f# – MemoryMappedFiles.MemoryMappedFile.CreateFromFile不会

在 windows下,当容量参数(最后一个参数)设置为比底层文件大时,此F#代码将文件从12个字节扩展到655346个字节.这似乎是扩展内存映射文件最干净的方法.在mono / linux下,它抛出一个ArgumentException：capacity,除非该文件与映射的容量一样长.是否有一种干净的方式来获取单声道扩展文件,或者我必须先预先扩展文件才能映射？

let Main () =
    let path = "parts.pash"
    let l = 65536L
    let mm =    MemoryMappedFiles.MemoryMappedFile.CreateFromFile(path,FileMode.OpenOrCreate,"pashmap",l)

    ()

Main()

错误信息

Unhandled Exception: System.ArgumentException: capacity at
System.IO.MemoryMappedFiles.MemoryMappedFile.CreateFromFile
(System.String path,FileMode mode,System.String mapName,Int64
capacity,MemoryMappedFileAccess access) [0x00000] in :0 at
System.IO.MemoryMappedFiles.MemoryMappedFile.CreateFromFile
(System.String path,Int64
capacity) [0x00000] in :0 at Program.Main ()
[0x00000] in :0 at
.$Program.main@ () [0x00000] in :0

单声道版本：

[daz@clowder pash]$mono --version
Mono JIT compiler version 2.10.1 (tarball Mon Apr  4 10:40:52 PDT 2011)
Copyright (C) 2002-2011 Novell,Inc and Contributors. www.mono-project.com
        TLS:           __thread
        SIGSEGV:       altstack
        Notifications: epoll
        Architecture:  x86
        Disabled:      none
        Misc:          softdebug
        LLVM:          supported,not enabled.
        GC:            Included Boehm (with typed GC and Parallel Mark)

编辑：似乎内存映射的不同底层行为在API中公开,因此您需要将文件自己扩展到正确的长度以进行平台中立

let f = File.Open(path,FileMode.Append,FileAccess.Write)
let pad = l- FileInfo(path).Length
let padding = Array.create (int32 pad) 0uy
f.Write(padding,int pad)
f.Close()