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Rotor

rotor is event loop friendly C++ actor micro framework, github abf gitee

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features

• minimalistic loop agnostic core
• erlang-like hierarchical supervisors, see this and this
• various event loops supported (wx, boost-asio, ev) or planned (uv, gtk, etc.)
• asynchronous message passing interface
• request-response messaging with cancellation capabilities, see
• MPMC (multiple producers multiple consumers) messaging, aka pub-sub
• cross-platform (windows, macosx, linux)
• inspired by The Reactive Manifesto and sobjectizer

messaging performance

Setup: Intel Core i7-8550U, Void Linux 5.15.

(1) Backend-independent; Can be measured with examples/boost-asio/ping-pong-single-simple, examples/ev/ping-pong-ev.

(2) Does not apply to wx-backend; can be measured with examples/thread/ping-pong-thread, examples/boost-asio/ping-pong-2-threads, examples/ev/ping-pong-ev-2-threads.

(3) Backend-independent inter-thread messaging when build with BUILD_THREAD_UNSAFE=True. rotor objects (messages and actors) cannot be accessed from different threads, cross-thread message sending facility cannot be used. This option is mainly targeted for single-threaded apps.

license

MIT

documentation

Please read tutorial, design principles and manual here

embedded

Looking for something actor-flavored, but suitable for embedded applications? Take a look into my rotor-light project.

Changelog

0.32 (18-Dec-2024)

• [feature] added make_routed_message() free function. The function is used for "synchronized" message post-processing, i.e. once a message has been delivered and processed by all recipients (can be zero), then it is routed to the specifed address to do cleanup.

Example:

1. an db-actor and opens transaction and reads data (i.e. as std::string_views, owned by db)
2. actors sends broadcast message to all interesting parties to deserialized data
3. after the step 2 is finished the db-actor closes transaction and releases acquired resources.

The make_routed_message is needed to perform recipient-agnostic 3rd step.

The alternative is to create a copy (snapshot) of data (i.e. std::string instead of std::string_view), but that seems redundant.

• [improvement, breaking] add void* parameter to message_visitor_t

0.31 (18-Oct-2024)

• [bugfix, fltk] more realiable message delivery for fltk backend

0.30 (23-Apr-2024)

• [feature] added fltk-backend
• [feature, conan] enable_fltk option which add fltk-support
• [example] added /examples/ping-pong-fltk.cpp and examples/ping-pong-fltk_and_thread.cpp
• [bugfix] wx-backend building and testing
• [improvement, breaking] output directories are set to bin for cmake
• [improvement, breaking] actor_base_t::make_error() is marked as const

0.29 (24-Feb-2024)

• [bugfix] fix segfault in delivery plugin in debugging mode (try to set env ROTOR_INSPECT_DELIVERY=99 to see)

0.28 (22-Jan-2024)

• [cmake, bugfix] add missing header into installation

0.27 (21-Jan-2024)

• [feature] new interface message_visitor_t
• [feature] new interface message_stringifier_t and the default implementation default_stringifier_t which allows to dump messages. It is not a production but a diagnostic/debug tool, due to performance restrictions.
• [feature] system_context_t provides a reference to default message_stringifier_t; it is possible to have a custom one
• [feature, breaking] extended_error_t holds a reference to a request message, which caused an error
• [examples, tests, win32] fix ev examples and tests
• [example] modernize examples/thread/sha512.cpp to use recent openssl version
• [breaking] cmake requirements are lowered to 3.15
• [breaking] fix minor compilation warnings

0.26 (08-Jan-2024)

• [feature] start_timer callback not only method, but any invocable
• [feature, conan] enable_ev option which add libev
• [breaking, conan] boost minimum version 1.83.0
• [testing, conan] remove catch2 from sources and make it dependencies
• [bugfix, breaking] make plugins more dll-friendly
• [breaking] cmake minimum version 3.23
• [breaking] rename registry_t::revese_map_t revese_map -> registry_t::reverse_map_t reverse_map
• [breaking] rename struct cancelation_t -> cancellation_t
• [doc] fix multiple typos

0.25 (26-Dec-2022)

• [bugfix] avoid response messages loose their order relative to regular message
• [bugfix, example] add missing header

0.24 (04-Jun-2022)

• [feature] improve inter-thread messaging performance up to 15% by using boost::unordered_map instead of std::unordered_map
• [bugfix, breaking] avoid introducing unnecessary event loops latency by intensive polling of rotor queues; affects asio and ev loops
• [bugfix] registry_plugin_t, allow to discover aliased services (#46)

0.23 (23-Apr-2022)

• [bugfix] fix compilation issues of messages.cpp on some platforms
• [bugfix, msvc] fix compilation issues of registry plugin for shared library on msvc-16+

0.22 (21-Apr-2022)

• [feature] possibly to install via conan center
• [feature, breaking] possibility to build rotor as shared library
• [feature] add shutdown flag checker (see my blog)
• [bugfix] requests do not outlive actors (i.e. they are cancelled on shutdown_finish)
• [example] there is my another open-source project syncspirit, which uses rotor under hood. I recommend to look at it, if the shipped examples are too-trivial, and don't give you an architectural insight of using rotor.

0.21 (25-Mar-2022)

• [improvement] preliminary support of conan package manager
• [bugfix] fix compilation warnings on Windows/MSVC
• [bugfix] add missing header for rotor::thread installation

0.20 (20-Feb-2022)

• [improvement] superviser can create spawner, which has a policy to auto-spawns new actor instance if previous instance has been shutdown. This is similar to escalate_failure supervising in erlang, see dedicated article
• [improvement] actor can now autoshutdown_supervisor(), when it shutdown
• [improvement] actor can now escalate_failure(), i.e. trigger shutdown own supervisor when it finished with failure
• [improvement] messages delivery order is persevered per-locality (see issue #41)
• [example] examples/thread/ping-pong-spawner (new)
• [example] examples/autoshutdown (new)
• [example] examples/escalate-failure (new)
• [documentation] updated Design principles
• [documentation] updated Examples
• [documentation] updated Introduction

0.19 (31-Dec-2021)

• [improvement] performance improvement in inter-thread (+20%) and cross-thread messaging
• [bugfix] supervisor does not shut self down in rare conditions, when it fails to initialize self
• [bugfix] link_server plugin should ignore unlink_notifications
• [bugfix] avoid cycle (i.e. memleak) in rare cases when supervisor is shutdown, but an external message arrives for processing

0.18 (03-Dec-2021)

• [improvement] add static_assert for noexcept check of a hanler signature
• [improvement] add gitee mirror
• [bugfix] fix potential use-after-free in ev backend

0.17 (23-Oct-2021)

• [bugfix] fix installation issues with cmake (thanks to @melpon)
• [bugfix] fix missing header (thanks to @melpon)
• [ci] drop travis-ci in the sake of circle-ci

0.16 (22-Aug-2021)

• [improvement] significant message throughtput increase for std::thread, boost-asio and ev backends (upto 5x times)
• [improvement] extended_error can now access to root reason
• [improvement] delivery plugin in debug mode dumps discovery requests and responses
• [improvement/breaking] more details on fatal error (system_context)
• [example] examples/thread/ping-pong-thread.cpp (new)
• [example] examples/ev/ping-pong-ev-2-threads (new)

0.15 (02-Apr-2021)

• [bugfix] lifetime_plugin_t do not unsubscribe from foreign to me subscriptions
• [bugfix] foreigners_support_plugin_t more safely deliver a message for a foreign subscriber (actor)

0.14 (20-Feb-2021)

• the dedicated article with highlights: en and ru
• [improvement] actor identity has been introduced. It can be configured or generated via address_maker plugin
• [improvement] actor::do_shutdown() - optionally takes shutdown reason
• [improvement/breaking] instead of using std::error_code the extended_error class is used. It wraps std::error_code, provides string context and pointer to the next extended_error cause. This greatly simplifies error tracking of errors. Every response now contains ee field instead of ec.
• [improvement] actor has shutdown reason (in form of extended_error pointer)
• [improvement] delivery plugin in debug mode it dumps shutdown reason in shutdown trigger messages
• [improvement] actor identity has on_unlink method to get it know, when it has been unlinked from server actor
• [improvement] add resources plugin for supervisor
• [breaking] all responses now have extended_error pointer instead of std::error_code
• [breaking] shutdown_request_t and shutdown_trigger_t messages how have shutdown reason (in form of extended_error pointer)
• [bugfix] link_client_plugin_t do not invoke custom callback, before erasing request in case of failure
• [bugfix] child_manager_plugin_t reactivate self if a child was created from other plugin.
• [bugfix] registry actor incorrectly resolves postponed requests to wrong addresses

0.13 (26-Dec-2020)

• [improvement] delivery plugin in debug mode dumps discarded messages
• [breaking] state_response_t has been removed
• [bugfix] allow to acquire & release resources in via resources_plugin_t, during other plugin configuration
• [bugfix] foreigners_support_plugin_t did not deactivated self properly, caused assertion fail on supervisor shutdown, when there was foreign subscriptions
• [bugfix] link_client_plugin_t did not notified linked server-actors, if its actor is going to shutdown; now server-actors are requested to unlink
• [bugfix] starter_plugin_t sometimes crashed when subscription confirmation message arrives when actor is in non-initializing phase (i.e. shutting down)
• [bugfix] root supervisor is not shutdown properly when it is linked as "server"

0.12 (08-Dec-2020)

• [improvement] added std::thread backend (supervisor)
• [bugfix] active timers, if any, are cancelled upon actor shutdown finish
• [bugfix] supervisor shutdown message is lost in rare cases right after child actor start
• [example] examples/thread/sha512.cpp (new)
• [documentation] updated Event loops & platforms
• [documentation] updated Patterns with Blocking I/O multiplexing
• [deprecated] state_response_t, state_request_t will be removed in v0.13

0.11 (20-Nov-2020)

• [improvement] when supervisor shuts self down due to child init failure, the supervisor init error code is "failure escalation"
• [documentation] updated Advanced examples,
• [bugfix] when actor shuts self down all its timers are properly cancelled
• [bugfix] in rare case supervisor starts, event if child failed to init
• [bugfix] asio: more correct timers cancellation implementation
• [bugfix] ev: more correct shutdown (avoid memory leaks in rare cases)

0.10 (09-Nov-2020)

• [improvement/breaking] Generic timers interface
• [improvement] Request cancellation support
• [improvement] added make_response methods when message should be created, but send later delayed
• [improvement] more debug information in message delivery plugin
• [documentation] Integration with event loops
• [documentation] Requests cancellation and timers are demonstrated in the Advanced Examples section
• [example] examples/boost-asio/ping-pong-timer.cpp (new)
• [example] examples/boost-asio/beast-scrapper.cpp (updated)
• [bugfix] avoid double configuration of a plugin in certain cases when interacting with resources plugin
• [bugfix] more correct cmake installation (thanks to Jorge López Tello, @LtdJorge)

0.09 (03-Oct-2020)

• the dedicated article with highlights: en and ru
• [improvement] rewritten whole documentation
• [improvement/breaking] plugin system where introduced for actors instead of behaviors
• [improvement] actor_config_t was introduced, which now holds pointer to supervisor, init and shutdown timeouts
• [improvement] builder pattern was introduced to simplify actors construction
• [breaking] supervisor_config_t was changed (inherited from actor_config_t)
• [breaking] actor_base_t and supervisor_t constructors has changed - now appropriate config is taken as single parameter. All descendant classes should be changed
• [breaking] if a custom config type is used for actors/supervisors, they should define config_t inside the class, and templated config_builder_t.
• [breaking] supervisor in actor is now accessible via pointer instead of reference
• [bugfix] supervisor_ev_t not always correctly released EV-resources, which lead to leak
• [bugfix] actor_base_t can be shutted down properly even if it did not started yet

0.08 (12-Apr-2020)

• [bugfix] message's arguments are more correctly forwarded
• [bugfix] actor's arguments are more correctly forwarded in actor's creation inrotor::supervisor_t and rotor::asio::supervisor_asio_t
• [bugfix] rotor::asio::forwarder_t now more correctly dispatches boost::asio events to actor methods; e.g. it works correctly now with async_accept method of socket_acceptor

0.07 (02-Apr-2020)

• [improvement] more modern cmake usage

0.06 (09-Nov-2019)

• [improvement] registry actor was added to allow via name/address runtime matching do services discovery
• [improvement, breaking] minor changes in supervisor behavior: now it is considered initialized when all its children confirmed initialization
• [improvement] supervisor_policy_t was introduced to control supervisor behavior on a child-actor startup failure
• [example] examples/ev/pong-registry.cpp how to use registry
• [doc] patterns/Registry was added

0.05 (22-Sep-2019)

• [improvement] response can be inherited from rotor::arc_base, to allow forwarding requests without copying it (i.e. just intrusive pointer is created)
• [example] examples/boost-asio/beast-scrapper.cpp has been added; it demonstrates an app with pool of actor workers with request-response forwarding

0.04 (14-Sep-2019)

• [improvement] the request-response approach is integrated to support basic reliable messaging: response notification failure will be delivered, if the expected response will not arrive in-time
• [improvement] lambda subscribers are supported
• [improvement] actor behavior has been introduced to offload actor's interface
• [breaking] supervisor is constructed with help of supervisor_config_t, which contains shutdown timeout value
• [breaking] supervisor does not spawns timeout timer for overall shutdown procedure, instead per-child timers are spawned. The root supervisor the same way monitors child-supervisor shut down
• [breaking] supervisor create_actor method now takes child max init time value. If it does not confirm, the child actor will be asked for shut down.
• [breaking] shutdown request sent to an child actor now timeout-tracked by supervisor. The message type has changed to message::shutdown_request_t
• [breaking] init request sent to an child actor now timeout-tracked by supervisor. The message type has changed to message::init_request_t
• [breaking] actor's state request message type now message::state_request_t, which follows the generic request/response pattern. The response type is now message::state_response_t.
• [breaking] {asio, ev, ws} supervisor configs are renamed to have corresponding suffix.

0.03 (25-Aug-2019)

• [improvement] locality notion was introduced, which led to possibility to build supervising trees, see blog-cpp-supervisors
• [breaking] the outbound field in rotor::supervisor_t was renamed just to queue
• [breaking] rotor::address_t now contains const void* locality
• [breaking] rotor::asio::supervisor_config_t now contains std::shared_ptr to strand, instead of creating private strand for each supervisor
• [bugfix] redundant do_start() method in rotor::supervisor_t was removed, since supervisor now is able to start self after completing initialization.
• [bugfix] rotor::supervisor_t sends initialize_actor_t to self to advance own state to INITIALIZED via common actor mechanism, instead of changing state directly on early initialization phase (do_initialize)
• [bugfix] rotor::asio::forwarder_t now more correctly dispatches boost::asio events to actor methods
• [bugfix] rotor::ev::supervisor_ev_t properly handles refcounter

0.02 (04-Aug-2019)

• Added libev support

0.01 (24-Jul-2019)

• Initial version