<br/>
The S4U interface (SimGrid for you) mixes the full power of SimGrid
-with the full power of C++. This is the prefered interface to describe
-abstract algorithms in the domains of Cloud, P2P, HPC, IoT and similar
+with the full power of C++. This is the preferred interface to describe
+abstract algorithms in the domains of Cloud, P2P, HPC, IoT, and similar
settings.
+Currently (v3.21), S4U is definitely the way to go for long-term
+projects. It is feature complete, but may still evolve slightly in the
+future releases. It can already be used to do everything that can be
+done in SimGrid, but you may have to adapt your code in future
+releases. When this happens, compiling your code will produce
+deprecation warnings for 4 releases (one year) before the removal of
+the old symbols.
+If you want an API that will never ever evolve in the future, you
+should use the deprecated MSG API instead.
+
-------------
Main Concepts
-------------
and other |Activities|_, so that they get reflected within the
simulator. These activities take place on resources such as |Hosts|_,
|Links|_ and |Storages|_. SimGrid predicts the time taken by each
-activity and orchestrates accordingly the actors waiting for the
+activity and orchestrates the actors accordingly, waiting for the
completion of these activities.
When **communicating**, data is not directly sent to other actors but
-posted onto a |Mailbox|_ that serve as rendez-vous point between
+posted onto a |Mailbox|_ that serves as a rendez-vous point between
communicating actors. This means that you don't need to know who you
-are talking to, you just put your communication `Send` request in a
-mailbox, and it will be matched with a complementary `Receive`
+are talking to, you just put your communication `Put` request in a
+mailbox, and it will be matched with a complementary `Get`
request. Alternatively, actors can interact through **classical
synchronization mechanisms** such as |Barrier|_, |Semaphore|_,
|Mutex|_ and |ConditionVariable|_.
- :ref:`class s4u::Link <exhale_class_classsimgrid_1_1s4u_1_1Link>`
Interconnecting hosts.
- :ref:`class s4u::NetZone <exhale_class_classsimgrid_1_1s4u_1_1NetZone>`:
- Sub-region of the platform, containing resources (Hosts, Link, etc).
+ Sub-region of the platform, containing resources (Hosts, Links, etc).
- :ref:`class s4u::Storage <exhale_class_classsimgrid_1_1s4u_1_1Storage>`
Resource on which actors can write and read data.
- :ref:`class s4u::VirtualMachine <exhale_class_classsimgrid_1_1s4u_1_1VirtualMachine>`:
.. |Mutex| replace:: **Mutex**
.. _Mutex: api/classsimgrid_1_1s4u_1_1Mutex.html
+.. THE EXAMPLES
+
+.. include:: ../../examples/s4u/README.rst
+
----------
Activities
----------
-Activities represent the actions that consumes a resource, such as
+Activities represent the actions that consume a resource, such as a
:ref:`s4u::Comm <exhale_class_classsimgrid_1_1s4u_1_1Comm>` that
consumes the *transmiting power* of :ref:`s4u::Link
<exhale_class_classsimgrid_1_1s4u_1_1Link>` resources.
completion of that communication. Asynchronous communications do not
block the actor during their execution but progress on their own.
-Once your asynchronous activity is started, you can test for
+Once your asynchronous activity is started, you can test for its
completion using :cpp:func:`s4u::Activity::test() <simgrid::s4u::Activity::test>`.
This function returns ``true`` if the activity completed already.
You can also use :cpp:func:`s4u::Activity::wait() <simgrid::s4u::Activity::wait>`
-to block until the completion of the activity. To wait at most for a given period,
+to block until the completion of the activity. To wait for at most a given amount of time,
use :cpp:func:`s4u::Activity::wait_for() <simgrid::s4u::Activity::wait_for>`.
Finally, to wait at most until a specified time limit, use
:cpp:func:`s4u::Activity::wait_until() <simgrid::s4u::Activity::wait_until>`.
:end-before: init-end
:dedent: 4
-You then start all communications that should occur concurrently with
+Then, you start all the communications that should occur concurrently with
:cpp:func:`s4u::Mailbox::put_async() <simgrid::s4u::Mailbox::put_async>`.
Finally, the actor waits for the completion of all of them at once
with
.. literalinclude:: ../../examples/s4u/async-waitall/s4u-async-waitall.cpp
:language: c++
- :start-after: send-begin
- :end-before: send-end
+ :start-after: put-begin
+ :end-before: put-end
:dedent: 4
.....................
Sometimes, you want to change the setting of an activity before it even starts.
+
+.. todo:: write this section
+
+-----------------
+Memory Management
+-----------------
+
+For sake of simplicity, we use `RAII
+<https://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization>`_
+everywhere in S4U. This is an idiom where resources are automatically
+managed through the context. Provided that you never manipulate
+objects of type Foo directly but always FooPtr references (which are
+defined as `boost::intrusive_ptr
+<http://www.boost.org/doc/libs/1_61_0/libs/smart_ptr/intrusive_ptr.html>`_
+<Foo>), you will never have to explicitely release the resource that
+you use nor to free the memory of unused objects.
+
+Here is a little example:
+
+.. code-block:: cpp
+
+ void myFunc()
+ {
+ simgrid::s4u::MutexPtr mutex = simgrid::s4u::Mutex::create(); // Too bad we cannot use `new`
+
+ mutex->lock(); // use the mutex as a simple reference
+ // bla bla
+ mutex->unlock();
+
+ } // The mutex gets automatically freed because the only existing reference gets out of scope
