src/AmqpLinkSettings.cs

// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

namespace Microsoft.Azure.Amqp
{
    using System;
    using Microsoft.Azure.Amqp.Framing;

    /// <summary>
    /// Settings of a link.
    /// </summary>
    public sealed class AmqpLinkSettings : Attach
    {
        uint linkCredit;
        TimeSpan operationTimeout;

        /// <summary>
        /// Initializes the settings object.
        /// </summary>
        public AmqpLinkSettings()
        {
        }

        /// <summary>
        /// Gets or sets the total link credit.
        /// </summary>
        public uint TotalLinkCredit
        {
            get
            {
                return this.linkCredit;
            }

            set
            {
                this.linkCredit = value;
                this.FlowThreshold = Math.Min(100, (int)(this.linkCredit * 2 / 3));
            }
        }

        /// <summary>
        /// Gets or sets the cache size for prefetched messages. Applies to <see cref="ReceivingAmqpLink"/> only.
        /// </summary>
        /// <remarks>If set, it takes precedence over <see cref="TotalLinkCredit"/>. The link does it best effort to limit
        /// the total prefetched messages to this limit. It is ignored when a message listener callback is registered.</remarks>
        public long? TotalCacheSizeInBytes
        {
            get;
            set;
        }

        /// <summary>
        /// The number of messages that have been settled by the application by
        /// calling one of the state update methods on <see cref="ReceivingAmqpLink"/>.
        /// A flow is sent when the threshold is reached.
        /// </summary>
        public int FlowThreshold
        {
            get;
            set;
        }

        /// <summary>
        /// Sends a flow based on <see cref="FlowThreshold"/>.
        /// </summary>
        public bool AutoSendFlow
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the <see cref="SettleMode"/> of the link.
        /// </summary>
        public SettleMode SettleType
        {
            get 
            {
                return this.SettleType(); 
            }

            set
            {
                this.SndSettleMode = null;
                this.RcvSettleMode = null;
                switch (value)
                {
                    case SettleMode.SettleOnSend:
                        this.SndSettleMode = (byte)SenderSettleMode.Settled;
                        break;
                    case SettleMode.SettleOnReceive:
                        break;
                    case SettleMode.SettleOnDispose:
                        this.RcvSettleMode = (byte)ReceiverSettleMode.Second;
                        break;
                }
            }
        }

        /// <summary>
        /// Gets or sets the default operation timeout when not explicitly specified in an API.
        /// </summary>
        public TimeSpan OperationTimeout
        {
            get { return this.operationTimeout == default ? AmqpConstants.DefaultTimeout : this.operationTimeout; }
            set { this.operationTimeout = value; }
        }

        internal TimeSpan OperationTimeoutInternal => this.operationTimeout;

        /// <summary>
        /// Creates a settings object from an <see cref="Attach"/> received from remote.
        /// </summary>
        /// <param name="attach">The attach received from remote.</param>
        /// <returns>An AmqpLinkSettings object.</returns>
        public static AmqpLinkSettings Create(Attach attach)
        {
            AmqpLinkSettings settings = new AmqpLinkSettings();
            settings.LinkName = attach.LinkName;
            settings.Role = !attach.Role.Value;
            settings.Source = attach.Source;
            settings.Target = attach.Target;
            settings.SndSettleMode = attach.SndSettleMode;
            settings.RcvSettleMode = attach.RcvSettleMode;
            settings.MaxMessageSize = attach.MaxMessageSize;
            settings.DesiredCapabilities = attach.DesiredCapabilities;
            settings.OfferedCapabilities = attach.OfferedCapabilities;
            settings.Properties = attach.Properties;
            if (settings.Role.Value)
            {
                settings.TotalLinkCredit = AmqpConstants.DefaultLinkCredit;
                settings.AutoSendFlow = true;
            }
            else
            {
                settings.InitialDeliveryCount = 0;
            }

            return settings;
        }

        /// <summary>
        /// Determines whether two link settings are equal based on <see cref="Attach.LinkName"/>
        /// and <see cref="Attach.Role"/>. Name comparison is case insensitive.
        /// </summary>
        /// <param name="obj">The object to compare with the current object.</param>
        /// <returns>True if the specified object is equal to the current object; otherwise, false.</returns>
        public override bool Equals(object obj)
        {
            AmqpLinkSettings other = obj as AmqpLinkSettings;
            if (other == null || other.LinkName == null)
            {
                return false;
            }

            return this.LinkName.Equals(other.LinkName, StringComparison.CurrentCultureIgnoreCase) &&
                this.Role == other.Role;
        }

        /// <summary>
        /// Gets a hash code of the object.
        /// </summary>
        public override int GetHashCode()
        {
            return (this.LinkName.GetHashCode() * 397) + this.Role.GetHashCode();
        }

        /// <summary>
        /// Create default link settings for the given role, link name, and address.
        /// </summary>
        /// <param name="role">The link type to create this settings for.</param>
        /// <param name="name">The link name to create this settings for.</param>
        /// <param name="address">The link address to create this settings for.</param>
        /// <returns>A default AmqpLinkSettings object.</returns>
        internal static AmqpLinkSettings Create(bool role, string name, string address)
        {
            AmqpLinkSettings linkSettings = new AmqpLinkSettings();
            linkSettings.LinkName = name;
            if (!role)
            {
                linkSettings.Role = false;
                linkSettings.Source = new Source();
                linkSettings.Target = new Target() { Address = address };
            }
            else
            {
                linkSettings.Role = true;
                linkSettings.Source = new Source() { Address = address };
                linkSettings.TotalLinkCredit = AmqpConstants.DefaultLinkCredit;
                linkSettings.AutoSendFlow = true;
                linkSettings.Target = new Target();
            }

            return linkSettings;
        }
    }
}