linuxquestions.org からの xpost、申し訳ありません...
単純なプロキシが splice() を使用することでメリットが得られるかどうかを確認する小さなテスト プログラムを作成しましたが、パイプから TCP ソケットに接続したデータをソケットの反対側から読み取るには、常に 200 ミリ秒かかります。
これをテストするPerlプログラムは次のとおりです。
package test_pipes_2;
use strict;
use warnings;
use IO::Handle();
use POSIX qw(:errno_h);
use Time::HiRes qw(time);
use English qw(-no_match_vars);
use IO::Socket::INET;
use Socket qw(IPPROTO_TCP TCP_NODELAY);
__PACKAGE__->run if not caller;
sub run {
my( $class ) = @ARG;
pipe my $parent_reader, my $child_writer;
my $parent_reader_fd = fileno $parent_reader;
my $child_writer_fd = fileno $child_writer;
pipe my $child_reader, my $parent_writer;
my $child_reader_fd = fileno $child_reader;
my $parent_writer_fd = fileno $parent_writer;
my $server = IO::Socket::INET->new(
LocalAddr => '127.0.0.1:9000',
Type => SOCK_STREAM,
Listen => 5,
ReuseAddr => 1,
Blocking => 1,
) || die $OS_ERROR;
my $client_browser = IO::Socket::INET->new(
PeerAddr => '127.0.0.1:9000',
Type => SOCK_STREAM,
Blocking => 1,
) || die $OS_ERROR;
# setsockopt $client_browser, IPPROTO_TCP, TCP_NODELAY, 1;
my $client_browser_fd = fileno $client_browser;
my $server_browser = $server->accept() || die $OS_ERROR;
# setsockopt $server_browser, IPPROTO_TCP, TCP_NODELAY, 1;
my $server_browser_fd = fileno $server_browser;
for( 1 .. 3 ) { # 100_000
syswrite $client_browser, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n";
$server_browser->recv( my $request1, 4096, POSIX::MSG_PEEK );
syscall 313, $server_browser_fd, undef, $child_writer_fd, undef, 4096, 1;
sysread $parent_reader, my $request2, 4096;
my $response = "200 OK\n<head><title>html</title></head><body>body from $PID</body>";
syswrite $parent_writer, $response;
syscall 313, $child_reader_fd, undef, $server_browser_fd, undef, 4096, 1;
# syswrite $server_browser, "\n"; # eliminates delay, adds syscall...
sysread $client_browser, my $response1, 4096;
# chomp $response1;
if( $response1 ne $response ) {
warn 'Got wrong response: ', $response1 // 'undef';
no warnings 'once';
$DB::single = 1;
}
}
}
1;
次に、strace 出力のサンプルを示します。
socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 8 <0.000010>
setsockopt(8, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 <0.000006>
bind(8, {sa_family=AF_INET, sin_port=htons(9000), sin_addr=inet_addr("127.0.0.1")}, 16) = 0 <0.000008>
listen(8, 5) = 0 <0.000008>
socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 9 <0.000006>
connect(9, {sa_family=AF_INET, sin_port=htons(9000), sin_addr=inet_addr("127.0.0.1")}, 16) = 0 <0.000037>
accept(8, {sa_family=AF_INET, sin_port=htons(49361), sin_addr=inet_addr("127.0.0.1")}, [16]) = 10 <0.000007>
write(9, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 41) = 41 <0.000014>
recvfrom(10, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 4096, MSG_PEEK, {sa_family=0x8b60 /* AF_??? */, sa_data="(\10\2\0\300\321\177\0\0\1\0\0\0\0"...}, [0]) = 41 <0.000007>
splice(0xa, 0, 0x5, 0, 0x1000, 0x1) = 41 <0.000007>
read(4, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 4096) = 41 <0.000005>
write(7, "200 OK\n<head><title>html</title></head><body>body from 14019</body>"..., 67) = 67 <0.000005>
splice(0x6, 0, 0xa, 0, 0x1000, 0x1) = 67 <0.000007>
read(9, "200 OK\n<head><title>html</title></head><body>body from 14019</body>"..., 4096) = 67 <0.200331>
write(9, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 41) = 41 <0.000016>
recvfrom(10, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 4096, MSG_PEEK, {sa_family=0x8b60 /* AF_??? */, sa_data="(\10\2\0\300\321\177\0\0\1\0\0\0\0"...}, [0]) = 41 <0.000008>
splice(0xa, 0, 0x5, 0, 0x1000, 0x1) = 41 <0.000006>
read(4, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 4096) = 41 <0.000005>
write(7, "200 OK\n<head><title>html</title></head><body>body from 14019</body>"..., 67) = 67 <0.000005>
splice(0x6, 0, 0xa, 0, 0x1000, 0x1) = 67 <0.000006>
read(9, "200 OK\n<head><title>html</title></head><body>body from 14019</body>"..., 4096) = 67 <0.200622>
write(9, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 41) = 41 <0.000018>
recvfrom(10, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 4096, MSG_PEEK, {sa_family=0x8b60 /* AF_??? */, sa_data="(\10\2\0\300\321\177\0\0\1\0\0\0\0"...}, [0]) = 41 <0.000007>
splice(0xa, 0, 0x5, 0, 0x1000, 0x1) = 41 <0.000006>
read(4, "HTTP/1.1 GET /foo/\r\nLocation: foo.com\r\n\r\n"..., 4096) = 41 <0.000005>
write(7, "200 OK\n<head><title>html</title></head><body>body from 14019</body>"..., 67) = 67 <0.000005>
splice(0x6, 0, 0xa, 0, 0x1000, 0x1) = 67 <0.000005>
read(9, "200 OK\n<head><title>html</title></head><body>body from 14019</body>"..., 4096) = 67 <0.200649
~200ms の read(9,...) 呼び出しに注意してください。「\n」を送信する行のコメントを外すと、遅延はありません。私は何を間違っていますか？ありがとう！