Added

• CAF now ships an all-new "flow API". This allows users to express data flows at a high level of abstraction with a ReactiveX-style interface. Please refer to new examples and the documentation for more details, as this is a large addition that we cannot cover in-depth here.
• CAF has received a new module: caf.net. This module enables CAF applications to interface with network protocols more directly than caf.io. The new module contains many low-level building blocks for implementing bindings to network protocols. However, CAF also ships ready-to-use, high-level APIs for WebSocket and HTTP. Please have a look at our new examples that showcase the new APIs!
• To complement the flow API as well as the new networking module, CAF also received a new set of async building blocks. Most notably, this includes asynchronous buffers for the flow API and futures / promises that enable the new HTTP request API. We plan on making these building blocks more general in the future for supporting a wider range of use cases.
• JSON inspectors now allow users to use a custom type_id_mapper to generate and parse JSON text that uses different names for the types than the C++ API.

Fixed

• Passing a response promise to a run-delayed continuation could result in a heap-use-after-free if the actor terminates before the action runs. The destructor of the promise now checks for this case.
• Accessing URI fields now always returns the normalized string.
• The JSON parser no longer chokes when encountering null as last value before the closing parenthesis.
• The JSON reader now automatically widens integers to doubles as necessary.
• Module options (e.g. for the middleman) now show up in --long-help output.
• Fix undefined behavior in the Qt group chat example (#1336).
• The ..._instance convenience functions on the registry metric now properly support double metrics and histograms.
• Parsing deeply nested JSON inputs no longer produces a stack overflow. Instead, the parser rejects any JSON with too many nesting levels.
• The spinlock-based work-stealing implementation had severe performance issues on Windows in some cases. We have switched to a regular, mutex-based approach to avoid performance degradations. The new implementation also uses the mutexes for interruptible waiting on the work queues, which improves the responsiveness of the actor system (#1343).

Changed

• Remote spawning of actors is no longer considered experimental.
• The output of --dump-config now prints valid config file syntax.
• When starting a new thread via CAF, the thread hooks API now receives an additional tag that identifies the component responsible for launching the new thread.
• Response promises now hold a strong reference to their parent actor to avoid broken_promise errors in some (legitimate) edge cases (#1361).
• The old, experimental stream API in CAF has been replaced by a new API that is based on the new flow API.

Deprecated

• The obsolete meta-programming utilities replies_to and reacts_to no longer serve any purpose and are thus deprecated.
• The types caf::byte, caf::optional and caf::string_view became obsolete after switching to C++17. Consequently, these types are now deprecated in favor of their standard library counterpart.
• The group-based pub/sub mechanism never fit nicely into the typed messaging API and the fact that group messages use the regular mailbox makes it hard to separate regular communication from multi-cast messages. Hence, we decided to drop the group API and instead focus on the new flows and streams that can replace group-communication in many use cases.
• The "actor-composition operator" was added as a means to enable the first experimental streaming API. With that gone, there's no justification to keep this feature. While it has some neat niche-applications, the prevent some optimization we would like to apply to the messaging layer. Hence, we will remove this feature without a replacement.

Removed

• The template type caf::variant also became obsolete when switching to C++17. Unfortunately, the implementation was not as standalone as its deprecated companions and some of the free functions like holds_alternative were too greedy and did not play nicely with ADL when using std::variant in the same code base. Since fixing caf::variant does not seem to be worth the time investment, we remove this type without a deprecation cycle.

Added

• When adding CAF with exceptions enabled (default), the unit test framework now offers new check macros:
  • CAF_CHECK_NOTHROW(expr)
  • CAF_CHECK_THROWS_AS(expr, type)
  • CAF_CHECK_THROWS_WITH(expr, str)
  • CAF_CHECK_THROWS_WITH_AS(expr, str, type)

Fixed

• The DSL function run_until miscounted the number of executed events, also causing run_once to report a wrong value. Both functions now return the correct result.
• Using allow(...).with(...) in unit tests without a matching message crashed the program. By adding a missing NULL-check, allow is now always safe to use.
• Passing a response promise to a run-delayed continuation could result in a heap-use-after-free if the actor terminates before the action runs. The destructor of the promise now checks for this case.
• Fix OpenSSL 3.0 warnings when building the OpenSSL module by switching to newer EC-curve API.
• When working with settings, put, put_missing, get_if, etc. now gracefully handle the global category when explicitly using it.
• Messages created from a message_builder did not call the destructors for their values, potentially causing memory leaks (#1321).

Changed

• Since support of Qt 5 expired, we have ported the Qt examples to version 6. Hence, building the Qt examples now requires Qt in version 6.
• When compiling CAF with exceptions enabled (default), REQUIRE* macros, expect and disallow no longer call abort(). Instead, they throw an exception that only stops the current test instead of stopping the entire test program.
• Reporting of several unit test macros has been improved to show correct line numbers and provide better diagnostic of test errors.

Fixed

• 0.18.4 introduced a potential crash when using the OpenSSL module and encountering SSL_ERROR_WANT_READ. The crash manifested if CAF resumed a write operation but failed to fully reset its state. The state management (and consequently the crash) has been fixed.
• CAF now clears the actor registry before calling the destructors of loaded modules. This fixes undefined behavior that could occur in rare cases where actor cleanup code could run after loaded modules had been destroyed.

Added

• The new class caf::telemetry::importer::process allows users to get access to process metrics even when not configuring CAF to export metrics to Prometheus via HTTP.

Changed

• Message views now perform the type-check in their constructor. With this change, the make_* utility functions are no longer mandatory and users may instead simply construct the view directly.

Fixed

• Printing a config_value that contains a zero duration timespan now properly prints 0s instead of 1s (#1262). This bug most notably showed up when setting a timespan parameter such as caf.middleman.heartbeat-interval via config file or CLI to 0s and then printing the config parameter, e.g., via --dump-config.
• Blocking actors now release their private thread before decrementing the running-actors count to resolve a race condition during system shutdown that could result in the system hanging (#1266).
• When using the OpenSSL module, CAF could run into a state where the SSL layer wants to read data while CAF is trying to send data. In this case, CAF did not properly back off, causing high CPU load due to spinning and in some scenarios never recovering. This issue has been resolved by properly handling SSL_ERROR_WANT_READ on the transport (#1060).
• Scheduled actors now accept default handlers for down messages etc. with non-const apply operator such as lambda expressions declared as mutable.

Removed

• Dropped three obsolete (and broken) macros in the unit_test.hpp header: CAF_CHECK_FAILED, CAF_CHECK_FAIL and CAF_CHECK_PASSED.

Added

• The actor_system_config now has an additional member called config_file_path_alternatives. With this, users can configure fallback paths for locating a configuration file. For example, an application my-app on a UNIX-like system could set config_file_path to my-app.conf and then add /etc/my-app.conf to config_file_path_alternatives in order to follow the common practice of looking into the current directory first before looking for a system-wide configuration file.

Changed

• Counters in histogram buckets are now always integers, independently on the value type of the histogram. Buckets can never increase by fractional values.

Deprecated

• All parse function overloads in actor_system_config that took a custom configuration file path as argument were deprecated in favor of consistently asking users to use the config_file_path and config_file_path_alternatives member variables instead

Fixed

• For types that offer implicit type conversion, trying to construct a result<T> could result in ambiguity since compilers could construct either T itself or expected<T> for calling a constructor of result<T>. To fix the ambiguity, result<T> now accepts any type that allows constructing a T internally without requiring a type conversion to T as an argument (#1245).
• Fix configuration parameter lookup for the work-stealing scheduler policy.
• Applications that expose metrics to Prometheus properly terminate now.

Added

• CAF includes two new inspector types for consuming and generating JSON-formatted text: json_writer and json_reader.

Changed

• Setter functions for fields may now return either bool, caf::error or void. Previously, CAF only allowed bool.

Fixed

• Passing a getter and setter pair to an inspector via apply produced a compiler error for non-builtin types. The inspection API now recursively inspects user-defined types instead, as was the original intend (#1216).
• The handle type typed_actor now can construct from a typed_actor_pointer. This resolves a compiler error when trying to initialize a handle for my_handle from a self pointer of type my_handle::pointer_view (#1218).
• Passing a function reference to the constructor of an actor caused a compiler error when building with logging enabled. CAF now properly handles this edge case and logs such constructor arguments as <unprintable> (#1229).
• The CLI parser did not recognize metrics filters. Hence, passing --caf.metrics-filters.actors.includes=... to a CAF application resulted in an error. The includes and excludes filters are now consistently handled and accepted in config files as well as on the command line (#1238).
• Silence a deprecated-enum-conversion warning for std::byte (#1230).
• Fix heap-use-after-free when accessing the meta objects table in applications that leave the main function while the actor system and its worker threads are still running (#1241).
• The testing DSL now properly accounts for the message prioritization of actors (suspending regular behavior until receiving the response) when using request.await (#1232).

Fixed

• Version 0.18.0 introduced a regression on the system parameter caf.middleman.heartbeat-interval (#1235). We have addressed the issue by porting the original fix for CAF 0.17.5 (#1095) to the 0.18 series.

Added

• The enum caf::sec received an additional error code: connection_closed.
• The new byte_span and const_byte_span aliases provide convenient definitions when working with sequences of bytes.
• The base metrics now include four new histograms for illuminating the I/O module: caf.middleman.inbound-messages-size, caf.middleman.outbound-messages-size, caf.middleman.deserialization-time and caf.middleman.serialization-time.
• The macro CAF_ADD_TYPE_ID now accepts an optional third parameter for allowing users to override the default type name.
• The new function pair get_as and get_or model type conversions on a config_value. For example, get_as<int>(x) would convert the content of x to an int by either casting numeric values to int (with bound checks) or trying to parse the input of x if it contains a string. The function get_or already existed for settings, but we have added new overloads for generalizing the function to config_value as well.
• The typed_response_promise received additional member functions to mirror the interface of the untyped response_promise.
• Configuration files now allow dot-separated notation for keys. For example, users may write caf.scheduler.max-threads = 4 instead of the nested form caf { scheduler { max-threads = 4 } }.

Deprecated

• The new get_as and get_or function pair makes type conversions on a config_value via get, get_if, etc. obsolete. We will retain the STL-style interface for treating a config_value as a variant-like type.

Changed

• When using CAF_MAIN, CAF now looks for the correct default config file name, i.e., caf-application.conf.
• Simplify the type inspection API by removing the distinction between apply_object and apply_value. Instead, inspectors only offer apply and users may now also call map, list, and tuple for unboxing simple wrapper types. Furthermore, CAF no longer automatically serializes enumeration types using their underlying value because this is fundamentally unsafe.
• CAF no longer parses the input to string options on the command line. For example, my_app '--msg="hello"' results in CAF storing "hello" (including the quotes) for the config option msg. Previously, CAF tried to parse any string input on the command-line that starts with quotes in the same way it would parse strings from a config file, leading to very unintuitive results in some cases (#1113).
• Response promises now implicitly share their state when copied. Once the reference count for the state reaches zero, CAF now produces a broken_promise error if the actor failed to fulfill the promise by calling either dispatch or delegate.

Fixed

• Setting an invalid credit policy no longer results in a segfault (#1140).
• Version 0.18.0-rc.1 introduced a regression that prevented CAF from writing parameters parsed from configuration files back to variables. The original behavior has been restored, i.e., variables synchronize with user input from configuration files and CLI arguments (#1145).
• Restore correct functionality of middleman::remote_lookup (#1146). This fixes a regression introduced in version 0.18.0-rc.1
• Fixed an endless recursion when using the default_inspector from inspect overloads (#1147).
• CAF 0.18 added support for make_behavior in state classes. However, CAF erroneously picked this member function over running the function body when spawning function-based actors (#1149).
• When passing nullptr or custom types with implicit conversions to const char* to deep_to_string, CAF could run into a segfault in the former case or do unexpected things in the latter case. The stringification inspector now matches precisely on pointer types to stop the compiler from doing implicit conversions in the first place.
• Building executables that link to CAF on 32-bit Linux versions using GCC failed due to undefined references to __atomic_fetch symbols. Adding a CMake dependency for caf_core to libatomic gets executables to compile and link as expected (#1153).
• Fixed a regression for remote groups introduced in 0.18.0-rc.1 (#1157).
• CAF 0.18 introduced the option to set different excluded-components filters for file and console log output. However, CAF rejected all events that matched either filter. The new implementation uses the intersection of both filters to reject log messages immediately (before enqueueing it to the logger's queue) and then applies the filters individually when generating file or console output.
• Fix memory leaks when deserializing URIs and when detaching the content of messages (#1160).
• Fix undefined behavior in string_view::compare (#1164).
• Fix undefined behavior when passing --config-file= (i.e., without actual argument) to CAF applications (#1167).
• Protect against self-assignment in a couple of CAF classes (#1169).
• Skipping high-priority messages resulted in CAF lowering the priority to normal. This unintentional demotion has been fixed (#1171).
• Fix undefined behavior in the experimental datagram brokers (#1174).
• Response promises no longer send empty messages in response to asynchronous messages.
• CAF_ADD_TYPE_ID now works with types that live in namespaces that also exist as nested namespace in CAF such as detail or io (#1195).
• Solved a race condition on detached actors that blocked ordinary shutdown of actor systems in some cases (#1196).

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 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. This is an experimental API that requires building CAF with the CMake option CAF_ENABLE_ACTOR_PROFILER (#981).
• Add compact from..to..step 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).
• 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).
• 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 make working with message easier by providing a std::tuple-like interface (#1034).
• The class exit_msg finally got its missing operator== (#1039).
• 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 more.

Deprecated

• 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.
• Actors that die due to an unhandled exception now use sec::runtime_error consistently. This makes exit_reason::unhandled_exception obsolete.

Changed

• 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. On Windows, this change finally enables building native DLL files.
• 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 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 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 binary_(de)serializer but significantly boosts performance in the hot code paths of CAF (#975).
• With C++17, we no longer support compilers without support for thread_local. Consequently, we removed all workarounds and switched to the C++ keyword (#996).
• Our manual now uses reStructuredText instead of LaTeX. We hope this makes extending the manual easier and lowers the barrier to entry for new contributors.
• A stateful_actor now forwards excess arguments to the State rather than to the Base. This enables states with non-default constructors. When using stateful_actor<State> as pointer type in function-based actors, nothing 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 actors).
• 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 or not is now only for the default handler to decide. Consequently, default 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 exclusively use the new configuration syntax (please consult the manual for 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 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.

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 OpenCL dead and gone. There is only legacy support available and recent 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.
• All member functions of scheduled_actor for adding stream managers (such as make_source) were removed in favor their free-function equivalent, e.g., attach_stream_source
• The configuration format of CAF has come a long way since first starting to 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 default file name for configuration files is caf-application.conf.

Fixed

• 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 garbage values (#1107). The fixed packing / unpacking routines for IEEE 754 values keep these non-numeric values intact now. It is worth mentioning that 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 actors that produce a signaling NaN trigger trap handlers before sending the result to another actor.
• The URI parser stored IPv4 addresses as strings (#1123). Users can now safely assume that the parsed URI for tcp://127.0.0.1:8080 returns an IP address when calling authority().host.

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.

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 CAF_ADD_ATOM exists, since the atom text is still mandatory. Assigning type IDs has no immediate effect by default. However, the new function actor_system_config::add_message_types accepts an ID block and adds 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 --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.

Changed

• Our manual now uses reStructuredText instead of LaTeX (backport from 0.18).

Fixed

• Fix handling of OS-specific threading dependency in CMake.
• Fix uninstall target when building CAF as CMake subdirectory (backport from 0.18).
• Fix potential deadlock with inline_all_enqueues (backport from 0.18).
• Exceptions while handling requests now trigger error messages (backport from 0.18).
• Fix build on GCC 7.2
• 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 source (#1076). The handshake process for a graceful shutdown has been fixed.
• Fixed a compiler error on Clang 10 (#1077).
• Setting lists and dictionaries on the command line now properly overrides 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"].
• Fixed a type mismatch in the parameter middleman.heartbeat-interval (#1095). CAF consistently uses timespan for this parameter now.

• Accept numbers as keys in the config syntax (#1014)
• Fix behavior of inline_all_enqueues in the testing DSL (#1016)
• Make sure actors that receive stream input shut down properly (#1019)
• Fix undesired function hiding in fused_downstream_manager (#1020)
• Improve to_string output for caf::error (#1021)
• 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)
• Simplify crosscompilation: remove build dependency on code generators (#1026)
• Leave CXX settings to the (CMake) parent when building as subdirectory (#1032)
• Build without documentation in subdirectory mode (#1037)
• Allow parents to set OPENSSL_INCLUDE_DIR in subdirectory mode (#1037)
• Add -pthread flag on UNIX when looking for libc++ support (#1038)
• Add missing operator== for exit_msg (#1039)
• Avoid producing unexpected log files (#1024)

• Add support for OpenBSD (#955)
• Provide uniform access to actor properties (#958)
• Fix bug in stream managers that caused finalizers to get called twice (#937)
• Fix verbosity level with disabled console output (#953)
• Fix excessive buffering in stream stages (#952)
• Add missing to_string(pec) (#940)

• Add support for OpenBSD

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

• Backport parser fixes
• Fix several warnings

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

Backports two fixes (41c1270 and f3f72bb) to the CAF 0.15 series.

• Parallelize deserialization of messages received over the network (#821). Moving the deserialization out of the I/O loop significantly increases performance. In our benchmark, CAF now handles twice as many messages per second.
• 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.
• Fix performance of thread-safe actor clock (#849). This clock type is used whenever sending requests, delayed messages, receive timeouts etc. CAF can handle about 10x more timeouts per second after the patch.
• 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'
  }
  

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

• Fix linker issue with socket_guard
• Add copy-on-write tuple implementation
• Add missing function overload to caf::dictionary
• Implement graceful shutdown of TCP connections
• Consitently use ISO 8601 for printing timestamps
• Fix logger output for class names
• Fix deserializing into non-empty vectors
• Add to_lowercase convenience function for atoms
• Use bounded queue for the logger
• Fix caf::split algorithm
• Add --libs-only convenience option to configure script
• Fix several compiler warnings
• Improve error reporting on function-based actors
• Fix subtle bug in actor destruction
• Dequeue high-priority messages first

Changes:

• Fix memory leak in copy-on-write pointer (e.g. used by caf::message)

Changes:

• Add an example for the streaming API
• Make build_config.hpp part of the build
• Implement noexcept-correctness for variant
• Fix potential deadlock in the thread-safe clock
• Implement graceful shutdown of streams after quit
• Integrate manual into the main repository
• Give CAF threads recognizable names for debugging
• Demote internal messages from INFO to DEBUG level
• Fix dictionary emplace with char array
• Set CLOEXEC flag on socket/accept/pipe calls
• Add non-overriding receive timouts to actor clock
• Use insert for faster appending in xsputn
• Allow different log levels for file and console
• Add --extra-flags= option to configure script
• Make COW pointer implementation publicly available
• Fix various missing includes and forward declarations

Changes:

• Revise config value API
  • Deprecate all individual members of actor_system_config
  • Add get_or(name, default) API for accessing settings
• Implement CE-0002
• Add experimental streaming feature
• Add C++17-compatible string_view class
• Remove legacy ASIO-based multiplexer
• Add IP address and subnet classes for v4 and v6
• Add URI abstraction according to RFC 3986
• Improve testing DSLs for deterministic testing
• Fix the "quiet" log level and output to uncolored terminals

Changes:

• Fix move ctor of actor system config (#667)

Changes:

• Fix behavior of result<unit_t> (#652)
• Fix compilation errors on Windows (#644)
• Fix build with OpenSSL <= 1.0.1 (#629)
• Fix bulid for MinGW (#643)
• Fix compilation error with the Python module
• Fix compilation error with MSVC v140_clang_c2
• Add experimental support for UDP brokers
• New actor clock abstraction that allows actors to cancel timeouts
• Implement C++17-compatible n-ary visit for variant

Changes:

• Fix a connection issue caused by re-used socket IDs (#606)
• Fix memory issues when linking to many actors (#605)
• Fix potential deadlock in network backend (#604)
• Add hooks for running code whenever CAF starts/terminates a thread (#603)
• Fix default value for config parameter that could freeze the system (#599)

Changes:

• Add experimental OpenSSL module
• Add (very) experimental support for streams using micro batching
• Fix parse issue with XCode (#551)
• Fix a bug with nested request(...).await(...) statements (#550)
• Fix FreeBSD 12 build with Clang 4.0 (#545)
• Fix serialization of std::vector<bool> (#540)
• Fix potential deadlock when linking actors (#536)
• Fix to_string unit test on Raspbian (#534)
• Add reuse flag to publish_local_groups (#526)
• Adopt C++17 API for caf::variant (#525)

Fixes:

• compiler error in typed_actor.hpp
• redundant-move warnings

Changes:

• Allow calling set_down_handler from within a down handler
• Fix race condition when spawning blocking actors
• Implement colored output of caf-test on Windows
• Improve logger component
• Enable removal of all workers at once in an actor_pool

Changes:

• Fix timeout handling in blocking actors
• Add delegate function to response_promise
• Add ccache build option
• Make variant comparable and serializable
• Make logger configurable
• Add new timestamp type representing UNIX time