Created
February 5, 2018 20:46
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Used for synchronization of two storages
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| using System; | |
| using System.Collections.Generic; | |
| using System.Diagnostics; | |
| using System.Threading; | |
| namespace ConsoleApplication1 | |
| { | |
| /// <summary> | |
| /// Performs synchronization between continuous collection and unknown collection. | |
| /// For example, between continuous MSSQL table ids and unknown mapped id in other system, like ElasticSearch. | |
| /// It is useful to synchronize collections in different systems. | |
| /// </summary> | |
| /// <typeparam name="TAKey"></typeparam> | |
| /// <typeparam name="TBKey"></typeparam> | |
| public abstract class PagedMapSync<TAKey, TBKey> | |
| { | |
| /// <summary> | |
| /// Get or sets batch size. Possible to change in runtime. | |
| /// </summary> | |
| public volatile int BatchSize; | |
| public int Offset => _offset; | |
| public event EventHandler OnStart; | |
| public event EventHandler OnProgress; | |
| public event EventHandler OnFinish; | |
| private int _offset; | |
| private readonly object _lock = new object(); | |
| private CancellationToken? _ct; | |
| protected PagedMapSync(int batchSize = 100) | |
| { | |
| BatchSize = batchSize; | |
| } | |
| protected bool IsCancellationRequested => _ct?.IsCancellationRequested ?? false; | |
| public void Sync(CancellationToken? ct = null) | |
| { | |
| lock (_lock) | |
| { | |
| _ct = ct; | |
| try | |
| { | |
| OnStart?.Invoke(this, new EventArgs()); | |
| _offset = 0; | |
| while (!IsCancellationRequested) | |
| { | |
| var batchSize = BatchSize; | |
| if(!ProcessBatch(_offset, batchSize)) | |
| break; | |
| _offset += batchSize; | |
| OnProgress?.Invoke(this, new EventArgs()); | |
| } | |
| OnFinish?.Invoke(this, new EventArgs()); | |
| } | |
| finally | |
| { | |
| _ct = null; | |
| } | |
| } | |
| } | |
| private bool ProcessBatch(int offset, int count) | |
| { | |
| IReadOnlyList<TAKey> pagedIds; | |
| if (!TryGetPagedValues(offset, count, out pagedIds)) | |
| { | |
| return false; | |
| } | |
| Debug.Assert(pagedIds != null); | |
| var unpagedIds = OnMap(pagedIds); | |
| Debug.Assert(unpagedIds != null); | |
| Debug.Assert(pagedIds.Count == unpagedIds.Count); | |
| OnSync(pagedIds, unpagedIds); | |
| return true; | |
| } | |
| protected abstract bool TryGetPagedValues(int offset, int count, out IReadOnlyList<TAKey> pagedIds); | |
| /// <summary> | |
| /// Performs mapping of one element to another in coresponding position | |
| /// </summary> | |
| /// <param name="pagedIds"></param> | |
| /// <returns></returns> | |
| protected abstract IReadOnlyList<TBKey> OnMap(IReadOnlyList<TAKey> pagedIds); | |
| /// <summary> | |
| /// Performs sync of two subcollections. Paged ids is LEFT JOIN'ed with unpaged ids -> corresponding items will be filled or default. | |
| /// </summary> | |
| /// <param name="pagedIds"></param> | |
| /// <param name="unpagedIds"></param> | |
| protected abstract void OnSync(IReadOnlyList<TAKey> pagedIds, IReadOnlyList<TBKey> unpagedIds); | |
| } | |
| } |
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