2 /* module - module handling, along with module dependencies and local state */
4 /* Copyright (C) 2006 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. */
10 #include "gras/module.h"
11 #include "virtu_private.h"
13 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(gras_modules,gras,"Module and moddata handling");
15 /* IMPLEMENTATION NOTE
17 The goal of this module is quite difficult. We want to have several modules,
18 each of them having globals which have to be initialized in any unix
19 process. Let's call them world-wide globals. An example may be the messages
20 dictionnary, which is world-wide to detect definition discrepencies when
23 And then, the module may want to have some globals specific to a gras process,
24 just like userdata stuff allows to have per-process globals. Let's call them
25 process-wide globals. An example may be the list of attached callbacks.
27 That is why we have 4 functions per module: the join function is called by any
28 process, and is in charge of creating the process-wide globals. If it is the
29 first time a process uses the module, it also calls the init function, in
30 charge of initializing the world-wide globals. We have the symmetric functions
31 leave, called by any process not using the module anymore, and exit, in charge
32 of freeing the world-wide globals when no process use it anymore.
34 One can see this as a factory of factories. the init function is a factory
35 creating the module, which contains a factory (the join function) able to
36 create process-wide globals. The fact that indeed the calling sequence goes
37 from join to init and not the other side is just an implementation bias ;)
39 Then again, we want these functionalities to be quick. We want to access
40 the process-wide globals by providing their rank in a dynar, we don't want to
41 search them in a dictionary. This is especially true in the module
42 implementation, where each functions is likely to require them to work. The
43 position could be a stored in a global variable only visible from the module
46 The need for an array in which to store the globals does not hold for
47 world-wide globals: only one instance of them can exist in the same unix naming
48 space. Thus, there is no need to put them in an array, we can actually declare
49 them as regular C globals.
51 The next trick comes from the fact that the user may (and will) mess up and not
52 get all modules initialized in the same order in every process. So, the rank of
53 module data cannot be the order in which a process called the join
54 function. This has to be a world-wide global instead.
56 And finally, if we want to get the ability to destroy modules (one day, they
57 will load their code in as plugin), we want to give the module handling library
58 (ie, this file) to modify the variable containing the rank of module in the
59 tables. This is why we have the ID field in the module structure: it points
60 exactly to the implementation side global.
62 Yeah, I know. All this is not that clear. But at least, writing this helped me
63 to design that crap ;)
67 typedef struct s_gras_module {
70 unsigned int datasize;
71 int refcount; /* Number of processes using this module */
72 /* FIXME: we should keep a count of references within a given process to
73 allow modules initializing other modules while tracking dependencies
74 properly and leave() only when needed. This would allow dynamic module
77 int *p_id; /* where the module stores the libdata ID (a global somewhere), to tweak it on need */
78 void_f_void_t init_f; /* First time the module is referenced. */
79 void_f_void_t exit_f; /* When last process referencing it stops doing so. */
80 void_f_pvoid_t join_f; /* Called by each process in initialization phase (init_f called once for all processes) */
81 void_f_pvoid_t leave_f; /* Called by each process in finalization phase. Should free moddata passed */
82 } s_gras_module_t, *gras_module_t;
84 static xbt_set_t _gras_modules = NULL; /* content: s_gras_module_t */
86 static void gras_module_freep(void *p) {
87 free( ((gras_module_t)p) ->name);
93 * @brief Declaring a new GRAS module
94 * @param name: name of the module, of course (beware of dupplicates!)
95 * @param datasize: the size of your data, ie of the state this module has on each process
96 * @param ID: address of a global you use as parameter to gras_module_data_by_id
97 * @param init_f: function called the first time a module gets by a process of the naming space.
98 * A classical use is to declare some messages the module uses, as well as the initialization
99 * of module constants (accross processes boundaries in SG).
100 * @param exit_f: function called when the last process of this naming space unref this module.
101 * @param join_f: function called each time a process references the module.
102 * It is passed the moddata already malloced, and should initialize the fields as it wants.
103 * It can also attach some callbacks to the module messages.
104 * @param leave_f: function called each time a process unrefs the module.
105 * It is passed the moddata, and should free any memory allocated by init_f.
106 * It should alse disconnect any attached callbacks.
109 void gras_module_add(const char *name, unsigned int datasize, int *ID,
110 void_f_void_t init_f, void_f_void_t exit_f,
111 void_f_pvoid_t join_f, void_f_pvoid_t leave_f) {
112 gras_module_t mod=NULL;
114 volatile int found = 0;
117 _gras_modules = xbt_set_new();
120 mod=(gras_module_t)xbt_set_get_by_name (_gras_modules,name);
123 if (e.category != not_found_error)
129 xbt_assert1(mod->init_f == init_f,
130 "Module %s reregistered with a different init_f!", name);
131 xbt_assert1(mod->exit_f == exit_f,
132 "Module %s reregistered with a different exit_f!", name);
133 xbt_assert1(mod->join_f == join_f,
134 "Module %s reregistered with a different join_f!", name);
135 xbt_assert1(mod->leave_f == leave_f,
136 "Module %s reregistered with a different leave_f!", name);
137 xbt_assert1(mod->datasize == datasize,
138 "Module %s reregistered with a different datasize!", name);
139 xbt_assert1(mod->p_id == ID,
140 "Module %s reregistered with a different p_id field!", name);
142 DEBUG1("Module %s already registered. Ignoring re-registration",name);
146 VERB1("Register module %s",name);
147 mod = xbt_new(s_gras_module_t, 1);
148 mod->name = xbt_strdup(name);
149 mod->name_len = strlen(name);
151 mod->datasize = datasize;
153 mod->init_f = init_f;
154 mod->exit_f = exit_f;
155 mod->join_f = join_f;
156 mod->leave_f = leave_f;
159 *mod->p_id = xbt_set_length(_gras_modules);
161 xbt_set_add(_gras_modules,(void*)mod,gras_module_freep);
164 /* shutdown the module mechanism (world-wide cleanups) */
165 void gras_moddata_exit(void) {
166 xbt_set_free(&_gras_modules);
169 /* frees the moddata on this host (process-wide cleanups) */
170 void gras_moddata_leave(void) {
171 gras_procdata_t *pd=gras_procdata_get();
173 xbt_dynar_free(&pd->moddata);
176 /* Removes & frees a given moddata from the current host */
177 static void moddata_freep(void *p) {
178 gras_procdata_t *pd=gras_procdata_get();
179 int id = xbt_dynar_search (pd->moddata, p);
180 gras_module_t mod = (gras_module_t)xbt_set_get_by_id(_gras_modules, id);
182 (*mod->leave_f)(gras_moddata_by_id(id));
185 void gras_module_join(const char *name) {
188 gras_module_t mod = (gras_module_t)xbt_set_get_by_name(_gras_modules, name);
190 VERB2("Join to module %s (%p)",name,mod);
193 if (mod->refcount == 0) {
194 VERB1("Init module %s",name);
195 mod->name = xbt_strdup(name);
199 DEBUG3("Module %s already inited. Refcount=%d ID=%d",
200 mod->name, mod->refcount,*(mod->p_id));
205 pd=gras_procdata_get();
207 if (!pd->moddata) /* Damn. I must be the first module on this process. Scary ;)*/
208 pd->moddata = xbt_dynar_new(sizeof(gras_module_t),&moddata_freep);
210 moddata = xbt_malloc(mod->datasize);
212 xbt_dynar_set(pd->moddata, *(mod->p_id), &moddata);
214 (*mod->join_f)(moddata);
216 DEBUG2("Module %s joined successfully (ID=%d)", name,*(mod->p_id));
218 void gras_module_leave(const char *name) {
220 gras_module_t mod = (gras_module_t)xbt_set_get_by_name(_gras_modules, name);
222 VERB1("Leave module %s",name);
225 moddata = gras_moddata_by_id( *(mod->p_id) );
226 (*mod->leave_f)(moddata);
230 if (!mod->refcount) {
231 VERB1("Exit module %s",name);
235 /* Don't remove the module for real, sets don't allow to
244 void *gras_moddata_by_id(unsigned int ID) {
245 gras_procdata_t *pd=gras_procdata_get();
248 xbt_dynar_get_cpy(pd->moddata, ID, &p);