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1 .. S4U (Simgrid for you) is the next interface of SimGrid, expected to be released with SimGrid 4.0.
2 ..
3 .. Even if it is not completely rock stable yet, it may well already fit
4 .. your needs. You are welcome to try it and report any interface
5 .. glitches that you see. Be however warned that the interface may change
6 .. until the final release.  You will have to adapt your code on the way.
7 .. 
8 .. This file follows the ReStructured syntax to be included in the
9 .. documentation, but it should remain readable directly.
10
11
12 S4U Examples
13 ************
14
15 SimGrid comes with an extensive set of examples, documented on this
16 page. Most of them only demonstrate one single feature, with some
17 larger examplars listed below. 
18
19 The C++ examples can be found under examples/s4u while python examples
20 are in examples/python. Each such directory contains the source code (also listed
21 from this page), and the so-called tesh file containing how to call
22 the binary obtained by compiling this example and also the expected
23 output. Tesh files are used to turn each of our examples into an
24 integration test. Some examples also contain other files, on need.
25
26 A good way to bootstrap your own project is to copy and combine some
27 of the provided examples to constitute the skeleton of what you plan
28 to simulate.
29
30 ===========================
31 Actors: the Active Entities
32 ===========================
33
34
35 Starting and Stoping Actors
36 ---------------------------
37
38   - **Creating actors:**
39     Most actors are started from the deployment XML file, but there is other methods.
40     This example show them all.
41     `examples/python/actor-create/actor-create_d.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-create/actor-create_d.xml>`_
42     
43     - |cpp| `examples/s4u/actor-create/s4u-actor-create.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-create/s4u-actor-create.cpp>`_
44     - |py|  `examples/python/actor-create/actor-create.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-create/actor-create.py>`_
45
46   - **React to the end of actors:**
47     You can attach a callback to the end of actors. There is two ways
48     of doing so, depending of whether you want your callback to be
49     executed when a specific actor ends (with ```this_actor::on_exit()```)
50     or whether it should be executed when any actor ends (with
51     ```Actor::on_destruction()```)
52
53     - |cpp| `examples/s4u/actor-exiting/s4u-actor-exiting.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-exiting/s4u-actor-exiting.cpp>`_
54
55   - **Kill actors:**
56     Actors can forcefully stop other actors.
57     
58     - |cpp| `examples/s4u/actor-kill/s4u-actor-kill.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-kill/s4u-actor-kill.cpp>`_
59       :cpp:func:`void simgrid::s4u::Actor::kill(void)`,
60       :cpp:func:`void simgrid::s4u::Actor::kill_all()`,
61       :cpp:func:`simgrid::s4u::this_actor::exit`.
62     - |py| `examples/python/actor-kill/actor-kill.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-kill/actor-kill.py>`_
63       :py:func:`simgrid.Actor.kill`,
64       :py:func:`simgrid.Actor.kill_all`, 
65       :py:func:`simgrid.this_actor.exit`.
66
67   - **Controling the actor life cycle from the XML:**
68     You can specify a start time and a kill time in the deployment
69     file.
70     |br| `examples/s4u/actor-lifetime/s4u-actor-lifetime.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-lifetime/s4u-actor-lifetime.cpp>`_
71     |br| `examples/s4u/actor-lifetime/s4u-actor-lifetime_d.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-lifetime/s4u-actor-lifetime_d.xml>`_
72
73   - **Daemonize actors:**
74     Some actors may be intended to simulate daemons that run in background. This example show how to transform a regular
75     actor into a daemon that will be automatically killed once the simulation is over.
76     
77     - |cpp| `examples/s4u/actor-daemon/s4u-actor-daemon.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-daemon/s4u-actor-daemon.cpp>`_
78     - |py|  `examples/python/actor-daemon/actor-daemon.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-daemon/actor-daemon.py>`_
79     
80 Inter-Actors Interactions
81 -------------------------
82
83   - **Suspend and Resume actors:**    
84     Actors can be suspended and resumed during their executions.
85     
86     - |cpp| `examples/s4u/actor-suspend/s4u-actor-suspend.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-suspend/s4u-actor-suspend.cpp>`_
87       :cpp:func:`simgrid::s4u::this_actor::suspend()`,
88       :cpp:func:`simgrid::s4u::Actor::suspend()`, :cpp:func:`simgrid::s4u::Actor::resume()`, :cpp:func:`simgrid::s4u::Actor::is_suspended()`.
89     - |py|  `examples/python/actor-suspend/actor-suspend.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-suspend/actor-suspend.py>`_
90       :py:func:`simgrid.this_actor.suspend()`,
91       :py:func:`simgrid.Actor.suspend()`, :py:func:`simgrid.Actor.resume()`, :py:func:`simgrid.Actor.is_suspended()`.
92
93   - **Migrating Actors:**
94     Actors can move or be moved from a host to another very easily.
95     
96     - |cpp| `examples/s4u/actor-migrate/s4u-actor-migrate.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-migrate/s4u-actor-migrate.cpp>`_
97       :cpp:func:`simgrid::s4u::this_actor::migrate()`
98     - |py|  `examples/python/actor-migrate/actor-migrate.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-migrate/actor-migrate.py>`_
99       :py:func:`simgrid.this_actor.migrate()`
100
101   - **Waiting for the termination of an actor:** (joining on it)
102     You can block the current actor until the end of another actor.
103     
104     - |cpp| `examples/s4u/actor-join/s4u-actor-join.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-join/s4u-actor-join.cpp>`_
105       :cpp:func:`simgrid::s4u::Actor::join()`
106     - |py|  `examples/python/actor-join/actor-join.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-join/actor-join.py>`_
107       :py:func:`simgrid.Actor.join()`
108
109   - **Yielding to other actors**.
110     The ```yield()``` function interrupts the execution of the current
111     actor, leaving a chance to the other actors that are ready to run
112     at this timestamp.
113     
114     - |cpp| `examples/s4u/actor-yield/s4u-actor-yield.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-yield/s4u-actor-yield.cpp>`_
115       :cpp:func:`simgrid::s4u::this_actor::yield()`
116     - |py|  `examples/python/actor-yield/actor-yield.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-yield/actor-yield.py>`_
117       :py:func:`simgrid.this_actor.yield_()`
118
119 Traces Replay as a Workload
120 ---------------------------
121
122 This section details how to run trace-driven simulations. It is very
123 handy when you want to test an algorithm or protocol that only react
124 to external events. For example, many P2P protocols react to user
125 requests, but do nothing if there is no such event.
126
127 In such situations, you should write your protocol in C++, and separate
128 the workload that you want to play onto your protocol in a separate
129 text file. Declare a function handling each type of the events in your
130 trace, register them using :cpp:func:`xbt_replay_action_register()` in
131 your main, and then run the simulation.
132
133 Then, you can either have one trace file containing all your events,
134 or a file per simulated process: the former may be easier to work
135 with, but the second is more efficient on very large traces. Check
136 also the tesh files in the example directories for details.
137
138   - **Communication replay:**
139     Presents a set of event handlers reproducing classical communication
140     primitives (asynchronous send/receive at the moment).
141     |br| `examples/s4u/replay-comm/s4u-replay-comm.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/replay-comm/s4u-replay-comm.cpp>`_
142
143   - **I/O replay:**
144     Presents a set of event handlers reproducing classical I/O
145     primitives (open, read, close).
146     |br| `examples/s4u/replay-storage/s4u-replay-storage.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/replay-storage/s4u-replay-storage.cpp>`_
147
148 ==========================
149 Activities: what Actors do
150 ==========================
151
152 Communications on the Network
153 -----------------------------
154
155  - **Basic asynchronous communications:**
156    Illustrates how to have non-blocking communications, that are
157    communications running in the background leaving the process free
158    to do something else during their completion. The main functions
159    involved are :cpp:func:`simgrid::s4u::Mailbox::put_async()` and 
160    :cpp:func:`simgrid::s4u::Comm::wait()`.
161    |br| `examples/s4u/async-wait/s4u-async-wait.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-wait/s4u-async-wait.cpp>`_
162
163  - **Waiting for all communications in a set:**
164    The :cpp:func:`simgrid::s4u::Comm::wait_all()` function is useful
165    when you want to block until all activities in a given set have
166    completed. 
167    |br| `examples/s4u/async-waitall/s4u-async-waitall.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-waitall/s4u-async-waitall.cpp>`_
168
169  - **Waiting for the first completed communication in a set:**
170    The :cpp:func:`simgrid::s4u::Comm::wait_any()` function is useful
171    when you want to block until one activity of the set completes, no
172    matter which terminates first.    
173    |br| `examples/s4u/async-waitany/s4u-async-waitany.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-waitany/s4u-async-waitany.cpp>`_
174
175 .. todo:: add the `ready` example here
176    
177 .. _s4u_ex_execution:
178
179 Executions on the CPU
180 ---------------------
181
182   - **Basic execution:**
183     The computations done in your program are not reported to the
184     simulated world, unless you explicitely request the simulator to pause
185     the actor until a given amount of flops gets computed on its simulated
186     host. Some executions can be given an higher priority so that they
187     get more resources.
188     
189     - |cpp| `examples/s4u/exec-basic/s4u-exec-basic.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-basic/s4u-exec-basic.cpp>`_
190     - |py|  `examples/python/exec-basic/exec-basic.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-basic/exec-basic.py>`_
191
192   - **Asynchronous execution:**
193     You can start asynchronous executions, just like you would fire
194     background threads.
195     |br| `examples/s4u/exec-async/s4u-exec-async.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-async/s4u-exec-async.cpp>`_
196     
197   - **Monitoring asynchronous executions:**
198     This example shows how to start an asynchronous execution, and
199     monitor its status.
200     |br| `examples/s4u/exec-monitor/s4u-exec-monitor.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-monitor/s4u-exec-monitor.cpp>`_
201     
202   - **Remote execution:**
203     Before its start, you can change the host on which a given execution will occur.
204     |br| `examples/s4u/exec-remote/s4u-exec-remote.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-remote/s4u-exec-remote.cpp>`_
205
206   - **Using Pstates on a host:**
207     Shows how define a set of pstatesfor a host in the XML, and how the current
208     pstate can be accessed/changed with :cpp:func:`simgrid::s4u::Host::get_pstate_speed` and :cpp:func:`simgrid::s4u::Host::set_pstate`.
209     |br| `examples/s4u/exec-dvfs/s4u-exec-dvfs.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-dvfs/s4u-exec-dvfs.cpp>`_
210     |br| `examples/platforms/energy_platform.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/energy_platform.xml>`_
211
212   - **Parallel executions:**
213     These objects are convenient abstractions of parallel
214     computational kernels that span over several machines, such as a
215     PDGEM and the other ScaLAPACK routines.
216     |br| `examples/s4u/exec-ptask/s4u-exec-ptask.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-ptask/s4u-exec-ptask.cpp>`_
217
218 I/O on Disks and Files
219 ----------------------
220
221 SimGrid provides two levels of abstraction to interact with the
222 simulated storages. At the simplest level, you simply create read and
223 write actions on the storage resources.
224
225   - **Access to raw storage devices:**
226     This example illustrates how to simply read and write data on a
227     simulated storage resource.
228     |br| `examples/s4u/io-storage-raw/s4u-io-storage-raw.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/io-storage-raw/s4u-io-storage-raw.cpp>`_
229
230 The FileSystem plugin provides a more detailed view, with the
231 classical operations over files: open, move, unlink, and of course
232 read and write. The file and disk sizes are also dealt with and can
233 result in short reads and short write, as in reality.
234
235   - **File Management:**
236     This example illustrates the use of operations on files
237     (read, write, seek, tell, unlink, etc).
238     |br| `examples/s4u/io-file-system/s4u-io-file-system.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/io-file-system/s4u-io-file-system.cpp>`_
239
240   - **Remote I/O:**
241     I/O operations on files can also be done in a remote fashion, 
242     i.e. when the accessed disk is not mounted on the caller's host.
243     |br| `examples/s4u/io-file-remote/s4u-io-file-remote.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/io-file-remote/s4u-io-file-remote.cpp>`_
244
245 Classical synchronization objects
246 ---------------------------------
247
248  - **Mutex:**
249    Shows how to use simgrid::s4u::Mutex synchronization objects.
250    |br| `examples/s4u/synchro-mutex/s4u-synchro-mutex.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-mutex/s4u-synchro-mutex.cpp>`_
251
252  - **Barrier:**
253    Shows how to use simgrid::s4u::Barrier synchronization objects.
254    |br| `examples/s4u/synchro-barrier/s4u-synchro-barrier.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-barrier/s4u-synchro-barrier.cpp>`_
255
256  - **Semaphore:**
257    Shows how to use simgrid::s4u::Semaphore synchronization objects.
258    |br| `examples/s4u/synchro-semaphore/s4u-synchro-semaphore.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-semaphore/s4u-synchro-semaphore.cpp>`_
259
260 =============================
261 Interacting with the Platform
262 =============================
263
264  - **Retrieving the list of hosts matching a given criteria:**
265    Shows how to filter the actors that match a given criteria.
266    |br| `examples/s4u/engine-filtering/s4u-engine-filtering.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/engine-filtering/s4u-engine-filtering.cpp>`_
267
268  - **User-defined properties:**
269    You can attach arbitrary information to most platform elements from
270    the XML file, and then interact with these values from your
271    program. Note that the changes are not written permanently on disk,
272    in the XML file nor anywhere else. They only last until the end of
273    your simulation.
274    
275    - :cpp:func:`simgrid::s4u::Actor::get_property()` and :cpp:func:`simgrid::s4u::Actor::set_property()`
276    - :cpp:func:`simgrid::s4u::Host::get_property()` and :cpp:func:`simgrid::s4u::Host::set_property()`
277    - :cpp:func:`simgrid::s4u::Link::get_property()` and :cpp:func:`simgrid::s4u::Link::set_property()`
278    - :cpp:func:`simgrid::s4u::NetZone::get_property()` and :cpp:func:`simgrid::s4u::NetZone::set_property()`
279      
280    |br| `examples/s4u/platform-properties/s4u-platform-properties.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/platform-properties/s4u-platform-properties.cpp>`_
281    |br| `examples/s4u/platform-properties/s4u-platform-properties_d.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/platform-properties/s4u-platform-properties_d.xml>`_
282    |br| `examples/platforms/prop.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/prop.xml>`_
283
284 =================
285 Energy Simulation
286 =================
287
288   - **Describing the energy profiles in the platform:**
289     This platform file contains the energy profile of each links and
290     hosts, which is necessary to get energy consumption predictions.
291     As usual, you should not trust our example, and you should strive
292     to double-check that your instanciation matches your target platform.
293     |br| `examples/platforms/energy_platform.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/energy_platform.xml>`_
294
295   - **Consumption due to the CPU:** 
296     This example shows how to retrieve the amount of energy consumed
297     by the CPU during computations, and the impact of the pstate.
298     |br| `examples/s4u/energy-exec/s4u-energy-exec.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-exec/s4u-energy-exec.cpp>`_
299
300   - **Consumption due to the network:**
301     This example shows how to retrieve and display the energy consumed
302     by the network during communications.
303     |br| `examples/s4u/energy-link/s4u-energy-link.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-link/s4u-energy-link.cpp>`_
304
305   - **Modeling the shutdown and boot of hosts:**
306     Simple example of model of model for the energy consumption during
307     the host boot and shutdown periods.
308     |br| `examples/s4u/energy-boot/platform_boot.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-boot/platform_boot.xml>`_
309     |br| `examples/s4u/energy-boot/s4u-energy-boot.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-boot/s4u-energy-boot.cpp>`_
310
311 =======================
312 Tracing and Visualizing
313 =======================
314
315 Tracing can be activated by various configuration options which
316 are illustrated in these example. See also the 
317 :ref:`full list of options related to tracing <tracing_tracing_options>`.
318
319 It is interesting to run the process-create example with the following
320 options to see the task executions:
321
322   - **Platform Tracing:**
323     This program is a toy example just loading the platform, so that
324     you can play with the platform visualization. Recommanded options:
325     ``--cfg=tracing:yes --cfg=tracing/categorized:yes``
326     |br| `examples/s4u/trace-platform/s4u-trace-platform.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/trace-platform/s4u-trace-platform.cpp>`_
327
328 ========================
329 Larger SimGrid Examplars
330 ========================
331
332 This section contains application examples that are somewhat larger
333 than the previous examples.
334
335   - **Ping Pong:**
336     This simple example just sends one message back and forth.
337     The tesh file laying in the directory show how to start the simulator binary, highlighting how to pass options to 
338     the simulators (as detailed in Section :ref:`options`). 
339     |br| `examples/s4u/app-pingpong/s4u-app-pingpong.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-pingpong/s4u-app-pingpong.cpp>`_
340
341   - **Token ring:**
342     Shows how to implement a classical communication pattern, where a
343     token is exchanged along a ring to reach every participant.
344     |br| `examples/s4u/app-token-ring/s4u-app-token-ring.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-token-ring/s4u-app-token-ring.cpp>`_
345
346   - **Master Workers:**
347     Another good old example, where one Master process has a bunch of task to dispatch to a set of several Worker 
348     processes. This example comes in two equivalent variants, one
349     where the actors are specified as simple functions (which is easier to
350     understand for newcomers) and one where the actors are specified
351     as classes (which is more powerful for the users wanting to build
352     their own projects upon the example).
353     |br| `examples/s4u/app-masterworkers/s4u-app-masterworkers-class.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-masterworkers/s4u-app-masterworkers-class.cpp>`_
354     |br| `examples/s4u/app-masterworkers/s4u-app-masterworkers-fun.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-masterworkers/s4u-app-masterworkers-fun.cpp>`_
355     
356 Data diffusion
357 --------------
358
359   - **Bit Torrent:** 
360     Classical protocol for Peer-to-Peer data diffusion.
361     |br| `examples/s4u/app-bittorrent/s4u-bittorrent.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-bittorrent/s4u-bittorrent.cpp>`_
362     
363   - **Chained Send:** 
364     Data broadcast over a ring of processes.
365     |br| `examples/s4u/app-chainsend/s4u-app-chainsend.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-chainsend/s4u-app-chainsend.cpp>`_
366
367 Distributed Hash Tables (DHT)
368 -----------------------------
369
370   - **Chord Protocol** 
371     One of the most famous DHT protocol.
372     |br| `examples/s4u/dht-chord/s4u-dht-chord.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/dht-chord/s4u-dht-chord.cpp>`_
373
374 .. TODO:: document here the examples about plugins
375
376 .. |br| raw:: html
377
378    <br />
379
380 .. |cpp| image:: /img/lang_cpp.png
381    :align: middle
382    :width: 12
383
384 .. |py| image:: /img/lang_python.png
385    :align: middle
386    :width: 12