tf::ObserverInterface Class Reference

class to derive an executor observer More...

#include <observer.hpp>

Inheritance diagram for tf::ObserverInterface:

Public Member Functions
virtual	~ObserverInterface ()=default
	virtual destructor
virtual void	set_up (size_t num_workers)=0
	constructor-like method to call when the executor observer is fully created
virtual void	on_entry (WorkerView w, TaskView task_view)=0
	method to call before a worker thread executes a closure
virtual void	on_exit (WorkerView w, TaskView task_view)=0
	method to call after a worker thread executed a closure

Friends
class	Executor

Detailed Description

class to derive an executor observer

The tf::ObserverInterface class let users define custom methods to monitor the behaviors of an executor. This is particularly useful when you want to inspect the performance of an executor and visualize when each thread participates in the execution of a task. To prevent users from direct access to the internal threads and tasks, tf::ObserverInterface provides immutable wrappers, tf::WorkerView and tf::TaskView, over workers and tasks.

Please refer to tf::WorkerView and tf::TaskView for details.

Example usage:

struct MyObserver : public tf::ObserverInterface {
 
  MyObserver(const std::string& name) {
    std::cout << "constructing observer " << name << '\n';
  }
 
  void set_up(size_t num_workers) override final {
    std::cout << "setting up observer with " << num_workers << " workers\n";
  }
 
  void on_entry(WorkerView w, tf::TaskView tv) override final {
    std::ostringstream oss;
    oss << "worker " << w.id() << " ready to run " << tv.name() << '\n';
    std::cout << oss.str();
  }
 
  void on_exit(WorkerView w, tf::TaskView tv) override final {
    std::ostringstream oss;
    oss << "worker " << w.id() << " finished running " << tv.name() << '\n';
    std::cout << oss.str();
  }
};
  
tf::Taskflow taskflow;
tf::Executor executor;
 
// insert tasks into taskflow
// ...
  
// create a custom observer
std::shared_ptr<MyObserver> observer = executor.make_observer<MyObserver>("MyObserver");
 
// run the taskflow
executor.run(taskflow).wait();

Member Function Documentation

on_entry()

virtual void tf::ObserverInterface::on_entry ( WorkerView  w, TaskView  task_view  )

pure virtual

method to call before a worker thread executes a closure

Parameters

w	an immutable view of this worker thread
task_view	a constant wrapper object to the task

on_exit()

virtual void tf::ObserverInterface::on_exit ( WorkerView  w, TaskView  task_view  )

pure virtual

method to call after a worker thread executed a closure

Parameters

w	an immutable view of this worker thread
task_view	a constant wrapper object to the task

set_up()

virtual void tf::ObserverInterface::set_up ( size_t  num_workers )

pure virtual

constructor-like method to call when the executor observer is fully created

Parameters

num_workers

the number of the worker threads in the executor

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The documentation for this class was generated from the following file:

• observer.hpp