378 lines
12 KiB
C#
378 lines
12 KiB
C#
/*************************************************************************
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* ModernUO *
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* Copyright 2019-2020 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: Pipe.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System;
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using System.Buffers;
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using System.Runtime.CompilerServices;
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using System.Threading;
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namespace Server.Network
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{
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public interface IPipeTask<T> : INotifyCompletion
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{
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public IPipeTask<T> GetAwaiter();
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public bool IsCompleted { get; }
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public T GetResult();
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public void OnCompleted(Action continuation);
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}
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public class Pipe<T>
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{
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public readonly struct Result
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{
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public bool Closed { get; }
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public Result(bool closed) => Closed = closed;
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}
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public class PipeWriter<T>
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{
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private readonly Pipe<T> _pipe;
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public PipeWriter(Pipe<T> pipe) => _pipe = pipe;
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public bool GetAvailable(ArraySegment<T>[] segments)
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{
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var read = _pipe._readIdx;
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var write = _pipe._writeIdx;
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if (read <= write)
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{
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var readZero = read == 0;
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var sz = _pipe.Size - write - (readZero ? 1 : 0);
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segments[0] = sz == 0 ? ArraySegment<T>.Empty : new ArraySegment<T>(_pipe._buffer, (int)write, (int)sz);
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segments[1] = readZero ? ArraySegment<T>.Empty : new ArraySegment<T>(_pipe._buffer, 0, (int)read - 1);
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}
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else
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{
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var sz = read - write - 1;
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segments[0] = sz == 0 ? ArraySegment<T>.Empty : new ArraySegment<T>(_pipe._buffer, (int)write, (int)sz);
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segments[1] = ArraySegment<T>.Empty;
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}
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return !_pipe._closed;
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public bool GetAvailable(out CircularBuffer<T> buffer)
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{
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var read = _pipe._readIdx;
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var write = _pipe._writeIdx;
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Span<T> first;
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Span<T> second;
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if (read <= write)
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{
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var readZero = read == 0;
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var sz = _pipe.Size - write - (readZero ? 1 : 0);
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first = sz == 0 ? Span<T>.Empty : _pipe._buffer.AsSpan((int)write, (int)sz);
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second = readZero ? Span<T>.Empty : _pipe._buffer.AsSpan(0, (int)read - 1);
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}
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else
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{
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var sz = read - write - 1;
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first = sz == 0 ? Span<T>.Empty : _pipe._buffer.AsSpan((int)write, (int)sz);
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second = Span<T>.Empty;
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}
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buffer = new CircularBuffer<T>(first, second);
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return !_pipe._closed;
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}
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public void Advance(uint count)
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{
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var read = _pipe._readIdx;
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var write = _pipe._writeIdx;
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if (count == 0)
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{
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return;
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}
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if (count > _pipe.Size - 1)
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{
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throw new InvalidOperationException();
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}
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if (read <= write)
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{
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if (count > read + _pipe.Size - write - 1)
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{
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throw new InvalidOperationException();
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}
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var sz = Math.Min(count, _pipe.Size - write);
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write += sz;
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if (write > _pipe.Size - 1)
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{
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write = 0;
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}
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count -= sz;
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if (count > 0)
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{
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if (count >= read)
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{
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throw new InvalidOperationException();
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}
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write = count;
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}
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}
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else
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{
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if (count > read - write - 1)
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{
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throw new InvalidOperationException();
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}
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write += count;
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}
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// It's never valid to advance the write pointer to become equal to
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// the read pointer. Check that here.
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if (write == read)
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{
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throw new InvalidOperationException("Write index equals read index after advance");
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}
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_pipe._writeIdx = write;
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}
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public void Close()
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{
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_pipe._closed = true;
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Flush();
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}
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public void Flush()
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{
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var waiting = _pipe._awaitBeginning;
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if (!waiting)
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{
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return;
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}
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Action continuation;
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do
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{
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continuation = _pipe._readerContinuation;
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} while (continuation == null);
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_pipe._readerContinuation = null;
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_pipe._awaitBeginning = false;
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ThreadPool.UnsafeQueueUserWorkItem(state => continuation(), true);
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}
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}
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public class PipeReader<T> : IPipeTask<Result>
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{
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private readonly Pipe<T> _pipe;
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internal PipeReader(Pipe<T> pipe) => _pipe = pipe;
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public uint GetAvailable()
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{
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var read = _pipe._readIdx;
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var write = _pipe._writeIdx;
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if (read <= write)
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{
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return write - read;
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}
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return write + _pipe.Size - read;
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}
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private ArraySegment<T>[] _segments;
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public IPipeTask<Result> Read(ArraySegment<T>[] segments)
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{
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if (_pipe._awaitBeginning)
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{
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throw new Exception("Double await on reader");
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}
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_segments = segments;
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return this;
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public bool TryRead(out CircularBuffer<T> buffer)
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{
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var read = _pipe._readIdx;
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var write = _pipe._writeIdx;
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Span<T> first;
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Span<T> second;
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if (read <= write)
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{
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first = write - read == 0 ? Span<T>.Empty : _pipe._buffer.AsSpan((int)read, (int)(write - read));
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second = Span<T>.Empty;
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}
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else
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{
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first = _pipe.Size - read == 0 ? Span<T>.Empty : _pipe._buffer.AsSpan((int)read, (int)(_pipe.Size - read));
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second = write == 0 ? Span<T>.Empty : _pipe._buffer.AsSpan(0, (int)write);
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}
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buffer = new CircularBuffer<T>(first, second);
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return !_pipe._closed;
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public void TryRead(ArraySegment<T>[] segments)
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{
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var read = _pipe._readIdx;
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var write = _pipe._writeIdx;
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if (read <= write)
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{
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segments[0] = write - read == 0 ? ArraySegment<T>.Empty : new ArraySegment<T>(_pipe._buffer, (int)read, (int)(write - read));
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segments[1] = ArraySegment<T>.Empty;
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}
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else
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{
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segments[0] = _pipe.Size - read == 0 ? ArraySegment<T>.Empty : new ArraySegment<T>(_pipe._buffer, (int)read, (int)(_pipe.Size - read));
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segments[1] = write == 0 ? ArraySegment<T>.Empty : new ArraySegment<T>(_pipe._buffer, 0, (int)write);
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}
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}
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public void Advance(uint count)
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{
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var read = _pipe._readIdx;
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var write = _pipe._writeIdx;
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if (read <= write)
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{
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if (count > write - read)
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{
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throw new InvalidOperationException();
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}
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read += count;
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}
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else
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{
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var sz = Math.Min(count, _pipe.Size - read);
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read += sz;
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if (read > _pipe.Size - 1)
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{
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read = 0;
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}
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count -= sz;
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if (count > 0)
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{
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if (count > write)
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{
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throw new InvalidOperationException();
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}
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read = count;
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}
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}
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_pipe._readIdx = read;
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}
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#region Awaitable
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// The following makes it possible to await the reader. Do not use any of this directly.
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public IPipeTask<Result> GetAwaiter() => this;
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public bool IsCompleted
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{
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get
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{
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if (GetAvailable() > 0)
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{
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return true;
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}
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_pipe._awaitBeginning = true;
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return false;
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}
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}
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public Result GetResult()
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{
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if (_pipe._closed)
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{
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_segments = null;
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return new Result(true);
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}
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if (_segments != null)
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{
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TryRead(_segments);
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_segments = null;
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}
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return new Result(false);
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}
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public void OnCompleted(Action continuation) => _pipe._readerContinuation = continuation;
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#endregion
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}
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private readonly T[] _buffer;
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private volatile uint _writeIdx;
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private volatile uint _readIdx;
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private bool _closed;
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public PipeWriter<T> Writer { get; }
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public PipeReader<T> Reader { get; }
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public uint Size => (uint)_buffer.Length;
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public Pipe(T[] buf)
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{
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_buffer = buf;
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_writeIdx = 0;
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_readIdx = 0;
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_closed = false;
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Writer = new PipeWriter<T>(this);
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Reader = new PipeReader<T>(this);
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}
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#region Awaitable
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private volatile bool _awaitBeginning;
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private volatile Action _readerContinuation;
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#endregion
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}
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}
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