ThrottleEnabledStream.cs

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namespace Duplicati.StreamUtil;

/// <summary>
/// A stream that wraps another stream and throttles read and write operations.
/// </summary>
public sealed class ThrottleEnabledStream : WrappingStream
{
    /// <summary>
    /// The throttle manager that determines how long to delay read operations.
    /// </summary>
    public ThrottleManager ReadThrottleManager { get; }

    /// <summary>
    /// The throttle manager that determines how long to delay write operations.
    /// </summary>
    public ThrottleManager WriteThrottleManager { get; }

    /// <summary>
    /// Creates a new ThrottleEnabledStream.
    /// </summary>
    /// <param name="baseStream">The stream to wrap.</param>
    /// <param name="readThrottleManager">The throttle manager to use for reads.</param>
    /// <param name="writeThrottleManager">The throttle manager to use for writes.</param>
    public ThrottleEnabledStream(Stream baseStream, ThrottleManager readThrottleManager, ThrottleManager writeThrottleManager)
        : base(baseStream)
    {
        ReadThrottleManager = readThrottleManager;
        WriteThrottleManager = writeThrottleManager;
    }

    /// <summary>
    /// Creates a new ThrottleEnabledStream.
    /// </summary>
    /// <param name="baseStream">The stream to wrap.</param>
    /// <param name="throttleManager">The throttle manager to use for both reads and writes.</param>
    public ThrottleEnabledStream(Stream baseStream, ThrottleManager throttleManager)
        : this(baseStream, throttleManager, throttleManager) { }

    /// <summary>
    /// Creates a new ThrottleEnabledStream.
    /// </summary>
    /// <param name="baseStream">The stream to wrap.</param>
    /// <param name="readThrottle">The throttle limit for reads in bytes/s.</param>
    /// <param name="writeThrottle">The throttle limit for writes in bytes/s.</param>
    public ThrottleEnabledStream(Stream baseStream, int readThrottle, int writeThrottle)
        : this(baseStream, new ThrottleManager() { Limit = readThrottle }, new ThrottleManager() { Limit = writeThrottle }) { }

    /// <inheritdoc />
    public override int Read(byte[] buffer, int offset, int count)
    {
        int bytesRead = BaseStream.Read(buffer, offset, count);
        ReadThrottleManager.SleepForSize(bytesRead);
        return bytesRead;
    }

    /// <inheritdoc />
    public override void Write(byte[] buffer, int offset, int count)
    {
        BaseStream.Write(buffer, offset, count);
        WriteThrottleManager.SleepForSize(count);

    }

    /// <inheritdoc />
    public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
    {
        int bytesRead = await BaseStream.ReadAsync(buffer, offset, count, cancellationToken);
        await ReadThrottleManager.WaitForSize(bytesRead, cancellationToken);
        return bytesRead;
    }

    /// <inheritdoc />
    public override async Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
    {
        await BaseStream.WriteAsync(buffer, offset, count, cancellationToken);
        await WriteThrottleManager.WaitForSize(count, cancellationToken);
    }
}