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Changelog History
Page 1

  • v0.18.0-rc.1

    September 09, 2020

    โž• Added

    • The new fan_out_request function streamlines fan-out/fan-in work flows (see
      the new example in examples/message_passing/fan_out_request.cpp as well as
      ๐Ÿ‘ the new manual entry). The policy-based design further allows us to support
      more use cases in the future (#932, #964).
    • We introduced the lightweight template class error_code as an alternative to
      the generic but more heavyweight class error. The new error code abstraction
      simply wraps an enumeration type without allowing users to add additional
      context such as error messages. However, whenever such information is
      unneeded, the new class is much more efficient than using error.
    • Tracing messages in distributed systems is a common practice for monitoring
      and debugging message-based systems. The new tracing_data abstraction in CAF
      enables users to augment messages between actors with arbitrary meta data.
      ๐Ÿ— This is an experimental API that requires building CAF with the CMake option
    • โž• Add compact list notation in configuration files. For
      example, [1..3] expands to [1, 2, 3] and [4..-4..-2] expands to
      [4, 2, 0, -2, -4] (#999).
    • ๐Ÿ‘ Allow config keys to start with numbers (#1014).
    • The fan_out_request function got an additional policy for picking just the
      fist result: select_any (#1012).
    • โš™ Run-time type information in CAF now uses 16-bit type IDs. Users can assign
      this ID by specializing type_id manually (not recommended) or use the new
      API for automatically assigning ascending IDs inside CAF_BEGIN_TYPE_ID_BLOCK
      and CAF_END_TYPE_ID_BLOCK code blocks.
    • The new typed view types typed_message_view and const_typed_message_view
      ๐Ÿ‘‰ make working with message easier by providing a std::tuple-like interface
    • The class exit_msg finally got its missing operator== (#1039).
    • ๐Ÿ“œ The class node_id received an overload for parse to allow users to convert
      the output of to_string back to the original ID (#1058).
    • Actors can now monitor and demonitor CAF nodes (#1042). Monitoring a CAF
      node causes the actor system to send a node_down_msg to the observer when
      losing connection to the monitored node.
    • In preparation of potential future API additions/changes, CAF now includes an
      RFC4122-compliant uuid class.
    • The new trait class is_error_code_enum allows users to enable conversion of
      custom error code enums to error and error_code.
    • CAF now enables users to tap into internal CAF metrics as well as adding their
      own instrumentation! Since this addition is too large to cover in a changelog
      entry, please have a look at the new Metrics Section of the manual to learn

    ๐Ÿ—„ Deprecated

    • 0๏ธโƒฃ The to_string output for error now renders the error code enum by default.
      This renders the member functions actor_system::render and
      actor_system_config::render obsolete.
    • ๐Ÿ‘ป Actors that die due to an unhandled exception now use sec::runtime_error
      consistently. This makes exit_reason::unhandled_exception obsolete.

    ๐Ÿ”„ Changed

    • ๐Ÿ— CAF now requires C++17 to build.
    • On UNIX, CAF now uses visibility hidden by default. All API functions and
      types that form the ABI are explicitly exported using module-specific macros.
      ๐Ÿ On Windows, this change finally enables building native DLL files.
    • ๐Ÿ’… We switched our coding style to the C++17 nested namespace syntax.
    • CAF used to generate the same node ID when running on the same machine and
      only differentiates actors systems by their process ID. When running CAF
      instances in a container, this process ID is most likely the same for each
      โš™ run. This means two containers can produce the same node ID and thus
      equivalent actor IDs. In order to make it easier to use CAF in a containerized
      environment, we now generate unique (random) node IDs (#970).
    • We did a complete redesign of all things serialization. The central class
      ๐Ÿšš data_processor got removed. The two classes for binary serialization no
      longer extend the generic interfaces serializer and deserializer in order
      to avoid the overhead of dynamic dispatching as well as the runtime cost of
      error return values. This set of changes leads so some code duplication,
      because many CAF types now accept a generic (de)serializer as well as a
      ๐ŸŽ binary_(de)serializer but significantly boosts performance in the hot code
      paths of CAF (#975).
    • ๐Ÿ‘ With C++17, we no longer support compilers without support for thread_local.
      ๐Ÿšš Consequently, we removed all workarounds and switched to the C++ keyword
    • Our manual now uses reStructuredText instead of LaTeX. We hope this makes
      extending the manual easier and lowers the barrier to entry for new
    • A stateful_actor now forwards excess arguments to the State rather than to
      0๏ธโƒฃ the Base. This enables states with non-default constructors. When using
      stateful_actor<State> as pointer type in function-based actors, nothing
      ๐Ÿ”„ changes (i.e. the new API is backwards compatible for this case). However,
      calling spawn<stateful_actor<State>>(xs...) now initializes the State with
      the argument pack xs... (plus optionally a self pointer as first
      argument). Furthermore, the state class can now provide a make_behavior
      member function to initialize the actor (this has no effect for function-based
    • In order to stay more consistent with naming conventions of the standard
      library, we have renamed some values of the pec enumeration:
      • illegal_escape_sequence => invalid_escape_sequence
      • illegal_argument => invalid_argument
      • illegal_category => invalid_category
    • CAF no longer automagically flattens tuple, optional, or expected when
      returning these types from message handlers. Users can simply replace
      std::tuple<A, B, C> with caf::result<A, B, C> for returning more than one
      value from a message handler.
    • A caf::result can no longer represent skip. Whether a message gets skipped
      0๏ธโƒฃ or not is now only for the default handler to decide. Consequently, default
      ๐Ÿ– handlers now return skippable_result instead of result<message>. A
      skippable result is a variant over delegated<message>, message, error,
      or skip_t. The only good use case for message handlers that skip a message
      in their body was in typed actors for getting around the limitation that a
      typed behavior always must provide all message handlers (typed behavior assume
      a complete implementation of the interface). This use case received direct
      support: constructing a typed behavior with partial_behavior_init as first
      argument suppresses the check for completeness.
    • In order to reduce complexity of typed actors, CAF defines interfaces as a set
      of function signatures rather than using custom metaprogramming facilities.
      Function signatures must always wrap the return type in a result<T>. For
      example: typed_actor<result<double>(double)>. We have reimplemented the
      metaprogramming facilities racts_to<...> and replies_to<...>::with<...>
      as an alternative way of writing the function signature.
    • All parsing functions in actor_system_config that take an input stream
      ๐Ÿ”ง exclusively use the new configuration syntax (please consult the manual for
      ๐Ÿ”ง details and examples for the configuration syntax).
    • The returned string of name() must not change during the lifetime of an
      actor. Hence, stateful_actor now only considers static name members in its
      State for overriding this function. CAF always assumed names belonging to
      types, but did not enforce it because the name was only used for logging.
      Since the new metrics use this name for filtering now, we enforce static names
      in order to help avoid hard-to-find issues with the filtering mechanism.
    • The type inspection API received a complete overhaul. The new DSL for writing
      inspect functions exposes the entire structure of an object to CAF. This
      enables inspectors to read and write a wider range of data formats. In
      ๐Ÿ”ง particular human-readable, structured data such as configuration files, JSON,
      XML, etc. The inspection API received too many changes to list them here.
      Please refer to the manual section on type inspection instead.

    โœ‚ Removed

    • A vendor-neutral API for GPGPU programming sure sounds great. Unfortunately,
      OpenCL did not catch on in the way we had hoped. At this point, we can call
      ๐Ÿ‘ OpenCL dead and gone. There is only legacy support available and recent
      ๐Ÿ”– versions of the standard were never implemented in the first place.
      Consequently, we've dropped the opencl module.
    • The old duration type is now superseded by timespan (#994).
    • The enum match_result became obsolete. Individual message handlers can no
      longer skip messages. Hence, message handlers can only succeed (match) or not.
      Consequently, invoking a message handler or behavior now returns a boolean.
    • โฑ All member functions of scheduled_actor for adding stream managers (such as
      ๐Ÿšš make_source) were removed in favor their free-function equivalent, e.g.,
    • ๐Ÿ”ง The configuration format of CAF has come a long way since first starting to
      ๐Ÿ‘ allow user-defined configuration via .ini files. Rather than sticking with
      the weird hybrid that evolved over the years, we finally get rid of the last
      pieces of INI syntax and go with the much cleaner, scoped syntax. The new
      ๐Ÿ”ง default file name for configuration files is caf-application.conf.

    ๐Ÿ›  Fixed

    • ๐Ÿ›  Fix uninstall target when building CAF as CMake subdirectory.
    • Using inline_all_enqueues in deterministic unit tests could result in
      deadlocks when calling blocking functions in message handlers. This function
      now behaves as expected (#1016).
    • Exceptions while handling requests now trigger error messages (#1055).
    • The member function demonitor falsely refused typed actor handles. Actors
      could monitor typed actors but not demonitoring it again. This member function
      is now a template that accepts any actor handle in the same way monitor
      already did.
    • The typed_actor_view decorator lacked several member functions such as
      link_to, send_exit, etc. These are now available.
    • Constructing a typed_actor handle from a pointer view failed du to a missing
      constructor overload. This (explicit) overload now exists and the conversion
      should work as expected.
    • Sending floating points to remote actors changed infinity and NaN to
      ๐Ÿ›  garbage values (#1107). The fixed packing / unpacking routines for IEEE 754
      values keep these non-numeric values intact now. It is worth mentioning that
      โฌ‡๏ธ the new algorithm downgrades signaling NaN values to silent NaN values,
      because the standard API does not provide predicates to distinguish between the
      two. This should have no implications for real-world applications, because
      ๐Ÿšฆ actors that produce a signaling NaN trigger trap handlers before sending
      the result to another actor.
    • ๐Ÿ“œ The URI parser stored IPv4 addresses as strings (#1123). Users can now safely
      ๐Ÿ“œ assume that the parsed URI for tcp:// returns an IP address
      when calling authority().host.
  • v0.17.7

    ๐Ÿ›  Fixed

    • Datagram servants of UDP socket managers were not added as children to their parent broker on creation, which prevented proper system shutdown in some cases. Adding all servants consistently to the broker should make sure UDP brokers terminate correctly (#1133).
    • Backport stream manager fix from CAF 0.18 for fused downstream managers that prevent loss of messages during regular actor shutdown.
  • v0.17.6

    July 24, 2020

    ๐Ÿ›  Fixed

    • Trying to connect to an actor published via the OpenSSL module with the I/O
      module no longer hangs indefinitely (#1119). Instead, the OpenSSL module
      immediately closes the socket if initializing the SSL session fails.
  • v0.17.5

    May 13, 2020

    โž• Added

    • In order to allow users to start migrating towards upcoming API changes, CAF
      0.17.5 includes a subset of the CAF 0.18 type_id API. Listing all
      user-defined types between CAF_BEGIN_TYPE_ID_BLOCK and
      CAF_END_TYPE_ID_BLOCK assigns ascending type IDs. Only one syntax for
      โž• CAF_ADD_ATOM exists, since the atom text is still mandatory. Assigning type
      0๏ธโƒฃ IDs has no immediate effect by default. However, the new function
      actor_system_config::add_message_types accepts an ID block and adds
      โš™ runtime-type information for all types in the block.
    • In order to opt into the compile-time checks for all message types, users can
      set the CAF_ENABLE_TYPE_ID_CHECKS CMake flag to ON (pass
      ๐Ÿ— --enable-type-id-checks when using the configure script). Building CAF
      with this option causes compiler errors when sending a type without a type ID.
      This option in conjunction with the new add_message_types function removes a
      common source of bugs: forgetting to call add_message_type<T> for all types
      that can cross the wire.

    ๐Ÿ”„ Changed

    • Our manual now uses reStructuredText instead of LaTeX (backport from

    ๐Ÿ›  Fixed

    • ๐Ÿ›  Fix handling of OS-specific threading dependency in CMake.
    • ๐Ÿ›  Fix uninstall target when building CAF as CMake subdirectory (backport from
    • Fix potential deadlock with inline_all_enqueues (backport from 0.18).
    • Exceptions while handling requests now trigger error messages (backport from
    • ๐Ÿ›  Fix build on GCC 7.2
    • ๐Ÿ›  Fix build error in the OpenSSL module under some MSVC configurations
    • Serializer and deserializer now accept std::chrono::time_point for all clock
      types instead of hard-wiring std::system_clock.
    • In some edge cases, actors failed to shut down properly when hosting a stream
      ๐Ÿ›  source (#1076). The handshake process for a graceful shutdown has been fixed.
    • ๐Ÿ›  Fixed a compiler error on Clang 10 (#1077).
    • ๐Ÿ’ป Setting lists and dictionaries on the command line now properly overrides
      ๐Ÿ”ง default values and values from configuration files instead of appending to
      them (#942).
    • Using unquoted strings in command-line arguments inside lists now works as
      expected. For example, --foo=abc,def is now equivalent to
      --foo=["abc", "def"].
  • v0.17.4

    February 08, 2019
    • Accept numbers as keys in the config syntax (#1014)
    • Fix behavior of inline_all_enqueues in the testing DSL (#1016)
    • ๐Ÿ‘‰ Make sure actors that receive stream input shut down properly (#1019)
    • Fix undesired function hiding in fused_downstream_manager (#1020)
    • ๐Ÿ‘Œ Improve to_string output for caf::error (#1021)
    • ๐Ÿ›  Fix path recognition in the URI parser, e.g., file:/// is now valid (#1013)
    • Properly report errors to users while connecting two CAF nodes (#1023)
    • ๐Ÿ— Simplify crosscompilation: remove build dependency on code generators (#1026)
    • ๐Ÿ— Leave CXX settings to the (CMake) parent when building as subdirectory (#1032)
    • ๐Ÿ“š Build without documentation in subdirectory mode (#1037)
    • Allow parents to set OPENSSL_INCLUDE_DIR in subdirectory mode (#1037)
    • โž• Add -pthread flag on UNIX when looking for libc++ support (#1038)
    • โž• Add missing operator== for exit_msg (#1039)
    • ๐ŸŒฒ Avoid producing unexpected log files (#1024)
  • v0.17.3

    November 11, 2019
    • โž• Add support for OpenBSD (#955)
    • Provide uniform access to actor properties (#958)
    • ๐Ÿ›  Fix bug in stream managers that caused finalizers to get called twice (#937)
    • ๐Ÿ›  Fix verbosity level with disabled console output (#953)
    • ๐Ÿ›  Fix excessive buffering in stream stages (#952)
    • โž• Add missing to_string(pec) (#940)
  • v0.17.2

    October 20, 2019
    • โž• Add scheduled_send for delayed sends with absolute timeout (#901)
    • ๐Ÿ‘ Allow actors based on composable behaviors to use the streaming API (#902)
    • ๐Ÿ›  Fix memory leak when deserializing node_id (#905)
    • ๐Ÿ›  Fix composition of statically typed actors using streams (#908)
    • โฌ‡๏ธ Reduce stack usage of serializers (#912)
    • ๐Ÿ›  Fix several warnings on GCC and Clang (#915)
    • ๐Ÿง Use default installation directories on GNU/Linux (#917)
    • Fix holds_alternative and get_if for settings (#920)
    • ๐Ÿ‘Œ Support arbitrary list and map types in config_value (#925)
    • ๐Ÿ‘ Allow users to extend config_value API (#929, #938)
    • ๐Ÿ›  Fix silent dropping of errors in response handlers (#935)
    • ๐Ÿ›  Fix stall in remote_group on error (#933)
  • v0.17.1

    August 31, 2019
    • ๐Ÿ›  Fix endless loop in config parser (#894)
    • ๐Ÿ›  Fix debug build with Clang 7 on Linux (#861)
    • ๐Ÿ›  Fix type-specific parsing of config options (#814)
    • ๐Ÿ‘Œ Improve CMake setup when building CAF as subfolder (#866)
    • ๐Ÿ›  Fix potential deadlock in proxy registry (#880)
    • ๐Ÿ›  Fix output of --dump-config (#876)
    • ๐Ÿ›  Fix potential segfault when using streams with trace logging enabled (#878)
    • Properly set CLI remainder (#871)
    • ๐Ÿ‘Œ Support nesting of group names in .ini files (#870)
    • ๐Ÿ‘Œ Support all alphanumeric characters in config group names (#869)
    • ๐Ÿ›  Fix handling of containers with user-defined types (#867)
    • Fix defaulted_function_deleted warning on Clang (#859)
  • v0.17.0

    July 27, 2019
    • Parallelize deserialization of messages received over the network (#821).
      Moving the deserialization out of the I/O loop significantly increases
      ๐ŸŽ performance. In our benchmark, CAF now handles twice as many messages per
    • โž• Add marker to make categories optional on the CLI: Categories are great at
      organizing program options. However, on the CLI they get in the way quickly.
      This change allows developers to prefix category names with ? to make it
      optional on the CLI.
    • ๐Ÿ›  Fix performance of thread-safe actor clock (#849). This clock type is used
      whenever sending requests, delayed messages, receive timeouts etc. CAF can
      ๐Ÿ– handle about 10x more timeouts per second after the patch.
    • ๐Ÿ˜Œ Relax ini syntax for maps by making = for defining maps and , for
      separating key-value pairs optional. For example, this change allows to
      rewrite an entry like this:

      logger = { console-verbosity='trace', console='colored'}

    to a slightly less noisy version such as this:

    logger { console-verbosity='trace'console='colored'}
    • ๐Ÿ‘ Allow apps to always use the caf::logger, whether or not CAF was compiled
      ๐ŸŒฒ with logging enabled.
    • ๐Ÿ›  Fix over- and underflow checks in number parser (#852).
    • ๐Ÿ›  Fix multicast address detection in caf::ipv4_address.cpp (#853).
    • ๐Ÿ›  Fix disconnect issue / WSAGetLastError usage on Windows (#846).
    • ๐Ÿ›  Fix --config-file option (#841).
    • ๐Ÿ›  Fix parsing of CLI arguments for strings and atom values.
    • โž• Add conversion from nullptr to intrusive and COW pointer types.
    • ๐Ÿ‘ Streamline direct node-to-node communication and support multiple app
    • Reimplement binary_serializer and binary_deserializer without STL-style
      ๐ŸŽ stream buffers for better performance.
    • ๐Ÿ‘Œ Support move-only behavior functions.
    • ๐Ÿ‘ Allow users to omit global in config files.
    • ๐Ÿ‘ Allow IPO on GCC/Clang (#824).
  • v0.16.5

    November 11, 2019

    โž• Added

    • ๐Ÿ‘Œ Support for OpenBSD.