#####################################################################
########################### CORE ###################################
#####################################################################
/** \addtogroup GRAS_API
\htmlonly
\endhtmlonly
\section GRAS_funct API documentation
GRAS offers the following functionnalities
- \ref GRAS_comm: Exchanging messages between peers
- \ref GRAS_dd : any data which may transit on the network must be
described beforehand so that GRAS can handle the platform
heterogeneity and convert them if needed.
- \ref GRAS_sock : this is how to open a communication channel to
other processes, and retrive information about them.
- \ref GRAS_msg : communications are message oriented. You have to
describe all possible messages and their payload beforehand, and
can then attach callbacks to the arrival of a given kind of message.
- \ref GRAS_timer : this is how to program repetitive and delayed
tasks, not unlike cron(8) and at(1). This cannot be used to timeout
a function (like setitimer(2) or signal(2) games could do).
- \ref GRAS_run: Running both on top of the simulator and on
top of real platforms, and portability support.
- \ref GRAS_virtu : You naturally don't want to call the
gettimeofday(2) function in simulation mode since it would give
you the time on the host running the simulation, not the time in
the simulated world (you are belonging to).\n
This a system call virtualization layer, which also acts as a
portability layer.
- \ref GRAS_globals : The use of globals is forbidden since the
"processes" are threads in simulation mode. \n
This is how to let GRAS handle your globals properly.
- \ref GRAS_emul : Support to emulate code excution (ie, reporting
execution time into the simulator and having code sections specific
to simulation or to real mode).
\section GRAS_example Examples
There is for now rather few examples of GRAS, but it's better than
nothing, isn't it?
- \ref GRAS_ex_ping
- \ref GRAS_ex_mmrpc
- \ref GRAS_ex_token
- \ref GRAS_ex_timer
The initiatic tour of the tutorial also contains several examples. The
most proeminent one is:
- \ref GRAS_tut_tour_explicitwait_use
\section GRAS_tut_presentation Tutorial
We even have a tutorial for the GRAS framework. It details in a
hopefully pedagogic order all the points of the API, along with example
of use for each of them. Unfortunately, it is not finished yet (the main
part missing is the one on how to describe data). Here is the table of
content:
- \ref GRAS_tut_intro
- \ref GRAS_tut_intro_what
- \ref GRAS_tut_intro_model
- \ref GRAS_tut_tour
- \ref GRAS_tut_tour_install
- \ref GRAS_tut_tour_setup
- \ref GRAS_tut_tour_simpleexchange
- \ref GRAS_tut_tour_args
- \ref GRAS_tut_tour_callbacks
- \ref GRAS_tut_tour_globals
- \ref GRAS_tut_tour_logs
- \ref GRAS_tut_tour_timers
- \ref GRAS_tut_tour_exceptions
- \ref GRAS_tut_tour_rpc
- \ref GRAS_tut_tour_explicitwait
- \ref GRAS_tut_tour_message_recaping
\section GRAS_howto_presentation HOWTOs
The tutorial and the API documentation present the framework little
piece by little piece and provide a lot of information on each of them.
Quite orthogonally to this, the HOWTOs try to present transversal
aspects of the framework to give you some broader point of view on it.
How infortunate it is that only one such HOWTO exist for now...
- \ref GRAS_howto
- \ref GRAS_howto_design
@{ */
/** @defgroup GRAS_comm Communication facilities */
/** @defgroup GRAS_run Virtualization */
/** @defgroup GRAS_ex Examples */
/** @defgroup GRAS_tut GRAS Tutorial */
/** @} */
#####################################################################
/** @addtogroup GRAS_comm
Here are the communication facilities. GRAS allows you to exchange
messages on sockets (which can be seen as pipes between
processes). On reception, messages start callbacks (that's the
default communication mode, not the only one). All messages of a given
type convey the same kind of data, and you have to describe it
beforehand.
Timers are also seen as a mean of communication (with yourself). It
allows you to run a repetitive task ("do this every N second until I tell
you to stop"), or to deffer a treatment ("do this in 3 sec").
@{ */
/** @defgroup GRAS_dd Data description */
/** @defgroup GRAS_sock Sockets */
/** @defgroup GRAS_msg Messages */
/** @defgroup GRAS_timer Timers */
/** @} */
#####################################################################
/** @addtogroup GRAS_run
Virtualization facilities allow your code to run both on top of the simulator or in real setting.
@{ */
/** @defgroup GRAS_globals Globals */
/** @defgroup GRAS_emul Emulation support */
/** @defgroup GRAS_virtu Syscalls */
/** @} */
#####################################################################
/** @addtogroup GRAS_ex
There is for now rather few examples of GRAS, but it's better than
nothing, isn't it?
- \ref GRAS_ex_ping
- \ref GRAS_ex_mmrpc
- \ref GRAS_ex_token
- \ref GRAS_ex_timer
The initiatic tour of the tutorial also contains several examples. The
most proeminent one is:
- \ref GRAS_tut_tour_explicitwait_use
\htmlonly \endhtmlonly
There is some more examples in the distribution, under the directory
examples/gras.
*/
#####################################################################
######################### EXAMPLES #################################
#####################################################################
---------------------------------------------------------------------
------------------------- Ping Pong ---------------------------------
---------------------------------------------------------------------
/** \page GRAS_ex_ping The classical Ping-Pong in GRAS
This example implements the very classical ping-pong in GRAS. It
involves a client (initiating the ping-pong) and a server (answering to
client's requests).
It works the following way:
- Both the client and the server register all needed messages
- The server registers a callback to the ping message, which sends pong
to the expeditor
- The client sends the ping message to the server, and waits for the
pong message as an answer.
This example resides in the examples/gras/ping/ping.c file. Yes, both
the code of the client and of the server is placed in the same file. See
the \ref GRAS_tut_tour_setup of the tutorial if wondering.
\section GRAS_ex_ping_toc Table of contents of the ping example
- \ref GRAS_ex_ping_common
- \ref GRAS_ex_ping_initial
- \ref GRAS_ex_ping_register
- \ref GRAS_ex_ping_server
- \ref GRAS_ex_ping_serdata
- \ref GRAS_ex_ping_sercb
- \ref GRAS_ex_ping_sermain
- \ref GRAS_ex_ping_client
- \ref GRAS_ex_ping_climain
\dontinclude gras/ping/ping_common.c
\section GRAS_ex_ping_common 1) Common code to the client and the server
\subsection GRAS_ex_ping_initial 1.a) Initial settings
Let's first load the module header and declare a logging category (see
\ref XBT_log for more info on logging).
\skip include
\until XBT_LOG
The module header ping.h reads:
\dontinclude gras/ping/ping.h
\skip include
\until argv
\until argv
\subsection GRAS_ex_ping_register 1.b) Register the messages
This function, called by both the client and the server is in charge of
declaring the existing messages to GRAS. Since the payload does not
involve any newly created types but only int, this is quite easy.
(to exchange more complicated types, see \ref GRAS_dd or
\ref GRAS_ex_mmrpc for an example).
\dontinclude gras/ping/ping_common.c
\skip register_messages
\until }
[Back to \ref GRAS_ex_ping_toc]
\section GRAS_ex_ping_server 2) Server's code
\subsection GRAS_ex_ping_serdata 2.a) The server's globals
In order to ensure the communication between the "main" and the callback
of the server, we need to declare some globals. We have to put them in a
struct definition so that they can be handled properly in GRAS (see the
\ref GRAS_tut_tour_globals for more info).
\dontinclude gras/ping/ping_server.c
\skip typedef struct
\until }
\subsection GRAS_ex_ping_sercb 2.b) The callback to the ping message
Here is the callback run when the server receives any ping message (this
will be registered later by the server).
\skip server_cb_ping_handler
\until end_of_server_cb_ping_handler
\subsection GRAS_ex_ping_sermain 2.c) The "main" of the server
This is the "main" of the server. As explained in the tutorial, \ref
GRAS_tut_tour_setup, you must not write any main()
function yourself. Instead, you just have to write a regular function
like this one which will act as a main.
\skip server
\until end_of_server
[Back to \ref GRAS_ex_ping_toc]
\section GRAS_ex_ping_client 3) Client's code
\subsection GRAS_ex_ping_climain 3.a) Client's "main" function
This function is quite straightforward, and the inlined comments should
be enough to understand it.
\dontinclude gras/ping/ping_client.c
\skip client
\until end_of_client
[Back to \ref GRAS_ex_ping_toc]
*/
---------------------------------------------------------------------
--------------------- Simple Token Ring -----------------------------
---------------------------------------------------------------------
/** \page GRAS_ex_token Token Ring example
This example implements the token ring algorithm. It involves several
nodes arranged in a ring (each of them have a left and a right neighbour)
and exchanging a "token". This algorithm is one of the solution to ensure
the mutual exclusion between distributed processes. There is only one
token at any time, so the process in its possession is ensured to be the
only one having it. So, if there is an action you want all processes to
do alternativly, but you cannot afford to have two processes doing it at
the same time, let the process having the token doing it.
Actually, there is a lot of different token ring algorithms in the
litterature, so this example implements one of them: the simplest one.
The ring is static (no new node can join it, and you'll get trouble if
one node dies or leaves), and nothing is done for the case in which the
token is lost.
- \ref GRAS_ex_stoken_deploy
- \ref GRAS_ex_stoken_global
- \ref GRAS_ex_stoken_callback
- \ref GRAS_ex_stoken_main
\section GRAS_ex_stoken_deploy 1) Deployment file
Here is the deployment file:
\include examples/gras/mutual_exclusion/simple_token/simple_token.xml
The neighbour of each node is given at startup as command line argument.
Moreover, one of the nodes is instructed by a specific argument (the one
on Tremblay here) to create the token at the begining of the algorithm.
\section GRAS_ex_stoken_global 2) Global definition
The token is incarned by a specific message, which circulates from node
to node (the payload is an integer incremented at each hop). So, the most
important part of the code is the message callback, which forwards the
message to the next node. That is why we have to store all variable in a
global, as explained in the \ref GRAS_globals section.
\dontinclude examples/gras/mutual_exclusion/simple_token/simple_token.c
\skip typedef
\until }
\section GRAS_ex_stoken_callback 3) The callback
Even if this is the core of this algorithm, this function is quite
straightforward.
\skip node_cb_stoken_handler
\until end_of_node_cb_stoken_handler
\section GRAS_ex_stoken_main 4) The main function
This function is splited in two parts: The first one performs all the
needed initialisations (points 1-7) while the end (point 8. below) calls
gras_msg_handle() as long as the planned amount of ring loops are not
performed.
\skip node
\until end_of_node
*/
---------------------------------------------------------------------
-------------------------- MM RPC -----------------------------------
---------------------------------------------------------------------
/** \page GRAS_ex_mmrpc A simple RPC for matrix multiplication
This example implements a remote matrix multiplication. It involves a client
(creating the matrices and sending the multiplications requests) and a server
(computing the multiplication on client's behalf).
This example also constitutes a more advanced example of data description
mechanisms, since the message payload type is a bit more complicated than in
other examples such as the ping one (\ref GRAS_ex_ping).
It works the following way (not very different from the ping example):
- Both the client and the server register all needed messages and datatypes
- The server registers a callback to the "request" message, which computes
what needs to be and returns the result to the expeditor.
- The client creates two matrices, ask for their multiplication and check
the server's answer.
This example resides in the examples/gras/mmrpc/mmrpc.c file. (See
the \ref GRAS_tut_tour_setup of the tutorial if wondering why both the server
and the client live in the same source file)
\section GRAS_ex_mmrpc_toc Table of contents of the mmrpc example
- \ref GRAS_ex_mmrpc_common
- \ref GRAS_ex_mmrpc_header
- \ref GRAS_ex_mmrpc_dataregister
- \ref GRAS_ex_mmrpc_logdef
- \ref GRAS_ex_mmrpc_msgregister
- \ref GRAS_ex_mmrpc_server
- \ref GRAS_ex_mmrpc_serinc
- \ref GRAS_ex_mmrpc_sercb
- \ref GRAS_ex_mmrpc_sermain
- \ref GRAS_ex_mmrpc_client
- \ref GRAS_ex_mmrpc_cliinc
- \ref GRAS_ex_mmrpc_climain
\section GRAS_ex_mmrpc_common 1) Common code to the client and the server (mmrpc_common.c and mmrpc.h)
\subsection GRAS_ex_mmrpc_header 1.a) Module header (mmrpc.h)
This loads the gras header and declare the function's prototypes as well
as the matrix size.
\dontinclude gras/mmrpc/mmrpc.h
\skip include
\until argv
\until argv
\subsection GRAS_ex_mmrpc_dataregister 1.b) Register the data types (mmrpc.h)
The messages involved in a matrix of double. This type is automatically
known by the GRAS mecanism, using the gras_datadesc_matrix() function of the
xbt/matrix module.
\subsection GRAS_ex_mmrpc_logdef 1.c) Logging category definition (mmrpc_common.c)
Let's first load the module header and declare a logging category (see
\ref XBT_log for more info on logging). This logging category does live
in this file (ie the required symbols are defined here and declared as
"extern" in any other file using them). That is why we use
\ref XBT_LOG_NEW_DEFAULT_CATEGORY here and
\ref XBT_LOG_EXTERNAL_DEFAULT_CATEGORY in mmrpc_client.c and mmrpc_server.c.
\dontinclude gras/mmrpc/mmrpc_common.c
\skip include
\until XBT_LOG
\subsection GRAS_ex_mmrpc_msgregister 1.d) Register the messages (mmrpc_common.c)
This function, called by both the client and the server is in charge of
declaring the existing messages to GRAS.
The datatype description builded that way can then be used to build an array datatype or
to declare messages.
\skip register_messages
\until }
[Back to \ref GRAS_ex_mmrpc_toc]
\section GRAS_ex_mmrpc_server 2) Server's code (mmrpc_server.c)
\subsection GRAS_ex_mmrpc_serinc 2.a) Server intial settings
All module symbols live in the mmrpc_common.c file. We thus have to
define \ref GRAS_DEFINE_TYPE_EXTERN to the preprocessor so that the
\ref GRAS_DEFINE_TYPE symbols don't get included here. Likewise, we use
\ref XBT_LOG_EXTERNAL_DEFAULT_CATEGORY to get the log category in here.
\dontinclude gras/mmrpc/mmrpc_server.c
\skip define
\until XBT_LOG
\subsection GRAS_ex_mmrpc_sercb 2.b) The callback to the mmrpc message
Here is the callback run when the server receives any mmrpc message (this
will be registered later by the server). Note the way we get the message
payload. In the ping example, there was one additional level of pointer
indirection (see \ref GRAS_ex_ping_sercb). This is because the payload is
an array here (ie a pointer) whereas it is a scalar in the ping example.
\skip server_cb_request_handler
\until end_of_server_cb_request_handler
\subsection GRAS_ex_mmrpc_sermain 2.c) The "main" of the server
This is the "main" of the server. As explained in the tutorial, \ref
GRAS_tut_tour_setup, you must not write any main()
function yourself. Instead, you just have to write a regular function
like this one which will act as a main.
\skip server
\until end_of_server
[Back to \ref GRAS_ex_mmrpc_toc]
\section GRAS_ex_mmrpc_client 3) Client's code (mmrpc_client.c)
\subsection GRAS_ex_mmrpc_cliinc 2.a) Server intial settings
As for the server, some extra love is needed to make sure that automatic
datatype parsing and log categories do work even if we are using several
files.
\dontinclude gras/mmrpc/mmrpc_client.c
\skip define
\until XBT_LOG
\subsection GRAS_ex_mmrpc_climain 3.b) Client's "main" function
This function is quite straightforward, and the inlined comments should
be enough to understand it.
\dontinclude gras/mmrpc/mmrpc_client.c
\skip argv
\until end_of_client
[Back to \ref GRAS_ex_mmrpc_toc]
*/
---------------------------------------------------------------------
---------------------------- Timers ---------------------------------
---------------------------------------------------------------------
/** \page GRAS_ex_timer Some timer games
This example fools around with the GRAS timers (\ref GRAS_timer). It is
mainly a regression test, since it uses almost all timer features.
The main program registers a repetititive task and a delayed one, and
then loops until the still_to_do variables of its globals reach
0. The delayed task set it to 5, and the repetititive one decrease it
each time. Here is an example of output:
\verbatim Initialize GRAS
Initialize XBT
[1108335471] Programming the repetitive_action with a frequency of 1.000000 sec
[1108335471] Programming the delayed_action for after 2.000000 sec
[1108335471] Have a rest
[1108335472] Canceling the delayed_action.
[1108335472] Re-programming the delayed_action for after 2.000000 sec
[1108335472] Repetitive_action has nothing to do yet
[1108335473] Repetitive_action has nothing to do yet
[1108335473] delayed_action setting globals->still_to_do to 5
[1108335474] repetitive_action decrementing globals->still_to_do. New value: 4
[1108335475] repetitive_action decrementing globals->still_to_do. New value: 3
[1108335476] repetitive_action decrementing globals->still_to_do. New value: 2
[1108335477] repetitive_action decrementing globals->still_to_do. New value: 1
[1108335478] repetitive_action decrementing globals->still_to_do. New value: 0
Exiting GRAS\endverbatim
Source code:
- \ref GRAS_ex_timer_decl
- \ref GRAS_ex_timer_delay
- \ref GRAS_ex_timer_repeat
- \ref GRAS_ex_timer_main
\dontinclude timer.c
\section GRAS_ex_timer_decl 1. Declarations and headers
\skip include
\until my_globals
\section GRAS_ex_timer_delay 2. Source code of the delayed action
\skip repetitive_action
\until end_of_repetitive_action
\section GRAS_ex_timer_repeat 3. Source code of the repetitive action
\skip delayed_action
\until end_of_delayed_action
\section GRAS_ex_timer_main 4. Source code of main function
\skip client
\until end_of_client
*/