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CsvReaderAdapter.cs
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CsvReaderAdapter.cs
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// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System.Buffers;
using Microsoft.NET.StringTools;
using Sylvan.Data.Csv;
namespace NuGet.Insights.Worker
{
public class CsvReaderAdapter : ICsvReader
{
private static readonly ConcurrentDictionary<Type, string> TypeToHeader = new ConcurrentDictionary<Type, string>();
/// <summary>
/// Needed due to these big guys:
/// - GR.PageRender.Razor 1.6.0 - massive number of content files, ~2,078,825 bytes
/// - GR.PageRender.Razor 1.7.0 - massive number of content files, ~2,095,119 bytes
/// </summary>
public const int MaxBufferSize = 4 * 1024 * 1024;
private readonly ILogger<CsvReaderAdapter> _logger;
public CsvReaderAdapter(ILogger<CsvReaderAdapter> logger)
{
_logger = logger;
}
public string GetHeader<T>() where T : ICsvRecord
{
var type = typeof(T);
return TypeToHeader.GetOrAdd(type, _ =>
{
var headerWriter = Activator.CreateInstance<T>();
using var stringWriter = new StringWriter();
headerWriter.WriteHeader(stringWriter);
return stringWriter.ToString().TrimEnd();
});
}
public IEnumerable<T> GetRecordsEnumerable<T>(TextReader reader, int bufferSize) where T : ICsvRecord
{
ValidateHeader<T>(reader);
var pool = ArrayPool<char>.Shared;
var buffer = pool.Rent(bufferSize);
try
{
using var csvReader = GetCsvDataReader(reader, buffer);
var factory = Activator.CreateInstance<T>();
while (csvReader.Read())
{
var i = 0;
var record = (T)factory.ReadNew(() => csvReader.GetString(i++));
yield return record;
}
}
finally
{
pool.Return(buffer);
}
}
public CsvReaderResult<T> GetRecords<T>(TextReader reader, int bufferSize) where T : ICsvRecord
{
ValidateHeader<T>(reader);
var allRecords = new List<T>();
var pool = ArrayPool<char>.Shared;
var buffer = pool.Rent(bufferSize);
try
{
using var csvReader = GetCsvDataReader(reader, buffer);
var factory = Activator.CreateInstance<T>();
while (csvReader.Read())
{
var i = 0;
ICsvRecord record;
try
{
record = factory.ReadNew(() => csvReader.GetString(i++));
}
catch (Exception ex)
{
_logger.LogError(
ex,
$"Could not read CSV on row {{RowNumber}} and field ordinal {{FieldOrdinal}}.{Environment.NewLine}Field: {{Field}}{Environment.NewLine}Line: {{Line}}",
csvReader.RowNumber,
i - 1,
csvReader[i - 1],
new string(csvReader.GetRawRecordSpan()));
throw;
}
allRecords.Add((T)record);
}
return new CsvReaderResult<T>(CsvReaderResultType.Success, allRecords);
}
catch (CsvRecordTooLargeException ex) when (bufferSize < MaxBufferSize)
{
_logger.LogInformation(
ex,
"Could not read CSV with buffer size {BufferSize} on row {RowNumBer} and field ordinal {FieldOrdinal}.",
bufferSize,
ex.RowNumber,
ex.FieldOrdinal);
return new CsvReaderResult<T>(CsvReaderResultType.BufferTooSmall, records: null);
}
finally
{
pool.Return(buffer);
}
}
private void ValidateHeader<T>(TextReader reader) where T : ICsvRecord
{
var actualHeader = reader.ReadLine();
var expectedHeader = GetHeader<T>();
if (actualHeader != expectedHeader)
{
throw new InvalidOperationException(
"The header in the blob doesn't match the header for the readers being added." + Environment.NewLine +
"Expected: " + expectedHeader + Environment.NewLine +
"Actual: " + actualHeader);
}
}
private static CsvDataReader GetCsvDataReader(TextReader reader, char[] buffer)
{
return CsvDataReader.Create(reader, buffer, new CsvDataReaderOptions
{
HasHeaders = false,
Delimiter = ',',
StringFactory = StringFactory,
});
}
private static string StringFactory(char[] buffer, int offset, int length)
{
if (length < 2048)
{
return Strings.WeakIntern(new ReadOnlySpan<char>(buffer, offset, length));
}
else
{
return new string(buffer, offset, length);
}
}
}
}