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[/
/ Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
/
/ Distributed under the Boost Software License, Version 1.0. (See accompanying
/ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/]
[section:implementation Platform-Specific Implementation]
This design note lists platform-specific implementation details, such as the
default demultiplexing mechanism, the number of threads created internally, and
when threads are created.
[heading Linux Kernel 2.4]
Demultiplexing mechanism:
* Uses `select` for demultiplexing. This means that the number of file
descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
Threads:
* Demultiplexing using `select` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading Linux Kernel 2.6]
Demultiplexing mechanism:
* Uses `epoll` for demultiplexing.
Threads:
* Demultiplexing using `epoll` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading Solaris]
Demultiplexing mechanism:
* Uses [^/dev/poll] for demultiplexing.
Threads:
* Demultiplexing using [^/dev/poll] is performed in one of the threads that
calls `io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading QNX Neutrino]
Demultiplexing mechanism:
* Uses `select` for demultiplexing. This means that the number of file
descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
Threads:
* Demultiplexing using `select` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading Mac OS X]
Demultiplexing mechanism:
* Uses `kqueue` for demultiplexing.
Threads:
* Demultiplexing using `kqueue` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading FreeBSD]
Demultiplexing mechanism:
* Uses `kqueue` for demultiplexing.
Threads:
* Demultiplexing using `kqueue` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading AIX]
Demultiplexing mechanism:
* Uses `select` for demultiplexing. This means that the number of file
descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
Threads:
* Demultiplexing using `select` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading HP-UX]
Demultiplexing mechanism:
* Uses `select` for demultiplexing. This means that the number of file
descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
Threads:
* Demultiplexing using `select` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading Tru64]
Demultiplexing mechanism:
* Uses `select` for demultiplexing. This means that the number of file
descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
Threads:
* Demultiplexing using `select` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading Windows 95, 98 and Me]
Demultiplexing mechanism:
* Uses `select` for demultiplexing.
Threads:
* Demultiplexing using `select` is performed in one of the threads that calls
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[heading Windows NT, 2000, XP, 2003 and Vista]
Demultiplexing mechanism:
* Uses overlapped I/O and I/O completion ports for all asynchronous socket
operations except for asynchronous connect.
* Uses `select` for emulating asynchronous connect.
Threads:
* Demultiplexing using I/O completion ports is performed in all threads that call
`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
`io_service::poll_one()`.
* An additional thread per `io_service` is used for the `select`
demultiplexing. This thread is created on the first call to `async_connect()`.
* An additional thread per `io_service` is used to emulate asynchronous host
resolution. This thread is created on the first call to either
`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
[endsect]
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