.. S4U (Simgrid for you) is the modern interface of SimGrid, which new project should use.
..
.. This file follows the ReStructured syntax to be included in the
.. documentation, but it should remain readable directly.

.. _s4u_examples:

Examples
********

SimGrid comes with an extensive set of examples, documented on this
page. Most of them only demonstrate one single feature, with some
larger exemplars listed below. 

The C++ examples can be found under examples/cpp while python examples
are in examples/python. Each such directory contains the source code (also listed
from this page), and the so-called tesh file containing how to call
the binary obtained by compiling this example and also the expected
output. Tesh files are used to turn each of our examples into an
integration test. Some examples also contain other files, on need.

A good way to bootstrap your own project is to copy and combine some
of the provided examples to constitute the skeleton of what you plan
to simulate.

.. _s4u_ex_actors:

===========================
Actors: the Active Entities
===========================

Starting and Stopping Actors
----------------------------

  - **Creating actors:**
    Most actors are started from the deployment XML file because this
    is a :ref:`better scientific habit <howto_science>`, but you can
    also create them directly from your code.

    .. tabs::
    
       .. example-tab:: examples/cpp/actor-create/s4u-actor-create.cpp
       
          You create actors either:
             
          - Directly with :cpp:func:`simgrid::s4u::Actor::create`
          - From XML with :cpp:func:`simgrid::s4u::Engine::register_actor` (if your actor is a class)
            or :cpp:func:`simgrid::s4u::Engine::register_function` (if your actor is a function)
            and then :cpp:func:`simgrid::s4u::Engine::load_deployment`
             
       .. example-tab:: examples/python/actor-create/actor-create.py
       
          You create actors either:
            
          - Directly with :py:func:`simgrid.Actor.create()`
          - From XML with :py:func:`simgrid.Engine.register_actor()` and then :py:func:`simgrid.Engine.load_deployment()`
             
       .. example-tab:: examples/c/actor-create/actor-create.c
       
          You create actors either:
            
          - Directly with :cpp:func:`sg_actor_create` followed by :cpp:func:`sg_actor_start`.
          - From XML with :cpp:func:`simgrid_register_function` and then :cpp:func:`simgrid_load_deployment`.
             
       .. example-tab:: examples/python/actor-create/actor-create_d.xml
       
          The following file is used in both C++ and Python.

  - **React to the end of actors:** You can attach callbacks to the end of
    actors. There are several ways of doing so, depending on whether you want to
    attach your callback to a given actor and on how you define the end of a
    given actor. User code probably wants to react to the termination of an actor
    while some plugins want to react to the destruction (memory collection) of
    actors.

    .. tabs::
    
       .. example-tab:: examples/cpp/actor-exiting/s4u-actor-exiting.cpp

          This example shows how to attach a callback to:

          - the end of a specific actor: :cpp:func:`simgrid::s4u::Actor::on_exit()`
          - the end of any actor: :cpp:member:`simgrid::s4u::Actor::on_termination()`
          - the destruction of any actor: :cpp:member:`simgrid::s4u::Actor::on_destruction()`

       .. example-tab:: examples/c/actor-exiting/actor-exiting.c

          This example shows how to attach a callback to the end of a specific actor with 
          :cpp:func:`sg_actor_on_exit()`.

  - **Kill actors:**
    Actors can forcefully stop other actors.

    .. tabs::

       .. example-tab:: examples/cpp/actor-kill/s4u-actor-kill.cpp

          See also :cpp:func:`void simgrid::s4u::Actor::kill(void)`, :cpp:func:`void simgrid::s4u::Actor::kill_all()`,
          :cpp:func:`simgrid::s4u::this_actor::exit`, :cpp:func:`simgrid::s4u::Actor::on_exit`.

       .. example-tab:: examples/python/actor-kill/actor-kill.py

          See also :py:func:`simgrid.Actor.kill`, :py:func:`simgrid.Actor.kill_all`, :py:func:`simgrid.this_actor.exit`,
          :py:func:`simgrid.this_actor.on_exit`.

       .. example-tab:: examples/c/actor-kill/actor-kill.c

          See also :cpp:func:`sg_actor_kill`, :cpp:func:`sg_actor_kill_all`, :cpp:func:`sg_actor_exit`, :cpp:func:`sg_actor_on_exit`.

  - **Controlling the actor life cycle from the XML:**
    You can specify a start time and a kill time in the deployment file.

    .. tabs::

       .. example-tab:: examples/cpp/actor-lifetime/s4u-actor-lifetime.cpp

          This file is not really interesting: the important matter is in the XML file.

       .. example-tab:: examples/cpp/actor-lifetime/s4u-actor-lifetime_d.xml

          This demonstrates the ``start_time`` and ``kill_time`` attribute of the :ref:`pf_tag_actor` tag.

       .. example-tab:: examples/python/actor-lifetime/actor-lifetime.py

          This file is not really interesting: the important matter is in the XML file.

       .. example-tab:: examples/c/actor-lifetime/actor-lifetime.c

          This file is not really interesting: the important matter is in the XML file.

  - **Daemonize actors:**
    Some actors may be intended to simulate daemons that run in the background.
    This example shows how to transform a regular
    actor into a daemon that will be automatically killed once the simulation is over.
    
    .. tabs::

       .. example-tab:: examples/cpp/actor-daemon/s4u-actor-daemon.cpp

          See also :cpp:func:`simgrid::s4u::Actor::daemonize()` and :cpp:func:`simgrid::s4u::Actor::is_daemon()`.

       .. example-tab:: examples/python/actor-daemon/actor-daemon.py

          See also :py:func:`simgrid.Actor.daemonize()` and :py:func:`simgrid.Actor.is_daemon()`.

       .. example-tab:: examples/c/actor-daemon/actor-daemon.c

          See also :cpp:func:`sg_actor_daemonize` and :cpp:func:`sg_actor_is_daemon`.

  - **Specify the stack size to use**
    The stack size can be specified by default on the command line,
    globally by changing the configuration with :cpp:func:`simgrid::s4u::Engine::set_config`,
    or for a specific actor using :cpp:func:`simgrid::s4u::Actor::set_stacksize` before its start.
    
    .. tabs::

       .. example-tab:: examples/cpp/actor-stacksize/s4u-actor-stacksize.cpp

       .. example-tab:: examples/c/actor-stacksize/actor-stacksize.c

Inter-Actors Interactions
-------------------------

See also the examples on :ref:`inter-actors communications
<s4u_ex_communication>` and the ones on :ref:`classical
synchronization objects <s4u_ex_IPC>`.

  - **Suspend and Resume actors:**    
    Actors can be suspended and resumed during their executions.

    .. tabs::

       .. example-tab:: examples/cpp/actor-suspend/s4u-actor-suspend.cpp

          See also :cpp:func:`simgrid::s4u::this_actor::suspend()`,
          :cpp:func:`simgrid::s4u::Actor::suspend()`, :cpp:func:`simgrid::s4u::Actor::resume()`, and
          :cpp:func:`simgrid::s4u::Actor::is_suspended()`.

       .. example-tab:: examples/python/actor-suspend/actor-suspend.py

          See also :py:func:`simgrid.this_actor.suspend()`,
          :py:func:`simgrid.Actor.suspend()`, :py:func:`simgrid.Actor.resume()`, and
          :py:func:`simgrid.Actor.is_suspended()`.

       .. example-tab:: examples/c/actor-suspend/actor-suspend.c

          See also :cpp:func:`sg_actor_suspend()`, :cpp:func:`sg_actor_resume()`, and 
          :cpp:func:`sg_actor_is_suspended()`.

  - **Migrating Actors:**
    Actors can move or be moved from a host to another very easily. It amounts to setting them on a new host.

    .. tabs::

       .. example-tab:: examples/cpp/actor-migrate/s4u-actor-migrate.cpp

          See also :cpp:func:`simgrid::s4u::this_actor::set_host()` and :cpp:func:`simgrid::s4u::Actor::set_host()`.

       .. example-tab:: examples/python/actor-migrate/actor-migrate.py

          See also :py:func:`simgrid.this_actor.set_host()` and :py:func:`simgrid.Actor.set_host()`.

       .. example-tab:: examples/c/actor-migrate/actor-migrate.c

          See also :cpp:func:`sg_actor_set_host()`.

  - **Waiting for the termination of an actor:** (joining on it)
    You can block the current actor until the end of another actor.

    .. tabs::

       .. example-tab:: examples/cpp/actor-join/s4u-actor-join.cpp

          See also :cpp:func:`simgrid::s4u::Actor::join()`.

       .. example-tab:: examples/python/actor-join/actor-join.py

          See also :py:func:`simgrid.Actor.join()`.

       .. example-tab:: examples/c/actor-join/actor-join.c

          See also :cpp:func:`sg_actor_join`.

  - **Yielding to other actors**.
    The ```yield()``` function interrupts the execution of the current
    actor, leaving a chance to the other actors that are ready to run
    at this timestamp.

    .. tabs::

       .. example-tab:: examples/cpp/actor-yield/s4u-actor-yield.cpp

          See also :cpp:func:`simgrid::s4u::this_actor::yield()`.

       .. example-tab:: examples/python/actor-yield/actor-yield.py

          See also :py:func:`simgrid.this_actor.yield_()`.

       .. example-tab:: examples/c/actor-yield/actor-yield.c

          See also :cpp:func:`sg_actor_yield()`.

Traces Replay as a Workload
---------------------------

This section details how to run trace-driven simulations. It is very
handy when you want to test an algorithm or protocol that only reacts
to external events. For example, many P2P protocols react to user
requests, but do nothing if there is no such event.

In such situations, you should write your protocol in C++, and separate
the workload that you want to play onto your protocol in a separate
text file. Declare a function handling each type of the events in your
trace, register them using :cpp:func:`xbt_replay_action_register()` in
your main, and then run the simulation.

Then, you can either have one trace file containing all your events,
or a file per simulated process: the former may be easier to work
with, but the second is more efficient on very large traces. Check
also the tesh files in the example directories for details.

  - **Communication replay:**
    Presents a set of event handlers reproducing classical communication
    primitives (asynchronous send/receive at the moment).

    .. tabs::

       .. example-tab:: examples/cpp/replay-comm/s4u-replay-comm.cpp

  - **I/O replay:**
    Presents a set of event handlers reproducing classical I/O
    primitives (open, read, close).

    .. tabs::

       .. example-tab:: examples/cpp/replay-io/s4u-replay-io.cpp

==========================
Activities: what Actors do
==========================

.. _s4u_ex_communication:

Communications on the Network
-----------------------------

  - **Basic communications:**
    This simple example just sends one message back and forth.
    The tesh file laying in the directory shows how to start the simulator binary, highlighting how to pass options to 
    the simulators (as detailed in Section :ref:`options`).

    .. tabs::

       .. example-tab:: examples/cpp/comm-pingpong/s4u-comm-pingpong.cpp

       .. example-tab:: examples/c/comm-pingpong/comm-pingpong.c


 - **Basic asynchronous communications:**
   Illustrates how to have non-blocking communications, that are
   communications running in the background leaving the process free
   to do something else during their completion. 

   .. tabs::

      .. example-tab:: examples/cpp/comm-wait/s4u-comm-wait.cpp

         See also :cpp:func:`simgrid::s4u::Mailbox::put_async()` and :cpp:func:`simgrid::s4u::Comm::wait()`.

      .. example-tab:: examples/python/comm-wait/comm-wait.py

         See also :py:func:`simgrid.Mailbox.put_async()` and :py:func:`simgrid.Comm.wait()`.

      .. example-tab:: examples/c/comm-wait/comm-wait.c

         See also :cpp:func:`sg_mailbox_put_async()` and :cpp:func:`sg_comm_wait()`.

 - **Waiting for communications with timeouts:**
   This example is very similar to the previous one, simply adding how to declare timeouts when waiting on asynchronous communication.

   .. tabs::

      .. example-tab:: examples/cpp/comm-waituntil/s4u-comm-waituntil.cpp

         See also :cpp:func:`simgrid::s4u::Activity::wait_until()` and :cpp:func:`simgrid::s4u::Comm::wait_for()`.

 - **Suspending communications:**
   The ``suspend()`` and ``resume()`` functions allow to block the
   progression of a given communication for a while and then unblock it.
   ``is_suspended()`` can be used to retrieve whether the activity is
   currently blocked or not.
   
   .. tabs::

      .. example-tab:: examples/cpp/comm-suspend/s4u-comm-suspend.cpp

         See also :cpp:func:`simgrid::s4u::Activity::suspend()`
	 :cpp:func:`simgrid::s4u::Activity::resume()` and
	 :cpp:func:`simgrid::s4u::Activity::is_suspended()`.

	 
 - **Waiting for all communications in a set:**
   The ``wait_all()`` function is useful when you want to block until
   all activities in a given set have been completed. 
   
   .. tabs::

      .. example-tab:: examples/cpp/comm-waitall/s4u-comm-waitall.cpp

         See also :cpp:func:`simgrid::s4u::Comm::wait_all()`.

      .. example-tab:: examples/python/comm-waitall/comm-waitall.py

         See also :py:func:`simgrid.Comm.wait_all()`.

      .. example-tab:: examples/c/comm-waitall/comm-waitall.c

         See also :cpp:func:`sg_comm_wait_all()`.

 - **Waiting for the first completed communication in a set:**
   The ``wait_any()`` function is useful
   when you want to block until one activity of the set completes, no
   matter which terminates first.
   
   .. tabs::

      .. example-tab:: examples/cpp/comm-waitany/s4u-comm-waitany.cpp

         See also :cpp:func:`simgrid::s4u::Comm::wait_any()`.

      .. example-tab:: examples/python/comm-waitany/comm-waitany.py

         See also :py:func:`simgrid.Comm.wait_any()`.
	 
      .. example-tab:: examples/c/comm-waitany/comm-waitany.c

         See also :cpp:func:`sg_comm_wait_any`.
     
.. _s4u_ex_execution:

Executions on the CPU
---------------------

  - **Basic execution:**
    The computations done in your program are not reported to the
    simulated world unless you explicitly request the simulator to pause
    the actor until a given amount of flops gets computed on its simulated
    host. Some executions can be given a higher priority so that they
    get more resources.

    .. tabs::

       .. example-tab:: examples/cpp/exec-basic/s4u-exec-basic.cpp

          See also :cpp:func:`void simgrid::s4u::this_actor::execute(double)`
          and :cpp:func:`void simgrid::s4u::this_actor::execute(double, double)`.

       .. example-tab:: examples/python/exec-basic/exec-basic.py

          See also :py:func:`simgrid.this_actor.execute()`.

       .. example-tab:: examples/c/exec-basic/exec-basic.c

          See also :cpp:func:`void sg_actor_execute(double)`
          and :cpp:func:`void sg_actor_execute_with_priority(double, double)`.

  - **Asynchronous execution:**
    You can start asynchronous executions, just like you would fire
    background threads.

    .. tabs::

       .. example-tab:: examples/cpp/exec-async/s4u-exec-async.cpp

          See also :cpp:func:`simgrid::s4u::this_actor::exec_init()`,
          :cpp:func:`simgrid::s4u::Activity::start()`,
          :cpp:func:`simgrid::s4u::Activity::wait()`,
          :cpp:func:`simgrid::s4u::Activity::get_remaining()`,
          :cpp:func:`simgrid::s4u::Exec::get_remaining_ratio()`,
          :cpp:func:`simgrid::s4u::this_actor::exec_async()` and
          :cpp:func:`simgrid::s4u::Activity::cancel()`.

       .. example-tab:: examples/python/exec-async/exec-async.py
    
          See also :py:func:`simgrid.this_actor::exec_init()`,
          :py:func:`simgrid.Activity::start()`,
          :py:func:`simgrid.Activity.wait()`,
          :py:func:`simgrid.Activity.get_remaining()`,
          :py:func:`simgrid.Exec.get_remaining_ratio()`,
          :py:func:`simgrid.this_actor.exec_async()` and
          :py:func:`simgrid.Activity.cancel()`.
 
       .. example-tab:: examples/c/exec-async/exec-async.c

          See also :cpp:func:`sg_actor_exec_init()`,
          :cpp:func:`sg_exec_start()`,
          :cpp:func:`sg_exec_wait()`,
          :cpp:func:`sg_exec_get_remaining()`,
          :cpp:func:`sg_exec_get_remaining_ratio()`,
          :cpp:func:`sg_actor_exec_async()` and
          :cpp:func:`sg_exec_cancel()`,
          
  - **Remote execution:**
    You can start executions on remote hosts, or even change the host
    on which they occur during their execution.

    .. tabs::

       .. example-tab:: examples/cpp/exec-remote/s4u-exec-remote.cpp

          See also :cpp:func:`simgrid::s4u::Exec::set_host()`.

       .. example-tab:: examples/python/exec-remote/exec-remote.py

          See also :py:func:`simgrid.Exec.set_host()`.

       .. example-tab:: examples/c/exec-remote/exec-remote.c

          See also :cpp:func:`sg_exec_set_host()`.

  - **Parallel executions:**
    These objects are convenient abstractions of parallel
    computational kernels that span over several machines, such as a
    PDGEM and the other ScaLAPACK routines. Note that this only works
    with the "ptask_L07" host model (``--cfg=host/model:ptask_L07``).
    
    This example demonstrates several kinds of parallel tasks: regular
    ones, communication-only (without computation), computation-only
    (without communication), synchronization-only (neither
    communication nor computation). It also shows how to reconfigure a
    task after its start, to change the number of hosts it runs onto.
    This allows simulating malleable tasks.

    .. tabs::

       .. example-tab:: examples/cpp/exec-ptask/s4u-exec-ptask.cpp
    
          See also :cpp:func:`simgrid::s4u::this_actor::parallel_execute()`.

  - **Using Pstates on a host:**
    This example shows how to define a set of pstates in the XML. The current pstate
    of a host can then be accessed and changed from the program.

    .. tabs::

       .. example-tab:: examples/cpp/exec-dvfs/s4u-exec-dvfs.cpp

          See also :cpp:func:`simgrid::s4u::Host::get_pstate_speed` and :cpp:func:`simgrid::s4u::Host::set_pstate`.

       .. example-tab:: examples/c/exec-dvfs/exec-dvfs.c

          See also :cpp:func:`sg_host_get_pstate_speed` and :cpp:func:`sg_host_set_pstate`.

       .. example-tab:: examples/python/exec-dvfs/exec-dvfs.py

          See also :py:func:`Host.get_pstate_speed` and :py:func:`Host.set_pstate`.

       .. example-tab:: examples/platforms/energy_platform.xml

.. _s4u_ex_disk_io:

I/O on Disks and Files
----------------------

SimGrid provides two levels of abstraction to interact with the
simulated disks. At the simplest level, you simply create read and
write actions on the disk resources.

  - **Access to raw disk devices:**
    This example illustrates how to simply read and write data on a
    simulated disk resource.

    .. tabs::

       .. example-tab:: examples/cpp/io-disk-raw/s4u-io-disk-raw.cpp

       .. example-tab:: examples/c/io-disk-raw/io-disk-raw.c

       .. example-tab:: examples/platforms/hosts_with_disks.xml

          This shows how to declare disks in XML.

The FileSystem plugin provides a more detailed view, with the
classical operations over files: open, move, unlink, and of course,
read and write. The file and disk sizes are also dealt with and can
result in short reads and short writes, as in reality.

  - **File Management:**
    This example illustrates the use of operations on files
    (read, write, seek, tell, unlink, etc).

    .. tabs::

       .. example-tab:: examples/cpp/io-file-system/s4u-io-file-system.cpp

  - **Remote I/O:**
    I/O operations on files can also be done remotely, 
    i.e. when the accessed disk is not mounted on the caller's host.

    .. tabs::

       .. example-tab:: examples/cpp/io-file-remote/s4u-io-file-remote.cpp

       .. example-tab:: examples/c/io-file-remote/io-file-remote.c

.. _s4u_ex_IPC:

Classical synchronization objects
---------------------------------

 - **Barrier:**
   Shows how to use :cpp:type:`simgrid::s4u::Barrier` synchronization objects.

   .. tabs::

      .. example-tab:: examples/cpp/synchro-barrier/s4u-synchro-barrier.cpp

 - **Condition variable: basic usage**
   Shows how to use :cpp:type:`simgrid::s4u::ConditionVariable` synchronization objects.

   .. tabs::

      .. example-tab:: examples/cpp/synchro-condition-variable/s4u-synchro-condition-variable.cpp

 - **Condition variable: timeouts**
   Shows how to specify timeouts when blocking on condition variables.

   .. tabs::

      .. example-tab:: examples/cpp/synchro-condition-variable-waituntil/s4u-synchro-condition-variable-waituntil.cpp

 - **Mutex:**
   Shows how to use :cpp:type:`simgrid::s4u::Mutex` synchronization objects.

   .. tabs::

      .. example-tab:: examples/cpp/synchro-mutex/s4u-synchro-mutex.cpp

 - **Semaphore:**
   Shows how to use :cpp:type:`simgrid::s4u::Semaphore` synchronization objects.

   .. tabs::

      .. example-tab:: examples/cpp/synchro-semaphore/s4u-synchro-semaphore.cpp

      .. example-tab:: examples/c/synchro-semaphore/synchro-semaphore.c

=============================
Interacting with the Platform
=============================

 - **User-defined properties:**
   You can attach arbitrary information to most platform elements from
   the XML file, and then interact with these values from your
   program. Note that the changes are not written permanently on disk,
   in the XML file nor anywhere else. They only last until the end of
   your simulation.

   .. tabs::

      .. example-tab:: examples/cpp/platform-properties/s4u-platform-properties.cpp

         - :cpp:func:`simgrid::s4u::Actor::get_property()` and :cpp:func:`simgrid::s4u::Actor::set_property()`
         - :cpp:func:`simgrid::s4u::Host::get_property()` and :cpp:func:`simgrid::s4u::Host::set_property()`
         - :cpp:func:`simgrid::s4u::Link::get_property()` and :cpp:func:`simgrid::s4u::Link::set_property()`
         - :cpp:func:`simgrid::s4u::NetZone::get_property()` and :cpp:func:`simgrid::s4u::NetZone::set_property()`

      .. example-tab:: examples/c/platform-properties/platform-properties.c

         - :cpp:func:`sg_actor_get_property_value()`
         - :cpp:func:`sg_host_get_property_value()` and :cpp:func:sg_host_set_property_value()`
         - :cpp:func:`sg_zone_get_property_value()` and :cpp:func:`sg_zone_set_property_value()`

      .. group-tab:: XML

         **Deployment file:**

         .. showfile:: examples/cpp/platform-properties/s4u-platform-properties_d.xml
            :language: xml

         |br|
         **Platform file:**

         .. showfile:: examples/platforms/prop.xml
            :language: xml

 - **Retrieving the netzones matching given criteria:**
   Shows how to filter the cluster netzones.

   .. tabs::

      .. example-tab:: examples/cpp/routing-get-clusters/s4u-routing-get-clusters.cpp

 - **Retrieving the list of hosts matching given criteria:**
   Shows how to filter the actors that match given criteria.

   .. tabs::

      .. example-tab:: examples/cpp/engine-filtering/s4u-engine-filtering.cpp

 - **Specifying state profiles:** shows how to specify when the
   resources must be turned off and on again, and how to react to such
   failures in your code. See also :ref:`howto_churn`.

   .. tabs::

      .. example-tab:: examples/cpp/platform-failures/s4u-platform-failures.cpp

      .. example-tab:: examples/c/platform-failures/platform-failures.c

      .. group-tab:: XML

         .. showfile:: examples/platforms/small_platform_failures.xml
            :language: xml

         .. showfile:: examples/platforms/profiles/jupiter_state.profile

         .. showfile:: examples/platforms/profiles/bourassa_state.profile

         .. showfile:: examples/platforms/profiles/fafard_state.profile

 - **Specifying speed profiles:** shows how to specify an external
   load to resources, variating their peak speed over time.

   .. tabs::

      .. example-tab:: examples/cpp/platform-profile/s4u-platform-profile.cpp

      .. group-tab:: XML  

         .. showfile:: examples/platforms/small_platform_profile.xml
            :language: xml

         .. showfile:: examples/platforms/profiles/jupiter_speed.profile

         .. showfile:: examples/platforms/profiles/link1_bandwidth.profile

         .. showfile:: examples/platforms/profiles/link1_latency.profile

=================
Energy Simulation
=================

  - **Describing the energy profiles in the platform:**
    The first platform file contains the energy profile of each link and
    host for a wired network, which is necessary to get energy consumption
    predictions. The second platform file is the equivalent for a wireless
    network. As usual, you should not trust our example, and you should
    strive to double-check that your instantiation matches your target
    platform.

    .. tabs::

       .. group-tab:: XML

	  .. showfile:: examples/platforms/energy_platform.xml
	     :language: xml

	  .. showfile:: examples/platforms/wifi_energy.xml
	     :language: xml

  - **Consumption due to the CPU:** 
    This example shows how to retrieve the amount of energy consumed
    by the CPU during computations, and the impact of the pstate.

    .. tabs::

       .. example-tab:: examples/cpp/energy-exec/s4u-energy-exec.cpp

       .. example-tab:: examples/c/energy-exec/energy-exec.c

  - **Consumption due to the wired network:**
    This example shows how to retrieve and display the energy consumed
    by the wired network during communications.

    .. tabs::

       .. example-tab:: examples/cpp/energy-link/s4u-energy-link.cpp

  - **Consumption due to the wireless network:**
    This example shows how to retrieve and display the energy consumed
    by the wireless network during communications.

    .. tabs::

       .. example-tab:: examples/cpp/energy-wifi/s4u-energy-wifi.cpp

  - **Modeling the shutdown and boot of hosts:**
    Simple example of a model for the energy consumption during
    the host boot and shutdown periods.

    .. tabs::

       .. example-tab:: examples/cpp/energy-boot/platform_boot.xml

       .. example-tab:: examples/cpp/energy-boot/s4u-energy-boot.cpp

=======================
Tracing and Visualizing
=======================

Tracing can be activated by various configuration options which
are illustrated in these examples. See also the 
:ref:`full list of options related to tracing <tracing_tracing_options>`.

It is interesting to run the process-create example with the following
options to see the task executions:

  - **Platform Tracing:**
    This program is a toy example just loading the platform so that
    you can play with the platform visualization. Recommended options:
    ``--cfg=tracing:yes --cfg=tracing/categorized:yes``

    .. tabs::

       .. example-tab:: examples/cpp/trace-platform/s4u-trace-platform.cpp

  - **Setting Categories**
    This example declares several tracing categories that are used to
    classify its tasks. When the program is executed, the tracing mechanism
    registers the resource utilization of hosts and links according to these
    categories. Recommended options:
    ``--cfg=tracing:yes --cfg=tracing/categorized:yes --cfg=tracing/uncategorized:yes``

    .. tabs::

       .. example-tab:: examples/cpp/trace-categories/s4u-trace-categories.cpp

  - **Master Workers tracing**
    This is an augmented version of our basic master/worker example using
    several tracing features. It traces resource usage, sorted out in several
    categories; Trace marks and user variables are also used. Recommended
    options: ``--cfg=tracing/categorized:yes --cfg=tracing/uncategorized:yes``

    .. tabs::

       .. example-tab:: examples/cpp/trace-masterworkers/s4u-trace-masterworkers.cpp

  - **Process migration tracing**
    This version is enhanced so that the process migrations can be displayed
    as arrows in a Gantt-chart visualization. Recommended options to that
    extend: ``--cfg=tracing:yes --cfg=tracing/actor:yes``

    .. tabs::

       .. example-tab:: examples/cpp/trace-process-migration/s4u-trace-process-migration.cpp

..
    TODO: These tracing examples should be integrated in the examples to not
    duplicate the C++ files. A full command line to see the result in the right
    tool (vite/FrameSoc) should be given along with some screenshots.

Tracing user variables
----------------------

You can also attach your own variables to any resource described in the platform
file. The following examples illustrate this feature.  They have to be run with
the following options: ``--cfg=tracing:yes --cfg=tracing/platform:yes``

  - **Attaching variables to Hosts**

    .. tabs::

       .. example-tab:: examples/cpp/trace-host-user-variables/s4u-trace-host-user-variables.cpp

  - **Attaching variables to Links**
    The tricky part is that you have to know the name of the link you want to
    enhance with a variable.

    .. tabs::

       .. example-tab:: examples/cpp/trace-link-user-variables/s4u-trace-link-user-variables.cpp

  - **Attaching variables to network Routes**
    It is often easier to update a given variable for all links of a given
    network path (identified by its source and destination hosts) instead of
    knowing the name of each specific link.

    .. tabs::

       .. example-tab::  examples/cpp/trace-route-user-variables/s4u-trace-route-user-variables.cpp

========================
Larger SimGrid Exemplars
========================

This section contains application examples that are somewhat larger
than the previous examples.

  - **Token ring:**
    Shows how to implement a classical communication pattern, where a
    token is exchanged along a ring to reach every participant.

    .. tabs::

       .. example-tab:: examples/cpp/app-token-ring/s4u-app-token-ring.cpp

       .. example-tab:: examples/c/app-token-ring/app-token-ring.c

  - **Master Workers:**
    Another good old example, where one Master process has a bunch of tasks to dispatch to a set of several Worker 
    processes.

    .. tabs::

       .. group-tab:: C++

          This example comes in two equivalent variants, one where the actors
          are specified as simple functions (which is easier to understand for
          newcomers) and one where the actors are specified as classes (which is
          more powerful for the users wanting to build their own projects upon
          the example).

          .. showfile:: examples/cpp/app-masterworkers/s4u-app-masterworkers-class.cpp
             :language: cpp

          .. showfile:: examples/cpp/app-masterworkers/s4u-app-masterworkers-fun.cpp
             :language: cpp

       .. group-tab:: C

          .. showfile:: examples/c/app-masterworker/app-masterworker.c
             :language: cpp
    
Data diffusion
--------------

  - **Bit Torrent:** 
    Classical protocol for Peer-to-Peer data diffusion.

    .. tabs::

       .. group-tab:: C++

          .. showfile:: examples/cpp/app-bittorrent/s4u-bittorrent.cpp
             :language: cpp

          .. showfile:: examples/cpp/app-bittorrent/s4u-peer.cpp
             :language: cpp

          .. showfile:: examples/cpp/app-bittorrent/s4u-tracker.cpp
             :language: cpp

       .. group-tab:: C

          .. showfile:: examples/c/app-bittorrent/app-bittorrent.c
             :language: cpp

          .. showfile:: examples/c/app-bittorrent/bittorrent-peer.c
             :language: cpp

          .. showfile:: examples/c/app-bittorrent/tracker.c
             :language: cpp

  - **Chained Send:** 
    Data broadcast over a ring of processes.

    .. tabs::

       .. example-tab:: examples/cpp/app-chainsend/s4u-app-chainsend.cpp

       .. group-tab:: C

          .. showfile:: examples/c/app-chainsend/chainsend.c
             :language: c

          .. showfile:: examples/c/app-chainsend/broadcaster.c
             :language: c

          .. showfile:: examples/c/app-chainsend/peer.c
             :language: c

Distributed Hash Tables (DHT)
-----------------------------

  - **Chord Protocol** 
    One of the most famous DHT protocol.

    .. tabs::

       .. group-tab:: C++

          .. showfile:: examples/cpp/dht-chord/s4u-dht-chord.cpp
             :language: cpp

          .. showfile:: examples/cpp/dht-chord/s4u-dht-chord-node.cpp
             :language: cpp

  - **Kademlia**
    Another well-known DHT protocol.

    .. tabs::

       .. group-tab:: C++

          .. showfile:: examples/cpp/dht-kademlia/s4u-dht-kademlia.cpp
             :language: cpp

          .. showfile:: examples/cpp/dht-kademlia/routing_table.cpp
             :language: cpp

          .. showfile:: examples/cpp/dht-kademlia/answer.cpp
             :language: cpp

          .. showfile:: examples/cpp/dht-kademlia/node.cpp
             :language: cpp

       .. group-tab:: C

          .. showfile:: examples/c/dht-kademlia/dht-kademlia.c
             :language: cpp

          .. showfile:: examples/c/dht-kademlia/routing_table.c
             :language: cpp

          .. showfile:: examples/c/dht-kademlia/answer.c
             :language: cpp

          .. showfile:: examples/c/dht-kademlia/message.c
             :language: cpp

          .. showfile:: examples/c/dht-kademlia/node.c
             :language: cpp

.. _s4u_ex_clouds:

Simulating Clouds
-----------------

  - **Cloud basics**
    This example starts some computations both on PMs and VMs and
    migrates some VMs around.

    .. tabs::

       .. example-tab:: examples/cpp/cloud-simple/s4u-cloud-simple.cpp

       .. example-tab:: examples/c/cloud-simple/cloud-simple.c

  - **Migrating VMs**
    This example shows how to migrate VMs between PMs.

    .. tabs::

       .. example-tab:: examples/cpp/cloud-migration/s4u-cloud-migration.cpp

       .. example-tab:: examples/c/cloud-migration/cloud-migration.c

=======================
Model-Related Examples
=======================

  - **ns-3 as a SimGrid Network Model**
    This simple ping-pong example demonstrates how to use the bindings to the Network
    Simulator. The most interesting is probably not the C++ files since
    they are unchanged from the other simulations, but the associated files,
    such as the platform file to see how to declare a platform to be used 
    with the ns-3 bindings of SimGrid and the tesh file to see how to 
    start a simulation in these settings.

    .. tabs::

      .. example-tab:: examples/cpp/network-ns3/s4u-network-ns3.cpp

      .. group-tab:: XML

         **Platform files:**

         .. showfile:: examples/platforms/small_platform_one_link_routes.xml
            :language: xml
	    
  - **wifi links**
  
    This demonstrates how to declare a wifi zone in your platform and
    how to use it in your simulation. For that, you should have a link
    whose sharing policy is set to `WIFI`. Such links can have more
    than one bandwidth value (separated by commas), corresponding to
    the several SNR level of your wifi link.
    
    In this case, SimGrid automatically switches to validated
    performance models of wifi networks, where the time is shared
    between users instead of the bandwidth for wired links (the
    corresponding publication is currently being written).
    
    If your wifi link provides more than one SNR level, you can switch
    the level of a given host using
    :cpp:func:`simgrid::s4u::Link::set_host_wifi_rate`. By default,
    the first level is used.

    .. tabs::

      .. example-tab:: examples/cpp/network-wifi/s4u-network-wifi.cpp

      .. group-tab:: XML

         **Platform files:**

         .. showfile:: examples/platforms/wifi.xml
            :language: xml

===============
Plugin Examples
===============

It is possible to extend SimGrid without modifying its internals by
attaching code to the existing signals and by adding extra data to the
simulation objects through extensions. How to do that is not exactly
documented yet, and you should look for examples in the src/plugins
directory.

This section documents how the existing plugins can be used. Remember
that you are very welcome to modify the plugins to fit your needs. It
should be much easier than modifying the SimGrid kernel.

  - **Monitoring the host load**

    .. tabs::

      .. example-tab:: examples/cpp/plugin-host-load/s4u-plugin-host-load.cpp

      .. example-tab:: examples/c/plugin-host-load/plugin-host-load.c

  - **Monitoring the link load**

    .. tabs::

      .. example-tab:: examples/cpp/plugin-link-load/s4u-plugin-link-load.cpp

=======================
Model-Checking Examples
=======================

The model-checker can be used to exhaustively search for issues in the
tested application. It must be activated at compile-time, but this
mode is rather experimental in SimGrid (as of v3.25). You should not
enable it unless you really want to formally verify your applications:
SimGrid is slower and may be less robust when MC is enabled.

  - **Failing assert**
    In this example, two actors send some data to a central server,
    which asserts that the messages are always received in the same order.
    This is wrong, and the model-checker correctly finds a
    counter-example to that assertion.

    .. tabs::

       .. example-tab:: examples/cpp/mc-failing-assert/s4u-mc-failing-assert.cpp

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