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Class ILLIXR::switchboard

ClassList > ILLIXR > switchboard

A manager for typesafe, threadsafe, named event-streams (called topics). More...

  • #include <switchboard.hpp>

Inherits the following classes: ILLIXR::phonebook::service

Classes

Type Name
class buffered_reader <typename Specific_event>
class event
Virtual class for event types.
class event_wrapper <typename Underlying_type>
Helper class for making event types.
class network_writer <typename Serializable_event>
class reader <typename Specific_event>
A handle which can read the latest event on a topic.
class writer <typename Specific_event>
A handle which can publish events to a topic.

Public Types

Type Name
typedef std::shared_ptr< Specific_event > ptr
The type of shared pointer returned by switchboard.

Public Attributes

Type Name
coordinate_system root_coordinates

Public Functions

Type Name
std::vector< std::string > env_names () const
Get a vector of the currently known environment variables.
buffered_reader< Specific_event > get_buffered_reader (const std::string & topic_name)
std::string get_env (const std::string & var, std::string _default="")
Switchboard access point for environment variables.
bool get_env_bool (const std::string & var, const std::string & def="false")
Get the boolean value of the given environment variable.
const char * get_env_char (const std::string & var, const std::string _default="")
Get a char* of the given environment variable.
network_writer< Specific_event > get_network_writer (const std::string & topic_name, network::topic_config config={})
reader< Specific_event > get_reader (const std::string & topic_name)
Gets a handle to read to the latest value from the topic topic_name .
topic & get_topic (const std::string & topic_name)
writer< Specific_event > get_writer (const std::string & topic_name)
Gets a handle to publish to the topic topic_name .
void schedule (plugin_id_t plugin_id, std::string topic_name, std::function< void(ptr< const Specific_event > &&, std::size_t)> fn)
Schedules the callback fn every time an event is published totopic_name .
void set_env (const std::string & var, const std::string & val)
Set the local environment variable to the given value.
void stop ()
Stops calling switchboard callbacks.
switchboard (const phonebook * pb)
bool topic_exists (const std::string & topic_name)

Public Functions inherited from ILLIXR::phonebook::service

See ILLIXR::phonebook::service

Type Name
virtual ~service () = default

Detailed Description

  • Writing: One can write to a topic (in any thread) through the object returned by get_writer().
  • There are two ways of reading: asynchronous reading and synchronous reading:
  • Asynchronous reading returns the most-recent event on the topic (idempotently). One can do this through (in any thread) the object returned by get_reader().
  • Synchronous reading schedules a callback to be executed on every event which gets published. One can schedule computation by schedule(), which will run the computation in a thread managed by switchboard.
// Get a reader on topic1
switchboard::reader<topic1_type> topic1 = switchboard.get_reader<topic1_type>("topic1");

// Get a writer on topic2
switchboard::writer<topic2_type> topic2 = switchboard.get_writer<topic2_type>("topic2");

while (true) {
    // Read topic 1
    switchboard::ptr<topic1_type> event1 = topic1.get_rw();

    // Write to topic 2 using topic 1 input
    topic2.put(topic2.allocate<topic2_type>( do_something(event1->foo) ));
}

// Read topic 3 synchronously
switchboard.schedule<topic3_type>(plugin_id, "topic3", [&](switchboard::ptr<topic3_type> event3, std::size_t it) {
    // This is a lambda expression
    // https://en.cppreference.com/w/cpp/language/lambda
    std::cout << "Got a new event on topic3: " << event3->foo << " for iteration " << it << std::endl;
});

Public Types Documentation

typedef ptr

The type of shared pointer returned by switchboard. 

using ILLIXR::switchboard::ptr =  std::shared_ptr<Specific_event>;

TODO: Make this agnostic to the type of ptr Currently, it depends on ptr == shared_ptr

Public Attributes Documentation

variable root_coordinates

coordinate_system ILLIXR::switchboard::root_coordinates;

Public Functions Documentation

function env_names

Get a vector of the currently known environment variables. 

inline std::vector< std::string > ILLIXR::switchboard::env_names () const

function get_buffered_reader

template<typename Specific_event>
inline buffered_reader< Specific_event > ILLIXR::switchboard::get_buffered_reader (
    const std::string & topic_name
)

function get_env

Switchboard access point for environment variables. 

inline std::string ILLIXR::switchboard::get_env (
    const std::string & var,
    std::string _default=""
)

If the given variable var has a non-empty entry in the map, that value is returned. If the entry is empty then the system getenv is called. If this is non-empty then that value is stored and returned, otherwise the default value is returned (not stored).

function get_env_bool

Get the boolean value of the given environment variable. 

inline bool ILLIXR::switchboard::get_env_bool (
    const std::string & var,
    const std::string & def="false"
)

function get_env_char

Get a char* of the given environment variable. 

inline const char * ILLIXR::switchboard::get_env_char (
    const std::string & var,
    const std::string _default=""
)

function get_network_writer

template<typename Specific_event>
inline network_writer< Specific_event > ILLIXR::switchboard::get_network_writer (
    const std::string & topic_name,
    network::topic_config config={}
)

function get_reader

Gets a handle to read to the latest value from the topic topic_name . 

template<typename Specific_event>
inline reader < Specific_event > ILLIXR::switchboard::get_reader (
    const std::string & topic_name
)

This is safe to be called from any thread.

Exception:

  • If topic already exists, and its type does not match the event.

function get_topic

inline topic & ILLIXR::switchboard::get_topic (
    const std::string & topic_name
)

function get_writer

Gets a handle to publish to the topic topic_name . 

template<typename Specific_event>
inline writer < Specific_event > ILLIXR::switchboard::get_writer (
    const std::string & topic_name
)

This is safe to be called from any thread.

Exception:

  • If topic already exists, and its type does not match the event.

function schedule

Schedules the callback fn every time an event is published totopic_name . 

template<typename Specific_event>
inline void ILLIXR::switchboard::schedule (
    plugin_id_t plugin_id,
    std::string topic_name,
    std::function< void( ptr < const Specific_event > &&, std::size_t)> fn
)

Switchboard maintains a threadpool to call fn.

This is safe to be called from any thread.

Exception:

  • if topic already exists and its type does not match the event.

function set_env

Set the local environment variable to the given value. 

inline void ILLIXR::switchboard::set_env (
    const std::string & var,
    const std::string & val
)

function stop

Stops calling switchboard callbacks. 

inline void ILLIXR::switchboard::stop ()

This is safe to be called from any thread.

Leave topics in place, so existing reader/writer handles will not crash.

function switchboard

inline explicit ILLIXR::switchboard::switchboard (
    const phonebook * pb
)

If pb is null, then logging is disabled.

function topic_exists

inline bool ILLIXR::switchboard::topic_exists (
    const std::string & topic_name
)

The documentation for this class was generated from the following file /home/friedel/devel/ILLIXR/include/illixr/switchboard.hpp