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Memoize Keccaks #7333

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Memoize Keccaks #7333

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9845360
Keccak memoize
benaadams Aug 15, 2024
1de1eeb
Reduce ClockCache contention
benaadams Aug 15, 2024
efc9c2c
More variance in Bytes GetHashCode
benaadams Aug 15, 2024
4d15fa7
Feedback
benaadams Aug 15, 2024
597c7bd
Also do storage keys
benaadams Aug 16, 2024
3bc29e7
formatting
benaadams Aug 16, 2024
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12 changes: 9 additions & 3 deletions src/Nethermind/Nethermind.Core/Caching/ClockCache.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;

using Nethermind.Core.Threading;
Expand Down Expand Up @@ -74,7 +75,8 @@ private bool SetSlow(TKey key, TValue val)
return false;
}

int offset = _cacheMap.Count;
int offset = _count;
Debug.Assert(_cacheMap.Count == _count);
if (FreeOffsets.Count > 0)
{
offset = FreeOffsets.Dequeue();
Expand All @@ -86,14 +88,16 @@ private bool SetSlow(TKey key, TValue val)

_cacheMap[key] = new LruCacheItem(offset, val);
KeyToOffset[offset] = key;
_count++;
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Debug.Assert(_cacheMap.Count == _count);

return true;
}

private int Replace(TKey key)
{
int position = Clock;
int max = _cacheMap.Count;
int max = _count;
while (true)
{
if (position >= max)
Expand All @@ -108,6 +112,7 @@ private int Replace(TKey key)
{
ThrowInvalidOperationException();
}
_count--;
break;
}

Expand All @@ -132,6 +137,7 @@ public bool Delete(TKey key)

if (_cacheMap.Remove(key, out LruCacheItem? ov))
{
_count--;
KeyToOffset[ov.Offset] = default;
ClearAccessed(ov.Offset);
FreeOffsets.Enqueue(ov.Offset);
Expand All @@ -157,7 +163,7 @@ public bool Contains(TKey key)
return _cacheMap.ContainsKey(key);
}

public int Count => _cacheMap.Count;
public int Count => _count;

private class LruCacheItem(int offset, TValue v)
{
Expand Down
3 changes: 3 additions & 0 deletions src/Nethermind/Nethermind.Core/Caching/ClockCacheBase.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ public abstract class ClockCacheBase<TKey>
protected Queue<int> FreeOffsets { get; } = new();

protected int Clock { get; set; } = 0;
// Use local count to avoid lock contention with reads on ConcurrentDictionary.Count
protected int _count = 0;

protected ClockCacheBase(int maxCapacity)
{
Expand All @@ -35,6 +37,7 @@ protected void Clear()
{
if (MaxCapacity == 0) return;

_count = 0;
Clock = 0;
FreeOffsets.Clear();
KeyToOffset.AsSpan().Clear();
Expand Down
12 changes: 9 additions & 3 deletions src/Nethermind/Nethermind.Core/Caching/ClockKeyCache.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;

using Nethermind.Core.Threading;
Expand Down Expand Up @@ -51,7 +52,8 @@ private bool SetSlow(TKey key)
return false;
}

offset = _cacheMap.Count;
offset = _count;
Debug.Assert(_cacheMap.Count == _count);
if (FreeOffsets.Count > 0)
{
offset = FreeOffsets.Dequeue();
Expand All @@ -63,14 +65,16 @@ private bool SetSlow(TKey key)

_cacheMap[key] = offset;
KeyToOffset[offset] = key;
_count++;
Debug.Assert(_cacheMap.Count == _count);

return true;
}

private int Replace(TKey key)
{
int position = Clock;
int max = _cacheMap.Count;
int max = _count;
while (true)
{
if (position >= max)
Expand All @@ -85,6 +89,7 @@ private int Replace(TKey key)
{
ThrowInvalidOperationException();
}
_count--;
break;
}

Expand All @@ -108,6 +113,7 @@ public bool Delete(TKey key)

if (_cacheMap.Remove(key, out int offset))
{
_count--;
ClearAccessed(offset);
FreeOffsets.Enqueue(offset);
return true;
Expand All @@ -131,5 +137,5 @@ public bool Contains(TKey key)
return _cacheMap.ContainsKey(key);
}

public int Count => _cacheMap.Count;
public int Count => _count;
}
2 changes: 1 addition & 1 deletion src/Nethermind/Nethermind.Core/Caching/LruCache.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ public LruCache(int maxCapacity, int startCapacity, string name)
_name = name;
_maxCapacity = maxCapacity;
_cacheMap = typeof(TKey) == typeof(byte[])
? new Dictionary<TKey, LinkedListNode<LruCacheItem>>((IEqualityComparer<TKey>)Bytes.EqualityComparer)
? new Dictionary<TKey, LinkedListNode<LruCacheItem>>((IEqualityComparer<TKey>)(object)Bytes.EqualityComparer)
: new Dictionary<TKey, LinkedListNode<LruCacheItem>>(startCapacity); // do not initialize it at the full capacity
}

Expand Down
2 changes: 1 addition & 1 deletion src/Nethermind/Nethermind.Core/Caching/LruKeyCache.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ public LruKeyCache(int maxCapacity, int startCapacity, string name)
_maxCapacity = maxCapacity;
_name = name ?? throw new ArgumentNullException(nameof(name));
_cacheMap = typeof(TKey) == typeof(byte[])
? new Dictionary<TKey, LinkedListNode<TKey>>((IEqualityComparer<TKey>)Bytes.EqualityComparer)
? new Dictionary<TKey, LinkedListNode<TKey>>((IEqualityComparer<TKey>)(object)Bytes.EqualityComparer)
: new Dictionary<TKey, LinkedListNode<TKey>>(startCapacity); // do not initialize it at the full capacity
}

Expand Down
91 changes: 81 additions & 10 deletions src/Nethermind/Nethermind.Core/Crypto/Keccak.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,17 +5,21 @@
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Nethermind.Core.Caching;
using Nethermind.Core.Extensions;

namespace Nethermind.Core.Crypto
{
[DebuggerStepThrough]
[DebuggerDisplay("{ToString()}")]
public static class ValueKeccak
{
private const int MaxCacheLength = 32;
private static readonly HashCache _cache = new();
/// <returns>
/// <string>0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470</string>
/// </returns>
public static readonly ValueHash256 OfAnEmptyString = InternalCompute(Array.Empty<byte>());
public static readonly ValueHash256 OfAnEmptyString = new("0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470");

/// <returns>
/// <string>0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347</string>
Expand Down Expand Up @@ -48,6 +52,17 @@ public static ValueHash256 Compute(string input)
return InternalCompute(System.Text.Encoding.UTF8.GetBytes(input));
}

private readonly struct BytesWrapper(byte[] bytes) : IEquatable<BytesWrapper>
{
internal readonly byte[] _bytes = bytes;
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public static implicit operator BytesWrapper(byte[] bytes) => new(bytes);
public static implicit operator BytesWrapper(ReadOnlySpan<byte> bytes) => new(bytes.ToArray());
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Can we search by Span without allocating first, like in SpanDictionary?

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Not in the regular ConcurrentDictionary; though it should live an die pretty fast in Gen0.

Also another reason to limiting to 32 bytes

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Well it is good I made SpanConcurrentDictionary ]:->

public bool Equals(BytesWrapper other) => Bytes.EqualityComparer.Equals(_bytes, other._bytes);
public override bool Equals(object? obj) => obj is BytesWrapper other && Equals(other);
public override int GetHashCode() => Bytes.EqualityComparer.GetHashCode(_bytes);
}

[SkipLocalsInit]
[DebuggerStepThrough]
public static ValueHash256 Compute(ReadOnlySpan<byte> input)
{
Expand All @@ -56,16 +71,72 @@ public static ValueHash256 Compute(ReadOnlySpan<byte> input)
return OfAnEmptyString;
}

Unsafe.SkipInit(out ValueHash256 keccak);
KeccakHash.ComputeHashBytesToSpan(input, MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref keccak, 1)));
return keccak;
Unsafe.SkipInit(out ValueHash256 hash);
Unsafe.SkipInit(out BytesWrapper cacheKey);
if (input.Length <= MaxCacheLength)
{
cacheKey = input;
if (_cache.TryGet(cacheKey, out hash)) return hash;
}

KeccakHash.ComputeHashBytesToSpan(input, MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref hash, 1)));
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if (input.Length <= MaxCacheLength)
{
_cache.Set(cacheKey, hash);
}
return hash;
}

internal static ValueHash256 InternalCompute(byte[] input)
{
Unsafe.SkipInit(out ValueHash256 keccak);
KeccakHash.ComputeHashBytesToSpan(input, MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref keccak, 1)));
return keccak;
if (input is null || input.Length == 0)
{
return OfAnEmptyString;
}

Unsafe.SkipInit(out ValueHash256 hash);
if (input.Length <= MaxCacheLength && _cache.TryGet(input, out hash))
{
return hash;
}

KeccakHash.ComputeHashBytesToSpan(input, MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref hash, 1)));
if (input.Length <= MaxCacheLength)
{
_cache.Set(input, hash);
}
return hash;
}

private sealed class HashCache
{
private const int CacheCount = 256;
private const int CacheMax = CacheCount - 1;
private readonly ClockCache<BytesWrapper, ValueHash256>[] _caches;
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Quite a lot of objects here 😢


public HashCache()
{
_caches = new ClockCache<BytesWrapper, ValueHash256>[CacheCount];
for (int i = 0; i < _caches.Length; i++)
{
// Cache per nibble to reduce contention as is very parallel
_caches[i] = new ClockCache<BytesWrapper, ValueHash256>(512);
}
}

public bool Set(BytesWrapper bytes, in ValueHash256 hash)
{
ClockCache<BytesWrapper, ValueHash256> cache = _caches[GetCacheIndex(bytes)];
return cache.Set(bytes, hash);
}

private static int GetCacheIndex(BytesWrapper bytes) => bytes._bytes[^1] & CacheMax;

public bool TryGet(BytesWrapper bytes, out ValueHash256 hash)
{
ClockCache<BytesWrapper, ValueHash256> cache = _caches[GetCacheIndex(bytes)];
return cache.TryGet(bytes, out hash);
}
}
}

Expand All @@ -82,17 +153,17 @@ public static class Keccak
/// <returns>
/// <string>0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470</string>
/// </returns>
public static readonly Hash256 OfAnEmptyString = new Hash256(ValueKeccak.InternalCompute(Array.Empty<byte>()));
public static readonly Hash256 OfAnEmptyString = new(ValueKeccak.OfAnEmptyString);

/// <returns>
/// <string>0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347</string>
/// </returns>
public static readonly Hash256 OfAnEmptySequenceRlp = new Hash256(ValueKeccak.InternalCompute([192]));
public static readonly Hash256 OfAnEmptySequenceRlp = new(ValueKeccak.OfAnEmptySequenceRlp);

/// <summary>
/// 0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421
/// </summary>
public static Hash256 EmptyTreeHash = new Hash256(ValueKeccak.InternalCompute([128]));
public static Hash256 EmptyTreeHash = new(ValueKeccak.EmptyTreeHash);

/// <returns>
/// <string>0x0000000000000000000000000000000000000000000000000000000000000000</string>
Expand Down
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