Perl6 IO::Socket::Async 截断数据

Question

我正在使用 IO::Socket::Async 在 P6 中重写我的 P5 套接字服务器，但是接收到的数据在末尾被截断了 1 个字符，并且在下一个连接中收到了 1 个字符。来自 Perl6 Facebook 组的人 (Jonathan Worthington) 指出，这可能是由于字符串的性质和字节在 P6 中的处理方式非常不同。引用:

In Perl 6, strings and bytes are handled very differently. Of note, strings work at grapheme level. When receiving Unicode data, it's not only possible that a multi-byte sequence will be split over packets, but also a multi-codepoint sequence. For example, one packet might have the letter "a" at the end, and the next one would be a combining acute accent. Therefore, it can't safely pass on the "a" until it's seen how the next packet starts.

我的 P6 在 MoarVM

上运行

https://pastebin.com/Vr8wqyVu

use Data::Dump;
use experimental :pack;

my $socket = IO::Socket::Async.listen('0.0.0.0', 7000);

react {
    whenever $socket -> $conn {
        my $line = '';
        whenever $conn {

            say "Received --> "~$_;
            $conn.print: &translate($_) if $_.chars ge 100;  
            $conn.close;              

        }
    }
    CATCH {
        default {
            say .^name, ': ', .Str;
            say "handled in $?LINE";
        }
    }
}

sub translate($raw) {

    my $rawdata = $raw;
    $raw ~~ s/^\s+|\s+$//; # remove heading/trailing whitespace

    my $minus_checksum = substr($raw, 0, *-2);
    my $our_checksum = generateChecksum($minus_checksum);
    my $data_checksum = ($raw, *-2);

    # say $our_checksum;
    return $our_checksum;

}

sub generateChecksum($minus_checksum) {

    # turn string into Blob
    my Blob $blob = $minus_checksum.encode('utf-8');
    # unpack Blob into ascii list
    my @array = $blob.unpack("C*");
    # perform bitwise operation for each ascii in the list
    my $dec +^= $_ for $blob.unpack("C*");
    # only take 2 digits
    $dec = sprintf("%02d", $dec) if $dec ~~ /^\d$/;
    $dec = '0'.$dec if $dec ~~ /^[a..fA..F]$/;
    $dec = uc $dec;
    # convert it to hex
    my $hex = sprintf '%02x', $dec;
    return uc $hex; 

}

结果

Received --> $16AA861013034151986|10001000181123062657411200000000000010235444112500000000.600000000345.4335N10058.8249E00015
Received --> 0
Received --> $16AA861013037849727|1080100018112114435541120000000000000FBA00D5122500000000.600000000623.9080N10007.8627E00075
Received --> D
Received --> $08AA863835028447675|18804000181121183810421100002A300000100900000000.700000000314.8717N10125.6499E00022
Received --> 7
Received --> $08AA863835028447675|18804000181121183810421100002A300000100900000000.700000000314.8717N10125.6499E00022
Received --> 7
Received --> $08AA863835028447675|18804000181121183810421100002A300000100900000000.700000000314.8717N10125.6499E00022
Received --> 7
Received --> $08AA863835028447675|18804000181121183810421100002A300000100900000000.700000000314.8717N10125.6499E00022
Received --> 7

Answer 1

首先，TCP 连接是流，因此无法保证发送的 "messages" 将在接收端接收为等效的 "messages"。发送的内容可以作为正常 TCP 行为的一部分进行拆分或合并，甚至在考虑 Perl 6 行为之前。任何需要 "messages" 抽象的东西都需要在 TCP 流之上构建它（例如，通过将数据作为行发送，或者通过发送以字节为单位的大小，然后是数据）。

在 Perl 6 中，通过套接字到达的数据公开为 Supply。 whenever $conn { } 是 whenever $conn.Supply { } 的缩写（whenever 会强制将给定的任何内容转换为 Supply）。默认 Supply 是字符 1，解码为 UTF-8 为 Perl 6 Str 流。正如您已经收到的答复中所述，Perl 6 中的字符串在字素级别工作，因此它会保留一个字符，以防下一个通过网络到达的是组合字符。这就是您正在经历的 "truncation"。（有些东西永远不能组合。例如， \n 永远不能在其上放置组合字符。这意味着面向行的协议不会遇到这种行为，可以简单地实现为 whenever $conn.Supply.lines { }.)

有几个选项可用：

执行 whenever $conn.Supply(:bin) { }，这将传送二进制 Blob 对象，这将对应于 OS 传递给 VM 的内容。然后可以根据需要 .decode'。这可能是您最好的选择。
指定不支持组合字符的编码，例如whenever $conn.Supply(:enc('latin-1')) { }。（但是，请注意，由于 \r\n 是 1 个字素，因此如果消息以 \r 结尾，那么它将被阻止以防下一个数据包与 \n 一起出现）。

在这两种情况下，消息在传输过程中仍有可能被拆分，但这些将（分别完全和大部分）避免字素规范化所需要的保持一个后退的要求。

Perl6 IO::Socket::Async 截断数据

Perl6 IO::Socket::Async truncates data

io-socket

moarvm

raku