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 symetric 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 functionnalities 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 dictionnary. 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);
92 * @brief Declaring a new GRAS module
93 * @param name: name of the module, of course (beware of dupplicates!)
94 * @param datasize: the size of your data, ie of the state this module has on each process
95 * @param ID: address of a global you use as parameter to gras_module_data_by_id
96 * @param init_f: function called the first time a module gets by a process of the naming space.
97 * A classical use is to declare some messages the module uses, as well as the initialization
98 * of module constants (accross processes boundaries in SG).
99 * @param exit_f: function called when the last process of this naming space unref this module.
100 * @param join_f: function called each time a process references the module.
101 * It is passed the moddata already malloced, and should initialize the fields as it wants.
102 * It can also attach some callbacks to the module messages.
103 * @param leave_f: function called each time a process unrefs the module.
104 * It is passed the moddata, and should free any memory allocated by init_f.
105 * It should alse disconnect any attached callbacks.
108 void gras_module_add(const char *name, unsigned int datasize, int *ID,
109 void_f_void_t *init_f, void_f_void_t *exit_f,
110 void_f_pvoid_t *join_f, void_f_pvoid_t *leave_f) {
111 gras_module_t mod=NULL;
113 volatile int found = 0;
116 _gras_modules = xbt_set_new();
119 mod=(gras_module_t)xbt_set_get_by_name (_gras_modules,name);
122 if (e.category != not_found_error)
128 xbt_assert1(mod->init_f == init_f,
129 "Module %s reregistered with a different init_f!", name);
130 xbt_assert1(mod->exit_f == exit_f,
131 "Module %s reregistered with a different exit_f!", name);
132 xbt_assert1(mod->join_f == join_f,
133 "Module %s reregistered with a different join_f!", name);
134 xbt_assert1(mod->leave_f == leave_f,
135 "Module %s reregistered with a different leave_f!", name);
136 xbt_assert1(mod->datasize == datasize,
137 "Module %s reregistered with a different datasize!", name);
138 xbt_assert1(mod->p_id == ID,
139 "Module %s reregistered with a different p_id field!", name);
141 DEBUG1("Module %s already registered. Ignoring re-registration",name);
145 VERB1("Register module %s",name);
146 mod = xbt_new(s_gras_module_t, 1);
147 mod->name = xbt_strdup(name);
148 mod->name_len = strlen(name);
150 mod->datasize = datasize;
152 mod->init_f = init_f;
153 mod->exit_f = exit_f;
154 mod->join_f = join_f;
155 mod->leave_f = leave_f;
158 *mod->p_id = xbt_set_length(_gras_modules);
160 xbt_set_add(_gras_modules,(void*)mod,gras_module_freep);
163 /* shutdown the module mechanism (world-wide cleanups) */
164 void gras_moddata_exit(void) {
165 xbt_set_free(&_gras_modules);
168 /* frees the moddata on this host (process-wide cleanups) */
169 void gras_moddata_leave(void) {
170 gras_procdata_t *pd=gras_procdata_get();
172 xbt_dynar_free(&pd->moddata);
175 /* Removes & frees a given moddata from the current host */
176 static void moddata_freep(void *p) {
177 gras_procdata_t *pd=gras_procdata_get();
178 int id = xbt_dynar_search (pd->moddata, p);
179 gras_module_t mod = (gras_module_t)xbt_set_get_by_id(_gras_modules, id);
181 (*mod->leave_f)(gras_moddata_by_id(id));
184 void gras_module_join(const char *name) {
187 gras_module_t mod = (gras_module_t)xbt_set_get_by_name(_gras_modules, name);
189 VERB2("Join to module %s (%p)",name,mod);
192 if (mod->refcount == 0) {
193 VERB1("Init module %s",name);
194 mod->name = xbt_strdup(name);
198 DEBUG3("Module %s already inited. Refcount=%d ID=%d",
199 mod->name, mod->refcount,*(mod->p_id));
204 pd=gras_procdata_get();
206 if (!pd->moddata) /* Damn. I must be the first module on this process. Scary ;)*/
207 pd->moddata = xbt_dynar_new(sizeof(gras_module_t),&moddata_freep);
209 moddata = xbt_malloc(mod->datasize);
211 xbt_dynar_set(pd->moddata, *(mod->p_id), &moddata);
213 (*mod->join_f)(moddata);
215 DEBUG2("Module %s joined successfully (ID=%d)", name,*(mod->p_id));
217 void gras_module_leave(const char *name) {
219 gras_module_t mod = (gras_module_t)xbt_set_get_by_name(_gras_modules, name);
221 VERB1("Leave module %s",name);
224 moddata = gras_moddata_by_id( *(mod->p_id) );
225 (*mod->leave_f)(moddata);
229 if (!mod->refcount) {
230 VERB1("Exit module %s",name);
234 /* Don't remove the module for real, sets don't allow to
243 void *gras_moddata_by_id(unsigned int ID) {
244 gras_procdata_t *pd=gras_procdata_get();
247 xbt_dynar_get_cpy(pd->moddata, ID, &p);