在 Rebol 中读取大型二进制文件失败

发布于 2024-09-05 11:36:45 字数 240 浏览 2 评论 0原文

以下 Rebol 代码由于内存不足错误而失败：

read/binary http://mirror.bytemark.co.uk/ubuntu-releases/lucid/
            ubuntu-10.04-desktop-i386.iso

How can I use Rebol to read Large bin files over HTTP?

原文

The following Rebol code fails due to an out of memory error:

read/binary http://mirror.bytemark.co.uk/ubuntu-releases/lucid/
            ubuntu-10.04-desktop-i386.iso

How can I use Rebol to read large binary files over HTTP?

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捶死心动 2024-09-12 11:36:45

Rebol 2 端口有些混乱。因此，您不能直接应用如何分段读取大文件的示例因为 read 在 R2 中的 port! 上不起作用（更不用说 read/part 起作用了）。

但是，如果您跳过一些麻烦并使用 /direct 细化直接打开文件，您会得到一些有用的东西：

; Rebol 2 chunking http download sample

filename: %ubuntu-10.04-desktop-i386.iso
base-url: http://mirror.bytemark.co.uk/ubuntu-releases/lucid/
chunk-size: 32000

in-port: open/binary/direct rejoin [base-url filename]
out-port: open/binary/direct filename
while [not none? data: copy/part in-port chunk-size] [
    append out-port data
]
close in-port
close out-port

(更新：我没有请注意 Sunanda 引用的 READ-IO 示例，因为我不太使用 R2，也没有见过 READ-IO。它可能也可以在 http 上工作并且具有更好的性能，但我会让你

在 Rebol 3 中进行比较。您可以从端口读取和写入！。这意味着对大文件示例的修改应该可以工作，理论上...

; Rebol 3 chunking http download sample
; Warning: does not work in A99 release

filename: %ubuntu-10.04-desktop-i386.iso
base-url: http://mirror.bytemark.co.uk/ubuntu-releases/lucid/
chunk-size: 32000

in-port: open/read rejoin [base-url filename]
out-port: open/write filename
while [not empty? data: read/part in-port chunk-size] [
    write out-port data
]
close in-port
close out-port

然而，当前版本的 R3 alpha 中存在一个错误，该错误忽略了 /part如果方案是 HTTP，则在读取期间继续细化并返回整个文件的内容。 :(

Rebol 2 ports are something of a mess. So you can't directly apply the sample of how to read a large file in parts because read doesn't work on port! in R2 (much less does read/part work).

But if you jump through some hoops and use the /direct refinement to directly open the file, you get something that will work:

; Rebol 2 chunking http download sample

filename: %ubuntu-10.04-desktop-i386.iso
base-url: http://mirror.bytemark.co.uk/ubuntu-releases/lucid/
chunk-size: 32000

in-port: open/binary/direct rejoin [base-url filename]
out-port: open/binary/direct filename
while [not none? data: copy/part in-port chunk-size] [
    append out-port data
]
close in-port
close out-port

(UPDATE: I didn't notice the READ-IO sample that Sunanda cites, as I don't use R2 much and hadn't ever seen READ-IO. It may also work on http and have better performance. But I'll let you do that comparison. :P)

In Rebol 3, you can read and write from a port!. That means a modification of the large file sample should work, in theory...

; Rebol 3 chunking http download sample
; Warning: does not work in A99 release

filename: %ubuntu-10.04-desktop-i386.iso
base-url: http://mirror.bytemark.co.uk/ubuntu-releases/lucid/
chunk-size: 32000

in-port: open/read rejoin [base-url filename]
out-port: open/write filename
while [not empty? data: read/part in-port chunk-size] [
    write out-port data
]
close in-port
close out-port

Yet there's a bug in the current build of R3 alpha that ignores the /part refinement and goes ahead and returns the contents of the whole file during read if the scheme is HTTP. :(

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