[英]How can I improve the performance of this CopyTo method?
編輯:我現在已經解決了這個問題。 我的答案發布在下面,當 SO 允許我時將標記為已解決。
我有一個 CopyTo(和一個 CopyToAsync)方法來復制 C# 應用程序中的文件。 我發現與 Xcopy 之類的東西相比,復制文件實際上很慢。
我提取了 copy 方法的核心功能並將其放入測試控制台應用程序中,以獲得它與 Xcopy 相比的運行速度,發現結果實際上完全不同。
我得到的結果是:
異步方法:36.59 秒 - 平均速度:1512.63 mb/sec
同步方法:36.49 秒 - 平均速度:1516.72 mb/sec
XCOPY:5.62 秒 - 平均速度:9842.11 mb/sec
這三個都使用完全相同的文件和完全相同的目的地。
流擴展 class:
public static class StreamExtensions
{
const int DEFAULT_BUFFER = 0x1000; // 4096 bits
public static async Task CopyToAsync(this Stream source, Stream destination, IProgress<long> progress, CancellationToken cancellationToken = default, int bufferSize = DEFAULT_BUFFER)
{
var buffer = new byte[bufferSize];
int bytesRead;
long totalRead = 0;
while ((bytesRead = await source.ReadAsync(buffer, 0, buffer.Length, cancellationToken)) > 0)
{
await destination.WriteAsync(buffer, 0, bytesRead, cancellationToken);
cancellationToken.ThrowIfCancellationRequested();
totalRead += bytesRead;
progress.Report(totalRead);
}
}
public static void CopyTo(this Stream source, Stream destination, IProgress<long> progress, int bufferSize = DEFAULT_BUFFER)
{
var buffer = new byte[bufferSize];
int bytesRead;
long totalRead = 0;
while ((bytesRead = source.Read(buffer, 0, buffer.Length)) > 0)
{
destination.Write(buffer, 0, bytesRead);
totalRead += bytesRead;
progress.Report(totalRead);
}
}
}
IProgress<long>
object 是將文件進度報告回調用方法。
示例調用實現:
// Asynchronous version
public static async Task CopyFileSetAsync(Dictionary<string, string> fileSet)
{
for (var x = 0; x < fileSet.Count; x++)
{
var item = fileSet.ElementAt(x);
var from = item.Key;
var to = item.Value;
int currentProgress = 0;
long fileSize = new FileInfo(from).Length;
IProgress<long> progress = new SynchronousProgress<long>(value =>
{
decimal fileProg = (decimal)(value * 100) / fileSize;
if (fileProg != currentProgress)
{
currentProgress = (int)fileProg;
OnUpdateFileProgress(null, new FileProgressEventArgs(fileProg));
}
});
using (var outStream = new FileStream(to, FileMode.Create, FileAccess.Write, FileShare.Read))
{
using (var inStream = new FileStream(from, FileMode.Open, FileAccess.Read, FileShare.Read))
{
await inStream.CopyToAsync(outStream, progress);
}
}
OnUpdateFileProgress(null, new FileProgressEventArgs(100)); // Probably redundant
}
}
// Synchronous version
public static void CopyFileSet(Dictionary<string, string> fileSet)
{
for (var x = 0; x < fileSet.Count; x++)
{
var item = fileSet.ElementAt(x);
var from = item.Key;
var to = item.Value;
int currentProgress = 0;
long fileSize = new FileInfo(from).Length;
IProgress<long> progress = new SynchronousProgress<long>(value =>
{
decimal fileProg = (decimal)(value * 100) / fileSize;
if (fileProg != currentProgress)
{
currentProgress = (int)fileProg;
OnUpdateFileProgress(null, new FileProgressEventArgs(fileProg));
}
});
using (var outStream = new FileStream(to, FileMode.Create, FileAccess.Write, FileShare.Read))
{
using (var inStream = new FileStream(from, FileMode.Open, FileAccess.Read, FileShare.Read))
{
inStream.CopyTo(outStream, progress, 1024);
}
}
OnUpdateFileProgress(null, new FileProgressEventArgs(100)); // Probably redundant
}
}
有什么東西可以阻止它盡可能快地運行嗎? 我只是對它與復制相比慢了多少感到困惑。
編輯:修正了一個錯字,我在 IProgress 周圍忘記了一個 `
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