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216 lines
6.7 KiB
Plaintext
216 lines
6.7 KiB
Plaintext
[/
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/ Copyright (c) 2003-2007 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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/
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/ Distributed under the Boost Software License, Version 1.0. (See accompanying
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/ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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/]
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[section:implementation Platform-Specific Implementation]
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This design note lists platform-specific implementation details, such as the
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default demultiplexing mechanism, the number of threads created internally, and
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when threads are created.
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[heading Linux Kernel 2.4]
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Demultiplexing mechanism:
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* Uses `select` for demultiplexing. This means that the number of file
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descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
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Threads:
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* Demultiplexing using `select` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading Linux Kernel 2.6]
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Demultiplexing mechanism:
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* Uses `epoll` for demultiplexing.
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Threads:
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* Demultiplexing using `epoll` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading Solaris]
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Demultiplexing mechanism:
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* Uses [^/dev/poll] for demultiplexing.
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Threads:
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* Demultiplexing using [^/dev/poll] is performed in one of the threads that
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calls `io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading QNX Neutrino]
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Demultiplexing mechanism:
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* Uses `select` for demultiplexing. This means that the number of file
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descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
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Threads:
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* Demultiplexing using `select` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading Mac OS X]
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Demultiplexing mechanism:
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* Uses `kqueue` for demultiplexing.
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Threads:
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* Demultiplexing using `kqueue` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading FreeBSD]
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Demultiplexing mechanism:
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* Uses `kqueue` for demultiplexing.
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Threads:
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* Demultiplexing using `kqueue` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading AIX]
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Demultiplexing mechanism:
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* Uses `select` for demultiplexing. This means that the number of file
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descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
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Threads:
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* Demultiplexing using `select` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading HP-UX]
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Demultiplexing mechanism:
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* Uses `select` for demultiplexing. This means that the number of file
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descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
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Threads:
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* Demultiplexing using `select` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading Tru64]
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Demultiplexing mechanism:
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* Uses `select` for demultiplexing. This means that the number of file
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descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
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Threads:
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* Demultiplexing using `select` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading Windows 95, 98 and Me]
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Demultiplexing mechanism:
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* Uses `select` for demultiplexing.
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Threads:
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* Demultiplexing using `select` is performed in one of the threads that calls
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[heading Windows NT, 2000, XP, 2003 and Vista]
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Demultiplexing mechanism:
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* Uses overlapped I/O and I/O completion ports for all asynchronous socket
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operations except for asynchronous connect.
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* Uses `select` for `deadline_timer` operations and for emulating asynchronous
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connect.
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Threads:
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* Demultiplexing using I/O completion ports is performed in all threads that call
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`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
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`io_service::poll_one()`.
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* An additional thread per `io_service` is used for the `select`
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demultiplexing. This thread is created whenever the first `deadline_timer` is
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created, or on the first call to `async_connect()`.
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* An additional thread per `io_service` is used to emulate asynchronous host
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resolution. This thread is created on the first call to either
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`ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
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[endsect]
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