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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 See also the examples on :ref:`inter-actors communications
84 <s4u_ex_communication>` and the ones on :ref:`classical
85 synchronization objects <s4u_ex_IPC>`.
86
87   - **Suspend and Resume actors:**    
88     Actors can be suspended and resumed during their executions.
89     
90     - |cpp| `examples/s4u/actor-suspend/s4u-actor-suspend.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-suspend/s4u-actor-suspend.cpp>`_
91       :cpp:func:`simgrid::s4u::this_actor::suspend()`,
92       :cpp:func:`simgrid::s4u::Actor::suspend()`, :cpp:func:`simgrid::s4u::Actor::resume()`, :cpp:func:`simgrid::s4u::Actor::is_suspended()`.
93     - |py|  `examples/python/actor-suspend/actor-suspend.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-suspend/actor-suspend.py>`_
94       :py:func:`simgrid.this_actor.suspend()`,
95       :py:func:`simgrid.Actor.suspend()`, :py:func:`simgrid.Actor.resume()`, :py:func:`simgrid.Actor.is_suspended()`.
96
97   - **Migrating Actors:**
98     Actors can move or be moved from a host to another very easily.
99     
100     - |cpp| `examples/s4u/actor-migrate/s4u-actor-migrate.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-migrate/s4u-actor-migrate.cpp>`_
101       :cpp:func:`simgrid::s4u::this_actor::migrate()`
102     - |py|  `examples/python/actor-migrate/actor-migrate.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-migrate/actor-migrate.py>`_
103       :py:func:`simgrid.this_actor.migrate()`
104
105   - **Waiting for the termination of an actor:** (joining on it)
106     You can block the current actor until the end of another actor.
107     
108     - |cpp| `examples/s4u/actor-join/s4u-actor-join.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-join/s4u-actor-join.cpp>`_
109       :cpp:func:`simgrid::s4u::Actor::join()`
110     - |py|  `examples/python/actor-join/actor-join.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-join/actor-join.py>`_
111       :py:func:`simgrid.Actor.join()`
112
113   - **Yielding to other actors**.
114     The ```yield()``` function interrupts the execution of the current
115     actor, leaving a chance to the other actors that are ready to run
116     at this timestamp.
117     
118     - |cpp| `examples/s4u/actor-yield/s4u-actor-yield.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-yield/s4u-actor-yield.cpp>`_
119       :cpp:func:`simgrid::s4u::this_actor::yield()`
120     - |py|  `examples/python/actor-yield/actor-yield.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-yield/actor-yield.py>`_
121       :py:func:`simgrid.this_actor.yield_()`
122
123 Traces Replay as a Workload
124 ---------------------------
125
126 This section details how to run trace-driven simulations. It is very
127 handy when you want to test an algorithm or protocol that only react
128 to external events. For example, many P2P protocols react to user
129 requests, but do nothing if there is no such event.
130
131 In such situations, you should write your protocol in C++, and separate
132 the workload that you want to play onto your protocol in a separate
133 text file. Declare a function handling each type of the events in your
134 trace, register them using :cpp:func:`xbt_replay_action_register()` in
135 your main, and then run the simulation.
136
137 Then, you can either have one trace file containing all your events,
138 or a file per simulated process: the former may be easier to work
139 with, but the second is more efficient on very large traces. Check
140 also the tesh files in the example directories for details.
141
142   - **Communication replay:**
143     Presents a set of event handlers reproducing classical communication
144     primitives (asynchronous send/receive at the moment).
145     |br| `examples/s4u/replay-comm/s4u-replay-comm.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/replay-comm/s4u-replay-comm.cpp>`_
146
147   - **I/O replay:**
148     Presents a set of event handlers reproducing classical I/O
149     primitives (open, read, close).
150     |br| `examples/s4u/replay-storage/s4u-replay-storage.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/replay-storage/s4u-replay-storage.cpp>`_
151
152 ==========================
153 Activities: what Actors do
154 ==========================
155
156 .. _s4u_ex_communication:
157
158 Communications on the Network
159 -----------------------------
160
161  - **Basic asynchronous communications:**
162    Illustrates how to have non-blocking communications, that are
163    communications running in the background leaving the process free
164    to do something else during their completion. 
165    
166    - |cpp| `examples/s4u/async-wait/s4u-async-wait.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-wait/s4u-async-wait.cpp>`_
167      :cpp:func:`simgrid::s4u::Mailbox::put_async()` and :cpp:func:`simgrid::s4u::Comm::wait()`
168    - |py|  `examples/python/async-wait/async-wait.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/async-wait/async-wait.py>`_
169      :py:func:`simgrid.Mailbox.put_async()` :py:func:`simgrid.Comm.wait()`
170
171  - **Waiting for all communications in a set:**
172    The `wait_all()` function is useful when you want to block until
173    all activities in a given set have completed. 
174    
175    - |cpp| `examples/s4u/async-waitall/s4u-async-waitall.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-waitall/s4u-async-waitall.cpp>`_
176      :cpp:func:`simgrid::s4u::Comm::wait_all()`
177    - |py| `examples/python/async-waitall/async-waitall.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/async-waitall/async-waitall.py>`_
178      :py:func:`simgrid.Comm.wait_all()`
179
180  - **Waiting for the first completed communication in a set:**
181    The `wait_any()` function is useful
182    when you want to block until one activity of the set completes, no
183    matter which terminates first.
184    
185    - |cpp| `examples/s4u/async-waitany/s4u-async-waitany.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-waitany/s4u-async-waitany.cpp>`_
186      :cpp:func:`simgrid::s4u::Comm::wait_any()`
187    - |py| `examples/python/async-waitany/async-waitany.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/async-waitany/async-waitany.py>`_
188      :py:func:`simgrid.Comm.wait_any()`
189      
190 .. todo:: review the `ready` and `waituntil` examples and add them here.
191    
192 .. _s4u_ex_execution:
193
194 Executions on the CPU
195 ---------------------
196
197   - **Basic execution:**
198     The computations done in your program are not reported to the
199     simulated world, unless you explicitely request the simulator to pause
200     the actor until a given amount of flops gets computed on its simulated
201     host. Some executions can be given an higher priority so that they
202     get more resources.
203     
204     - |cpp| `examples/s4u/exec-basic/s4u-exec-basic.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-basic/s4u-exec-basic.cpp>`_
205     - |py|  `examples/python/exec-basic/exec-basic.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-basic/exec-basic.py>`_
206
207   - **Asynchronous execution:**
208     You can start asynchronous executions, just like you would fire
209     background threads.
210     
211     - |cpp| `examples/s4u/exec-async/s4u-exec-async.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-async/s4u-exec-async.cpp>`_
212     - |py|  `examples/python/exec-async/exec-async.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-async/exec-async.py>`_
213     
214   - **Remote execution:**
215     You can start executions on remote hosts, or even change the host
216     on which they occur during their execution.
217     
218     - |cpp| `examples/s4u/exec-remote/s4u-exec-remote.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-remote/s4u-exec-remote.cpp>`_
219     - |py| `examples/python/exec-remote/exec-remote.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-remote/exec-remote.py>`_
220
221   - **Parallel executions:**
222     These objects are convenient abstractions of parallel
223     computational kernels that span over several machines, such as a
224     PDGEM and the other ScaLAPACK routines. Note that this only works
225     with the "ptask_L07" host model (``--cfg=host/model:ptask_L07``).
226     |br| `examples/s4u/exec-ptask/s4u-exec-ptask.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-ptask/s4u-exec-ptask.cpp>`_
227     
228   - **Using Pstates on a host:**
229     `examples/platforms/energy_platform.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/energy_platform.xml>`_
230     shows how define a set of pstates in the XML. The current pstate
231     of an host can then be accessed and changed from the program.
232
233     - |cpp| `examples/s4u/exec-dvfs/s4u-exec-dvfs.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-dvfs/s4u-exec-dvfs.cpp>`_
234       :cpp:func:`simgrid::s4u::Host::get_pstate_speed` and :cpp:func:`simgrid::s4u::Host::set_pstate`.
235     - |py|  `examples/python/exec-dvfs/exec-dvfs.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-dvfs/exec-dvfs.py>`_
236       :py:func:`Host.get_pstate_speed` and :py:func:`Host.set_pstate`.
237
238 I/O on Disks and Files
239 ----------------------
240
241 SimGrid provides two levels of abstraction to interact with the
242 simulated storages. At the simplest level, you simply create read and
243 write actions on the storage resources.
244
245   - **Access to raw storage devices:**
246     This example illustrates how to simply read and write data on a
247     simulated storage resource.
248     |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>`_
249
250 The FileSystem plugin provides a more detailed view, with the
251 classical operations over files: open, move, unlink, and of course
252 read and write. The file and disk sizes are also dealt with and can
253 result in short reads and short write, as in reality.
254
255   - **File Management:**
256     This example illustrates the use of operations on files
257     (read, write, seek, tell, unlink, etc).
258     |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>`_
259
260   - **Remote I/O:**
261     I/O operations on files can also be done in a remote fashion, 
262     i.e. when the accessed disk is not mounted on the caller's host.
263     |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>`_
264
265 .. _s4u_ex_IPC:
266
267 Classical synchronization objects
268 ---------------------------------
269
270  - **Mutex:**
271    Shows how to use simgrid::s4u::Mutex synchronization objects.
272    |br| `examples/s4u/synchro-mutex/s4u-synchro-mutex.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-mutex/s4u-synchro-mutex.cpp>`_
273
274  - **Barrier:**
275    Shows how to use simgrid::s4u::Barrier synchronization objects.
276    |br| `examples/s4u/synchro-barrier/s4u-synchro-barrier.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-barrier/s4u-synchro-barrier.cpp>`_
277
278  - **Semaphore:**
279    Shows how to use simgrid::s4u::Semaphore synchronization objects.
280    |br| `examples/s4u/synchro-semaphore/s4u-synchro-semaphore.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-semaphore/s4u-synchro-semaphore.cpp>`_
281
282 =============================
283 Interacting with the Platform
284 =============================
285
286  - **Retrieving the list of hosts matching a given criteria:**
287    Shows how to filter the actors that match a given criteria.
288    |br| `examples/s4u/engine-filtering/s4u-engine-filtering.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/engine-filtering/s4u-engine-filtering.cpp>`_
289
290  - **User-defined properties:**
291    You can attach arbitrary information to most platform elements from
292    the XML file, and then interact with these values from your
293    program. Note that the changes are not written permanently on disk,
294    in the XML file nor anywhere else. They only last until the end of
295    your simulation.
296    
297    - :cpp:func:`simgrid::s4u::Actor::get_property()` and :cpp:func:`simgrid::s4u::Actor::set_property()`
298    - :cpp:func:`simgrid::s4u::Host::get_property()` and :cpp:func:`simgrid::s4u::Host::set_property()`
299    - :cpp:func:`simgrid::s4u::Link::get_property()` and :cpp:func:`simgrid::s4u::Link::set_property()`
300    - :cpp:func:`simgrid::s4u::NetZone::get_property()` and :cpp:func:`simgrid::s4u::NetZone::set_property()`
301      
302    |br| `examples/s4u/platform-properties/s4u-platform-properties.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/platform-properties/s4u-platform-properties.cpp>`_
303    |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>`_
304    |br| `examples/platforms/prop.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/prop.xml>`_
305
306  - **Specifying state profiles:** shows how to specify when the
307    resources must be turned off and on again, and how to react to such
308    failures in your code.
309    
310    |br| `examples/platforms/small_platform_with_failure.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/small_platform_with_failure.xml>`_
311    |br| The state profiles in `examples/platforms/profiles <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/profiles>`_
312
313  - **Specifying speed profiles:** shows how to specify an external
314    load to resources, variating their peak speed over time.
315    
316    |br| `examples/platforms/small_platform_profile.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/small_platform_profile.xml>`_
317    |br| The speed, bandwidth and latency profiles in `examples/platforms/profiles  <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/profiles>`_
318
319 =================
320 Energy Simulation
321 =================
322
323   - **Describing the energy profiles in the platform:**
324     This platform file contains the energy profile of each links and
325     hosts, which is necessary to get energy consumption predictions.
326     As usual, you should not trust our example, and you should strive
327     to double-check that your instanciation matches your target platform.
328     |br| `examples/platforms/energy_platform.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/energy_platform.xml>`_
329
330   - **Consumption due to the CPU:** 
331     This example shows how to retrieve the amount of energy consumed
332     by the CPU during computations, and the impact of the pstate.
333     |br| `examples/s4u/energy-exec/s4u-energy-exec.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-exec/s4u-energy-exec.cpp>`_
334
335   - **Consumption due to the network:**
336     This example shows how to retrieve and display the energy consumed
337     by the network during communications.
338     |br| `examples/s4u/energy-link/s4u-energy-link.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-link/s4u-energy-link.cpp>`_
339
340   - **Modeling the shutdown and boot of hosts:**
341     Simple example of model of model for the energy consumption during
342     the host boot and shutdown periods.
343     |br| `examples/s4u/energy-boot/platform_boot.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-boot/platform_boot.xml>`_
344     |br| `examples/s4u/energy-boot/s4u-energy-boot.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-boot/s4u-energy-boot.cpp>`_
345
346 =======================
347 Tracing and Visualizing
348 =======================
349
350 Tracing can be activated by various configuration options which
351 are illustrated in these example. See also the 
352 :ref:`full list of options related to tracing <tracing_tracing_options>`.
353
354 It is interesting to run the process-create example with the following
355 options to see the task executions:
356
357   - **Platform Tracing:**
358     This program is a toy example just loading the platform, so that
359     you can play with the platform visualization. Recommanded options:
360     ``--cfg=tracing:yes --cfg=tracing/categorized:yes``
361     |br| `examples/s4u/trace-platform/s4u-trace-platform.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/trace-platform/s4u-trace-platform.cpp>`_
362
363 ========================
364 Larger SimGrid Examplars
365 ========================
366
367 This section contains application examples that are somewhat larger
368 than the previous examples.
369
370   - **Ping Pong:**
371     This simple example just sends one message back and forth.
372     The tesh file laying in the directory show how to start the simulator binary, highlighting how to pass options to 
373     the simulators (as detailed in Section :ref:`options`). 
374     |br| `examples/s4u/app-pingpong/s4u-app-pingpong.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-pingpong/s4u-app-pingpong.cpp>`_
375
376   - **Token ring:**
377     Shows how to implement a classical communication pattern, where a
378     token is exchanged along a ring to reach every participant.
379     |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>`_
380
381   - **Master Workers:**
382     Another good old example, where one Master process has a bunch of task to dispatch to a set of several Worker 
383     processes. This example comes in two equivalent variants, one
384     where the actors are specified as simple functions (which is easier to
385     understand for newcomers) and one where the actors are specified
386     as classes (which is more powerful for the users wanting to build
387     their own projects upon the example).
388     |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>`_
389     |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>`_
390     
391 Data diffusion
392 --------------
393
394   - **Bit Torrent:** 
395     Classical protocol for Peer-to-Peer data diffusion.
396     |br| `examples/s4u/app-bittorrent/s4u-bittorrent.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-bittorrent/s4u-bittorrent.cpp>`_
397     
398   - **Chained Send:** 
399     Data broadcast over a ring of processes.
400     |br| `examples/s4u/app-chainsend/s4u-app-chainsend.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-chainsend/s4u-app-chainsend.cpp>`_
401
402 Distributed Hash Tables (DHT)
403 -----------------------------
404
405   - **Chord Protocol** 
406     One of the most famous DHT protocol.
407     |br| `examples/s4u/dht-chord/s4u-dht-chord.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/dht-chord/s4u-dht-chord.cpp>`_
408
409 .. TODO:: document here the examples about plugins
410
411 =======================
412 Model-Checking Examples
413 =======================
414
415 The model-checker can be used to exhaustively search for issues in the
416 tested application. It must be activated at compile time, but this
417 mode is rather experimental in SimGrid (as of v3.22). You should not
418 enable it unless you really want to formally verify your applications:
419 SimGrid is slower and maybe less robust when MC is enabled.
420
421   - **Failing assert**
422     In this example, two actors send some data to a central server,
423     which asserts that the messages are always received in the same order.
424     This is obviously wrong, and the model-checker correctly finds a
425     counter-example to that assertion.
426     |br| `examples/s4u/mc-failing-assert/s4u-mc-failing-assert.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/mc-failing-assert/s4u-mc-failing-assert.cpp>`_
427
428 .. |br| raw:: html
429
430    <br />
431
432 .. |cpp| image:: /img/lang_cpp.png
433    :align: middle
434    :width: 12
435
436 .. |py| image:: /img/lang_python.png
437    :align: middle
438    :width: 12