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Diffstat (limited to 'Xamarin.Forms.Core/SplitOrderedList.cs')
-rw-r--r-- | Xamarin.Forms.Core/SplitOrderedList.cs | 497 |
1 files changed, 497 insertions, 0 deletions
diff --git a/Xamarin.Forms.Core/SplitOrderedList.cs b/Xamarin.Forms.Core/SplitOrderedList.cs new file mode 100644 index 00000000..6f423210 --- /dev/null +++ b/Xamarin.Forms.Core/SplitOrderedList.cs @@ -0,0 +1,497 @@ +// 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<TKey, T> + { + 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<TKey> _comparer; + + readonly Node _head; + readonly Node _tail; + + Node[] _buckets = new Node[BucketSize]; + int _count; + int _size = 2; + + SimpleRwLock _slim = new SimpleRwLock(); + + public SplitOrderedList(IEqualityComparer<TKey> 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<T, bool> 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<T> 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<T> dataCreator) + { + Node current; + InsertInternal(key, subKey, data, dataCreator, out current); + return current.Data; + } + + public T InsertOrUpdate(uint key, TKey subKey, Func<T> addGetter, Func<T, T> 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<T> 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<T> 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); + } + } + } +}
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