redis/doc/modules/ROOT/pages/changelog.adoc

//
// Copyright (c) 2025 Marcelo Zimbres Silva (mzimbres@gmail.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)
//

= Changelog

== Boost 1.88

* (Issue https://github.com/boostorg/redis/issues/233[233])
  To deal with keys that might not exits in the Redis server, the
  library supports `std::optional`, for example
  `response<std::optional<std::vector<std::string>>>`. In some cases
  however, such as the https://redis.io/docs/latest/commands/mget/[MGET] command,
  each element in the vector might be non exiting, now it is possible
  to specify a response as `response<std::optional<std::vector<std::optional<std::string>>>>`.

* (Issue https://github.com/boostorg/redis/issues/225[225])
  Use `deferred` as the connection default completion token.

* (Issue https://github.com/boostorg/redis/issues/128[128])
  Adds a new `async_exec` overload that allows passing response
  adapters. This makes it possible to receive Redis responses directly
  in custom data structures thereby avoiding unnecessary data copying.
  Thanks to Ruben Perez (@anarthal) for implementing this feature.

* There are also other multiple small improvements in this release,
  users can refer to the git history for more details.

== Boost 1.87

* (Issue https://github.com/boostorg/redis/issues/205[205])
  Improves reaction time to disconnection by using `wait_for_one_error`
  instead of `wait_for_all`. The function `connection::async_run` was
  also changed to return EOF to the user when that error is received
  from the server. That is a breaking change.

* (Issue https://github.com/boostorg/redis/issues/210[210])
  Fixes the adapter of empty nested responses.

* (Issues https://github.com/boostorg/redis/issues/211[211] and https://github.com/boostorg/redis/issues/212[212])
  Fixes the reconnect loop that would hang under certain conditions,
  see the linked issues for more details.

* (Issue https://github.com/boostorg/redis/issues/219[219])
  Changes the default log level from `disabled` to `debug`.

== Boost 1.85

* (Issue https://github.com/boostorg/redis/issues/170[170])
  Under load and on low-latency networks it is possible to start
  receiving responses before the write operation completed and while
  the request is still marked as staged and not written. This messes
  up with the heuristics that classifies responses as unsolicited or
  not.

* (Issue https://github.com/boostorg/redis/issues/168[168]).
  Provides a way of passing a custom SSL context to the connection.
  The design here differs from that of Boost.Beast and Boost.MySql
  since in Boost.Redis the connection owns the context instead of only
  storing a reference to a user provided one. This is ok so because
  apps need only one connection for their entire application, which
  makes the overhead of one ssl-context per connection negligible.

* (Issue https://github.com/boostorg/redis/issues/181[181]).
  See a detailed description of this bug in
  https://github.com/boostorg/redis/issues/181#issuecomment-1913346983[this comment].

* (Issue https://github.com/boostorg/redis/issues/182[182]).
  Sets `"default"` as the default value of `config::username`. This
  makes it simpler to use the `requirepass` configuration in Redis.

* (Issue https://github.com/boostorg/redis/issues/189[189]).
  Fixes narrowing conversion by using `std::size_t` instead of
  `std::uint64_t` for the sizes of bulks and aggregates. The code
  relies now on `std::from_chars` returning an error if a value
  greater than 32 is received on platforms on which the size
  of `std::size_t` is 32.


== Boost 1.84 (First release in Boost)

* Deprecates the `async_receive` overload that takes a response. Users
  should now first call `set_receive_response` to avoid constantly and
  unnecessarily setting the same response.

* Uses `std::function` to type erase the response adapter. This change
  should not influence users in any way but allowed important
  simplification in the connections internals. This resulted in
  massive performance improvement.

* The connection has a new member `get_usage()` that returns the
  connection usage information, such as number of bytes written,
  received etc.

* There are massive performance improvements in the consuming of
  server pushes which are now communicated with an `asio::channel` and
  therefore can be buffered which avoids blocking the socket read-loop.
  Batch reads are also supported by means of `channel.try_send` and
  buffered messages can be consumed synchronously with
  `connection::receive`. The function `boost::redis::cancel_one` has
  been added to simplify processing multiple server pushes contained
  in the same `generic_response`.  *IMPORTANT*: These changes may
  result in more than one push in the response when
  `connection::async_receive` resumes. The user must therefore be
  careful when calling `resp.clear()`: either ensure that all message
  have been processed or just use `consume_one`.

== v1.4.2 (incorporates changes to conform the boost review and more)

* Adds `boost::redis::config::database_index` to make it possible to
  choose a database before starting running commands e.g. after an
  automatic reconnection.

* Massive performance improvement. One of my tests went from
  140k req/s to 390k/s. This was possible after a parser
  simplification that reduced the number of reschedules and buffer
  rotations.

* Adds Redis stream example.

* Renames the project to Boost.Redis and moves the code into namespace
  `boost::redis`.

* As pointed out in the reviews the `to_bulk` and `from_bulk` names were too
  generic for ADL customization points. They gained the prefix `boost_redis_`.

* Moves `boost::redis::resp3::request` to `boost::redis::request`.

* Adds new typedef `boost::redis::response` that should be used instead of
  `std::tuple`.

* Adds new typedef `boost::redis::generic_response` that should be used instead
  of `std::vector<resp3::node<std::string>>`.

* Renames `redis::ignore` to `redis::ignore_t`.

* Changes `async_exec` to receive a `redis::response` instead of an adapter,
  namely, instead of passing `adapt(resp)` users should pass `resp` directly.

* Introduces `boost::redis::adapter::result` to store responses to commands
  including possible resp3 errors without losing the error diagnostic part. To
  access values now use `std::get<N>(resp).value()` instead of
  `std::get<N>(resp)`.

* Implements full-duplex communication. Before these changes the connection
  would wait for a response to arrive before sending the next one. Now requests
  are continuously coalesced and written to the socket. `request::coalesce`
  became unnecessary and was removed. I could measure significative performance
  gains with these changes.

* Improves serialization examples using Boost.Describe to serialize to JSON and protobuf. See
  cpp20_json.cpp and cpp20_protobuf.cpp for more details.

* Upgrades to Boost 1.81.0.

* Fixes build with pass:[libc++].

* Adds high-level functionality to the connection classes. For
  example, `boost::redis::connection::async_run` will automatically
  resolve, connect, reconnect and perform health checks.

== v1.4.0-1

* Renames `retry_on_connection_lost` to `cancel_if_unresponded`.  (v1.4.1)
* Removes dependency on Boost.Hana, `boost::string_view`, Boost.Variant2 and Boost.Spirit.
* Fixes build and setup CI on windows.

== v1.3.0-1

* Upgrades to Boost 1.80.0

* Removes automatic sending of the `HELLO` command. This can't be
  implemented properly without bloating the connection class. It is
  now a user responsibility to send HELLO. Requests that contain it have
  priority over other requests and will be moved to the front of the
  queue, see `aedis::request::config` 

* Automatic name resolving and connecting have been removed from
  `aedis::connection::async_run`. Users have to do this step manually
  now. The reason for this change is that having them built-in doesn't
  offer enough flexibility that is need for boost users.

* Removes healthy checks and idle timeout. This functionality must now
  be implemented by users, see the examples. This is
  part of making Aedis useful to a larger audience and suitable for
  the Boost review process.

* The `aedis::connection` is now using a typeddef to a
  `net::ip::tcp::socket` and  `aedis::ssl::connection` to
  `net::ssl::stream<net::ip::tcp::socket>`.  Users that need to use
  other stream type must now specialize `aedis::basic_connection`.

* Adds a low level example of async code.

== v1.2.0

* `aedis::adapt` supports now tuples created with `std::tie`.
  `aedis::ignore` is now an alias to the type of `std::ignore`.

* Provides allocator support for the internal queue used in the
  `aedis::connection` class.

* Changes the behaviour of `async_run` to complete with success if
  asio::error::eof is received. This makes it easier to  write
  composed operations with awaitable operators.

* Adds allocator support in the `aedis::request` (a
  contribution from Klemens Morgenstern).

* Renames `aedis::request::push_range2` to `push_range`. The
  suffix 2 was used for disambiguation. Klemens fixed it with SFINAE.

* Renames `fail_on_connection_lost` to
  `aedis::request::config::cancel_on_connection_lost`. Now, it will
  only cause connections to be canceled when `async_run` completes.

* Introduces `aedis::request::config::cancel_if_not_connected` which will
  cause a request to be canceled if `async_exec` is called before a
  connection has been established.

* Introduces new request flag `aedis::request::config::retry` that if
  set to true will cause the request to not be canceled when it was
  sent to Redis but remained unresponded after `async_run` completed.
  It provides a way to avoid executing commands twice.

* Removes the `aedis::connection::async_run` overload that takes
  request and adapter as parameters.

* Changes the way `aedis::adapt()` behaves with
  `std::vector<aedis::resp3::node<T>>`. Receiving RESP3 simple errors,
  blob errors or null won't causes an error but will be treated as
  normal response.  It is the user responsibility to check the content
  in the vector.

* Fixes a bug in `connection::cancel(operation::exec)`. Now this
  call will only cancel non-written requests.

* Implements per-operation implicit cancellation support for
  `aedis::connection::async_exec`. The following call will `co_await (conn.async_exec(...) || timer.async_wait(...))`
  will cancel the request as long as it has not been written.

* Changes `aedis::connection::async_run` completion signature to
  `f(error_code)`. This is how is was in the past, the second
  parameter was not helpful.

* Renames `operation::receive_push` to `aedis::operation::receive`.

== v1.1.0-1

* Removes `coalesce_requests` from the `aedis::connection::config`, it
  became a request property now, see `aedis::request::config::coalesce`.

* Removes `max_read_size` from the `aedis::connection::config`. The maximum
  read size can be specified now as a parameter of the
  `aedis::adapt()` function.

* Removes `aedis::sync` class, see intro_sync.cpp for how to perform
  synchronous and thread safe calls. This is possible in Boost. 1.80
  only as it requires `boost::asio::deferred`. 

* Moves from `boost::optional` to `std::optional`. This is part of
  moving to pass:[C++17].

* Changes the behaviour of the second `aedis::connection::async_run` overload
  so that it always returns an error when the connection is lost.

* Adds TLS support, see intro_tls.cpp.

* Adds an example that shows how to resolve addresses over sentinels,
  see subscriber_sentinel.cpp.

* Adds a `aedis::connection::timeouts::resp3_handshake_timeout`. This is
  timeout used to send the `HELLO` command.

* Adds `aedis::endpoint` where in addition to host and port, users can
  optionally provide username, password and the expected server role
  (see `aedis::error::unexpected_server_role`).

* `aedis::connection::async_run` checks whether the server role received in
  the hello command is equal to the expected server role specified in
  `aedis::endpoint`. To skip this check let the role variable empty.

* Removes reconnect functionality from `aedis::connection`. It
  is possible in simple reconnection strategies but bloats the class
  in more complex scenarios, for example, with sentinel,
  authentication and TLS. This is trivial to implement in a separate
  coroutine. As a result the `enum event` and `async_receive_event`
  have been removed from the class too.

* Fixes a bug in `connection::async_receive_push` that prevented
  passing any response adapter other that `adapt(std::vector<node>)`.

* Changes the behaviour of `aedis::adapt()` that caused RESP3 errors
  to be ignored. One consequence of it is that `connection::async_run`
  would not exit with failure in servers that required authentication.

* Changes the behaviour of `connection::async_run` that would cause it
  to complete with success when an error in the
  `connection::async_exec` occurred.

* Ports the buildsystem from autotools to CMake.

== v1.0.0

* Adds experimental cmake support for windows users.

* Adds new class `aedis::sync` that wraps an `aedis::connection` in
  a thread-safe and synchronous API.  All free functions from the
  `sync.hpp` are now member functions of `aedis::sync`.

* Split `aedis::connection::async_receive_event` in two functions, one
  to receive events and another for server side pushes, see
  `aedis::connection::async_receive_push`.

* Removes collision between `aedis::adapter::adapt` and
  `aedis::adapt`.

* Adds `connection::operation` enum to replace `cancel_*` member
  functions with a single cancel function that gets the operations
  that should be cancelled as argument.

* Bugfix: a bug on reconnect from a state where the `connection` object
  had unsent commands. It could cause `async_exec` to never
  complete under certain conditions.

* Bugfix: Documentation of `adapt()` functions were missing from
  Doxygen.

== v0.3.0

* Adds `experimental::exec` and `receive_event` functions to offer a
  thread safe and synchronous way of executing requests across
  threads. See `intro_sync.cpp` and `subscriber_sync.cpp` for
  examples.

* `connection::async_read_push` was renamed to `async_receive_event`.

* `connection::async_receive_event` is now being used to communicate
  internal events to the user, such as resolve, connect, push etc. For
  examples see cpp20_subscriber.cpp and `connection::event`.

* The `aedis` directory has been moved to `include` to look more
  similar to Boost libraries. Users should now replace `-I/aedis-path`
  with `-I/aedis-path/include` in the compiler flags.

* The `AUTH` and `HELLO` commands are now sent automatically. This change was
  necessary to implement reconnection. The username and password
  used in `AUTH` should be provided by the user on
  `connection::config`.

* Adds support for reconnection. See `connection::enable_reconnect`.

* Fixes a bug in the `connection::async_run(host, port)` overload
  that was causing crashes on reconnection.

* Fixes the executor usage in the connection class. Before these
  changes it was imposing `any_io_executor` on users.

* `connection::async_receiver_event` is not cancelled anymore when
  `connection::async_run` exits. This change makes user code simpler.

* `connection::async_exec` with host and port overload has been
  removed. Use the other `connection::async_run` overload.

* The host and port parameters from `connection::async_run` have been
  move to `connection::config` to better support authentication and
  failover.

* Many simplifications in the `chat_room` example.

* Fixes build in clang the compilers and makes some improvements in
  the documentation.

== v0.2.0-1

* Fixes a bug that happens on very high load. (v0.2.1) 
* Major rewrite of the high-level API. There is no more need to use the low-level API anymore.
* No more callbacks: Sending requests follows the ASIO asynchronous model.
* Support for reconnection: Pending requests are not canceled when a connection is lost and are re-sent when a new one is established.
* The library is not sending HELLO-3 on user behalf anymore. This is important to support AUTH properly.

== v0.1.0-2

* Adds reconnect coroutine in the `echo_server` example. (v0.1.2)
* Corrects `client::async_wait_for_data` with `make_parallel_group` to launch operation. (v0.1.2)
* Improvements in the documentation. (v0.1.2)
* Avoids dynamic memory allocation in the client class after reconnection. (v0.1.2)
* Improves the documentation and adds some features to the high-level client. (v.0.1.1)
* Improvements in the design and documentation.

== v0.0.1

* First release to collect design feedback.