2 / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
4 / Distributed under the Boost Software License, Version 1.0. (See accompanying
5 / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
8 [section:history Revision History]
10 [heading Asio 1.10.9 / Boost 1.64]
12 * Added limited support for using regular file descriptors (where I/O
13 operations should never fail with `EAGAIN` or `EWOULDBLOCK`) with
14 `posix::stream_descriptor`, when using the Linux epoll backend.
15 * Changed to use `allocator_traits` to rebind allocators in C++11 or later.
16 * Eliminated a double "construction" issue in the converting move constructors.
17 * Added new `ssl::context_base` enumerations to enable support for any TLS
18 version, and improved consistency of SSL/TLS version handling across OpenSSL
20 * Applied more changes to address OpenSSL 1.1 compatibility.
21 * Fixed a compile error when OpenSSL compression is disabled at compile time.
22 * Suppressed some spurious unused variable warnings issued by [^gcc] ([ticket
24 * Worked around a new clang warning issued for usage of the comma operator.
25 * Fixed various header ordering problems.
26 * Changed to refer `std::atomic_thread_fence`, when available, to eliminate a
27 deprecated function warning on newest macOS SDK ([ticket 12482]).
28 * Added a workaround for broken `getaddrinfo` in Apple's NAT64 environment.
29 * Fixed an exception safety issue in the internal hash map implementation.
31 [heading Asio 1.10.8 / Boost 1.62]
33 * Added compatibility with OpenSSL 1.1.0 ([ticket 12238]).
34 * Fixed out-of-bounds iterator use in `asio::connect()` when the
35 `connect_condition` returns an end iterator ([ticket 12354]).
36 * Added a workaround for a move detection problem on MSVC 2015 Update 2
38 * Changed a workaround that was previously added for broken Windows firewalls
39 to only bind to 127.0.0.1 if `getsockname` reports 0.0.0.0 ([ticket
41 * Added call to `SSL_COMP_free_compression_methods` to fix two memory leaks
42 reported at shutdown, for OpenSSL versions >= 1.0.2 and < 1.1.0 ([ticket
44 * Fixed `use_future` compile error encountered on some standard library
45 implementations, by changing `std::allocator<void>` use to a non-void
47 * Enabled use of native `getaddrinfo` by default on Apple OSes, rather than
48 emulation in terms of `getipnodebyname`.
50 [heading Asio 1.10.7 / Boost 1.60]
52 * Added support for Windows 8.1 Store apps.
53 * Fixed macro multiple definition error on Microsoft Visual Studio 2015
55 * Changed Asio's SSL wrapper to respect OpenSSL's `OPENSSL_NO_SSL3` feature
56 test `#define` ([ticket 11754]).
57 * Changed Asio's SSL wrapper to use OpenSSL's new `SSL_CTX_clear_chain_certs`
58 function, if available.
59 * Suppressed a clang 3.6+ warning about unused typedefs ([ticket 11767]).
60 * Regenerated certificates used by SSL examples.
61 * Fixed buffer sizes passed to `strncat` in the `getaddrinfo` emulation and in
62 the SSL wrapper's password handling.
63 * Changed Windows backend to use non-macro `CreateEventW` rather than
64 `CreateEvent` ([ticket 11732]).
66 [heading Asio 1.10.6 / Boost 1.58]
68 * Ensured errors generated by Windows' `ConnectEx` function are mapped to their
69 portable equivalents ([ticket 10744]).
70 * Added new macro `BOOST_ASIO_DISABLE_CONNECTEX` to allow use of `ConnectEx` to
71 be explicitly disabled.
72 * Fixed a race condition in `windows::object_handle` when there are pending
73 wait operations on destruction ([ticket 10624]).
74 * Fixed IPv6 address parsing on FreeBSD, where a trailing scope ID would cause
75 conversion to fail with `EINVAL`.
76 * Worked around shared library visibility issues by ensuring Asio types use
77 default visibility ([ticket 9465], [ticket 11070]).
78 * Changed the SSL wrapper to call the password callback when loading an
79 in-memory key ([ticket 10828]).
80 * Fixed false SSL error reports by ensuring that the SSL error queue is cleared
81 prior to each operation.
82 * Fixed an `ssl::stream<>` bug that may result in spurious 'short read' errors.
83 * Removed a redundant null pointer check in the SSL engine ([ticket 10088]).
84 * Added options for disabling TLS v1.1 and v1.2 ([ticket 10690]).
85 * Removed use of deprecated OpenSSL function `ERR_remove_state`.
86 * Fixed detection of various C++11 features with Clang ([ticket 8835],
88 * Fixed detection of C++11 `std::addressof` with [^g++] ([ticket 10982]).
89 * Changed multicast test to treat certain `join_group` failures as non-fatal.
90 * Decoupled Asio unit tests from Boost.Test ([ticket 11116]).
91 * Changed the tutorial to use `std::endl` to ensure output is flushed.
92 * Fixed an unsigned integer overflow reported by Clang's integer sanitizer.
93 * Added support for move-only return types when using a `yield_context` object
94 with asynchronous operations.
95 * Changed `yield_context` to allow reentrant calls to the completion handler
96 from an initiating function.
97 * Updated detection of Windows Runtime to work with latest Windows SDK.
99 [heading Asio 1.10.5 / Boost 1.57]
101 * Fixed the [^kqueue] reactor so that it works on FreeBSD ([ticket 10606]).
102 * Fixed an issue in the [^kqueue] reactor which resulted in spinning when using
103 serial ports on Mac OS ([ticket 10496]).
104 * Fixed [^kqueue] reactor support for read-only file descriptors
106 * Fixed a compile error when using the [^/dev/poll] reactor ([ticket 10350],
108 * Changed the Windows backend to use `WSASocketW`, as `WSASocketA` has been
109 deprecated ([ticket 10534]).
110 * Fixed some warnings reported by Visual C++ 2013 ([ticket 10376]).
111 * Fixed integer type used in the WinRT version of the byte-order conversion
112 functions ([ticket 10539]).
113 * Changed documentation to indicate that `use_future` and `spawn()` are not
114 made available when including the `asio.hpp` convenience header ([ticket
116 * Explicitly marked `asio::strand` as deprecated. Use
117 `asio::io_service::strand` instead.
119 [heading Asio 1.10.4 / Boost 1.56]
121 * Stopped using certain Winsock functions that are marked as deprecated in the
122 latest Visual C++ and Windows SDK.
123 * Fixed a shadow variable warning on Windows.
124 * Fixed a regression in the [^kqueue] backend that was introduced in Asio
126 * Added a workaround for building the unit tests with [^gcc] on AIX.
128 [heading Asio 1.10.3]
130 * Worked around a [^gcc] problem to do with anonymous enums ([ticket 10042]).
131 * Reverted the Windows `HANDLE` backend change to ignore `ERROR_MORE_DATA`.
132 Instead, the error will be propagated as with any other (i.e. in an
133 `error_code` or thrown as a `system_error`), and the number of bytes
134 transferred will be returned. For code that needs to handle partial messages,
135 the `error_code` overload should be used ([ticket 10034]).
136 * Fixed an off-by-one error in the `signal_set` implementation's signal
137 number check ([ticket 9324]).
138 * Changed the Windows IOCP backend to not assume that
139 `SO_UPDATE_CONNECT_CONTEXT` is defined ([ticket 10016]).
140 * Fixed a Windows-specific issue, introduced in Asio 1.10.2, by using
141 `VerifyVersionInfo` rather than `GetVersionEx`, as `GetVersionEx` has been
143 * Changed to use SSE2 intrinsics rather than inline assembly, to allow the
144 Cray compiler to work.
146 [heading Asio 1.10.2]
148 * Fixed `asio::spawn()` to work correctly with new Boost.Coroutine interface
149 ([ticket 9442], [ticket 9928]).
150 * Ensured that incomplete `asio::spawn()` coroutines are correctly unwound when
151 cleaned up by the `io_service` destructor ([ticket 9731]).
152 * Fixed delegation of continuation hook for handlers produced by
153 `io_service::wrap()` and `strand::wrap()` ([ticket 9741]).
154 * Changed the Windows I/O completion port backend to use `ConnectEx`, if
155 available, for connection-oriented IP sockets.
156 * Changed the `io_service` backend for non-Windows (and non-IOCP Windows)
157 platforms to use a single condition variable per `io_service` instance.
158 This addresses a potential race condition when `run_one()` is used from
160 * Prevented integer overflow when computing timeouts based on some
161 `boost::chrono` and `std::chrono` clocks ([ticket 9662], [ticket 9778]).
162 * Made further changes to `EV_CLEAR` handling in the kqueue backend, to address
163 other cases where the `close()` system call may hang on Mac OS X.
164 * Fixed infinite recursion in implementation of
165 `resolver_query_base::flags::operator~` ([ticket 9548]).
166 * Made the `select` reactor more efficient on Windows for large numbers of
167 sockets ([ticket 9528]).
168 * Fixed a Windows-specific type-aliasing issue reported by [^gcc] ([ticket
170 * Prevented execution of compile-time-only buffer test to avoid triggering an
171 address sanitiser warning ([ticket 8295]).
172 * Disabled the `GetQueuedCompletionStatus` timeout workaround on recent
174 * Added support for string-based scope IDs when using link-local multicast
176 * Changed IPv6 multicast group join to use the address's scope ID as the
177 interface, if an interface is not explicitly specified.
178 * Fixed multicast test failure on Mac OS X and the BSDs by using a link-local
180 * Various minor documentation improvements ([ticket 8295], [ticket 9605],
183 [heading Asio 1.10.1 / Boost 1.55]
185 * Implemented a limited port to Windows Runtime. This support requires that the
186 language extensions be enabled. Due to the restricted facilities exposed by
187 the Windows Runtime API, the port also comes with the following caveats:
188 * The core facilities such as the `io_service`, `strand`, buffers, composed
189 operations, timers, etc., should all work as normal.
190 * For sockets, only client-side TCP is supported.
191 * Explicit binding of a client-side TCP socket is not supported.
192 * The `cancel()` function is not supported for sockets. Asynchronous
193 operations may only be cancelled by closing the socket.
194 * Operations that use `null_buffers` are not supported.
195 * Only `tcp::no_delay` and `socket_base::keep_alive` options are supported.
196 * Resolvers do not support service names, only numbers. I.e. you must
197 use "80" rather than "http".
198 * Most resolver query flags have no effect.
199 * Fixed a regression (introduced in Boost 1.54) where, on some platforms, errors
200 from `async_connect` were not correctly propagated through to the completion
201 handler ([ticket 8795]).
202 * Fixed a Windows-specific regression (introduced in Boost 1.54) that occurs
203 when multiple threads are running an `io_service`. When the bug occurs, the
204 result of an asynchronous operation (error and bytes tranferred) is
205 incorrectly discarded and zero values used instead. For TCP sockets this
206 results in spurious end-of-file notifications ([ticket 8933]).
207 * Fixed a bug in handler tracking, where it was not correctly printing out some
208 handler IDs ([ticket 8808]).
209 * Fixed the comparison used to test for successful synchronous accept
210 operations so that it works correctly with unsigned socket descriptors
212 * Ensured the signal number is correctly passed to the completion handler when
213 starting an `async_wait` on a signal that is already raised ([ticket 8738]).
214 * Suppressed a g++ 4.8+ warning about unused typedefs ([ticket 8980]).
215 * Enabled the move optimisation for handlers that use the default invocation
216 hook ([ticket 8624]).
217 * Clarified that programs must not issue overlapping `async_write_at`
218 operations ([ticket 8669]).
219 * Changed the Windows `HANDLE` backend to treat `ERROR_MORE_DATA` as a
220 non-fatal error when returned by `GetOverlappedResult` for a synchronous
221 read ([ticket 8722]).
222 * Visual C++ language extensions use `generic` as a keyword. Added a
223 workaround that renames the namespace to `cpp_generic` when those language
224 extensions are in effect.
225 * Fixed some asynchronous operations that missed out on getting `async_result`
226 support in Boost 1.54. In particular, the buffered stream templates have been
227 updated so that they adhere to current handler patterns ([ticket 9000],
229 * Enabled move support for Microsoft Visual Studio 2012 ([ticket 8959]).
230 * Added `use_future` support for Microsoft Visual Studio 2012.
231 * Removed a use of `std::min` in the Windows IOCP backend to avoid a
232 dependency on the `<algorithm>` header ([ticket 8758]).
233 * Eliminated some unnecessary handler copies.
234 * Fixed support for older versions of OpenSSL that do not provide the
235 `SSL_CTX_clear_options` function ([ticket 9273]).
236 * Fixed various minor and cosmetic issues in code and documentation
237 (including [ticket 8347], [ticket 8950], [ticket 8953], [ticket 8965],
238 [ticket 8997], [ticket 9230]).
240 [heading Asio 1.10.0 / Boost 1.54]
242 * Added new traits classes, `handler_type` and `async_result`, that allow the
243 customisation of the return type of an initiating function.
244 * Added the `asio::spawn()` function, a high-level wrapper for running
245 stackful coroutines, based on the Boost.Coroutine library. The `spawn()`
246 function enables programs to implement asynchronous logic in a synchronous
247 manner. For example: `size_t n = my_socket.async_read_some(my_buffer, yield);`.
248 For further information, see [link boost_asio.overview.core.spawn Stackful
250 * Added the `asio::use_future` special value, which provides first-class
251 support for returning a C++11 `std::future` from an asynchronous
252 operation's initiating function. For example:
253 `future<size_t> = my_socket.async_read_some(my_buffer, asio::use_future);`.
254 For further information, see [link boost_asio.overview.cpp2011.futures C++
255 2011 Support - Futures].
256 * Promoted the stackless coroutine class and macros to be part of Asio's
257 documented interface, rather than part of the HTTP server 4 example.
258 For further information, see [link boost_asio.overview.core.coroutine
259 Stackless Coroutines].
260 * Added a new handler hook called `asio_handler_is_continuation`.
261 Asynchronous operations may represent a continuation of the asynchronous
262 control flow associated with the current executing handler. The
263 `asio_handler_is_continuation` hook can be customised to return `true` if
264 this is the case, and Asio's implementation can use this knowledge to
265 optimise scheduling of the new handler. To cover common cases, Asio
266 customises the hook for strands, `spawn()` and composed asynchronous
268 * Added four new generic protocol classes, `generic::datagram_protocol`,
269 `generic::raw_protocol`, `generic::seq_packet_protocol` and
270 `generic::stream_protocol`, which implement the `Protocol` type
271 requirements, but allow the user to specify the address family (e.g.
272 `AF_INET`) and protocol type (e.g. `IPPROTO_TCP`) at runtime.
273 For further information, see [link
274 boost_asio.overview.networking.other_protocols Support for Other Protocols].
275 * Added C++11 move constructors that allow the conversion of a socket (or
276 acceptor) into a more generic type. For example, an `ip::tcp::socket` can
277 be converted into a `generic::stream_protocol::socket` via move
279 For further information, see [link
280 boost_asio.overview.networking.other_protocols Support for Other Protocols].
281 * Extended the `basic_socket_acceptor<>`'s `accept()` and `async_accept()`
282 functions to allow a new connection to be accepted directly into a socket
283 of a more generic type. For example, an `ip::tcp::acceptor` can be used to
284 accept into a `generic::stream_protocol::socket` object.
285 For further information, see [link
286 boost_asio.overview.networking.other_protocols Support for Other Protocols].
287 * Moved existing examples into a C++03-specific directory, and added a new
288 directory for C++11-specific examples. A limited subset of the C++03
289 examples have been converted to their C++11 equivalents.
290 * Various SSL enhancements. Thanks go to Nick Jones, on whose work these changes
292 * Added support for SSL handshakes with re-use of data already read from
293 the wire. New overloads of the `ssl::stream<>` class's `handshake()` and
294 `async_handshake()` functions have been added. These accept a
295 `ConstBufferSequence` to be used as initial input to the ssl engine for
296 the handshake procedure.
297 * Added support for creation of TLSv1.1 and TLSv1.2 `ssl::context` objects.
298 * Added a `set_verify_depth()` function to the `ssl::context` and
299 `ssl::stream<>` classes.
300 * Added the ability to load SSL certificate and key data from memory
301 buffers. New functions, `add_certificate_authority()`,
302 `use_certificate()`, `use_certificate_chain()`, `use_private_key()`,
303 `use_rsa_private_key()` and `use_tmp_dh()`, have been added to the
304 `ssl::context` class.
305 * Changed `ssl::context` to automatically disable SSL compression by
306 default. To enable, use the new `ssl::context::clear_options()` function,
307 as in `my_context.clear_options(ssl::context::no_compression)`.
308 * Fixed a potential deadlock in `signal_set` implementation.
309 * Fixed an error in acceptor example in documentation [ticket 8421].
310 * Fixed copy-paste errors in waitable timer documentation [ticket 8602].
311 * Added assertions to satisfy some code analysis tools [ticket 7739].
312 * Fixed a malformed `#warning` directive [ticket 7939].
313 * Fixed a potential data race in the Linux `epoll` implementation.
314 * Fixed a Windows-specific bug, where certain operations might generate an
315 `error_code` with an invalid (i.e. `NULL`) `error_category` [ticket 8613].
316 * Fixed `basic_waitable_timer`'s underlying implementation so that it can
317 handle any `time_point` value without overflowing the intermediate duration
319 * Fixed a problem with lost thread wakeups that can occur when making
320 concurrent calls to `run()` and `poll()` on the same `io_service` object
322 * Fixed implementation of asynchronous connect operation so that it can cope
323 with spurious readiness notifications from the reactor [ticket 7961].
324 * Fixed a memory leak in the `ssl::rfc2818_verification` class.
325 * Added a mechanism for disabling automatic Winsock initialisation [ticket
326 3605]. See the header file [^boost/asio/detail/winsock_init.hpp] for details.
328 [heading Asio 1.8.3 / Boost 1.53]
330 * Fixed some 64-to-32-bit conversion warnings ([ticket 7459]).
331 * Fixed some small errors in documentation and comments ([ticket 7761]).
332 * Fixed an error in the example embedded in `basic_socket::get_option`'s
333 documentation ([ticket 7562]).
334 * Changed to use `long` rather than `int` for SSL_CTX options, to match OpenSSL
336 * Changed to use `_snwprintf` to address a compile error due to the changed
337 `swprintf` signature in recent versions of MinGW ([ticket 7373]).
338 * Fixed a deadlock that can occur on Windows when shutting down a pool of
339 `io_service` threads due to running out of work ([ticket 7552]).
340 * Enabled the `noexcept` qualifier for error categories ([ticket 7797]).
341 * Changed UNIX domain socket example to treat errors from `accept` as non-fatal
343 * Added a small block recycling optimisation to improve default memory
344 allocation behaviour.
346 [heading Asio 1.8.2 / Boost 1.51]
348 * Fixed an incompatibility between `ip::tcp::iostream` and C++11
349 ([@https://svn.boost.org/trac/boost/ticket/7162 #7162]).
350 * Decorated GCC attribute names with underscores to prevent interaction
351 with user-defined macros
352 ([@https://svn.boost.org/trac/boost/ticket/6415 #6415]).
353 * Added missing `#include <cctype>`, needed for some versions of MinGW.
354 * Changed to use [^gcc]'s atomic builtins on ARM CPUs, when available
355 ([@https://svn.boost.org/trac/boost/ticket/7140 #7140]).
356 * Changed strand destruction to be a no-op, to allow strand objects to be
357 destroyed after their associated `io_service` has been destroyed.
358 * Added support for some newer versions of glibc which provide the
359 `epoll_create1()` function but always fail with `ENOSYS`
360 ([@https://svn.boost.org/trac/boost/ticket/7012 #7012]).
361 * Changed the SSL implementation to throw an exception if SSL engine
363 ([@https://svn.boost.org/trac/boost/ticket/6303 #6303]).
364 * Fixed another regression in `buffered_write_stream`
365 ([@https://svn.boost.org/trac/boost/ticket/6310 #6310]).
366 * Implemented various minor performance improvements, primarily targeted at
367 Linux x86 and x86-64 platforms.
369 [heading Asio 1.8.1 / Boost 1.50]
371 * Changed the `epoll_reactor` backend to do lazy registration for `EPOLLOUT`
373 * Fixed the `epoll_reactor` handling of out-of-band data, which was broken by
374 an incomplete fix in the last release.
375 * Changed Asio's SSL wrapper to respect OpenSSL's `OPENSSL_NO_ENGINE` feature
376 test `#define` ([@https://svn.boost.org/trac/boost/ticket/6432 #6432]).
377 * Fixed `windows::object_handle` so that it works with Windows compilers that
378 support C++11 move semantics (such as [^g++]).
379 * Improved the performance of strand rescheduling.
380 * Added support for [^g++] 4.7 when compiling in C++11 mode
381 ([@https://svn.boost.org/trac/boost/ticket/6620 #6620]).
382 * Fixed a problem where `signal_set` handlers were not being delivered when
383 the `io_service` was constructed with a `concurrency_hint` of 1
384 ([@https://svn.boost.org/trac/boost/ticket/6657 #6657]).
386 [heading Asio 1.8.0 / Boost 1.49]
388 * Added a new class template `basic_waitable_timer` based around the C++11 clock
389 type requirements. It may be used with the clocks from the C++11 `<chrono>`
390 library facility or, if those are not available, Boost.Chrono. The typedefs
391 `high_resolution_timer`, `steady_timer` and `system_timer` may be used to
392 create timer objects for the standard clock types.
393 * Added a new `windows::object_handle` class for performing waits on Windows
394 kernel objects. Thanks go to Boris Schaeling for contributing substantially
395 to the development of this feature.
396 * On Linux, `connect()` can return EAGAIN in certain circumstances. Remapped
397 this to another error so that it doesn't look like a non-blocking operation
398 ([@https://svn.boost.org/trac/boost/ticket/6048 #6048]).
399 * Fixed a compile error on NetBSD
400 ([@https://svn.boost.org/trac/boost/ticket/6098 #6098]).
401 * Fixed deadlock on Mac OS X
402 ([@https://svn.boost.org/trac/boost/ticket/6275 #6275]).
403 * Fixed a regression in `buffered_write_stream`
404 ([@https://svn.boost.org/trac/boost/ticket/6310 #6310]).
405 * Fixed a non-paged pool "leak" on Windows when an `io_service` is repeatedly
406 run without anything to do
407 ([@https://svn.boost.org/trac/boost/ticket/6321 #6321]).
408 * Reverted earlier change to allow some speculative operations to be performed
409 without holding the lock, as it introduced a race condition in some
410 multithreaded scenarios.
411 * Fixed a bug where the second buffer in an array of two buffers may be ignored
412 if the first buffer is empty.
414 [heading Asio 1.6.1 / Boost 1.48]
416 * Implemented various performance improvements, including:
417 * Using thread-local operation queues in single-threaded use cases (i.e. when
418 `concurrency_hint` is 1) to eliminate a lock/unlock pair.
419 * Allowing some `epoll_reactor` speculative operations to be performed
420 without holding the lock.
421 * Improving locality of reference by performing an `epoll_reactor`'s I/O
422 operation immediately before the corresponding handler is called. This also
423 improves scalability across CPUs when multiple threads are running the
425 * Specialising asynchronous read and write operations for buffer sequences
426 that are arrays (`boost::array` or `std::array`) of exactly two buffers.
427 * Fixed a compile error in the regex overload of `async_read_until`
428 ([@https://svn.boost.org/trac/boost/ticket/5688 #5688]).
429 * Fixed a Windows-specific compile error by explicitly specifying the
430 `signal()` function from the global namespace
431 ([@https://svn.boost.org/trac/boost/ticket/5722 #5722]).
432 * Changed the `deadline_timer` implementation so that it does not read the
433 clock unless the timer heap is non-empty.
434 * Changed the SSL stream's buffers' sizes so that they are large enough to hold
435 a complete TLS record ([@https://svn.boost.org/trac/boost/ticket/5854 #5854]).
436 * Fixed the behaviour of the synchronous `null_buffers` operations so that they
437 obey the user's non-blocking setting
438 ([@https://svn.boost.org/trac/boost/ticket/5756 #5756]).
439 * Changed to set the size of the select `fd_set` at runtime when using Windows.
440 * Disabled an MSVC warning due to const qualifier being applied to function type.
441 * Fixed a crash that occurs when using the Intel C++ compiler
442 ([@https://svn.boost.org/trac/boost/ticket/5763 #5763]).
443 * Changed the initialisation of the OpenSSL library so that it supports all
444 available algorithms.
445 * Fixed the SSL error mapping used when the session is gracefully shut down.
446 * Added some latency test programs.
447 * Clarified that a read operation ends when the buffer is full
448 ([@https://svn.boost.org/trac/boost/ticket/5999 #5999]).
449 * Fixed an exception safety issue in `epoll_reactor` initialisation
450 ([@https://svn.boost.org/trac/boost/ticket/6006 #6006]).
451 * Made the number of strand implementations configurable by defining
452 `BOOST_ASIO_STRAND_IMPLEMENTATIONS` to the desired number.
453 * Added support for a new `BOOST_ASIO_ENABLE_SEQUENTIAL_STRAND_ALLOCATION` flag
454 which switches the allocation of strand implementations to use a round-robin
455 approach rather than hashing.
456 * Fixed potential strand starvation issue that can occur when `strand.post()`
459 [heading Asio 1.6.0 / Boost 1.47]
461 * Added support for signal handling, using a new class called `signal_set`.
462 Programs may add one or more signals to the set, and then perform an
463 `async_wait()` operation. The specified handler will be called when one of
464 the signals occurs. The same signal number may be registered with multiple
465 `signal_set` objects, however the signal number must be used only with Asio.
466 Addresses [@https://svn.boost.org/trac/boost/ticket/2879 #2879].
467 * Added handler tracking, a new debugging aid. When enabled by defining
468 `BOOST_ASIO_ENABLE_HANDLER_TRACKING`, Asio writes debugging output to the
469 standard error stream. The output records asynchronous operations and the
470 relationships between their handlers. It may be post-processed using the
471 included [^handlerviz.pl] tool to create a visual representation of the
472 handlers (requires GraphViz).
473 * Added support for timeouts on socket iostreams, such as `ip::tcp::iostream`.
474 A timeout is set by calling `expires_at()` or `expires_from_now()` to
475 establish a deadline. Any socket operations which occur past the deadline
476 will put the iostream into a bad state.
477 * Added a new `error()` member function to socket iostreams, for retrieving the
478 error code from the most recent system call.
479 * Added a new `basic_deadline_timer::cancel_one()` function. This function lets
480 you cancel a single waiting handler on a timer. Handlers are cancelled in
482 * Added a new `transfer_exactly()` completion condition. This can be used to
483 send or receive a specified number of bytes even if the total size of the
484 buffer (or buffer sequence) is larger.
485 * Added new free functions `connect()` and `async_connect()`. These operations
486 try each endpoint in a list until the socket is successfully connected, and
487 are useful for creating TCP clients that work with both IPv4 and IPv6.
488 * Extended the `buffer_size()` function so that it works for buffer sequences
489 in addition to individual buffers.
490 * Added a new `buffer_copy()` function that can be used to copy the raw bytes
491 between individual buffers and buffer sequences.
492 * Added new non-throwing overloads of `read()`, `read_at()`, `write()` and
493 `write_at()` that do not require a completion condition.
494 * Added friendlier compiler errors for when a completion handler does not meet
495 the necessary type requirements. When C++0x is available (currently supported
496 for [^g++] 4.5 or later, and MSVC 10), `static_assert` is also used to
497 generate an informative error message. This checking may be disabled by
498 defining `BOOST_ASIO_DISABLE_HANDLER_TYPE_REQUIREMENTS`.
499 * Added a new, completely rewritten SSL implementation. The new implementation
500 compiles faster, shows substantially improved performance, and supports
501 custom memory allocation and handler invocation. It includes new API features
502 such as certificate verification callbacks and has improved error reporting.
503 The new implementation is source-compatible with the old for most uses.
504 However, if necessary, the old implementation may still be used by defining
505 `BOOST_ASIO_ENABLE_OLD_SSL`.
506 Addresses [@https://svn.boost.org/trac/boost/ticket/3702 #3702],
507 [@https://svn.boost.org/trac/boost/ticket/3958 #3958].
508 * Changed the separate compilation support such that, to use Asio's SSL
509 capabilities, you should also include `boost/asio/ssl/impl/src.hpp` in one
510 source file in your program.
511 * Changed the SSL implementation to support build environments where SSL v2 is
512 explicitly disabled ([@https://svn.boost.org/trac/boost/ticket/5453 #5453]).
513 * Made the `is_loopback()`, `is_unspecified()` and `is_multicast()` functions
514 consistently available across the `ip::address`, `ip::address_v4` and
515 `ip::address_v6` classes
516 ([@https://svn.boost.org/trac/boost/ticket/3939 #3939]).
517 * Added new `non_blocking()` functions for managing the non-blocking behaviour
518 of a socket or descriptor. The `io_control()` commands named `non_blocking_io`
519 are now deprecated in favour of these new functions.
520 * Added new `native_non_blocking()` functions for managing the non-blocking
521 mode of the underlying socket or descriptor. These functions are intended to
522 allow the encapsulation of arbitrary non-blocking system calls as
523 asynchronous operations, in a way that is transparent to the user of the
524 socket object. The functions have no effect on the behaviour of the
525 synchronous operations of the socket or descriptor.
526 * Added the `io_control()` member function for socket acceptors
527 ([@https://svn.boost.org/trac/boost/ticket/3297 #3297]).
528 * Added a `release()` member function to posix descriptors. This function
529 releases ownership of the underlying native descriptor to the caller.
530 Addresses [@https://svn.boost.org/trac/boost/ticket/3900 #3900].
531 * Added support for sequenced packet sockets (`SOCK_SEQPACKET`).
532 * Added a new `io_service::stopped()` function that can be used to determine
533 whether the `io_service` has stopped (i.e. a `reset()` call is needed prior
534 to any further calls to `run()`, `run_one()`, `poll()` or `poll_one()`).
535 * For consistency with the C++0x standard library, deprecated the `native_type`
536 typedefs in favour of `native_handle_type`, and the `native()` member
537 functions in favour of `native_handle()`.
538 * Added support for C++0x move construction and assignment to sockets, serial
539 ports, POSIX descriptors and Windows handles.
540 * Reduced the copying of handler function objects.
541 * Added support for C++0x move construction to further reduce (and in some
542 cases eliminate) copying of handler objects.
543 * Added support for the `fork()` system call. Programs that use `fork()` must
544 call `io_service.notify_fork()` at the appropriate times. Two new examples
545 have been added showing how to use this feature. Addresses
546 [@https://svn.boost.org/trac/boost/ticket/3238 #3238],
547 [@https://svn.boost.org/trac/boost/ticket/4162 #4162].
548 * Cleaned up the handling of errors reported by the `close()` system call. In
549 particular, assume that most operating systems won't have `close()` fail with
550 `EWOULDBLOCK`, but if it does then set the blocking mode and restart the call.
551 If any other error occurs, assume the descriptor is closed. Addresses
552 [@https://svn.boost.org/trac/boost/ticket/3307 #3307].
553 * Added new `asio::buffer()` overloads for `std::array`, when available.
554 * Changed the implementation to use the C++0x standard library templates
555 `array`, `shared_ptr`, `weak_ptr` and `atomic` when they are available,
556 rather than the Boost equivalents.
557 * Use C++0x variadic templates when available, rather than generating function
558 overloads using Boost.Preprocessor.
559 * Changed exception reporting to include the function name in exception `what()`
561 * Fixed insufficient initialisers warning with MinGW.
562 * Changed the `shutdown_service()` member functions to be private.
563 * Added archetypes for testing socket option functions.
564 * Changed the Boost.Asio examples so that they don't use Boost.Thread's
565 convenience header. Use the header file that is specifically for the
566 boost::thread class instead.
567 * Removed the dependency on OS-provided macros for the well-known IPv4 and IPv6
568 addresses. This should eliminate annoying "missing braces around initializer"
569 warnings ([@https://svn.boost.org/trac/boost/ticket/3741 #3741]).
570 * Reduced the size of `ip::basic_endpoint<>` objects (such as
571 `ip::tcp::endpoint` and `ip::udp::endpoint`).
572 * Changed the reactor backends to assume that any descriptors or sockets added
573 using `assign()` may have been `dup()`-ed, and so require explicit
574 deregistration from the reactor
575 ([@https://svn.boost.org/trac/boost/ticket/4971 #4971]).
576 * Removed the deprecated member functions named `io_service()`. The
577 `get_io_service()` member functions should be used instead.
578 * Removed the deprecated typedefs `resolver_query` and `resolver_iterator` from
579 the `ip::tcp`, `ip::udp` and `ip::icmp` classes.
580 * Modified the `buffers_iterator<>` and `ip::basic_resolver_iterator` classes
581 so that the value_type typedefs are non-const byte types.
582 * Fixed warnings reported by g++'s [^-Wshadow] compiler option
583 ([@https://svn.boost.org/trac/boost/ticket/3905 #3905]).
584 * Added an explicit cast to convert the `FIONBIO` constant to int, to suppress
585 a compiler warning on some platforms
586 ([@https://svn.boost.org/trac/boost/ticket/5128 #5128]).
587 * Changed most examples to treat a failure by an accept operation as non-fatal
588 ([@https://svn.boost.org/trac/boost/ticket/5124 #5124]).
589 * Fixed an error in the [^tick_count_timer] example by making the duration type
590 signed. Previously, a wait on an already-passed deadline would not return for
591 a very long time ([@https://svn.boost.org/trac/boost/ticket/5418 #5418]).
593 [heading Asio 1.4.9 / Boost 1.46.1]
595 * `EV_ONESHOT` seems to cause problems on some versions of Mac OS X, with the
596 `io_service` destructor getting stuck inside the `close()` system call.
597 Changed the kqueue backend to use `EV_CLEAR` instead
598 ([@https://svn.boost.org/trac/boost/ticket/5021 #5021]).
599 * Fixed compile failures with some versions of [^g++] due to the use of
600 anonymous enums ([@https://svn.boost.org/trac/boost/ticket/4883 #4883]).
601 * Fixed a bug on kqueue-based platforms, where some system calls that
602 repeatedly fail with `EWOULDBLOCK` are not correctly re-registered with
604 * Changed `asio::streambuf` to ensure that its internal pointers are updated
605 correctly after the data has been modified using `std::streambuf` member
607 * Fixed a bug that prevented the linger socket option from working on platforms
610 [heading Asio 1.4.8 / Boost 1.46]
612 * Fixed an integer overflow problem that occurs when
613 `ip::address_v4::broadcast()` is used on 64-bit platforms.
614 * Fixed a problem on older Linux kernels (where epoll is used without timerfd
615 support) that prevents timely delivery of deadline_timer handlers, after the
616 program has been running for some time
617 ([@https://svn.boost.org/trac/boost/ticket/5045 #5045]).
619 [heading Asio 1.4.7 / Boost 1.45]
621 * Fixed a problem on kqueue-based platforms where a `deadline_timer` may
622 never fire if the `io_service` is running in a background thread
623 ([@https://svn.boost.org/trac/boost/ticket/4568 #4568]).
624 * Fixed a const-correctness issue that prevented valid uses of
625 `has_service<>` from compiling
626 ([@https://svn.boost.org/trac/boost/ticket/4638 #4638]).
627 * Fixed MinGW cross-compilation
628 ([@https://svn.boost.org/trac/boost/ticket/4491 #4491]).
629 * Removed dependency on deprecated Boost.System functions
630 ([@https://svn.boost.org/trac/boost/ticket/4672 #4672]).
631 * Ensured `close()`\/`closesocket()` failures are correctly propagated
632 ([@https://svn.boost.org/trac/boost/ticket/4573 #4573]).
633 * Added a check for errors returned by `InitializeCriticalSectionAndSpinCount`
634 ([@https://svn.boost.org/trac/boost/ticket/4574 #4574]).
635 * Added support for hardware flow control on QNX
636 ([@https://svn.boost.org/trac/boost/ticket/4625 #4625]).
637 * Always use `pselect()` on HP-UX, if it is available
638 ([@https://svn.boost.org/trac/boost/ticket/4578 #4578]).
639 * Ensured handler arguments are passed as lvalues
640 ([@https://svn.boost.org/trac/boost/ticket/4744 #4744]).
641 * Fixed Windows build when thread support is disabled
642 ([@https://svn.boost.org/trac/boost/ticket/4680 #4680]).
643 * Fixed a Windows-specific problem where `deadline_timer` objects with expiry
644 times set more than 5 minutes in the future may never expire
645 ([@https://svn.boost.org/trac/boost/ticket/4745 #4745]).
646 * Fixed the `resolver` backend on BSD platforms so that an empty service name
647 resolves to port number `0`, as per the documentation
648 ([@https://svn.boost.org/trac/boost/ticket/4690 #4690]).
649 * Fixed read operations so that they do not accept buffer sequences of type
650 `const_buffers_1` ([@https://svn.boost.org/trac/boost/ticket/4746 #4746]).
651 * Redefined `Protocol` and `id` to avoid clashing with Objective-C++ keywords
652 ([@https://svn.boost.org/trac/boost/ticket/4191 #4191]).
653 * Fixed a `vector` reallocation performance issue that can occur when there are
654 many active `deadline_timer` objects
655 ([@https://svn.boost.org/trac/boost/ticket/4780 #4780]).
656 * Fixed the kqueue backend so that it compiles on NetBSD
657 ([@https://svn.boost.org/trac/boost/ticket/4662 #4662]).
658 * Fixed the socket `io_control()` implementation on 64-bit Mac OS X and BSD
659 platforms ([@https://svn.boost.org/trac/boost/ticket/4782 #4782]).
660 * Fixed a Windows-specific problem where failures from `accept()` are
661 incorrectly treated as successes
662 ([@https://svn.boost.org/trac/boost/ticket/4859 #4859]).
663 * Deprecated the separate compilation header `<boost/asio/impl/src.cpp>` in
664 favour of `<boost/asio/impl/src.hpp>`
665 ([@https://svn.boost.org/trac/boost/ticket/4560 #4560]).
667 [heading Asio 1.4.6 / Boost 1.44]
669 * Reduced compile times. (Note that some programs may need to add additional
670 `#include`s, e.g. if the program uses `boost::array` but does not explicitly
671 include `<boost/array.hpp>`.)
672 * Reduced the size of generated code.
673 * Refactored `deadline_timer` implementation to improve performance.
674 * Improved multiprocessor scalability on Windows by using a dedicated hidden
675 thread to wait for timers.
676 * Improved performance of `asio::streambuf` with `async_read()` and
677 `async_read_until()`. These read operations now use the existing capacity of
678 the `streambuf` when reading, rather than limiting the read to 512 bytes.
679 * Added optional separate compilation. To enable, add
680 `#include <boost/asio/impl/src.cpp>` to one source file in a program, then
681 build the program with `BOOST_ASIO_SEPARATE_COMPILATION` defined in the
682 project\/compiler settings. Alternatively, `BOOST_ASIO_DYN_LINK` may be
683 defined to build a separately-compiled Asio as part of a shared library.
684 * Added new macro `BOOST_ASIO_DISABLE_FENCED_BLOCK` to permit the disabling of
685 memory fences around completion handlers, even if thread support is enabled.
686 * Reworked timeout examples to better illustrate typical use cases.
687 * Ensured that handler arguments are passed as `const` types.
688 * Fixed incorrect parameter order in `null_buffers` variant of `async_send_to`
689 ([@https://svn.boost.org/trac/boost/ticket/4170 #4170]).
690 * Ensured `unsigned char` is used with `isdigit` in `getaddrinfo` emulation
691 ([@https://svn.boost.org/trac/boost/ticket/4201 #4201]).
692 * Fixed handling of very small but non-zero timeouts
693 ([@https://svn.boost.org/trac/boost/ticket/4205 #4205]).
694 * Fixed crash that occurred when an empty buffer sequence was passed to a
695 composed read or write operation.
696 * Added missing `operator+` overload in `buffers_iterator`
697 ([@https://svn.boost.org/trac/boost/ticket/4382 #4382]).
698 * Implemented cancellation of `null_buffers` operations on Windows.
700 [heading Asio 1.4.5 / Boost 1.43]
702 * Improved performance.
703 * Reduced compile times.
704 * Reduced the size of generated code.
705 * Extended the guarantee that background threads don't call user code to all
706 asynchronous operations
707 ([@https://svn.boost.org/trac/boost/ticket/3923 #3923]).
708 * Changed to use edge-triggered epoll on Linux.
709 * Changed to use `timerfd` for dispatching timers on Linux, when available.
710 * Changed to use one-shot notifications with kqueue on Mac OS X and BSD
712 * Added a bitmask type `ip::resolver_query_base::flags` as per the TR2 proposal.
713 This type prevents implicit conversion from `int` to `flags`, allowing the
714 compiler to catch cases where users incorrectly pass a numeric port number as
716 * Added `#define NOMINMAX` for all Windows compilers. Users can define
717 `BOOST_ASIO_NO_NOMINMAX` to suppress this definition
718 ([@https://svn.boost.org/trac/boost/ticket/3901 #3901]).
719 * Fixed a bug where 0-byte asynchronous reads were incorrectly passing an
720 `error::eof` result to the completion handler
721 ([@https://svn.boost.org/trac/boost/ticket/4023 #4023]).
722 * Changed the `io_control()` member functions to always call `ioctl` on the
723 underlying descriptor when modifying blocking mode
724 ([@https://svn.boost.org/trac/boost/ticket/3307 #3307]).
725 * Changed the resolver implementation to longer require the typedefs
726 `InternetProtocol::resolver_query` and `InternetProtocol::resolver_iterator`,
727 as neither typedef is part of the documented `InternetProtocol` requirements.
728 The corresponding typedefs in the `ip::tcp`, `ip::udp` and `ip::icmp` classes
729 have been deprecated.
730 * Fixed out-of-band handling for reactors not based on `select()`.
731 * Added new `BOOST_ASIO_DISABLE_THREADS` macro that allows Asio's threading
732 support to be independently disabled.
733 * Minor documentation improvements.
735 [heading Asio 1.4.4 / Boost 1.42]
737 * Added a new HTTP Server 4 example illustrating the use of stackless coroutines
739 * Changed handler allocation and invocation to use `boost::addressof` to get the
740 address of handler objects, rather than applying `operator&` directly
741 ([@https://svn.boost.org/trac/boost/ticket/2977 #2977]).
742 * Restricted MSVC buffer debugging workaround to 2008, as it causes a crash with
743 2010 beta 2 ([@https://svn.boost.org/trac/boost/ticket/3796 #3796],
744 [@https://svn.boost.org/trac/boost/ticket/3822 #3822]).
745 * Fixed a problem with the lifetime of handler memory, where Windows needs the
746 `OVERLAPPED` structure to be valid until both the initiating function call
747 has returned and the completion packet has been delivered.
748 * Don't block signals while performing system calls, but instead restart the
749 calls if they are interrupted.
750 * Documented the guarantee made by strand objects with respect to order of
752 * Changed strands to use a pool of implementations, to make copying of strands
754 * Ensured that kqueue support is enabled for BSD platforms
755 ([@https://svn.boost.org/trac/boost/ticket/3626 #3626]).
756 * Added a `boost_` prefix to the `extern "C"` thread entry point function
757 ([@https://svn.boost.org/trac/boost/ticket/3809 #3809]).
758 * In `getaddrinfo` emulation, only check the socket type (`SOCK_STREAM` or
759 `SOCK_DGRAM`) if a service name has been specified. This should allow the
760 emulation to work with raw sockets.
761 * Added a workaround for some broken Windows firewalls that make a socket
762 appear bound to 0.0.0.0 when it is in fact bound to 127.0.0.1.
763 * Applied a fix for reported excessive CPU usage under Solaris
764 ([@https://svn.boost.org/trac/boost/ticket/3670 #3670]).
765 * Added some support for platforms that use older compilers such as g++ 2.95
766 ([@https://svn.boost.org/trac/boost/ticket/3743 #3743]).
768 [heading Asio 1.4.3 / Boost 1.40]
770 * Added a new ping example to illustrate the use of ICMP sockets.
771 * Changed the `buffered*_stream<>` templates to treat 0-byte reads and writes as
772 no-ops, to comply with the documented type requirements for `SyncReadStream`,
773 `AsyncReadStream`, `SyncWriteStream` and `AsyncWriteStream`.
774 * Changed some instances of the `throw` keyword to `boost::throw_exception()` to
775 allow Asio to be used when exception support is disabled. Note that the SSL
776 wrappers still require exception support
777 ([@https://svn.boost.org/trac/boost/ticket/2754 #2754]).
778 * Made Asio compatible with the OpenSSL 1.0 beta
779 ([@https://svn.boost.org/trac/boost/ticket/3256 #3256]).
780 * Eliminated a redundant system call in the Solaris [^/dev/poll] backend.
781 * Fixed a bug in resizing of the bucket array in the internal hash maps
782 ([@https://svn.boost.org/trac/boost/ticket/3095 #3095]).
783 * Ensured correct propagation of the error code when a synchronous accept fails
784 ([@https://svn.boost.org/trac/boost/ticket/3216 #3216]).
785 * Ensured correct propagation of the error code when a synchronous read or
786 write on a Windows HANDLE fails.
787 * Fixed failures reported when `_GLIBCXX_DEBUG` is defined
788 ([@https://svn.boost.org/trac/boost/ticket/3098 #3098]).
789 * Fixed custom memory allocation support for timers
790 ([@https://svn.boost.org/trac/boost/ticket/3107 #3107]).
791 * Tidied up various warnings reported by g++
792 ([@https://svn.boost.org/trac/boost/ticket/1341 #1341],
793 [@https://svn.boost.org/trac/boost/ticket/2618 #2618]).
794 * Various documentation improvements, including more obvious hyperlinks to
795 function overloads, header file information, examples for the handler type
796 requirements, and adding enum values to the index
797 ([@https://svn.boost.org/trac/boost/ticket/3157 #3157],
798 [@https://svn.boost.org/trac/boost/ticket/2620 #2620]).
800 [heading Asio 1.4.2 / Boost 1.39]
802 * Implement automatic resizing of the bucket array in the internal hash maps.
803 This is to improve performance for very large numbers of asynchronous
804 operations and also to reduce memory usage for very small numbers. A new
805 macro `BOOST_ASIO_HASH_MAP_BUCKETS` may be used to tweak the sizes used for
806 the bucket arrays. (N.B. this feature introduced a bug which was fixed in
807 Asio 1.4.3 / Boost 1.40.)
808 * Add performance optimisation for the Windows IOCP backend for when no timers
810 * Prevent locale settings from affecting formatting of TCP and UDP endpoints
811 ([@https://svn.boost.org/trac/boost/ticket/2682 #2682]).
812 * Fix a memory leak that occurred when an asynchronous SSL operation's
813 completion handler threw an exception
814 ([@https://svn.boost.org/trac/boost/ticket/2910 #2910]).
815 * Fix the implementation of `io_control()` so that it adheres to the
816 documented type requirements for IoControlCommand
817 ([@https://svn.boost.org/trac/boost/ticket/2820 #2820]).
818 * Fix incompatibility between Asio and ncurses.h
819 ([@https://svn.boost.org/trac/boost/ticket/2156 #2156]).
820 * On Windows, specifically handle the case when an overlapped `ReadFile` call
821 fails with `ERROR_MORE_DATA`. This enables a hack where a
822 `windows::stream_handle` can be used with a message-oriented named pipe
823 ([@https://svn.boost.org/trac/boost/ticket/2936 #2936]).
824 * Fix system call wrappers to always clear the error on success, as POSIX
825 allows successful system calls to modify errno
826 ([@https://svn.boost.org/trac/boost/ticket/2953 #2953]).
827 * Don't include termios.h if `BOOST_ASIO_DISABLE_SERIAL_PORT` is defined
828 ([@https://svn.boost.org/trac/boost/ticket/2917 #2917]).
829 * Cleaned up some more MSVC level 4 warnings
830 ([@https://svn.boost.org/trac/boost/ticket/2828 #2828]).
831 * Various documentation fixes
832 ([@https://svn.boost.org/trac/boost/ticket/2871 #2871]).
834 [heading Asio 1.4.1 / Boost 1.38]
836 * Improved compatibility with some Windows firewall software.
837 * Ensured arguments to `windows::overlapped_ptr::complete()` are correctly
838 passed to the completion handler
839 ([@https://svn.boost.org/trac/boost/ticket/2614 #2614]).
840 * Fixed a link problem and multicast failure on QNX
841 ([@https://svn.boost.org/trac/boost/ticket/2504 #2504],
842 [@https://svn.boost.org/trac/boost/ticket/2530 #2530]).
843 * Fixed a compile error in SSL support on MinGW / g++ 3.4.5.
844 * Drop back to using a pipe for notification if eventfd is not available at
845 runtime on Linux ([@https://svn.boost.org/trac/boost/ticket/2683 #2683]).
846 * Various minor bug and documentation fixes
847 ([@https://svn.boost.org/trac/boost/ticket/2534 #2534],
848 [@https://svn.boost.org/trac/boost/ticket/2541 #2541],
849 [@https://svn.boost.org/trac/boost/ticket/2607 #2607],
850 [@https://svn.boost.org/trac/boost/ticket/2617 #2617],
851 [@https://svn.boost.org/trac/boost/ticket/2619 #2619]).
853 [heading Asio 1.4.0 / Boost 1.37]
855 * Enhanced CompletionCondition concept with the signature
856 `size_t CompletionCondition(error_code ec, size_t total)`, where the return
857 value indicates the maximum number of bytes to be transferred on the next
858 read or write operation. (The old CompletionCondition signature is still
859 supported for backwards compatibility).
860 * New windows::overlapped_ptr class to allow arbitrary overlapped I/O
861 functions (such as TransmitFile) to be used with Asio.
862 * On recent versions of Linux, an eventfd descriptor is now used (rather than
863 a pipe) to interrupt a blocked select/epoll reactor.
864 * Added const overloads of lowest_layer().
865 * Synchronous read, write, accept and connect operations are now thread safe
866 (meaning that it is now permitted to perform concurrent synchronous
867 operations on an individual socket, if supported by the OS).
868 * Reactor-based io_service implementations now use lazy initialisation to
869 reduce the memory usage of an io_service object used only as a message
872 [heading Asio 1.2.0 / Boost 1.36]
874 * Added support for serial ports.
875 * Added support for UNIX domain sockets.
876 * Added support for raw sockets and ICMP.
877 * Added wrappers for POSIX stream-oriented file descriptors (excluding regular
879 * Added wrappers for Windows stream-oriented `HANDLE`s such as named pipes
880 (requires `HANDLE`s that work with I/O completion ports).
881 * Added wrappers for Windows random-access `HANDLE`s such as files (requires
882 `HANDLE`s that work with I/O completion ports).
883 * Added support for reactor-style operations (i.e. they report readiness but
884 perform no I/O) using a new `null_buffers` type.
885 * Added an iterator type for bytewise traversal of buffer sequences.
886 * Added new `read_until()` and `async_read_until()` overloads that take a
887 user-defined function object for locating message boundaries.
888 * Added an experimental two-lock queue (enabled by defining
889 `BOOST_ASIO_ENABLE_TWO_LOCK_QUEUE`) that may provide better `io_service`
890 scalability across many processors.
891 * Various fixes, performance improvements, and more complete coverage of the
892 custom memory allocation support.
894 [heading Asio 1.0.0 / Boost 1.35]
896 First release of Asio as part of Boost.