From: <sten.kristian.ivarsson@gmail.com>
To: "'Ken Brown'" <kbrown@cornell.edu>
Cc: "'cygwin'" <cygwin@cygwin.com>
Subject: Sv: Sv: Sv: Named pipes and multiple writers
Date: Fri, 27 Mar 2020 15:53:36 +0100 [thread overview]
Message-ID: <00b901d60447$7ecb4c50$7c61e4f0$@gmail.com> (raw)
In-Reply-To: <b311d907-7376-5bc6-3216-7d2b96728dbc@cornell.edu>
[-- Attachment #1: Type: text/plain, Size: 1042 bytes --]
>On 3/26/2020 7:19 PM, Ken Brown via Cygwin wrote:
>> On 3/26/2020 6:39 PM, Ken Brown via Cygwin wrote:
>>> On 3/26/2020 6:01 PM, sten.kristian.ivarsson@gmail.com wrote:
>>>> The ENIXIO occurs when parallel child-processes simultaneously using
>>>> O_NONBLOCK opening the descriptor.
>>>
>>> This is consistent with my guess that the error is generated by
>>> fhandler_fifo::wait. I have a feeling that read_ready should have
>>> been created as a manual-reset event, and that more care is needed to
>>> make sure it's set when it should be.
>>>
>>>> I could provide a code-snippet
>>>> to reproduce it if wanted ?
>>>
>>> Yes, please!
>>
>> That might not be necessary. If you're able to build the git repo
>> master branch, please try the attached patch.
>Here's a better patch.
I finally succeeded to build latest master (make is not my favourite tool)
and added the patch, but still no success in my little test-program (see
attachment) when creating a write-file-descriptor with O_NONBLOCK
>Ken
[-- Attachment #2: pipe.cpp --]
[-- Type: text/plain, Size: 1671 bytes --]
#include <cstring>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <iostream>
#include <string>
namespace
{
auto error(const int error)
{
std::cerr << getpid() << "\terror:\t" << error << '\t' << std::strerror(error) << std::endl;
return error;
}
}
int main()
{
const auto name{"/tmp/my_name"};
const auto result = mkfifo(name, 0666);
if(result) return error(errno);
constexpr auto writers{5};
constexpr auto messages{4};
for(auto idx = 0; idx < writers; ++idx)
{
const auto pid = fork();
if(pid < 0) return error(errno);
if(pid == 0)
{
std::cout << "child " << getpid() << std::endl;
for(auto idx = 0; idx < messages; ++idx)
{
const auto wfd = open(name, O_WRONLY | O_NONBLOCK);
if(wfd < 0) return error(errno);
const auto msg{std::to_string(getpid())};
if(write(wfd, msg.data(), msg.size() + 1) < 0) error(errno);
close(wfd);
}
return 0;
}
}
{
std::cout << "parent" << std::endl;
const auto rfd = open(name, O_RDONLY);
const auto wfd = open(name, O_WRONLY);
if(rfd < 0) return error(errno);
for(auto idx = 0; idx < writers * messages; ++idx)
{
std::string buffer;
buffer.resize(80);
if(read(rfd, &buffer[0], buffer.size()) < 0) error(errno);
std::cout << buffer << std::endl;
}
close(wfd);
close(rfd);
}
if(unlink(name) < 0) return error(errno);
return 0;
}
next prev parent reply other threads:[~2020-03-27 14:53 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 11:11 sten.kristian.ivarsson
2020-03-25 12:44 ` Ken Brown
[not found] ` <18be01d602ab$0bbfca30$233f5e90$@gmail.com>
2020-03-26 14:06 ` Sv: " Ken Brown
2020-03-26 15:11 ` Ken Brown
2020-03-26 16:03 ` Norton Allen
2020-03-26 16:44 ` Ken Brown
2020-03-26 17:00 ` Norton Allen
2020-03-26 22:01 ` Sv: " sten.kristian.ivarsson
2020-03-26 22:39 ` Ken Brown
2020-03-26 23:19 ` Ken Brown
2020-03-27 13:10 ` Ken Brown
2020-03-27 14:53 ` sten.kristian.ivarsson [this message]
2020-03-27 22:56 ` Sv: " Ken Brown
2020-03-27 23:00 ` Ken Brown
2020-03-28 12:10 ` Sv: " sten.kristian.ivarsson
2020-03-28 15:43 ` Ken Brown
2020-03-29 2:19 ` Ken Brown
2020-03-30 17:44 ` Ken Brown
2020-03-31 21:10 ` Sv: " sten.kristian.ivarsson
2020-03-31 22:02 ` Ken Brown
2020-04-01 7:45 ` Sv: " sten.kristian.ivarsson
2020-04-01 13:47 ` Ken Brown
2020-04-01 8:52 ` sten.kristian.ivarsson
2020-04-01 16:15 ` Ken Brown
2020-04-01 17:14 ` Sv: " sten.kristian.ivarsson
2020-04-01 18:34 ` Ken Brown
2020-04-02 2:19 ` Ken Brown
2020-04-02 8:05 ` Sv: " sten.kristian.ivarsson
2020-04-02 12:47 ` Sv: Sv: Sv: Sv: Sv: Sv: Sv: Sv: Named pipes and multiple wri Gregery Barton
2020-04-02 18:21 ` Sv: Sv: Sv: Sv: Sv: Sv: Sv: Sv: Named pipes and multiple writers Ken Brown
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