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RecyclableMemoryStream.cs
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RecyclableMemoryStream.cs
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// The MIT License (MIT)
//
// Copyright (c) 2015-2016 Microsoft
//
// 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.
namespace Microsoft.IO
{
using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Threading;
/// <summary>
/// MemoryStream implementation that deals with pooling and managing memory streams which use potentially large
/// buffers.
/// </summary>
/// <remarks>
/// This class works in tandem with the RecyclableMemoryStreamManager to supply MemoryStream
/// objects to callers, while avoiding these specific problems:
/// 1. LOH allocations - since all large buffers are pooled, they will never incur a Gen2 GC
/// 2. Memory waste - A standard memory stream doubles its size when it runs out of room. This
/// leads to continual memory growth as each stream approaches the maximum allowed size.
/// 3. Memory copying - Each time a MemoryStream grows, all the bytes are copied into new buffers.
/// This implementation only copies the bytes when GetBuffer is called.
/// 4. Memory fragmentation - By using homogeneous buffer sizes, it ensures that blocks of memory
/// can be easily reused.
///
/// The stream is implemented on top of a series of uniformly-sized blocks. As the stream's length grows,
/// additional blocks are retrieved from the memory manager. It is these blocks that are pooled, not the stream
/// object itself.
///
/// The biggest wrinkle in this implementation is when GetBuffer() is called. This requires a single
/// contiguous buffer. If only a single block is in use, then that block is returned. If multiple blocks
/// are in use, we retrieve a larger buffer from the memory manager. These large buffers are also pooled,
/// split by size--they are multiples/exponentials of a chunk size (1 MB by default).
///
/// Once a large buffer is assigned to the stream the blocks are NEVER again used for this stream. All operations take place on the
/// large buffer. The large buffer can be replaced by a larger buffer from the pool as needed. All blocks and large buffers
/// are maintained in the stream until the stream is disposed (unless AggressiveBufferReturn is enabled in the stream manager).
///
/// </remarks>
public sealed class RecyclableMemoryStream : MemoryStream
{
private const long MaxStreamLength = Int32.MaxValue;
private static readonly byte[] emptyArray = new byte[0];
/// <summary>
/// All of these blocks must be the same size
/// </summary>
private readonly List<byte[]> blocks = new List<byte[]>(1);
/// <summary>
/// This buffer exists so that WriteByte can forward all of its calls to Write
/// without creating a new byte[] buffer on every call.
/// </summary>
private readonly byte[] byteBuffer = new byte[1];
private readonly Guid id;
private readonly RecyclableMemoryStreamManager memoryManager;
private readonly string tag;
/// <summary>
/// This list is used to store buffers once they're replaced by something larger.
/// This is for the cases where you have users of this class that may hold onto the buffers longer
/// than they should and you want to prevent race conditions which could corrupt the data.
/// </summary>
private List<byte[]> dirtyBuffers;
// long to allow Interlocked.Read (for .NET Standard 1.4 compat)
private long disposedState;
/// <summary>
/// This is only set by GetBuffer() if the necessary buffer is larger than a single block size, or on
/// construction if the caller immediately requests a single large buffer.
/// </summary>
/// <remarks>If this field is non-null, it contains the concatenation of the bytes found in the individual
/// blocks. Once it is created, this (or a larger) largeBuffer will be used for the life of the stream.
/// </remarks>
private byte[] largeBuffer;
/// <summary>
/// Unique identifier for this stream across it's entire lifetime
/// </summary>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
internal Guid Id
{
get
{
this.CheckDisposed();
return this.id;
}
}
/// <summary>
/// A temporary identifier for the current usage of this stream.
/// </summary>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
internal string Tag
{
get
{
this.CheckDisposed();
return this.tag;
}
}
/// <summary>
/// Gets the memory manager being used by this stream.
/// </summary>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
internal RecyclableMemoryStreamManager MemoryManager
{
get
{
this.CheckDisposed();
return this.memoryManager;
}
}
/// <summary>
/// Callstack of the constructor. It is only set if MemoryManager.GenerateCallStacks is true,
/// which should only be in debugging situations.
/// </summary>
internal string AllocationStack { get; }
/// <summary>
/// Callstack of the Dispose call. It is only set if MemoryManager.GenerateCallStacks is true,
/// which should only be in debugging situations.
/// </summary>
internal string DisposeStack { get; private set; }
#region Constructors
/// <summary>
/// Allocate a new RecyclableMemoryStream object.
/// </summary>
/// <param name="memoryManager">The memory manager</param>
public RecyclableMemoryStream(RecyclableMemoryStreamManager memoryManager)
: this(memoryManager, null, 0, null) { }
/// <summary>
/// Allocate a new RecyclableMemoryStream object
/// </summary>
/// <param name="memoryManager">The memory manager</param>
/// <param name="tag">A string identifying this stream for logging and debugging purposes</param>
public RecyclableMemoryStream(RecyclableMemoryStreamManager memoryManager, string tag)
: this(memoryManager, tag, 0, null) { }
/// <summary>
/// Allocate a new RecyclableMemoryStream object
/// </summary>
/// <param name="memoryManager">The memory manager</param>
/// <param name="tag">A string identifying this stream for logging and debugging purposes</param>
/// <param name="requestedSize">The initial requested size to prevent future allocations</param>
public RecyclableMemoryStream(RecyclableMemoryStreamManager memoryManager, string tag, int requestedSize)
: this(memoryManager, tag, requestedSize, null) { }
/// <summary>
/// Allocate a new RecyclableMemoryStream object
/// </summary>
/// <param name="memoryManager">The memory manager</param>
/// <param name="tag">A string identifying this stream for logging and debugging purposes</param>
/// <param name="requestedSize">The initial requested size to prevent future allocations</param>
/// <param name="initialLargeBuffer">An initial buffer to use. This buffer will be owned by the stream and returned to the memory manager upon Dispose.</param>
internal RecyclableMemoryStream(RecyclableMemoryStreamManager memoryManager, string tag, int requestedSize,
byte[] initialLargeBuffer)
: base(emptyArray)
{
this.memoryManager = memoryManager;
this.id = Guid.NewGuid();
this.tag = tag;
if (requestedSize < memoryManager.BlockSize)
{
requestedSize = memoryManager.BlockSize;
}
if (initialLargeBuffer == null)
{
this.EnsureCapacity(requestedSize);
}
else
{
this.largeBuffer = initialLargeBuffer;
}
if (this.memoryManager.GenerateCallStacks)
{
this.AllocationStack = Environment.StackTrace;
}
RecyclableMemoryStreamManager.Events.Writer.MemoryStreamCreated(this.id, this.tag, requestedSize);
this.memoryManager.ReportStreamCreated();
}
#endregion
#region Dispose and Finalize
~RecyclableMemoryStream()
{
this.Dispose(false);
}
/// <summary>
/// Returns the memory used by this stream back to the pool.
/// </summary>
/// <param name="disposing">Whether we're disposing (true), or being called by the finalizer (false)</param>
[SuppressMessage("Microsoft.Usage", "CA1816:CallGCSuppressFinalizeCorrectly",
Justification = "We have different disposal semantics, so SuppressFinalize is in a different spot.")]
protected override void Dispose(bool disposing)
{
if (Interlocked.CompareExchange(ref this.disposedState, 1, 0) != 0)
{
string doubleDisposeStack = null;
if (this.memoryManager.GenerateCallStacks)
{
doubleDisposeStack = Environment.StackTrace;
}
RecyclableMemoryStreamManager.Events.Writer.MemoryStreamDoubleDispose(this.id, this.tag,
this.AllocationStack,
this.DisposeStack,
doubleDisposeStack);
return;
}
RecyclableMemoryStreamManager.Events.Writer.MemoryStreamDisposed(this.id, this.tag);
if (this.memoryManager.GenerateCallStacks)
{
this.DisposeStack = Environment.StackTrace;
}
if (disposing)
{
this.memoryManager.ReportStreamDisposed();
GC.SuppressFinalize(this);
}
else
{
// We're being finalized.
RecyclableMemoryStreamManager.Events.Writer.MemoryStreamFinalized(this.id, this.tag, this.AllocationStack);
#if !NETSTANDARD1_4
if (AppDomain.CurrentDomain.IsFinalizingForUnload())
{
// If we're being finalized because of a shutdown, don't go any further.
// We have no idea what's already been cleaned up. Triggering events may cause
// a crash.
base.Dispose(disposing);
return;
}
#endif
this.memoryManager.ReportStreamFinalized();
}
this.memoryManager.ReportStreamLength(this.length);
if (this.largeBuffer != null)
{
this.memoryManager.ReturnLargeBuffer(this.largeBuffer, this.tag);
}
if (this.dirtyBuffers != null)
{
foreach (var buffer in this.dirtyBuffers)
{
this.memoryManager.ReturnLargeBuffer(buffer, this.tag);
}
}
this.memoryManager.ReturnBlocks(this.blocks, this.tag);
this.blocks.Clear();
base.Dispose(disposing);
}
/// <summary>
/// Equivalent to Dispose
/// </summary>
#if NETSTANDARD1_4
public void Close()
#else
public override void Close()
#endif
{
this.Dispose(true);
}
#endregion
#region MemoryStream overrides
/// <summary>
/// Gets or sets the capacity
/// </summary>
/// <remarks>Capacity is always in multiples of the memory manager's block size, unless
/// the large buffer is in use. Capacity never decreases during a stream's lifetime.
/// Explicitly setting the capacity to a lower value than the current value will have no effect.
/// This is because the buffers are all pooled by chunks and there's little reason to
/// allow stream truncation.
/// </remarks>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override int Capacity
{
get
{
this.CheckDisposed();
if (this.largeBuffer != null)
{
return this.largeBuffer.Length;
}
long size = (long)this.blocks.Count * this.memoryManager.BlockSize;
return (int)Math.Min(int.MaxValue, size);
}
set
{
this.CheckDisposed();
this.EnsureCapacity(value);
}
}
private int length;
/// <summary>
/// Gets the number of bytes written to this stream.
/// </summary>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override long Length
{
get
{
this.CheckDisposed();
return this.length;
}
}
private int position;
/// <summary>
/// Gets the current position in the stream
/// </summary>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override long Position
{
get
{
this.CheckDisposed();
return this.position;
}
set
{
this.CheckDisposed();
if (value < 0)
{
throw new ArgumentOutOfRangeException("value", "value must be non-negative");
}
if (value > MaxStreamLength)
{
throw new ArgumentOutOfRangeException("value", "value cannot be more than " + MaxStreamLength);
}
this.position = (int)value;
}
}
/// <summary>
/// Whether the stream can currently read
/// </summary>
public override bool CanRead => !this.Disposed;
/// <summary>
/// Whether the stream can currently seek
/// </summary>
public override bool CanSeek => !this.Disposed;
/// <summary>
/// Always false
/// </summary>
public override bool CanTimeout => false;
/// <summary>
/// Whether the stream can currently write
/// </summary>
public override bool CanWrite => !this.Disposed;
/// <summary>
/// Returns a single buffer containing the contents of the stream.
/// The buffer may be longer than the stream length.
/// </summary>
/// <returns>A byte[] buffer</returns>
/// <remarks>IMPORTANT: Doing a Write() after calling GetBuffer() invalidates the buffer. The old buffer is held onto
/// until Dispose is called, but the next time GetBuffer() is called, a new buffer from the pool will be required.</remarks>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
#if NETSTANDARD1_4
public byte[] GetBuffer()
#else
public override byte[] GetBuffer()
#endif
{
this.CheckDisposed();
if (this.largeBuffer != null)
{
return this.largeBuffer;
}
if (this.blocks.Count == 1)
{
return this.blocks[0];
}
// Buffer needs to reflect the capacity, not the length, because
// it's possible that people will manipulate the buffer directly
// and set the length afterward. Capacity sets the expectation
// for the size of the buffer.
var newBuffer = this.memoryManager.GetLargeBuffer(this.Capacity, this.tag);
// InternalRead will check for existence of largeBuffer, so make sure we
// don't set it until after we've copied the data.
this.InternalRead(newBuffer, 0, this.length, 0);
this.largeBuffer = newBuffer;
if (this.blocks.Count > 0 && this.memoryManager.AggressiveBufferReturn)
{
this.memoryManager.ReturnBlocks(this.blocks, this.tag);
this.blocks.Clear();
}
return this.largeBuffer;
}
/// <summary>
/// Returns an ArraySegment that wraps a single buffer containing the contents of the stream.
/// </summary>
/// <param name="buffer">An ArraySegment containing a reference to the underlying bytes.</param>
/// <returns>Always returns true.</returns>
/// <remarks>GetBuffer has no failure modes (it always returns something, even if it's an empty buffer), therefore this method
/// always returns a valid ArraySegment to the same buffer returned by GetBuffer.</remarks>
#if NET40 || NET45
public bool TryGetBuffer(out ArraySegment<byte> buffer)
#else
public override bool TryGetBuffer(out ArraySegment<byte> buffer)
#endif
{
this.CheckDisposed();
buffer = new ArraySegment<byte>(this.GetBuffer(), 0, (int)this.Length);
// GetBuffer has no failure modes, so this should always succeed
return true;
}
/// <summary>
/// Returns a new array with a copy of the buffer's contents. You should almost certainly be using GetBuffer combined with the Length to
/// access the bytes in this stream. Calling ToArray will destroy the benefits of pooled buffers, but it is included
/// for the sake of completeness.
/// </summary>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
#pragma warning disable CS0809
[Obsolete("This method has degraded performance vs. GetBuffer and should be avoided.")]
public override byte[] ToArray()
{
this.CheckDisposed();
var newBuffer = new byte[this.Length];
this.InternalRead(newBuffer, 0, this.length, 0);
string stack = this.memoryManager.GenerateCallStacks ? Environment.StackTrace : null;
RecyclableMemoryStreamManager.Events.Writer.MemoryStreamToArray(this.id, this.tag, stack, 0);
this.memoryManager.ReportStreamToArray();
return newBuffer;
}
#pragma warning restore CS0809
/// <summary>
/// Reads from the current position into the provided buffer
/// </summary>
/// <param name="buffer">Destination buffer</param>
/// <param name="offset">Offset into buffer at which to start placing the read bytes.</param>
/// <param name="count">Number of bytes to read.</param>
/// <returns>The number of bytes read</returns>
/// <exception cref="ArgumentNullException">buffer is null</exception>
/// <exception cref="ArgumentOutOfRangeException">offset or count is less than 0</exception>
/// <exception cref="ArgumentException">offset subtracted from the buffer length is less than count</exception>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override int Read(byte[] buffer, int offset, int count)
{
return this.SafeRead(buffer, offset, count, ref this.position);
}
/// <summary>
/// Reads from the specified position into the provided buffer
/// </summary>
/// <param name="buffer">Destination buffer</param>
/// <param name="offset">Offset into buffer at which to start placing the read bytes.</param>
/// <param name="count">Number of bytes to read.</param>
/// <param name="streamPosition">Position in the stream to start reading from</param>
/// <returns>The number of bytes read</returns>
/// <exception cref="ArgumentNullException">buffer is null</exception>
/// <exception cref="ArgumentOutOfRangeException">offset or count is less than 0</exception>
/// <exception cref="ArgumentException">offset subtracted from the buffer length is less than count</exception>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public int SafeRead(byte[] buffer, int offset, int count, ref int streamPosition)
{
this.CheckDisposed();
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
if (offset < 0)
{
throw new ArgumentOutOfRangeException(nameof(offset), "offset cannot be negative");
}
if (count < 0)
{
throw new ArgumentOutOfRangeException(nameof(count), "count cannot be negative");
}
if (offset + count > buffer.Length)
{
throw new ArgumentException("buffer length must be at least offset + count");
}
int amountRead = this.InternalRead(buffer, offset, count, streamPosition);
streamPosition += amountRead;
return amountRead;
}
#if NETCOREAPP2_1 || NETSTANDARD2_1
/// <summary>
/// Reads from the current position into the provided buffer
/// </summary>
/// <param name="buffer">Destination buffer</param>
/// <returns>The number of bytes read</returns>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override int Read(Span<byte> buffer)
{
return this.SafeRead(buffer, ref this.position);
}
/// <summary>
/// Reads from the specified position into the provided buffer
/// </summary>
/// <param name="buffer">Destination buffer</param>
/// <param name="streamPosition">Position in the stream to start reading from</param>
/// <returns>The number of bytes read</returns>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public int SafeRead(Span<byte> buffer, ref int streamPosition)
{
this.CheckDisposed();
int amountRead = this.InternalRead(buffer, streamPosition);
streamPosition += amountRead;
return amountRead;
}
#endif
/// <summary>
/// Writes the buffer to the stream
/// </summary>
/// <param name="buffer">Source buffer</param>
/// <param name="offset">Start position</param>
/// <param name="count">Number of bytes to write</param>
/// <exception cref="ArgumentNullException">buffer is null</exception>
/// <exception cref="ArgumentOutOfRangeException">offset or count is negative</exception>
/// <exception cref="ArgumentException">buffer.Length - offset is not less than count</exception>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override void Write(byte[] buffer, int offset, int count)
{
this.CheckDisposed();
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
if (offset < 0)
{
throw new ArgumentOutOfRangeException(nameof(offset), offset,
"Offset must be in the range of 0 - buffer.Length-1");
}
if (count < 0)
{
throw new ArgumentOutOfRangeException(nameof(count), count, "count must be non-negative");
}
if (count + offset > buffer.Length)
{
throw new ArgumentException("count must be greater than buffer.Length - offset");
}
int blockSize = this.memoryManager.BlockSize;
long end = (long)this.position + count;
// Check for overflow
if (end > MaxStreamLength)
{
throw new IOException("Maximum capacity exceeded");
}
this.EnsureCapacity((int)end);
if (this.largeBuffer == null)
{
int bytesRemaining = count;
int bytesWritten = 0;
var blockAndOffset = this.GetBlockAndRelativeOffset(this.position);
while (bytesRemaining > 0)
{
byte[] currentBlock = this.blocks[blockAndOffset.Block];
int remainingInBlock = blockSize - blockAndOffset.Offset;
int amountToWriteInBlock = Math.Min(remainingInBlock, bytesRemaining);
Buffer.BlockCopy(buffer, offset + bytesWritten, currentBlock, blockAndOffset.Offset,
amountToWriteInBlock);
bytesRemaining -= amountToWriteInBlock;
bytesWritten += amountToWriteInBlock;
++blockAndOffset.Block;
blockAndOffset.Offset = 0;
}
}
else
{
Buffer.BlockCopy(buffer, offset, this.largeBuffer, this.position, count);
}
this.position = (int)end;
this.length = Math.Max(this.position, this.length);
}
#if NETCOREAPP2_1 || NETSTANDARD2_1
/// <summary>
/// Writes the buffer to the stream
/// </summary>
/// <param name="source">Source buffer</param>
/// <exception cref="ArgumentNullException">buffer is null</exception>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override void Write(ReadOnlySpan<byte> source)
{
this.CheckDisposed();
int blockSize = this.memoryManager.BlockSize;
long end = (long)this.position + source.Length;
// Check for overflow
if (end > MaxStreamLength)
{
throw new IOException("Maximum capacity exceeded");
}
this.EnsureCapacity((int)end);
if (this.largeBuffer == null)
{
var blockAndOffset = this.GetBlockAndRelativeOffset(this.position);
while (source.Length > 0)
{
byte[] currentBlock = this.blocks[blockAndOffset.Block];
int remainingInBlock = blockSize - blockAndOffset.Offset;
int amountToWriteInBlock = Math.Min(remainingInBlock, source.Length);
source.Slice(0, amountToWriteInBlock)
.CopyTo(currentBlock.AsSpan(blockAndOffset.Offset));
source = source.Slice(amountToWriteInBlock);
++blockAndOffset.Block;
blockAndOffset.Offset = 0;
}
}
else
{
source.CopyTo(this.largeBuffer.AsSpan(this.position));
}
this.position = (int)end;
this.length = Math.Max(this.position, this.length);
}
#endif
/// <summary>
/// Returns a useful string for debugging. This should not normally be called in actual production code.
/// </summary>
public override string ToString()
{
return $"Id = {this.Id}, Tag = {this.Tag}, Length = {this.Length:N0} bytes";
}
/// <summary>
/// Writes a single byte to the current position in the stream.
/// </summary>
/// <param name="value">byte value to write</param>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override void WriteByte(byte value)
{
this.CheckDisposed();
this.byteBuffer[0] = value;
this.Write(this.byteBuffer, 0, 1);
}
/// <summary>
/// Reads a single byte from the current position in the stream.
/// </summary>
/// <returns>The byte at the current position, or -1 if the position is at the end of the stream.</returns>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override int ReadByte()
{
return this.SafeReadByte(ref this.position);
}
/// <summary>
/// Reads a single byte from the specified position in the stream.
/// </summary>
/// <param name="streamPosition">The position in the stream to read from</param>
/// <returns>The byte at the current position, or -1 if the position is at the end of the stream.</returns>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public int SafeReadByte(ref int streamPosition)
{
this.CheckDisposed();
if (streamPosition == this.length)
{
return -1;
}
byte value;
if (this.largeBuffer == null)
{
var blockAndOffset = this.GetBlockAndRelativeOffset(streamPosition);
value = this.blocks[blockAndOffset.Block][blockAndOffset.Offset];
}
else
{
value = this.largeBuffer[streamPosition];
}
streamPosition++;
return value;
}
/// <summary>
/// Sets the length of the stream
/// </summary>
/// <exception cref="ArgumentOutOfRangeException">value is negative or larger than MaxStreamLength</exception>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
public override void SetLength(long value)
{
this.CheckDisposed();
if (value < 0 || value > MaxStreamLength)
{
throw new ArgumentOutOfRangeException(nameof(value),
"value must be non-negative and at most " + MaxStreamLength);
}
this.EnsureCapacity((int)value);
this.length = (int)value;
if (this.position > value)
{
this.position = (int)value;
}
}
/// <summary>
/// Sets the position to the offset from the seek location
/// </summary>
/// <param name="offset">How many bytes to move</param>
/// <param name="loc">From where</param>
/// <returns>The new position</returns>
/// <exception cref="ObjectDisposedException">Object has been disposed</exception>
/// <exception cref="ArgumentOutOfRangeException">offset is larger than MaxStreamLength</exception>
/// <exception cref="ArgumentException">Invalid seek origin</exception>
/// <exception cref="IOException">Attempt to set negative position</exception>
public override long Seek(long offset, SeekOrigin loc)
{
this.CheckDisposed();
if (offset > MaxStreamLength)
{
throw new ArgumentOutOfRangeException(nameof(offset), "offset cannot be larger than " + MaxStreamLength);
}
int newPosition;
switch (loc)
{
case SeekOrigin.Begin:
newPosition = (int)offset;
break;
case SeekOrigin.Current:
newPosition = (int)offset + this.position;
break;
case SeekOrigin.End:
newPosition = (int)offset + this.length;
break;
default:
throw new ArgumentException("Invalid seek origin", nameof(loc));
}
if (newPosition < 0)
{
throw new IOException("Seek before beginning");
}
this.position = newPosition;
return this.position;
}
/// <summary>
/// Synchronously writes this stream's bytes to the parameter stream.
/// </summary>
/// <param name="stream">Destination stream</param>
/// <remarks>Important: This does a synchronous write, which may not be desired in some situations</remarks>
public override void WriteTo(Stream stream)
{
this.CheckDisposed();
if (stream == null)
{
throw new ArgumentNullException(nameof(stream));
}
if (this.largeBuffer == null)
{
int currentBlock = 0;
int bytesRemaining = this.length;
while (bytesRemaining > 0)
{
int amountToCopy = Math.Min(this.blocks[currentBlock].Length, bytesRemaining);
stream.Write(this.blocks[currentBlock], 0, amountToCopy);
bytesRemaining -= amountToCopy;
++currentBlock;
}
}
else
{
stream.Write(this.largeBuffer, 0, this.length);
}
}
#endregion
#region Helper Methods
private bool Disposed => Interlocked.Read(ref this.disposedState) != 0;
private void CheckDisposed()
{
if (this.Disposed)
{
throw new ObjectDisposedException($"The stream with Id {this.id} and Tag {this.tag} is disposed.");
}
}
private int InternalRead(byte[] buffer, int offset, int count, int fromPosition)
{
if (this.length - fromPosition <= 0)
{
return 0;
}
int amountToCopy;
if (this.largeBuffer == null)
{
var blockAndOffset = this.GetBlockAndRelativeOffset(fromPosition);
int bytesWritten = 0;
int bytesRemaining = Math.Min(count, this.length - fromPosition);
while (bytesRemaining > 0)
{
amountToCopy = Math.Min(this.blocks[blockAndOffset.Block].Length - blockAndOffset.Offset,
bytesRemaining);
Buffer.BlockCopy(this.blocks[blockAndOffset.Block], blockAndOffset.Offset, buffer,
bytesWritten + offset, amountToCopy);
bytesWritten += amountToCopy;
bytesRemaining -= amountToCopy;
++blockAndOffset.Block;
blockAndOffset.Offset = 0;
}
return bytesWritten;
}
amountToCopy = Math.Min(count, this.length - fromPosition);
Buffer.BlockCopy(this.largeBuffer, fromPosition, buffer, offset, amountToCopy);
return amountToCopy;
}
#if NETCOREAPP2_1 || NETSTANDARD2_1
private int InternalRead(Span<byte> buffer, int fromPosition)
{
if (this.length - fromPosition <= 0)
{
return 0;
}
int amountToCopy;
if (this.largeBuffer == null)
{
var blockAndOffset = this.GetBlockAndRelativeOffset(fromPosition);
int bytesWritten = 0;
int bytesRemaining = Math.Min(buffer.Length, this.length - fromPosition);
while (bytesRemaining > 0)
{
amountToCopy = Math.Min(this.blocks[blockAndOffset.Block].Length - blockAndOffset.Offset,
bytesRemaining);
this.blocks[blockAndOffset.Block].AsSpan(blockAndOffset.Offset, amountToCopy)
.CopyTo(buffer.Slice(bytesWritten));
bytesWritten += amountToCopy;
bytesRemaining -= amountToCopy;
++blockAndOffset.Block;
blockAndOffset.Offset = 0;
}
return bytesWritten;
}
amountToCopy = Math.Min(buffer.Length, this.length - fromPosition);
this.largeBuffer.AsSpan(fromPosition, amountToCopy).CopyTo(buffer);
return amountToCopy;
}
#endif
private struct BlockAndOffset
{
public int Block;
public int Offset;
public BlockAndOffset(int block, int offset)
{
this.Block = block;
this.Offset = offset;
}
}
private BlockAndOffset GetBlockAndRelativeOffset(int offset)
{
var blockSize = this.memoryManager.BlockSize;
return new BlockAndOffset(offset / blockSize, offset % blockSize);
}
private void EnsureCapacity(int newCapacity)
{
if (newCapacity > this.memoryManager.MaximumStreamCapacity && this.memoryManager.MaximumStreamCapacity > 0)
{
RecyclableMemoryStreamManager.Events.Writer.MemoryStreamOverCapacity(newCapacity,
this.memoryManager
.MaximumStreamCapacity, this.tag,
this.AllocationStack);
throw new InvalidOperationException("Requested capacity is too large: " + newCapacity + ". Limit is " +
this.memoryManager.MaximumStreamCapacity);
}
if (this.largeBuffer != null)
{
if (newCapacity > this.largeBuffer.Length)
{
var newBuffer = this.memoryManager.GetLargeBuffer(newCapacity, this.tag);
this.InternalRead(newBuffer, 0, this.length, 0);
this.ReleaseLargeBuffer();
this.largeBuffer = newBuffer;
}
}
else
{
while (this.Capacity < newCapacity)
{
blocks.Add((this.memoryManager.GetBlock()));
}
}
}
/// <summary>
/// Release the large buffer (either stores it for eventual release or returns it immediately).
/// </summary>
private void ReleaseLargeBuffer()
{
if (this.memoryManager.AggressiveBufferReturn)
{
this.memoryManager.ReturnLargeBuffer(this.largeBuffer, this.tag);
}