[/
 / Copyright (c) 2003-2010 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:history Revision History]

[heading Asio 1.4.7 / Boost 1.45]

* Fixed a problem on kqueue-based platforms where a `deadline_timer` may
  never fire if the `io_service` is running in a background thread
  ([@https://svn.boost.org/trac/boost/ticket/4568 #4568]).
* Fixed a const-correctness issue that prevented valid uses of
  `has_service<>` from compiling
  ([@https://svn.boost.org/trac/boost/ticket/4638 #4638]).
* Fixed MinGW cross-compilation
  ([@https://svn.boost.org/trac/boost/ticket/4491 #4491]).
* Removed dependency on deprecated Boost.System functions
  ([@https://svn.boost.org/trac/boost/ticket/4672 #4672]).
* Ensured `close()`\/`closesocket()` failures are correctly propagated
  ([@https://svn.boost.org/trac/boost/ticket/4573 #4573]).
* Added a check for errors returned by `InitializeCriticalSectionAndSpinCount`
  ([@https://svn.boost.org/trac/boost/ticket/4574 #4574]).
* Added support for hardware flow control on QNX
  ([@https://svn.boost.org/trac/boost/ticket/4625 #4625]).
* Always use `pselect()` on HP-UX, if it is available
  ([@https://svn.boost.org/trac/boost/ticket/4578 #4578]).
* Ensured handler arguments are passed as lvalues
  ([@https://svn.boost.org/trac/boost/ticket/4744 #4744]).
* Fixed Windows build when thread support is disabled
  ([@https://svn.boost.org/trac/boost/ticket/4680 #4680]).
* Fixed a Windows-specific problem where `deadline_timer` objects with expiry
  times set more than 5 minutes in the future may never expire
  ([@https://svn.boost.org/trac/boost/ticket/4745 #4745]).
* Fixed the `resolver` backend on BSD platforms so that an empty service name
  resolves to port number `0`, as per the documentation
  ([@https://svn.boost.org/trac/boost/ticket/4690 #4690]).
* Fixed read operations so that they do not accept buffer sequences of type
  `const_buffers_1` ([@https://svn.boost.org/trac/boost/ticket/4746 #4746]).
* Redefined `Protocol` and `id` to avoid clashing with Objective-C++ keywords
  ([@https://svn.boost.org/trac/boost/ticket/4191 #4191]).
* Fixed a `vector` reallocation performance issue that can occur when there are
  many active `deadline_timer` objects
  ([@https://svn.boost.org/trac/boost/ticket/4780 #4780]).
* Fixed the kqueue backend so that it compiles on NetBSD
  ([@https://svn.boost.org/trac/boost/ticket/4662 #4662]).
* Fixed the socket `io_control()` implementation on 64-bit Mac OS X and BSD
  platforms ([@https://svn.boost.org/trac/boost/ticket/4782 #4782]).
* Fixed a Windows-specific problem where failures from `accept()` are
  incorrectly treated as successes
  ([@https://svn.boost.org/trac/boost/ticket/4859 #4859]).
* Deprecated the separate compilation header `<boost/asio/impl/src.cpp>` in
  favour of `<boost/asio/impl/src.hpp>`
  ([@https://svn.boost.org/trac/boost/ticket/4560 #4560]).

[heading Asio 1.4.6 / Boost 1.44]

* Reduced compile times. (Note that some programs may need to add additional
  `#include`s, e.g. if the program uses `boost::array` but does not explicitly
  include `<boost/array.hpp>`.)
* Reduced the size of generated code.
* Refactored `deadline_timer` implementation to improve performance.
* Improved multiprocessor scalability on Windows by using a dedicated hidden
  thread to wait for timers.
* Improved performance of `asio::streambuf` with `async_read()` and 
  `async_read_until()`. These read operations now use the existing capacity of
  the `streambuf` when reading, rather than limiting the read to 512 bytes.
* Added optional separate compilation. To enable, add
  `#include <boost/asio/impl/src.cpp>` to one source file in a program, then
  build the program with `BOOST_ASIO_SEPARATE_COMPILATION` defined in the
  project\/compiler settings. Alternatively, `BOOST_ASIO_DYN_LINK` may be
  defined to build a separately-compiled Asio as part of a shared library.
* Added new macro `BOOST_ASIO_DISABLE_FENCED_BLOCK` to permit the disabling of
  memory fences around completion handlers, even if thread support is enabled.
* Reworked timeout examples to better illustrate typical use cases.
* Ensured that handler arguments are passed as `const` types.
* Fixed incorrect parameter order in `null_buffers` variant of `async_send_to`
  ([@https://svn.boost.org/trac/boost/ticket/4170 #4170]).
* Ensured `unsigned char` is used with `isdigit` in `getaddrinfo` emulation
  ([@https://svn.boost.org/trac/boost/ticket/4201 #4201]).
* Fixed handling of very small but non-zero timeouts
  ([@https://svn.boost.org/trac/boost/ticket/4205 #4205]).
* Fixed crash that occurred when an empty buffer sequence was passed to a
  composed read or write operation.
* Added missing `operator+` overload in `buffers_iterator`
  ([@https://svn.boost.org/trac/boost/ticket/4382 #4382]).
* Implemented cancellation of `null_buffers` operations on Windows.

[heading Asio 1.4.5 / Boost 1.43]

* Improved performance.
* Reduced compile times.
* Reduced the size of generated code.
* Extended the guarantee that background threads don't call user code to all
  asynchronous operations
  ([@https://svn.boost.org/trac/boost/ticket/3923 #3923]).
* Changed to use edge-triggered epoll on Linux.
* Changed to use `timerfd` for dispatching timers on Linux, when available.
* Changed to use one-shot notifications with kqueue on Mac OS X and BSD
  platforms.
* Added a bitmask type `ip::resolver_query_base::flags` as per the TR2 proposal.
  This type prevents implicit conversion from `int` to `flags`, allowing the
  compiler to catch cases where users incorrectly pass a numeric port number as
  the service name.
* Added `#define NOMINMAX` for all Windows compilers. Users can define
  `BOOST_ASIO_NO_NOMINMAX` to suppress this definition
  ([@https://svn.boost.org/trac/boost/ticket/3901 #3901]).
* Fixed a bug where 0-byte asynchronous reads were incorrectly passing an
  `error::eof` result to the completion handler
  ([@https://svn.boost.org/trac/boost/ticket/4023 #4023]).
* Changed the `io_control()` member functions to always call `ioctl` on the
  underlying descriptor when modifying blocking mode
  ([@https://svn.boost.org/trac/boost/ticket/3307 #3307]).
* Changed the resolver implementation to longer require the typedefs
  `InternetProtocol::resolver_query` and `InternetProtocol::resolver_iterator`,
  as neither typedef is part of the documented `InternetProtocol` requirements.
  The corresponding typedefs in the `ip::tcp`, `ip::udp` and `ip::icmp` classes
  have been deprecated.
* Fixed out-of-band handling for reactors not based on `select()`.
* Added new `BOOST_ASIO_DISABLE_THREADS` macro that allows Asio's threading
  support to be independently disabled.
* Minor documentation improvements.

[heading Asio 1.4.4 / Boost 1.42]

* Added a new HTTP Server 4 example illustrating the use of stackless coroutines
  with Asio.
* Changed handler allocation and invocation to use `boost::addressof` to get the
  address of handler objects, rather than applying `operator&` directly
  ([@https://svn.boost.org/trac/boost/ticket/2977 #2977]).
* Restricted MSVC buffer debugging workaround to 2008, as it causes a crash with
  2010 beta 2 ([@https://svn.boost.org/trac/boost/ticket/3796 #3796],
  [@https://svn.boost.org/trac/boost/ticket/3822 #3822]).
* Fixed a problem with the lifetime of handler memory, where Windows needs the
  `OVERLAPPED` structure to be valid until both the initiating function call
  has returned and the completion packet has been delivered.
* Don't block signals while performing system calls, but instead restart the
  calls if they are interrupted.
* Documented the guarantee made by strand objects with respect to order of
  handler invocation.
* Changed strands to use a pool of implementations, to make copying of strands
  cheaper.
* Ensured that kqueue support is enabled for BSD platforms
  ([@https://svn.boost.org/trac/boost/ticket/3626 #3626]).
* Added a `boost_` prefix to the `extern "C"` thread entry point function
  ([@https://svn.boost.org/trac/boost/ticket/3809 #3809]).
* In `getaddrinfo` emulation, only check the socket type (`SOCK_STREAM` or
  `SOCK_DGRAM`) if a service name has been specified. This should allow the
  emulation to work with raw sockets.
* Added a workaround for some broken Windows firewalls that make a socket
  appear bound to 0.0.0.0 when it is in fact bound to 127.0.0.1.
* Applied a fix for reported excessive CPU usage under Solaris
  ([@https://svn.boost.org/trac/boost/ticket/3670 #3670]).
* Added some support for platforms that use older compilers such as g++ 2.95
  ([@https://svn.boost.org/trac/boost/ticket/3743 #3743]).

[heading Asio 1.4.3 / Boost 1.40]

* Added a new ping example to illustrate the use of ICMP sockets.
* Changed the `buffered*_stream<>` templates to treat 0-byte reads and writes as
  no-ops, to comply with the documented type requirements for `SyncReadStream`,
  `AsyncReadStream`, `SyncWriteStream` and `AsyncWriteStream`.
* Changed some instances of the `throw` keyword to `boost::throw_exception()` to
  allow Asio to be used when exception support is disabled. Note that the SSL
  wrappers still require exception support
  ([@https://svn.boost.org/trac/boost/ticket/2754 #2754]).
* Made Asio compatible with the OpenSSL 1.0 beta
  ([@https://svn.boost.org/trac/boost/ticket/3256 #3256]).
* Eliminated a redundant system call in the Solaris [^/dev/poll] backend.
* Fixed a bug in resizing of the bucket array in the internal hash maps
  ([@https://svn.boost.org/trac/boost/ticket/3095 #3095]).
* Ensured correct propagation of the error code when a synchronous accept fails
  ([@https://svn.boost.org/trac/boost/ticket/3216 #3216]).
* Ensured correct propagation of the error code when a synchronous read or
  write on a Windows HANDLE fails.
* Fixed failures reported when `_GLIBCXX_DEBUG` is defined
  ([@https://svn.boost.org/trac/boost/ticket/3098 #3098]).
* Fixed custom memory allocation support for timers
  ([@https://svn.boost.org/trac/boost/ticket/3107 #3107]).
* Tidied up various warnings reported by g++
  ([@https://svn.boost.org/trac/boost/ticket/1341 #1341],
  [@https://svn.boost.org/trac/boost/ticket/2618 #2618]).
* Various documentation improvements, including more obvious hyperlinks to
  function overloads, header file information, examples for the handler type
  requirements, and adding enum values to the index
  ([@https://svn.boost.org/trac/boost/ticket/3157 #3157],
  [@https://svn.boost.org/trac/boost/ticket/2620 #2620]).

[heading Asio 1.4.2 / Boost 1.39]

* Implement automatic resizing of the bucket array in the internal hash maps.
  This is to improve performance for very large numbers of asynchronous
  operations and also to reduce memory usage for very small numbers. A new
  macro `BOOST_ASIO_HASH_MAP_BUCKETS` may be used to tweak the sizes used for
  the bucket arrays. (N.B. this feature introduced a bug which was fixed in
  Asio 1.4.3 / Boost 1.40.)
* Add performance optimisation for the Windows IOCP backend for when no timers
  are used.
* Prevent locale settings from affecting formatting of TCP and UDP endpoints
  ([@https://svn.boost.org/trac/boost/ticket/2682 #2682]).
* Fix a memory leak that occurred when an asynchronous SSL operation's
  completion handler threw an exception
  ([@https://svn.boost.org/trac/boost/ticket/2910 #2910]).
* Fix the implementation of `io_control()` so that it adheres to the
  documented type requirements for IoControlCommand
  ([@https://svn.boost.org/trac/boost/ticket/2820 #2820]).
* Fix incompatibility between Asio and ncurses.h
  ([@https://svn.boost.org/trac/boost/ticket/2156 #2156]).
* On Windows, specifically handle the case when an overlapped `ReadFile` call
  fails with `ERROR_MORE_DATA`. This enables a hack where a
  `windows::stream_handle` can be used with a message-oriented named pipe
  ([@https://svn.boost.org/trac/boost/ticket/2936 #2936]).
* Fix system call wrappers to always clear the error on success, as POSIX
  allows successful system calls to modify errno 
  ([@https://svn.boost.org/trac/boost/ticket/2953 #2953]).
* Don't include termios.h if `BOOST_ASIO_DISABLE_SERIAL_PORT` is defined
  ([@https://svn.boost.org/trac/boost/ticket/2917 #2917]).
* Cleaned up some more MSVC level 4 warnings
  ([@https://svn.boost.org/trac/boost/ticket/2828 #2828]).
* Various documentation fixes
  ([@https://svn.boost.org/trac/boost/ticket/2871 #2871]).

[heading Asio 1.4.1 / Boost 1.38]

* Improved compatibility with some Windows firewall software.
* Ensured arguments to `windows::overlapped_ptr::complete()` are correctly
  passed to the completion handler
  ([@https://svn.boost.org/trac/boost/ticket/2614 #2614]).
* Fixed a link problem and multicast failure on QNX
  ([@https://svn.boost.org/trac/boost/ticket/2504 #2504],
  [@https://svn.boost.org/trac/boost/ticket/2530 #2530]).
* Fixed a compile error in SSL support on MinGW / g++ 3.4.5.
* Drop back to using a pipe for notification if eventfd is not available at
  runtime on Linux ([@https://svn.boost.org/trac/boost/ticket/2683 #2683]).
* Various minor bug and documentation fixes
  ([@https://svn.boost.org/trac/boost/ticket/2534 #2534],
  [@https://svn.boost.org/trac/boost/ticket/2541 #2541],
  [@https://svn.boost.org/trac/boost/ticket/2607 #2607],
  [@https://svn.boost.org/trac/boost/ticket/2617 #2617],
  [@https://svn.boost.org/trac/boost/ticket/2619 #2619]).

[heading Asio 1.4.0 / Boost 1.37]

* Enhanced CompletionCondition concept with the signature
  `size_t CompletionCondition(error_code ec, size_t total)`, where the return
  value indicates the maximum number of bytes to be transferred on the next
  read or write operation. (The old CompletionCondition signature is still
  supported for backwards compatibility).
* New windows::overlapped_ptr class to allow arbitrary overlapped I/O
  functions (such as TransmitFile) to be used with Asio.
* On recent versions of Linux, an eventfd descriptor is now used (rather than
  a pipe) to interrupt a blocked select/epoll reactor.
* Added const overloads of lowest_layer().
* Synchronous read, write, accept and connect operations are now thread safe
  (meaning that it is now permitted to perform concurrent synchronous
  operations on an individual socket, if supported by the OS).
* Reactor-based io_service implementations now use lazy initialisation to
  reduce the memory usage of an io_service object used only as a message
  queue.

[heading Asio 1.2.0 / Boost 1.36]

* Added support for serial ports.
* Added support for UNIX domain sockets.
* Added support for raw sockets and ICMP.
* Added wrappers for POSIX stream-oriented file descriptors (excluding regular
  files).
* Added wrappers for Windows stream-oriented `HANDLE`s such as named pipes
  (requires `HANDLE`s that work with I/O completion ports).
* Added wrappers for Windows random-access `HANDLE`s such as files (requires
  `HANDLE`s that work with I/O completion ports).
* Added support for reactor-style operations (i.e. they report readiness but
  perform no I/O) using a new `null_buffers` type.
* Added an iterator type for bytewise traversal of buffer sequences.
* Added new `read_until()` and `async_read_until()` overloads that take a
  user-defined function object for locating message boundaries.
* Added an experimental two-lock queue (enabled by defining
  `BOOST_ASIO_ENABLE_TWO_LOCK_QUEUE`) that may provide better `io_service`
  scalability across many processors.
* Various fixes, performance improvements, and more complete coverage of the
  custom memory allocation support.

[heading Asio 1.0.0 / Boost 1.35]

First release of Asio as part of Boost.

[endsect]