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Lock optimisation through semaphore pooling #54

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Lock optimisation through semaphore pooling #54

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25 changes: 3 additions & 22 deletions FolderSyncNet.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,9 @@
<Reference Include="AsyncEnumerable, Version=4.0.2.0, Culture=neutral, PublicKeyToken=0426b068161bd1d1, processorArchitecture=MSIL">
<HintPath>packages\AsyncEnumerator.4.0.2\lib\net461\AsyncEnumerable.dll</HintPath>
</Reference>
<Reference Include="AsyncKeyedLock, Version=6.4.2.0, Culture=neutral, PublicKeyToken=c6dde91429ba0f2f, processorArchitecture=MSIL">
<HintPath>packages\AsyncKeyedLock.6.4.2\lib\netstandard2.0\AsyncKeyedLock.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Bcl.AsyncInterfaces, Version=7.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>packages\Microsoft.Bcl.AsyncInterfaces.7.0.0\lib\net462\Microsoft.Bcl.AsyncInterfaces.dll</HintPath>
</Reference>
Expand Down Expand Up @@ -329,31 +332,9 @@
<None Include="app.manifest">
<SubType>Designer</SubType>
</None>
<None Include="appsettings.debug6.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
<None Include="appsettings.debug2.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
<None Include="appsettings.debug7.json" />
<None Include="appsettings.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
<None Include="appsettings.prev.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
<None Include="appsettings.debug5.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
<None Include="appsettings.example.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
<None Include="appsettings.debug3.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
<None Include="appsettings.ipcam.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
<None Include="FolderSync.bat">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
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2 changes: 1 addition & 1 deletion InitialScan.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -242,7 +242,7 @@ private static IAsyncEnumerable<FileInfo> ProcessSubDirs(FolderSyncNetSource.Dir
var historyFileInfosDict = new Dictionary<string, CachedFileInfo>();
//var historyFileInfosTask = Task.CompletedTask;

AsyncLockQueueDictionary<string>.LockDictReleaser destOrHistoryDirCacheLock = null;
IDisposable destOrHistoryDirCacheLock = null;
//AsyncLockQueueDictionary<string>.LockDictReleaser historyDirCacheLock = null;

FileInfo[] fileInfos = null;
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129 changes: 16 additions & 113 deletions Synchronisation.cs
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Expand Up @@ -7,141 +7,43 @@
//

#define ASYNC
using AsyncKeyedLock;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using Nito.AsyncEx;

namespace FolderSync
{
public class AsyncLockQueueDictionary<KeyT>
where KeyT : IComparable<KeyT>, IEquatable<KeyT>
{
private static readonly bool IsStringDictionary = typeof(KeyT) == typeof(string);

private readonly object DictionaryAccessMutex = new object();
//private readonly SemaphoreSlim DictionaryAccessMutex = new SemaphoreSlim(1, 1);
private readonly Dictionary<KeyT, AsyncLockWithWaiterCount> LockQueueDictionary = new Dictionary<KeyT, AsyncLockWithWaiterCount>();

public sealed class AsyncLockWithWaiterCount
private readonly AsyncKeyedLocker<KeyT> LockQueueDictionary = new AsyncKeyedLocker<KeyT>(o =>
{
public readonly AsyncLock LockEntry;
#pragma warning disable S1104 //Warning S1104 Make this field 'private' and encapsulate it in a 'public' property.
public int WaiterCount;
#pragma warning restore S1104

public AsyncLockWithWaiterCount()
{
this.LockEntry = new AsyncLock();
this.WaiterCount = 1;
}
}
o.PoolSize = 20;
o.PoolInitialFill = 1;
});

public sealed class LockDictReleaser : IDisposable //TODO: implement IAsyncDisposable in .NET 5.0
{
private readonly KeyT Name;
private readonly AsyncLockWithWaiterCount LockEntry;
#if !NOASYNC
private readonly IDisposable LockHandle;
#endif
private readonly AsyncLockQueueDictionary<KeyT> AsyncLockQueueDictionary;

#if NOASYNC
internal LockDictReleaser(KeyT name, AsyncLockWithWaiterCount lockEntry, AsyncLockQueueDictionary<KeyT> asyncLockQueueDictionary)
#else
internal LockDictReleaser(KeyT name, AsyncLockWithWaiterCount lockEntry, IDisposable lockHandle, AsyncLockQueueDictionary<KeyT> asyncLockQueueDictionary)
#endif
{
this.Name = name;
this.LockEntry = lockEntry;
#if !NOASYNC
this.LockHandle = lockHandle;
#endif
this.AsyncLockQueueDictionary = asyncLockQueueDictionary;
}

public void Dispose()
{
#if NOASYNC
this.AsyncLockQueueDictionary.ReleaseLock(this.Name, this.LockEntry);
#else
this.AsyncLockQueueDictionary.ReleaseLock(this.Name, this.LockEntry, this.LockHandle);
#endif
}
}
private static readonly bool IsStringDictionary = typeof(KeyT) == typeof(string);

#if NOASYNC
private void ReleaseLock(KeyT name, AsyncLockWithWaiterCount lockEntry)
#else
private void ReleaseLock(KeyT name, AsyncLockWithWaiterCount lockEntry, IDisposable lockHandle)
#endif
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public async ValueTask<IDisposable> LockAsync(KeyT name)
{
#if NOASYNC
Monitor.Exit(lockEntry.LockEntry);
#else
lockHandle.Dispose();
#endif

lock (DictionaryAccessMutex)
//DictionaryAccessMutex.Wait();
//try
{
lockEntry.WaiterCount--;
Debug.Assert(lockEntry.WaiterCount >= 0);

if (lockEntry.WaiterCount == 0) //NB!
{
LockQueueDictionary.Remove(name);
}
}
//finally
//{
// DictionaryAccessMutex.Release();
//}
return await LockQueueDictionary.LockAsync(name).ConfigureAwait(false);
}

public async Task<LockDictReleaser> LockAsync(KeyT name, CancellationToken cancellationToken = default(CancellationToken))
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public async ValueTask<IDisposable> LockAsync(KeyT name, CancellationToken cancellationToken)
{
AsyncLockWithWaiterCount lockEntry;
#pragma warning disable PH_S023 //Message PH_S023 Using the blocking synchronization mechanics of a monitor inside an async method is discouraged; use SemaphoreSlim instead.
lock (DictionaryAccessMutex)
#pragma warning restore PH_S023
//await DictionaryAccessMutex.WaitAsync(cancellationToken);
//try
{
if (!LockQueueDictionary.TryGetValue(name, out lockEntry))
{
lockEntry = new AsyncLockWithWaiterCount();
LockQueueDictionary.Add(name, lockEntry);
}
else
{
lockEntry.WaiterCount++; //NB! must be done inside the lock and BEFORE waiting for the lock
}
}
//finally
//{
// DictionaryAccessMutex.Release();
//}

#if NOASYNC
#pragma warning disable PH_P006 //warning PH_P006 Favor the use of the lock-statement instead of the use of Monitor.Enter when no timeouts are needed.
Monitor.Enter(lockEntry.LockEntry);
#pragma warning restore PH_P006
return new LockDictReleaser(name, lockEntry, this);
#else
var lockHandle = await lockEntry.LockEntry.LockAsync(cancellationToken);
return new LockDictReleaser(name, lockEntry, lockHandle, this);
#endif
return await LockQueueDictionary.LockAsync(name, cancellationToken).ConfigureAwait(false);
}

public sealed class MultiLockDictReleaser : IDisposable //TODO: implement IAsyncDisposable in .NET 5.0
{
private readonly LockDictReleaser[] Releasers;
private readonly IDisposable[] Releasers;

public MultiLockDictReleaser(params LockDictReleaser[] releasers)
public MultiLockDictReleaser(params IDisposable[] releasers)
{
this.Releasers = releasers;
}
Expand All @@ -156,6 +58,7 @@ public void Dispose()
}
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
public async Task<MultiLockDictReleaser> LockAsync(KeyT name1, KeyT name2, CancellationToken cancellationToken = default(CancellationToken))
{
var names = new List<KeyT>()
Expand Down
1 change: 1 addition & 0 deletions packages.config
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
<package id="AlphaVSS" version="2.0.0" targetFramework="net48" />
<package id="AlphaVSS.Native.NetFx" version="2.0.0" targetFramework="net48" />
<package id="AsyncEnumerator" version="4.0.2" targetFramework="net48" />
<package id="AsyncKeyedLock" version="6.4.2" targetFramework="net48" />
<package id="Microsoft.Bcl.AsyncInterfaces" version="7.0.0" targetFramework="net48" />
<package id="Microsoft.Extensions.Configuration" version="7.0.0" targetFramework="net48" />
<package id="Microsoft.Extensions.Configuration.Abstractions" version="7.0.0" targetFramework="net48" />
Expand Down