// SplitOrderedList.cs // // Copyright (c) 2010 Jérémie "Garuma" Laval // // Permission is hereby granted, free of charge, to any person obtaining a copy // of this software and associated documentation files (the "Software"), to deal // in the Software without restriction, including without limitation the rights // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell // copies of the Software, and to permit persons to whom the Software is // furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in // all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN // THE SOFTWARE. // // using System; using System.Collections.Generic; using System.Threading; namespace Xamarin.Forms { internal class SplitOrderedList { const int MaxLoad = 5; const uint BucketSize = 512; static readonly byte[] ReverseTable = { 0, 128, 64, 192, 32, 160, 96, 224, 16, 144, 80, 208, 48, 176, 112, 240, 8, 136, 72, 200, 40, 168, 104, 232, 24, 152, 88, 216, 56, 184, 120, 248, 4, 132, 68, 196, 36, 164, 100, 228, 20, 148, 84, 212, 52, 180, 116, 244, 12, 140, 76, 204, 44, 172, 108, 236, 28, 156, 92, 220, 60, 188, 124, 252, 2, 130, 66, 194, 34, 162, 98, 226, 18, 146, 82, 210, 50, 178, 114, 242, 10, 138, 74, 202, 42, 170, 106, 234, 26, 154, 90, 218, 58, 186, 122, 250, 6, 134, 70, 198, 38, 166, 102, 230, 22, 150, 86, 214, 54, 182, 118, 246, 14, 142, 78, 206, 46, 174, 110, 238, 30, 158, 94, 222, 62, 190, 126, 254, 1, 129, 65, 193, 33, 161, 97, 225, 17, 145, 81, 209, 49, 177, 113, 241, 9, 137, 73, 201, 41, 169, 105, 233, 25, 153, 89, 217, 57, 185, 121, 249, 5, 133, 69, 197, 37, 165, 101, 229, 21, 149, 85, 213, 53, 181, 117, 245, 13, 141, 77, 205, 45, 173, 109, 237, 29, 157, 93, 221, 61, 189, 125, 253, 3, 131, 67, 195, 35, 163, 99, 227, 19, 147, 83, 211, 51, 179, 115, 243, 11, 139, 75, 203, 43, 171, 107, 235, 27, 155, 91, 219, 59, 187, 123, 251, 7, 135, 71, 199, 39, 167, 103, 231, 23, 151, 87, 215, 55, 183, 119, 247, 15, 143, 79, 207, 47, 175, 111, 239, 31, 159, 95, 223, 63, 191, 127, 255 }; static readonly byte[] LogTable = { 0xFF, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 }; readonly IEqualityComparer _comparer; readonly Node _head; readonly Node _tail; Node[] _buckets = new Node[BucketSize]; int _count; int _size = 2; SimpleRwLock _slim = new SimpleRwLock(); public SplitOrderedList(IEqualityComparer comparer) { _comparer = comparer; _head = new Node().Init(0); _tail = new Node().Init(ulong.MaxValue); _head.Next = _tail; SetBucket(0, _head); } public int Count { get { return _count; } } public bool CompareExchange(uint key, TKey subKey, T data, Func check) { Node node; uint b = key % (uint)_size; Node bucket; if ((bucket = GetBucket(b)) == null) bucket = InitializeBucket(b); if (!ListFind(ComputeRegularKey(key), subKey, bucket, out node)) return false; if (!check(node.Data)) return false; node.Data = data; return true; } public bool Delete(uint key, TKey subKey, out T data) { uint b = key % (uint)_size; Node bucket; if ((bucket = GetBucket(b)) == null) bucket = InitializeBucket(b); if (!ListDelete(bucket, ComputeRegularKey(key), subKey, out data)) return false; Interlocked.Decrement(ref _count); return true; } public bool Find(uint key, TKey subKey, out T data) { Node node; uint b = key % (uint)_size; data = default(T); Node bucket; if ((bucket = GetBucket(b)) == null) bucket = InitializeBucket(b); if (!ListFind(ComputeRegularKey(key), subKey, bucket, out node)) return false; data = node.Data; return !node.Marked; } public IEnumerator GetEnumerator() { Node node = _head.Next; while (node != _tail) { while (node.Marked || (node.Key & 1) == 0) { node = node.Next; if (node == _tail) yield break; } yield return node.Data; node = node.Next; } } public bool Insert(uint key, TKey subKey, T data) { Node current; return InsertInternal(key, subKey, data, null, out current); } public T InsertOrGet(uint key, TKey subKey, T data, Func dataCreator) { Node current; InsertInternal(key, subKey, data, dataCreator, out current); return current.Data; } public T InsertOrUpdate(uint key, TKey subKey, Func addGetter, Func updateGetter) { Node current; bool result = InsertInternal(key, subKey, default(T), addGetter, out current); if (result) return current.Data; // FIXME: this should have a CAS-like behavior return current.Data = updateGetter(current.Data); } public T InsertOrUpdate(uint key, TKey subKey, T addValue, T updateValue) { Node current; if (InsertInternal(key, subKey, addValue, null, out current)) return current.Data; // FIXME: this should have a CAS-like behavior return current.Data = updateValue; } // When we run out of space for bucket storage, we use a lock-based array resize void CheckSegment(uint segment, bool readLockTaken) { if (segment < _buckets.Length) return; if (readLockTaken) _slim.ExitReadLock(); try { _slim.EnterWriteLock(); while (segment >= _buckets.Length) Array.Resize(ref _buckets, _buckets.Length * 2); } finally { _slim.ExitWriteLock(); } if (readLockTaken) _slim.EnterReadLock(); } // Reverse integer bits static ulong ComputeDummyKey(uint key) { return (ulong)(((uint)ReverseTable[key & 0xff] << 24) | ((uint)ReverseTable[(key >> 8) & 0xff] << 16) | ((uint)ReverseTable[(key >> 16) & 0xff] << 8) | ReverseTable[(key >> 24) & 0xff]) << 1; } // Reverse integer bits and make sure LSB is set static ulong ComputeRegularKey(uint key) { return ComputeDummyKey(key) | 1; } // Bucket storage is abstracted in a simple two-layer tree to avoid too much memory resize Node GetBucket(uint index) { if (index >= _buckets.Length) return null; return _buckets[index]; } // Turn v's MSB off static uint GetParent(uint v) { uint t, tt; // Find MSB position in v int pos = (tt = v >> 16) > 0 ? (t = tt >> 8) > 0 ? 24 + LogTable[t] : 16 + LogTable[tt] : (t = v >> 8) > 0 ? 8 + LogTable[t] : LogTable[v]; return (uint)(v & ~(1 << pos)); } Node InitializeBucket(uint b) { Node current; uint parent = GetParent(b); Node bucket; if ((bucket = GetBucket(parent)) == null) bucket = InitializeBucket(parent); Node dummy = new Node().Init(ComputeDummyKey(b)); if (!ListInsert(dummy, bucket, out current, null)) return current; return SetBucket(b, dummy); } bool InsertInternal(uint key, TKey subKey, T data, Func dataCreator, out Node current) { Node node = new Node().Init(ComputeRegularKey(key), subKey, data); uint b = key % (uint)_size; Node bucket; if ((bucket = GetBucket(b)) == null) bucket = InitializeBucket(b); if (!ListInsert(node, bucket, out current, dataCreator)) return false; int csize = _size; if (Interlocked.Increment(ref _count) / csize > MaxLoad && (csize & 0x40000000) == 0) Interlocked.CompareExchange(ref _size, 2 * csize, csize); current = node; return true; } bool ListDelete(Node startPoint, ulong key, TKey subKey, out T data) { Node rightNode = null, rightNodeNext = null, leftNode = null; data = default(T); Node markedNode = null; do { rightNode = ListSearch(key, subKey, ref leftNode, startPoint); if (rightNode == _tail || rightNode.Key != key || !_comparer.Equals(subKey, rightNode.SubKey)) return false; data = rightNode.Data; rightNodeNext = rightNode.Next; if (!rightNodeNext.Marked) { if (markedNode == null) markedNode = new Node(); markedNode.Init(rightNodeNext); if (Interlocked.CompareExchange(ref rightNode.Next, markedNode, rightNodeNext) == rightNodeNext) break; } } while (true); if (Interlocked.CompareExchange(ref leftNode.Next, rightNodeNext, rightNode) != rightNode) ListSearch(rightNode.Key, subKey, ref leftNode, startPoint); return true; } bool ListFind(ulong key, TKey subKey, Node startPoint, out Node data) { Node rightNode = null, leftNode = null; data = null; rightNode = ListSearch(key, subKey, ref leftNode, startPoint); data = rightNode; return rightNode != _tail && rightNode.Key == key && _comparer.Equals(subKey, rightNode.SubKey); } bool ListInsert(Node newNode, Node startPoint, out Node current, Func dataCreator) { ulong key = newNode.Key; Node rightNode = null, leftNode = null; do { rightNode = current = ListSearch(key, newNode.SubKey, ref leftNode, startPoint); if (rightNode != _tail && rightNode.Key == key && _comparer.Equals(newNode.SubKey, rightNode.SubKey)) return false; newNode.Next = rightNode; if (dataCreator != null) newNode.Data = dataCreator(); if (Interlocked.CompareExchange(ref leftNode.Next, newNode, rightNode) == rightNode) return true; } while (true); } Node ListSearch(ulong key, TKey subKey, ref Node left, Node h) { Node leftNodeNext = null, rightNode = null; do { Node t = h; Node tNext = t.Next; do { if (!tNext.Marked) { left = t; leftNodeNext = tNext; } t = tNext.Marked ? tNext.Next : tNext; if (t == _tail) break; tNext = t.Next; } while (tNext.Marked || t.Key < key || (tNext.Key == key && !_comparer.Equals(subKey, t.SubKey))); rightNode = t; if (leftNodeNext == rightNode) { if (rightNode != _tail && rightNode.Next.Marked) continue; return rightNode; } if (Interlocked.CompareExchange(ref left.Next, rightNode, leftNodeNext) == leftNodeNext) { if (rightNode != _tail && rightNode.Next.Marked) continue; return rightNode; } } while (true); } Node SetBucket(uint index, Node node) { try { _slim.EnterReadLock(); CheckSegment(index, true); Interlocked.CompareExchange(ref _buckets[index], node, null); return _buckets[index]; } finally { _slim.ExitReadLock(); } } class Node { public T Data; public ulong Key; public bool Marked; public Node Next; public TKey SubKey; public Node Init(ulong key, TKey subKey, T data) { Key = key; SubKey = subKey; Data = data; Marked = false; Next = null; return this; } // Used to create dummy node public Node Init(ulong key) { Key = key; Data = default(T); Next = null; Marked = false; SubKey = default(TKey); return this; } // Used to create marked node public Node Init(Node wrapped) { Marked = true; Next = wrapped; Key = 0; Data = default(T); SubKey = default(TKey); return this; } } struct SimpleRwLock { const int RwWait = 1; const int RwWrite = 2; const int RwRead = 4; int _rwlock; public void EnterReadLock() { var sw = new SpinWait(); do { while ((_rwlock & (RwWrite | RwWait)) > 0) sw.SpinOnce(); if ((Interlocked.Add(ref _rwlock, RwRead) & (RwWait | RwWait)) == 0) return; Interlocked.Add(ref _rwlock, -RwRead); } while (true); } public void ExitReadLock() { Interlocked.Add(ref _rwlock, -RwRead); } public void EnterWriteLock() { var sw = new SpinWait(); do { int state = _rwlock; if (state < RwWrite) { if (Interlocked.CompareExchange(ref _rwlock, RwWrite, state) == state) return; state = _rwlock; } // We register our interest in taking the Write lock (if upgradeable it's already done) while ((state & RwWait) == 0 && Interlocked.CompareExchange(ref _rwlock, state | RwWait, state) != state) state = _rwlock; // Before falling to sleep while (_rwlock > RwWait) sw.SpinOnce(); } while (true); } public void ExitWriteLock() { Interlocked.Add(ref _rwlock, -RwWrite); } } } }