Nuclex.Support/Source/Tracking/TransactionGroup.cs

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#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2008 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using Nuclex.Support.Collections;
namespace Nuclex.Support.Tracking {
/// <summary>Forms a single transaction from a group of transactions</summary>
/// <typeparam name="TransactionType">Type of transactions to manage as a set</typeparam>
public class TransactionGroup<TransactionType> : Transaction, IDisposable, IProgressReporter
where TransactionType : Transaction {
/// <summary>will be triggered to report when progress has been achieved</summary>
public event EventHandler<ProgressReportEventArgs> AsyncProgressChanged;
/// <summary>Initializes a new transaction group</summary>
/// <param name="childs">Transactions to track with this group</param>
/// <remarks>
/// Uses a default weighting factor of 1.0 for all transactions.
/// </remarks>
public TransactionGroup(IEnumerable<TransactionType> childs)
: this() {
// Construct a WeightedTransaction with the default weight for each
// transaction and wrap it in an ObservedTransaction
foreach(TransactionType transaction in childs) {
this.children.Add(
new ObservedWeightedTransaction<TransactionType>(
new WeightedTransaction<TransactionType>(transaction),
new ObservedWeightedTransaction<TransactionType>.ReportDelegate(
asyncProgressUpdated
),
new ObservedWeightedTransaction<TransactionType>.ReportDelegate(
asyncChildEnded
)
)
);
}
// Since all transactions have a weight of 1.0, the total weight is
// equal to the number of transactions in our list
this.totalWeight = (float)this.children.Count;
}
/// <summary>Initializes a new transaction group</summary>
/// <param name="childs">Transactions to track with this group</param>
public TransactionGroup(
IEnumerable<WeightedTransaction<TransactionType>> childs
)
: this() {
// Construct an ObservedTransaction around each of the WeightedTransactions
foreach(WeightedTransaction<TransactionType> transaction in childs) {
this.children.Add(
new ObservedWeightedTransaction<TransactionType>(
transaction,
new ObservedWeightedTransaction<TransactionType>.ReportDelegate(
asyncProgressUpdated
),
new ObservedWeightedTransaction<TransactionType>.ReportDelegate(
asyncChildEnded
)
)
);
// Sum up the total weight
this.totalWeight += transaction.Weight;
}
}
/// <summary>Performs common initialization for the public constructors</summary>
private TransactionGroup() {
this.children = new List<ObservedWeightedTransaction<TransactionType>>();
}
/// <summary>Immediately releases all resources owned by the object</summary>
public void Dispose() {
if(this.children != null) {
// Dispose all the observed transactions, disconnecting the events from the
// actual transactions so the GC can more easily collect this class
for(int index = 0; index < this.children.Count; ++index)
this.children[index].Dispose();
this.children = null;
this.wrapper = null;
}
}
/// <summary>Childs contained in the transaction set</summary>
public IList<WeightedTransaction<TransactionType>> Children {
get {
// The wrapper is constructed only when needed. Most of the time, users will
// just create a transaction group and monitor its progress without ever using
// the Childs collection.
if(this.wrapper == null) {
// This doesn't need a lock because it's a stateless wrapper.
// If it is constructed twice, then so be it, no problem at all.
this.wrapper = new WeightedTransactionWrapperCollection<TransactionType>(
this.children
);
}
return this.wrapper;
}
}
/// <summary>Fires the progress update event</summary>
/// <param name="progress">Progress to report (ranging from 0.0 to 1.0)</param>
/// <remarks>
/// Informs the observers of this transactions about the achieved progress.
/// </remarks>
protected virtual void OnAsyncProgressChanged(float progress) {
OnAsyncProgressChanged(new ProgressReportEventArgs(progress));
}
/// <summary>Fires the progress update event</summary>
/// <param name="eventArguments">Progress to report (ranging from 0.0 to 1.0)</param>
/// <remarks>
/// Informs the observers of this transaction about the achieved progress.
/// Allows for classes derived from the transaction class to easily provide
/// a custom event arguments class that has been derived from the
/// transaction's ProgressUpdateEventArgs class.
/// </remarks>
protected virtual void OnAsyncProgressChanged(ProgressReportEventArgs eventArguments) {
EventHandler<ProgressReportEventArgs> copy = AsyncProgressChanged;
if(copy != null)
copy(this, eventArguments);
}
/// <summary>
/// Called when the progress of one of the observed transactions changes
/// </summary>
private void asyncProgressUpdated() {
float totalProgress = 0.0f;
// Calculate the sum of the progress reported by our child transactions,
// scaled to the weight each transaction has assigned to it.
for(int index = 0; index < this.children.Count; ++index) {
totalProgress +=
this.children[index].Progress * this.children[index].WeightedTransaction.Weight;
}
// Calculate the actual combined progress
if(this.totalWeight > 0.0f)
totalProgress /= this.totalWeight;
// Send out the progress update
OnAsyncProgressChanged(totalProgress);
}
/// <summary>
/// Called when an observed transaction ends
/// </summary>
private void asyncChildEnded() {
// If there's still at least one transaction going, don't report that
// the transaction group has finished yet.
for(int index = 0; index < this.children.Count; ++index)
if(!this.children[index].WeightedTransaction.Transaction.Ended)
return;
// All child transactions have ended, so the set has now ended as well
OnAsyncEnded();
}
/// <summary>Transactions being managed in the set</summary>
private List<ObservedWeightedTransaction<TransactionType>> children;
/// <summary>
/// Wrapper collection for exposing the child transactions under the
/// WeightedTransaction interface
/// </summary>
private volatile WeightedTransactionWrapperCollection<TransactionType> wrapper;
/// <summary>Summed weight of all transactions in the set</summary>
private float totalWeight;
}
} // namespace Nuclex.Support.Tracking