
+
+ public void remove () {
+ HazardPointer.Context ctx = new HazardPointer.Context ();
+ assert (valid);
+ if (Tower.remove<G> (_set._cmp, _prev, _curr)) {
+ AtomicInt.dec_and_test (ref _set._size);
+ }
+ _removed = true;
+ }
+
+ public bool valid { get { return _prev != null && !_removed; } }
+
+ public bool read_only { get { return true; } }
+
+ private bool _removed = false;
+ private ConcurrentSet<G> _set;
+ private Tower<G>? _prev[31 /*_MAX_HEIGHT*/];
+ private Tower<G> _curr;
+ }
+
+ private class Tower<G> {
+ public inline Tower (G data, uint8 height) {
+ _nodes = new TowerNode<G>[height];
+ _data = data;
+ _height = 0;
+ AtomicPointer.set (&_nodes[0]._backlink, null); // FIXME: This should be memory barrier
+ }
+
+ public inline Tower.head () {
+ _nodes = new TowerNode<G>[_MAX_HEIGHT];
+ _height = _MAX_HEIGHT;
+ }
+
+ inline ~Tower () {
+ for (uint i = 0; i < _height; i++) {
+ HazardPointer<Tower<G>>.set_pointer (&_nodes[i]._succ, null);
+ HazardPointer<Tower<G>>.set_pointer (&_nodes[i]._backlink, null);
+ }
+ _nodes = null;
+ }
+
+ public static inline bool search<G> (CompareDataFunc<G>? cmp, G key, ref Tower<G> prev, out Tower<G>? next, uint8 to_level = 0, uint8 from_level = (uint8)_MAX_HEIGHT - 1) {
+ assert (from_level >= to_level);
+ bool res = false;
+ next = null;
+ for (int i = from_level; i >= to_level; i--) {
+ res = search_helper<G> (cmp, key, ref prev, out next, (uint8)i);
+ }
+ return res;
+ }
+
+ private static inline bool search_helper<G> (CompareDataFunc<G>? cmp, G key, ref Tower<G>? prev, out Tower<G>? next, uint8 level) {
+ next = prev.get_next (level);
+ while (next != null && cmp(key, next._data) < 0 && proceed<G> (cmp, ref prev, ref next, level, true));
+ return next != null && cmp(key, next._data) == 0;
+ }
+
+ public static inline Tower<G>? insert<G> (CompareDataFunc<G>? cmp, ref Tower<G> prev, G key, uint8 chosen_level) {
+ return insert_helper<G> (cmp, ref prev, key, chosen_level, chosen_level);
+ }
+
+ private static inline Tower<G>? insert_helper<G> (CompareDataFunc<G>? cmp, ref Tower<G> prev, G key, uint8 chosen_level, uint8 level) {
+ Tower<G>? new_tower;
+ Tower<G>? next;
+ if (search_helper (cmp, key, ref prev, out next, level)) {
+ return null;
+ }
+ if (level > 0) {
+ Tower<G> prev_down = prev;
+ new_tower = insert_helper<G> (cmp, ref prev_down, key, chosen_level, level - 1);
+ } else {
+ new_tower = new Tower<G> (key, chosen_level + 1);
+ }
+ if (new_tower == null) {
+ return null;
+ }
+ while (true) {
+ State prev_state;
+ Tower<G>? prev_next = prev.get_succ (out prev_state, level);
+ if (prev_state == State.FLAGGED) {
+ prev_next.help_flagged (prev, level);
+ } else {
+ new_tower.set_succ (next, State.NONE, level);
+ bool result = prev.compare_and_exchange (next, State.NONE, new_tower, State.NONE, level);
+ if (result)
+ break;
+ prev_next = prev.get_succ (out prev_state, level);
+ if (prev_state == State.FLAGGED) {
+ prev_next.help_flagged (prev, level);
+ }
+ backtrace<G> (ref prev, level);
+ }
+ if (search_helper (cmp, key, ref prev, null, level)) {
+ return null;
+ }
+ }
+ GLib.AtomicInt.inc (ref new_tower._height);
+ if (new_tower.get_state (0) == State.MARKED) {
+ remove_level (cmp, ref prev, new_tower, level);
+ return null;
+ }
+ return new_tower;
+ }
+
+ public static inline bool remove_key<G> (CompareDataFunc<G>? cmp, Tower<G> arg_prev, G key, uint8 from_level = (uint8)_MAX_HEIGHT - 1) {
+ Tower<G> prev[31 /*_MAX_HEIGHT*/];
+ prev[from_level] = arg_prev;
+ for (int i = from_level; i >= 1; i--) {
+ Tower<G> next;
+ search_helper<G> (cmp, key, ref prev[i], out next, (uint8)i);
+ prev[i - 1] = prev[i];
+ }
+ Tower<G>? curr;
+ if (search_helper<G> (cmp, key, ref prev[0], out curr, 0)) {
+ return remove<G> (cmp, prev, curr);
+ } else {
+ return false;
+ }
+ }
+
+ public static inline bool remove<G> (CompareDataFunc<G>? cmp, Tower<G>[] prev, Tower<G> curr) {
+ assert (prev.length >= AtomicInt.get (ref curr._height));
+ bool removed = remove_level (cmp, ref prev[0], curr, 0);
+ for (int i = 1; i < prev.length; i++) {
+ remove_level (cmp, ref prev[i], curr, (uint8)i);
+ }
+ return removed;
+ }
+
+ private static inline bool remove_level (CompareDataFunc<G>? cmp, ref Tower<G> prev, Tower<G> curr, uint8 level) {
+ bool status;
+ bool flagged = curr.try_flag (cmp, ref prev, out status, level);
+ if (status) {
+ curr.help_flagged (prev, level);
+ }
+ return flagged;
+ }
+
+ public static inline bool proceed<G> (CompareDataFunc<G>? cmp, ref Tower<G>? arg_prev, ref Tower<G> arg_curr, uint8 level, bool force = false) {
+ Tower<G> curr = arg_curr;
+ Tower<G>? next = curr.get_next (level);
+ if (next != null) {
+ while (next.get_state (0) == State.MARKED) {
+ bool status;
+ next.try_flag (cmp, ref curr, out status, level);
+ if (status) {
+ next.help_flagged (curr, level);
+ }
+ next = curr.get_next (level);
+ }
+ }
+ bool success = next != null;
+ if (success || force) {
+ arg_prev = (owned)curr;
+ arg_curr = (owned)next;
+ }
+ return success;
+ }
+
+ public inline void help_marked (Tower<G> prev_tower, uint8 level) {
+ prev_tower.compare_and_exchange (this, State.FLAGGED, get_next (level), State.NONE, level);
+ }
+
+ public inline void help_flagged (Tower<G> prev, uint8 level) {
+ set_backlink (prev, level);
+ if (get_state (level) != State.MARKED)
+ try_mark (level);
+ help_marked (prev, level);
+ }
+
+ public inline void try_mark (uint8 level) {
+ do {
+ Tower<G>? next_tower = get_next (level);
+ bool result = compare_and_exchange (next_tower, State.NONE, next_tower, State.MARKED, level);
+ if (!result) {
+ State state;
+ next_tower = get_succ (out state, level);
+ if (state == State.FLAGGED)
+ help_flagged (next_tower, level);
+ }
+ } while (get_state (level) != State.MARKED);
+ }
+
+ public inline bool try_flag (CompareDataFunc<G>? cmp, ref Tower<G> prev_tower, out bool status, uint8 level) {
+ while (true) {
+ if (prev_tower.compare_succ (this, State.FLAGGED, level)) {
+ status = true;
+ return false;
+ }
+ bool result = prev_tower.compare_and_exchange (this, State.NONE, this, State.FLAGGED, level);
+ if (result) {
+ status = true;
+ return true;
+ }
+ State result_state;
+ Tower<G>? result_tower = prev_tower.get_succ (out result_state, level);
+ if (result_tower == this && result_state == State.FLAGGED) {
+ status = true;
+ return false;
+ }
+ backtrace<G> (ref prev_tower, level);
+ if (!search_helper (cmp, _data, ref prev_tower, null, level)) {
+ status = false;
+ return false;
+ }
+ }
+ }
+
+ public static inline void backtrace<G> (ref Tower<G>? curr, uint8 level) {
+ while (curr.get_state (level) == State.MARKED)
+ curr = curr.get_backlink (level);
+ }
+
+ public inline bool compare_and_exchange (Tower<G>? old_tower, State old_state, Tower<G>? new_tower, State new_state, uint8 level) {
+ return HazardPointer.compare_and_exchange_pointer<Tower<G>?> (&_nodes[level]._succ, old_tower, new_tower, 3, (size_t)old_state, (size_t)new_state);
+ }
+
+ public inline bool compare_succ (Tower<G>? next, State state, uint8 level) {
+ size_t cur = (size_t)AtomicPointer.get (&_nodes[level]._succ);
+ return cur == ((size_t)next | (size_t)state);
+ }
+
+ public inline Tower<G>? get_next (uint8 level) {
+ return get_succ (null, level);
+ }
+
+ public inline State get_state (uint8 level) {
+ return (State)((size_t)AtomicPointer.get (&_nodes[level]._succ) & 3);
+ }
+
+ public inline Tower<G>? get_succ (out State state, uint8 level) {
+ size_t rstate;
+ Tower<G>? succ = HazardPointer.get_pointer<Tower<G>> (&_nodes[level]._succ, 3, out rstate);
+ state = (State)rstate;
+ return (owned)succ;
+ }
+
+ public inline void set_succ (Tower<G>? next, State state, uint8 level) {
+ HazardPointer.set_pointer<Tower<G>> (&_nodes[level]._succ, next, 3, (size_t)state);
+ }
+
+ public inline Tower<G>? get_backlink (uint8 level) {
+ return HazardPointer.get_pointer<Tower<G>> (&_nodes[level]._backlink);
+ }
+
+ public inline void set_backlink (Tower<G>? backlink, uint8 level) {
+ HazardPointer.compare_and_exchange_pointer<Tower<G>?> (&_nodes[level]._backlink, null, backlink);
+ }
+
+ [NoArrayLength]
+ public TowerNode<G>[] _nodes;
+ public G _data;
+ public int _height;
+ }
+
+ private struct TowerNode<G> {
+ public Tower<G> *_succ;
+ public Tower<G> *_backlink;
+ }
+
+ private enum State {
+ NONE = 0,
+ MARKED = 1,
+ FLAGGED = 2
+ }
+}
+
projects / platform / upstream / libgee.git / commitdiff