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//------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//------------------------------------------------------------
namespace System.ServiceModel.Channels
{
using System;
using System.Collections.Generic;
using System.Runtime;
using System.Threading;
abstract class DeliveryStrategy<ItemType> : IDisposable
where ItemType : class, IDisposable
{
InputQueueChannel<ItemType> channel;
Action dequeueCallback;
int quota;
public DeliveryStrategy(InputQueueChannel<ItemType> channel, int quota)
{
if (quota <= 0)
{
throw Fx.AssertAndThrow("Argument quota must be positive.");
}
this.channel = channel;
this.quota = quota;
}
protected InputQueueChannel<ItemType> Channel
{
get
{
return this.channel;
}
}
public Action DequeueCallback
{
get
{
return this.dequeueCallback;
}
set
{
this.dequeueCallback = value;
}
}
public abstract int EnqueuedCount
{
get;
}
protected int Quota
{
get
{
return this.quota;
}
}
public abstract bool CanEnqueue(Int64 sequenceNumber);
public virtual void Dispose()
{
}
public abstract bool Enqueue(ItemType item, Int64 sequenceNumber);
}
class OrderedDeliveryStrategy<ItemType> : DeliveryStrategy<ItemType>
where ItemType : class, IDisposable
{
bool isEnqueueInOrder;
Dictionary<Int64, ItemType> items;
Action<object> onDispatchCallback;
Int64 windowStart;
public OrderedDeliveryStrategy(
InputQueueChannel<ItemType> channel,
int quota,
bool isEnqueueInOrder)
: base(channel, quota)
{
this.isEnqueueInOrder = isEnqueueInOrder;
this.items = new Dictionary<Int64, ItemType>();
this.windowStart = 1;
}
public override int EnqueuedCount
{
get
{
return this.Channel.InternalPendingItems + this.items.Count;
}
}
Action<object> OnDispatchCallback
{
get
{
if (this.onDispatchCallback == null)
{
this.onDispatchCallback = this.OnDispatch;
}
return this.onDispatchCallback;
}
}
public override bool CanEnqueue(long sequenceNumber)
{
if (this.EnqueuedCount >= this.Quota)
{
return false;
}
if (this.isEnqueueInOrder && (sequenceNumber > this.windowStart))
{
return false;
}
return (this.Channel.InternalPendingItems + sequenceNumber - this.windowStart < this.Quota);
}
public override bool Enqueue(ItemType item, long sequenceNumber)
{
if (sequenceNumber > this.windowStart)
{
this.items.Add(sequenceNumber, item);
return false;
}
this.windowStart++;
while (this.items.ContainsKey(this.windowStart))
{
if (this.Channel.EnqueueWithoutDispatch(item, this.DequeueCallback))
{
ActionItem.Schedule(this.OnDispatchCallback, null);
}
item = this.items[this.windowStart];
this.items.Remove(this.windowStart);
this.windowStart++;
}
return this.Channel.EnqueueWithoutDispatch(item, this.DequeueCallback);
}
static void DisposeItems(Dictionary<Int64, ItemType>.Enumerator items)
{
if (items.MoveNext())
{
using (ItemType item = items.Current.Value)
{
DisposeItems(items);
}
}
}
public override void Dispose()
{
DisposeItems(this.items.GetEnumerator());
this.items.Clear();
base.Dispose();
}
void OnDispatch(object state)
{
this.Channel.Dispatch();
}
}
class UnorderedDeliveryStrategy<ItemType> : DeliveryStrategy<ItemType>
where ItemType : class, IDisposable
{
public UnorderedDeliveryStrategy(InputQueueChannel<ItemType> channel, int quota)
: base(channel, quota)
{
}
public override int EnqueuedCount
{
get
{
return this.Channel.InternalPendingItems;
}
}
public override bool CanEnqueue(Int64 sequenceNumber)
{
return (this.EnqueuedCount < this.Quota);
}
public override bool Enqueue(ItemType item, long sequenceNumber)
{
return this.Channel.EnqueueWithoutDispatch(item, this.DequeueCallback);
}
}
}
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