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Added ConcurrentHashSet

tags/1.0-rc
RogueException 9 years ago
parent
89fadb52f6
commit
48dc622fb3
1 changed files with 475 additions and 0 deletions
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      src/Discord.Net/ConcurrentHashSet.cs

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src/Discord.Net/ConcurrentHashSet.cs View File

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using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Threading;

namespace Discord
{
//Based on https://github.com/dotnet/corefx/blob/master/src/System.Collections.Concurrent/src/System/Collections/Concurrent/ConcurrentDictionary.cs
//Copyright (c) .NET Foundation and Contributors
[DebuggerDisplay("Count = {Count}")]
internal class ConcurrentHashSet<T> : IEnumerable<T>
{
private sealed class Tables
{
internal readonly Node[] _buckets;
internal readonly object[] _locks;
internal volatile int[] _countPerLock;

internal Tables(Node[] buckets, object[] locks, int[] countPerLock)
{
_buckets = buckets;
_locks = locks;
_countPerLock = countPerLock;
}
}
private sealed class Node
{
internal readonly T _value;
internal volatile Node _next;
internal readonly int _hashcode;

internal Node(T key, int hashcode, Node next)
{
_value = key;
_next = next;
_hashcode = hashcode;
}
}

private const int DefaultCapacity = 31;
private const int MaxLockNumber = 1024;

private static int GetBucket(int hashcode, int bucketCount)
{
int bucketNo = (hashcode & 0x7fffffff) % bucketCount;
return bucketNo;
}
private static void GetBucketAndLockNo(int hashcode, out int bucketNo, out int lockNo, int bucketCount, int lockCount)
{
bucketNo = (hashcode & 0x7fffffff) % bucketCount;
lockNo = bucketNo % lockCount;
}
private static int DefaultConcurrencyLevel => PlatformHelper.ProcessorCount;

private volatile Tables _tables;
private readonly IEqualityComparer<T> _comparer;
private readonly bool _growLockArray;
private int _budget;

public int Count
{
get
{
int count = 0;

int acquiredLocks = 0;
try
{
AcquireAllLocks(ref acquiredLocks);

for (int i = 0; i < _tables._countPerLock.Length; i++)
count += _tables._countPerLock[i];
}
finally { ReleaseLocks(0, acquiredLocks); }

return count;
}
}
public bool IsEmpty
{
get
{
int acquiredLocks = 0;
try
{
// Acquire all locks
AcquireAllLocks(ref acquiredLocks);

for (int i = 0; i < _tables._countPerLock.Length; i++)
{
if (_tables._countPerLock[i] != 0)
return false;
}
}
finally { ReleaseLocks(0, acquiredLocks); }

return true;
}
}
public ReadOnlyCollection<T> Values
{
get
{
int locksAcquired = 0;
try
{
AcquireAllLocks(ref locksAcquired);
List<T> values = new List<T>();

for (int i = 0; i < _tables._buckets.Length; i++)
{
Node current = _tables._buckets[i];
while (current != null)
{
values.Add(current._value);
current = current._next;
}
}

return new ReadOnlyCollection<T>(values);
}
finally { ReleaseLocks(0, locksAcquired); }
}
}

public ConcurrentHashSet()
: this(DefaultConcurrencyLevel, DefaultCapacity, true, EqualityComparer<T>.Default) { }
public ConcurrentHashSet(int concurrencyLevel, int capacity)
: this(concurrencyLevel, capacity, false, EqualityComparer<T>.Default) { }
public ConcurrentHashSet(IEnumerable<T> collection)
: this(collection, EqualityComparer<T>.Default) { }
public ConcurrentHashSet(IEqualityComparer<T> comparer)
: this(DefaultConcurrencyLevel, DefaultCapacity, true, comparer) { }
public ConcurrentHashSet(IEnumerable<T> collection, IEqualityComparer<T> comparer)
: this(comparer)
{
if (collection == null) throw new ArgumentNullException(nameof(collection));
InitializeFromCollection(collection);
}
public ConcurrentHashSet(int concurrencyLevel, IEnumerable<T> collection, IEqualityComparer<T> comparer)
: this(concurrencyLevel, DefaultCapacity, false, comparer)
{
if (collection == null) throw new ArgumentNullException(nameof(collection));
if (comparer == null) throw new ArgumentNullException(nameof(comparer));
InitializeFromCollection(collection);
}
public ConcurrentHashSet(int concurrencyLevel, int capacity, IEqualityComparer<T> comparer)
: this(concurrencyLevel, capacity, false, comparer) { }
internal ConcurrentHashSet(int concurrencyLevel, int capacity, bool growLockArray, IEqualityComparer<T> comparer)
{
if (concurrencyLevel < 1) throw new ArgumentOutOfRangeException(nameof(concurrencyLevel));
if (capacity < 0) throw new ArgumentOutOfRangeException(nameof(capacity));
if (comparer == null) throw new ArgumentNullException(nameof(comparer));
if (capacity < concurrencyLevel)
capacity = concurrencyLevel;

object[] locks = new object[concurrencyLevel];
for (int i = 0; i < locks.Length; i++)
locks[i] = new object();

int[] countPerLock = new int[locks.Length];
Node[] buckets = new Node[capacity];
_tables = new Tables(buckets, locks, countPerLock);

_comparer = comparer;
_growLockArray = growLockArray;
_budget = buckets.Length / locks.Length;
}
private void InitializeFromCollection(IEnumerable<T> collection)
{
foreach (var value in collection)
{
if (value == null) throw new ArgumentNullException("key");

if (!TryAddInternal(value, _comparer.GetHashCode(value), false))
throw new ArgumentException();
}

if (_budget == 0)
_budget = _tables._buckets.Length / _tables._locks.Length;
}
public bool ContainsKey(T value)
{
if (value == null) throw new ArgumentNullException("key");
return ContainsKeyInternal(value, _comparer.GetHashCode(value));
}
private bool ContainsKeyInternal(T value, int hashcode)
{
Tables tables = _tables;

int bucketNo = GetBucket(hashcode, tables._buckets.Length);
Node n = Volatile.Read(ref tables._buckets[bucketNo]);

while (n != null)
{
if (hashcode == n._hashcode && _comparer.Equals(n._value, value))
return true;
n = n._next;
}
return false;
}

public bool TryAdd(T value)
{
if (value == null) throw new ArgumentNullException("key");
return TryAddInternal(value, _comparer.GetHashCode(value), true);
}
private bool TryAddInternal(T value, int hashcode, bool acquireLock)
{
while (true)
{
int bucketNo, lockNo;

Tables tables = _tables;
GetBucketAndLockNo(hashcode, out bucketNo, out lockNo, tables._buckets.Length, tables._locks.Length);

bool resizeDesired = false;
bool lockTaken = false;
try
{
if (acquireLock)
Monitor.Enter(tables._locks[lockNo], ref lockTaken);

if (tables != _tables)
continue;

Node prev = null;
for (Node node = tables._buckets[bucketNo]; node != null; node = node._next)
{
if (hashcode == node._hashcode && _comparer.Equals(node._value, value))
return false;
prev = node;
}

Volatile.Write(ref tables._buckets[bucketNo], new Node(value, hashcode, tables._buckets[bucketNo]));
checked { tables._countPerLock[lockNo]++; }

if (tables._countPerLock[lockNo] > _budget)
resizeDesired = true;
}
finally
{
if (lockTaken)
Monitor.Exit(tables._locks[lockNo]);
}

if (resizeDesired)
GrowTable(tables);
return true;
}
}

public bool TryRemove(T value)
{
if (value == null) throw new ArgumentNullException("key");
return TryRemoveInternal(value);
}
private bool TryRemoveInternal(T value)
{
int hashcode = _comparer.GetHashCode(value);
while (true)
{
Tables tables = _tables;

int bucketNo, lockNo;
GetBucketAndLockNo(hashcode, out bucketNo, out lockNo, tables._buckets.Length, tables._locks.Length);

lock (tables._locks[lockNo])
{
if (tables != _tables)
continue;

Node prev = null;
for (Node curr = tables._buckets[bucketNo]; curr != null; curr = curr._next)
{
if (hashcode == curr._hashcode && _comparer.Equals(curr._value, value))
{
if (prev == null)
Volatile.Write(ref tables._buckets[bucketNo], curr._next);
else
prev._next = curr._next;

value = curr._value;
tables._countPerLock[lockNo]--;
return true;
}
prev = curr;
}
}

value = default(T);
return false;
}
}
public void Clear()
{
int locksAcquired = 0;
try
{
AcquireAllLocks(ref locksAcquired);

Tables newTables = new Tables(new Node[DefaultCapacity], _tables._locks, new int[_tables._countPerLock.Length]);
_tables = newTables;
_budget = Math.Max(1, newTables._buckets.Length / newTables._locks.Length);
}
finally
{
ReleaseLocks(0, locksAcquired);
}
}
public IEnumerator<T> GetEnumerator()
{
Node[] buckets = _tables._buckets;

for (int i = 0; i < buckets.Length; i++)
{
Node current = Volatile.Read(ref buckets[i]);

while (current != null)
{
yield return current._value;
current = current._next;
}
}
}
IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();

private void GrowTable(Tables tables)
{
const int MaxArrayLength = 0X7FEFFFFF;
int locksAcquired = 0;
try
{
AcquireLocks(0, 1, ref locksAcquired);
if (tables != _tables)
return;

long approxCount = 0;
for (int i = 0; i < tables._countPerLock.Length; i++)
approxCount += tables._countPerLock[i];

if (approxCount < tables._buckets.Length / 4)
{
_budget = 2 * _budget;
if (_budget < 0)
_budget = int.MaxValue;
return;
}

int newLength = 0;
bool maximizeTableSize = false;
try
{
checked
{
newLength = tables._buckets.Length * 2 + 1;
while (newLength % 3 == 0 || newLength % 5 == 0 || newLength % 7 == 0)
newLength += 2;

if (newLength > MaxArrayLength)
maximizeTableSize = true;
}
}
catch (OverflowException)
{
maximizeTableSize = true;
}

if (maximizeTableSize)
{
newLength = MaxArrayLength;
_budget = int.MaxValue;
}

AcquireLocks(1, tables._locks.Length, ref locksAcquired);

object[] newLocks = tables._locks;

if (_growLockArray && tables._locks.Length < MaxLockNumber)
{
newLocks = new object[tables._locks.Length * 2];
Array.Copy(tables._locks, 0, newLocks, 0, tables._locks.Length);
for (int i = tables._locks.Length; i < newLocks.Length; i++)
newLocks[i] = new object();
}

Node[] newBuckets = new Node[newLength];
int[] newCountPerLock = new int[newLocks.Length];

for (int i = 0; i < tables._buckets.Length; i++)
{
Node current = tables._buckets[i];
while (current != null)
{
Node next = current._next;
int newBucketNo, newLockNo;
GetBucketAndLockNo(current._hashcode, out newBucketNo, out newLockNo, newBuckets.Length, newLocks.Length);

newBuckets[newBucketNo] = new Node(current._value, current._hashcode, newBuckets[newBucketNo]);

checked { newCountPerLock[newLockNo]++; }

current = next;
}
}

_budget = Math.Max(1, newBuckets.Length / newLocks.Length);
_tables = new Tables(newBuckets, newLocks, newCountPerLock);
}
finally { ReleaseLocks(0, locksAcquired); }
}

private void AcquireAllLocks(ref int locksAcquired)
{
AcquireLocks(0, 1, ref locksAcquired);
AcquireLocks(1, _tables._locks.Length, ref locksAcquired);
}
private void AcquireLocks(int fromInclusive, int toExclusive, ref int locksAcquired)
{
object[] locks = _tables._locks;

for (int i = fromInclusive; i < toExclusive; i++)
{
bool lockTaken = false;
try
{
Monitor.Enter(locks[i], ref lockTaken);
}
finally
{
if (lockTaken)
locksAcquired++;
}
}
}
private void ReleaseLocks(int fromInclusive, int toExclusive)
{
for (int i = fromInclusive; i < toExclusive; i++)
Monitor.Exit(_tables._locks[i]);
}
}

//https://github.com/dotnet/corefx/blob/d0dc5fc099946adc1035b34a8b1f6042eddb0c75/src/System.Threading.Tasks.Parallel/src/System/Threading/PlatformHelper.cs
//Copyright (c) .NET Foundation and Contributors
internal static class PlatformHelper
{
private const int PROCESSOR_COUNT_REFRESH_INTERVAL_MS = 30000;
private static volatile int s_processorCount;
private static volatile int s_lastProcessorCountRefreshTicks;
internal static int ProcessorCount
{
get
{
int now = Environment.TickCount;
if (s_processorCount == 0 || (now - s_lastProcessorCountRefreshTicks) >= PROCESSOR_COUNT_REFRESH_INTERVAL_MS)
{
s_processorCount = Environment.ProcessorCount;
s_lastProcessorCountRefreshTicks = now;
}

return s_processorCount;
}
}
}
}

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