如何动态扩展内存映射文件 [英] How to dynamically expand a Memory Mapped File
问题描述
我已经使用 C# 来解决以下需求..- 创建一个可以快速接收大量数据的应用程序- 您必须能够在接收到更多数据时分析接收到的数据.- 使用尽可能少的 CPU 和磁盘
I've used C# to solve the following requirement.. - create an app the can receive a lot of data fast - you must be able to analyse the received data while more are incoming. - use as little CPU and disk as possible
我对算法的想法是..
SIZE = 10MB
Create a mmf with the size of SIZE
On data recived:
if data can't fit mmf: increase mmf.size by SIZE
write the data to mmf
-> 使用之前的房间/空间"时，光盘上的大小以 10MB 为单位增加.
-> The size on the disc are increased in chuncks of 10MB when the previous "room/space" are used.
如何在 C# 中实现按 SIZE 增加 mmf.size"?我发现了很多关于创建 mmfs 和视图的简单示例，但唯一的地方(link) 我见过实际增加 mmfs 区域的代码使用无法编译的代码.任何帮助将不胜感激.
How is the "increase mmf.size by SIZE" done in C#? I have found a lot of simple examples on creating mmfs and views but the only place (link) I have seen code that acutally increases the mmfs area uses code that can't compile. Any help will be greatly appriciated.
编辑这会导致异常:
private void IncreaseFileSize()
{
int theNewMax = this.currentMax + INCREMENT_SIZE;
this.currentMax = theNewMax;
this.mmf.Dispose();
this.mmf = MemoryMappedFile.CreateFromFile(this.FileName, FileMode.Create, "MyMMF", theNewMax);
this.view = mmf.CreateViewAccessor(0, theNewMax);
}
抛出此异常:进程无法访问文件C:UsersmobergDocumentsdata.bin"，因为它正被另一个进程使用.
This exception is thrown : The process cannot access the file 'C:UsersmobergDocumentsdata.bin' because it is being used by another process.
推荐答案
一旦将文件映射到内存中，就无法增加其大小.这是内存映射文件的已知限制.
Once you map a file in memory, you cannot increase its size. This is a known limitation of memory mapped files.
...您必须计算或估计完成的文件的大小，因为文件映射对象的大小是静态的；一旦创建，它们的大小就不能增加或减少.
...you must calculate or estimate the size of the finished file because file mapping objects are static in size; once created, their size cannot be increased or decreased.
一种策略是使用存储在 非持久内存映射文件中的块给定的大小，比如 1GB 或 2GB.您将通过您自己设计的顶级 ViewAccessor 管理这些(可能从 MemoryMappedViewAccessor).
One strategy would be to use chunks stored in non-persisted memory mapped files of a given size, say 1GB or 2GB. You would manage these through a top level ViewAccessor of your own design (probably doing basic passthru of the methods you need from the MemoryMappedViewAccessor).
或者您可以创建一个您希望使用的最大大小的非持久内存映射文件(比如 8GB 开始，使用一个参数在您的系统启动时对其进行调整)应用程序)并检索每个逻辑块的 MemoryMappedViewAccessor.在请求每个视图之前，非持久化文件不会使用物理资源.
or you could just create a non-persisted memory mapped file of a maximal size you expect to use (say 8GB to start, with a parameter to tune it on start-up of your application) and retrieve MemoryMappedViewAccessor's per logical chunk. The non-persisted file will not use physical resources until each view is requested.
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