1 /* messaging - high level communication (send/receive messages) */
2 /* module's public interface exported to end user. */
4 /* Copyright (c) 2003-2007 Martin Quinson. All rights reserved. */
6 /* This program is free software; you can redistribute it and/or modify it
7 * under the terms of the license (GNU LGPL) which comes with this package. */
9 #ifndef GRAS_MESSAGES_H
10 #define GRAS_MESSAGES_H
13 #include "gras/transport.h"
14 #include "gras/datadesc.h"
18 /** @addtogroup GRAS_msg
19 * @brief Defining messages and callbacks, and exchanging messages
21 * There is two way to receive messages in GRAS. The first one is to
22 * register a given function as callback to a given type of messages (see
23 * \ref gras_cb_register and associated section). But you can also
24 * explicitely wait for a given message with the \ref gras_msg_wait
27 * Usually, both ways are not intended to be mixed of a given type of
28 * messages. But if you do so, it shouldn't trigger any issue. If the
29 * message arrives when gras_msg_wait is blocked, then it will be routed to
30 * it. If it arrives when before or after \ref gras_msg_wait, it will be
31 * passed to the callback.
33 * For an example of use, please refer to \ref GRAS_ex_ping. The archive
34 * contains much more examples, but their are not properly integrated into
35 * this documentation yet.
37 /** @defgroup GRAS_msg_decl Message declaration and retrival
40 * GRAS messages can only accept one type of payload. See \ref GRAS_dd for
41 * more information on how to describe data in GRAS.
43 * If you absolutely want use a message able to convey several datatypes,
44 * you can always say that it conveys a generic reference (see
45 * \ref gras_datadesc_ref_generic).
47 * In order to ease the upgrade of GRAS applications, it is possible to \e
48 * version the messages, ie to add a version number to the message (by
49 * default, the version is set to 0). Any messages of the wrong version will
50 * be ignored by the applications not providing any specific callback for
53 * This mechanism (stolen from the dynamic loader one) should ensure you to
54 * change the semantic of a given message while still understanding the old
58 /** \brief Opaque type */
59 typedef struct s_gras_msgtype *gras_msgtype_t;
61 XBT_PUBLIC(void) gras_msgtype_declare(const char *name,
62 gras_datadesc_type_t payload);
63 XBT_PUBLIC(void) gras_msgtype_declare_v(const char *name,
65 gras_datadesc_type_t payload);
67 XBT_PUBLIC(gras_msgtype_t) gras_msgtype_by_name(const char *name);
68 XBT_PUBLIC(gras_msgtype_t) gras_msgtype_by_name_or_null(const char *name);
69 XBT_PUBLIC(gras_msgtype_t) gras_msgtype_by_namev(const char *name,
71 XBT_PUBLIC(gras_msgtype_t) gras_msgtype_by_id(int id);
73 XBT_PUBLIC(void) gras_msgtype_dumpall(void);
77 /** @defgroup GRAS_msg_cb Callback declaration and use
81 * This is how to register a given function so that it gets called when a
82 * given type of message arrives.
84 * You can register several callbacks to the same kind of messages, and
85 * they will get stacked. The lastly added callback gets the message first.
86 * If it consumes the message, it should return a true value when done. If
87 * not, it should return 0, and the message will be passed to the second
88 * callback of the stack, if any.
93 /** \brief Context of callbacks (opaque structure, created by the middleware only, never by user) */
94 typedef struct s_gras_msg_cb_ctx *gras_msg_cb_ctx_t;
96 XBT_PUBLIC(void) gras_msg_cb_ctx_free(gras_msg_cb_ctx_t ctx);
97 XBT_PUBLIC(gras_socket_t) gras_msg_cb_ctx_from(gras_msg_cb_ctx_t ctx);
99 /** \brief Type of message callback functions.
101 * \param expeditor: a socket to contact who sent this message
102 * \param payload: the message itself
104 * \return true if the message was consumed by the callback,
105 * false if the message was refused by the callback (and should be
106 * passed to the next callback of the stack for this message)
108 * Once a such a function is registered to handle messages of a given
109 * type with \ref gras_cb_register(), it will be called each time such
110 * a message arrives (unless a gras_msg_wait() intercepts it on arrival).
112 * If the callback accepts the message, it should free it after use.
114 typedef int (*gras_msg_cb_t) (gras_msg_cb_ctx_t ctx, void *payload);
117 * @brief Bind the given callback to the given message type (described by its name)
120 * Several callbacks can be attached to a given message type. The lastly added one will get the message first, and
121 * if it returns a non-null value, the message will be passed to the second one.
122 * And so on until one of the callbacks accepts the message.
124 * Using gras_cb_register is a bit slower than using gras_cb_register_ since GRAS
125 * has to search for the given msgtype in the hash table, but you don't care in most case.
127 #define gras_cb_register(msgtype_name, cb) gras_cb_register_(gras_msgtype_by_name(msgtype_name),cb)
130 * @brief Unbind the given callback to the given message type (described by its name)
133 * Using gras_cb_unregister is a bit slower than using gras_cb_unregister_ since GRAS
134 * has to search for the given msgtype in the hash table, but you don't care in most case.
136 #define gras_cb_unregister(msgtype_name, cb) gras_cb_unregister_(gras_msgtype_by_name(msgtype_name),cb)
138 XBT_PUBLIC(void) gras_cb_register_(gras_msgtype_t msgtype, gras_msg_cb_t cb);
139 XBT_PUBLIC(void) gras_cb_unregister_(gras_msgtype_t msgtype,
144 /** @defgroup GRAS_msg_exchange Message exchange
150 /** \brief Send the data pointed by \a payload as a message \a msgname on the \a sock
153 * Using gras_msg_wait() is a bit slower than using gras_msg_wait_() since GRAS
154 * has to search for the given msgtype in the hash table.
156 #define gras_msg_send(sock,name,payload) gras_msg_send_(sock,gras_msgtype_by_name(name),payload)
157 XBT_PUBLIC(void) gras_msg_send_(gras_socket_t sock,
158 gras_msgtype_t msgtype, void *payload);
160 /** \brief Waits for a message to come in over a given socket
162 * @param timeout: How long should we wait for this message.
163 * @param msgt_want: type of awaited msg
164 * @param[out] expeditor: where to create a socket to answer the incomming message
165 * @param[out] payload: where to write the payload of the incomming message
166 * @return the error code (or no_error).
168 * Every message of another type received before the one waited will be queued
169 * and used by subsequent call to this function or gras_msg_handle().
171 * Using gras_msg_wait() is a bit slower than using gras_msg_wait_() since GRAS
172 * has to search for the given msgtype in the hash table.
175 #define gras_msg_wait(timeout,msgt_want,expeditor,payload) gras_msg_wait_(timeout,gras_msgtype_by_name(msgt_want),expeditor,payload)
176 XBT_PUBLIC(void) gras_msg_wait_(double timeout,
177 gras_msgtype_t msgt_want,
178 gras_socket_t * expeditor, void *payload);
179 XBT_PUBLIC(void) gras_msg_handleall(double period);
180 XBT_PUBLIC(void) gras_msg_handle(double timeOut);
184 /** @defgroup GRAS_msg_rpc RPC specific functions
187 * Remote Procedure Call (RPC) are a classical mecanism to request a service
188 * from a remote host. Using this set of functions, you let GRAS doing most of
189 * the work of sending the request, wait for an answer, make sure it is the
190 * right answer from the right host and so on. Any exception raised on the
191 * server is also passed over the network to the client.
193 * Callbacks are attached to RPC incomming messages the regular way using
194 * \ref gras_cb_register.
196 * For an example of use, check the examples/gras/rpc directory of the distribution.
201 XBT_PUBLIC(void) gras_msgtype_declare_rpc(const char *name,
207 XBT_PUBLIC(void) gras_msgtype_declare_rpc_v(const char *name,
216 /** @brief Conduct a RPC call
219 #define gras_msg_rpccall(server,timeout,msg,req,ans) gras_msg_rpccall_(server,timeout,gras_msgtype_by_name(msg),req,ans)
220 XBT_PUBLIC(void) gras_msg_rpccall_(gras_socket_t server,
222 gras_msgtype_t msgtype,
223 void *request, void *answer);
224 XBT_PUBLIC(gras_msg_cb_ctx_t)
226 /** @brief Launch a RPC call, but do not block for the answer
229 #define gras_msg_rpc_async_call(server,timeout,msg,req) gras_msg_rpc_async_call_(server,timeout,gras_msgtype_by_name(msg),req)
230 gras_msg_rpc_async_call_(gras_socket_t server,
232 gras_msgtype_t msgtype, void *request);
233 XBT_PUBLIC(void) gras_msg_rpc_async_wait(gras_msg_cb_ctx_t ctx, void *answer);
236 XBT_PUBLIC(void) gras_msg_rpcreturn(double timeOut, gras_msg_cb_ctx_t ctx,
242 /** @defgroup GRAS_msg_exchangeadv Message exchange (advanced interface)
248 /** @brief Message kind (internal enum) */
250 e_gras_msg_kind_unknown = 0,
252 e_gras_msg_kind_oneway = 1,
253 /**< good old regular messages */
255 e_gras_msg_kind_rpccall = 2,
257 /* HACK: e_gras_msg_kind_rpccall also designate RPC message *type* in
258 msgtype_t, not only in msg_t */
259 e_gras_msg_kind_rpcanswer = 3,
260 /**< RPC successful answer */
261 e_gras_msg_kind_rpcerror = 4,
262 /**< RPC failure on server (payload=exception); should not leak to user-space */
265 call cancel, and others
267 forwarding request and other application level routing stuff
271 e_gras_msg_kind_count = 5 /* sentinel, dont mess with */
275 /** @brief Message instance (internal struct) */
278 e_gras_msg_kind_t kind;
280 unsigned long int ID;
283 } s_gras_msg_t, *gras_msg_t;
285 typedef int (*gras_msg_filter_t) (gras_msg_t msg, void *ctx);
287 #define gras_msg_wait_ext(timeout, msg, expe, filter, fctx,got) gras_msg_wait_ext_(timeout, gras_msgtype_by_name(msg), expe, filter, fctx,got)
288 XBT_PUBLIC(void) gras_msg_wait_ext_(double timeout,
289 gras_msgtype_t msgt_want,
290 gras_socket_t expe_want,
291 gras_msg_filter_t filter,
292 void *filter_ctx, gras_msg_t msg_got);
294 XBT_PUBLIC(void) gras_msg_wait_or(double timeout,
295 xbt_dynar_t msgt_want,
296 gras_msg_cb_ctx_t * ctx,
297 int *msgt_got, void *payload);
303 #endif /* GRAS_MSG_H */