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Eclipse iceoryx hoofs overview

The iceoryx hoofs (Handy Objects Optimised For Safety) are our basic building blocks - the foundation of iceoryx. There are a wide variety of building blocks grouped together in modules, depending on where or how they are used.

Modules

The following sections have a column labeled internal to indicate that the API is not stable and can change anytime. You should never rely on it and there is no support if it is used and breaks your code after an update.

Some modules contain STL constructs which are not part of the C++14 standard as well as convenience constructs like the NewType. Since the classes re-implements some STL constructs, the C++ STL coding guidelines are used for all files in this module, to help the user to have a painless transition from the official STL types to ours. The API should also be identical to the corresponding STL types but we have to make exceptions here. For instance, we do not throw exceptions, try to avoid undefined behavior and we do not use dynamic memory. In these cases we adjusted the API to our use case.

Most of the headers are providing some example code on how the class should be used.

The module structure is a logical grouping. It is replicated for concurrent and posix implementations.

Memory & lifetime management (memory)

class internal description
unique_ptr Provides a heap-less unique_ptr implementation, unlike the STL
RelativePointer Pointer which can be stored in shared memory
ScopeGuard This is an abstraction of the C++ RAII idiom. Sometimes you have constructs where you would like to perform a certain task on creation and then again when they are getting out of scope, this is where ScopeGuard comes in. It is like a std::lock_guard or a std::shared_ptr but more generic.
scoped_static Helper function to limit lifetime of static or global variables to a scope
shared_memory_object/Allocator i Helper class for the SharedMemoryObject.
BumpAllocator i Implementation of a bump allocator

Container (container)

class internal description
vector Heap and exception free implementation of std::vector
list Heap and exception free, relocatable implementation of std::list
UninitializedArray Wrapper class for an uninitialized C-style array which can be zeroed via a template parameter

Vocabulary types (vocabulary)

class internal description
not_null Runtime check wrapper to make sure a pointer is not nullptr
optional C++11 implementation of the C++17 feature std::optional
variant C++11 implementation of the C++17 feature std::variant
expected Our base class used in error handling. Every function which can fail should return an expected. With this the user knows that this function can fail and that they have to do some kind of error handling. We got inspired by the C++ expected proposal and by the rust error handling concept.
string Heap and exception free implementation of std::string. Attention, since the string is stack based, std::string or char array which are assigned to this string will be truncated and zero-terminated if they exceed the string capacity.

Filesystem (filesystem)

class internal description
filesystem Implementation of C++17 filesystem features for instance iox::access_rights and iox::perms to abstract file permissions
AccessController i Interface for Access Control Lists (ACL).
FileLock File lock C++ wrapping class.
posix_access_rights Rights and user management interface.

Functional (functional)

class internal description
storable_function i A std::function alternative with configurable backend for memory storage.
function A stack-based std::function replacement based on storable_function
function_ref C++11 implementation of the next-gen C++ feature std::function_ref see function_ref proposal. It behaves like std::function but does not own the callable.

Utility (utility)

class internal description
system_configuration i Collection of free functions which acquire system information like the page-size.
UniqueId i Monotonic increasing IDs within a process.
into i

Primitives (primitives)

class internal description
type_traits Extended support for evaluating types on compile-time.
types Declares essential building block types like byte.
attributes C++17 and C++20 attributes are sometimes available through compiler extensions. The attribute macros defined in here (like IOX_FALLTHROUGH, IOX_MAYBE_UNUSED ... ) make sure that we are able to use them if the compiler supports it.
algorithm Implements min and max for an arbitrary number of values of the same type. For instance min(1,2,3,4,5);
size Helper functions to determine the size in generic ways

Buffer (buffer)

class internal description
FiFo i Single producer, single consumer lock-free FiFo
LockfreeQueue Multi producer, multi consumer lock-free FiFo with ringbuffer like overflow handling
LoFFLi i Lock-free LIFO based index manager (lock-free free list). One building block of our memory manager. After construction it contains the indices {0 ... n} which you can acquire and release.
SoFi i Single producer, single consumer lock-free safely overflowing FiFo (SoFi).
ResizeableLockFreeQueue Resizeable variant of the LockfreeQueue
stack Stack implementation with simple push/pop interface.
VariantQueue A queue which wraps multiple variants of Queues (FiFo, SoFi, ResizeableLockFreeQueue) - will be moved to iceoryx_posh -

Attribute overview of the available buffers

Data Structure Shared Memory usable Thread-Safe Lock-Free Concurrent Producers : Consumers Bounded Capacity Data Type Restriction Use Case
FiFo Yes Yes Yes 1:1 Yes Copyable FIFO Data transfer
LockfreeQueue Yes Yes Yes n:m Yes Copyable or Movable lock-free transfer of arbitrary data between multiple contexts in FIFO order with overflow handling (ringbuffer)
LoFFLi Yes Yes Yes n:m Yes int32 manage memory access, LIFO order
SoFi Yes Yes Yes 1:1 Yes Trivially Copyable lock-free transfer of small data (e.g. pointers) between two contexts in FIFO order with overflow handling (ringbuffer)
ResizeableLockFreeQueue Yes Yes Yes n:m Yes Copyable or Movable Resizeable variant of the LockfreeQueue
stack Yes No - - Yes None Stack for a single-threaded application

Inter-process communication (ipc)

class internal description
UnixDomainSocket i Interface for unix domain sockets.
SharedMemoryObject i Creates and maps existing shared memory into the application.
shared_memory_object/MemoryMap i Abstraction of mmap, munmap and helper class for the SharedMemoryObject.
shared_memory_object/SharedMemory i Abstraction of shared memory, see ManPage shm_overview and helper class for the SharedMemoryObject.

Threads & sychronisation (sync)

class internal description
PeriodicTask i Periodically executes a callable specified by the template parameter in a configurable time interval.
smart_lock i Creates arbitrary thread-safe constructs which then can be used like smart pointers. If some STL type should be thread safe use the smart_lock to create the thread safe version in one line. Based on some ideas presented in Wrapping C++ Member Function Calls
mutex i Mutex interface, see ManPage pthread_mutex_lock.
Scheduler Supported schedulers and functions to get their priority range are contained here.
UnnamedSemaphore Unamed semaphore interface, see ManPage sem_overview
NamedSemaphore Named semaphore interface, see ManPage sem_overview
thread Heap-less replacement for std::thread.
SignalGuard Helper class for signal handler registration.

Generalized design patterns & abstractions (design)

class internal description
Builder Macro which generates a setter method useful for a builder pattern.
posixCall Wrapper around C and POSIX function calls which performs a full error handling. Additionally, this wrapper makes sure that EINTR handling is performed correctly by repeating the system call.
functional_interface Constructs to easily add functional interfaces like and_then to object container.
NewType<T, Policies> C++11 implementation of Haskells NewType-pattern.
StaticLifetimeGuard Static instance manager which solves the singleton lifetime problem.
PolymorphicHandler Singleton handler with a default instance that can be changed at runtime.

Reporting (reporting)

The error handler is a central instance for collecting all errors and react to them. The error-handling.hpp contains a list of all error enum values. The error handler has different error levels, for more information see error-handling.md For information about how to use the logger API see error-handling.md.

class internal description
errorHandler Free function to call the error handler with a defined error and an error level, see header file for practical example.
ErrorHandler i error handler class only for testing purposes, should not be used directly
logger
requires Base for Expects/Ensures from the C++ Core Guideline

Time (time)

Never use physical properties like speed or time directly as integer or float in your code. Otherwise you encounter problems like this function void setTimeout(int timeout). What is the unit of the argument, seconds? minutes? If you use Duration you see it directly in the code.

void setTimeout(const Duration & timeout);

setTimeout(11_s); // 11 seconds
setTimeout(5_ms); // 5 milliseconds
class internal description
Duration i Represents the unit time, is convertible to timespec and timeval. User defined literals are available for convenience and readability.
`deadline_timer Polling based timer to check for an elapsed deadline.
adaptive_wait i Building block to realize busy waiting loops with low CPU load.
[Check out iceoryx_hoofs on GitHub :fontawesome-brands-github:](https://github.com/eclipse-iceoryx/iceoryx/tree/master/iceoryx_hoofs/){ .md-button }