3 /* log - a generic logging facility in the spirit of log4j */
5 /* Copyright (c) 2003, 2004 Martin Quinson. All rights reserved. */
7 /* This program is free software; you can redistribute it and/or modify it
8 * under the terms of the license (GNU LGPL) which comes with this package. */
13 #include <stdio.h> /* snprintf */
14 #include <stdlib.h> /* snprintf */
15 #include "gras_config.h" /* to get a working stdarg.h */
16 #include "portable.h" /* to get a working stdarg.h */
18 #include "xbt_modinter.h"
22 #include "xbt/sysdep.h"
24 #include "xbt/dynar.h"
26 /** \addtogroup XBT_log
28 * This section describes the API to the log functions used
29 * everywhere in this project.
31 \section XBT_log_toc Table of contents
43 - \ref log_API_example
52 \section log_overview 1. Introduction
54 This module is in charge of handling the log messages of every SimGrid
55 program. The main design goal are:
57 - <b>configurability</b>: the user can choose <i>at runtime</i> what messages to show and
58 what to hide, as well as how messages get displayed.
59 - <b>ease of use</b>: both to the programmer (using preprocessor macros black magic)
60 and to the user (with command line options)
61 - <b>performances</b>: logging shouldn't slow down the program when turned off, for example
62 - deal with <b>distributed settings</b>: SimGrid programs are [often] distributed ones,
63 and the logging mecanism allows to syndicate each and every log source into the same place.
64 At least, its design would allow to, once we write the last missing pieces
66 There is three main concepts in SimGrid's logging mecanism: <i>category</i>,
67 <i>priority</i> and <i>appender</i>. These three concepts work together to
68 enable developers to log messages according to message type and priority, and
69 to control at runtime how these messages are formatted and where they are
72 \subsection log_cat 1.1 Category hierarchy
74 The first and foremost advantage of any logging API over plain printf()
75 resides in its ability to disable certain log statements while allowing
76 others to print unhindered. This capability assumes that the logging space,
77 that is, the space of all possible logging statements, is categorized
78 according to some developer-chosen criteria.
80 This observation led to choosing category as the central concept of the
81 system. In a certain sense, they can be considered as logging topics or
84 \subsection log_pri 1.2 Logging priorities
86 The user can naturally declare interest into this or that logging category, but
87 he also can specify the desired level of details for each of them. This is
88 controled by the <i>priority</i> concept (which should maybe be renamed to
91 Empirically, the user can specify that he wants to see every debuging message
92 of GRAS while only being interested into the messages at level "error" or
93 higher about the XBT internals.
95 \subsection log_app 1.3 Message appenders
97 The message appenders are the elements in charge of actually displaying the
98 message to the user. For now, there is only one appender: the one able to print
99 stuff on stderr. But everything is in place internally to write new ones, such
100 as the one able to send the strings to a central server in charge of
101 syndicating the logs of every distributed daemons on a well known location.
103 It should also be possible to pass configuration informations to the appenders,
104 specifying for example that the message location (file and line number) is only
105 relevant to debugging information, not to critical error messages.
109 \subsection log_hist 1.4 History of this module
111 Historically, this module is an adaptation of the log4c project, which is dead
112 upstream, and which I was given the permission to fork under the LGPL licence
113 by the log4c's authors. The log4c project itself was loosely based on the
114 Apache project's Log4J, which also inspired Log4CC, Log4py and so on. Our work
115 differs somehow from these projects anyway, because the C programming language
116 is not object oriented.
118 \section log_API 2. Programmer interface
120 \subsection log_API_cat 2.1 Constructing the category hierarchy
122 Every category is declared by providing a name and an optional
123 parent. If no parent is explicitly named, the root category, LOG_ROOT_CAT is
124 the category's parent.
126 A category is created by a macro call at the top level of a file. A
127 category can be created with any one of the following macros:
129 - \ref XBT_LOG_NEW_CATEGORY(MyCat,desc); Create a new root
130 - \ref XBT_LOG_NEW_SUBCATEGORY(MyCat, ParentCat,desc);
131 Create a new category being child of the category ParentCat
132 - \ref XBT_LOG_NEW_DEFAULT_CATEGORY(MyCat,desc);
133 Like XBT_LOG_NEW_CATEGORY, but the new category is the default one
135 - \ref XBT_LOG_NEW_DEFAULT_SUBCATEGORY(MyCat, ParentCat,desc);
136 Like XBT_LOG_NEW_SUBCATEGORY, but the new category is the default one
139 The parent cat can be defined in the same file or in another file (in
140 which case you want to use the \ref XBT_LOG_EXTERNAL_CATEGORY macro to make
141 it visible in the current file), but each category may have only one
144 Typically, there will be a Category for each module and sub-module, so you
145 can independently control logging for each module.
147 For a list of all existing categories, please refer to the \ref XBT_log_cats
148 section. This file is generated automatically from the SimGrid source code, so
149 it should be complete and accurate.
151 \section log_API_pri 2.2 Declaring message priority
153 A category may be assigned a threshold priorty. The set of priorites are
154 defined by the \ref e_xbt_log_priority_t enum. All logging request under
155 this priority will be discarded.
157 If a given category is not assigned a threshold priority, then it inherits
158 one from its closest ancestor with an assigned threshold. To ensure that all
159 categories can eventually inherit a threshold, the root category always has
160 an assigned threshold priority.
162 Logging requests are made by invoking a logging macro on a category. All of
163 the macros have a printf-style format string followed by arguments. If you
164 compile with the -Wall option, gcc will warn you for unmatched arguments, ie
165 when you pass a pointer to a string where an integer was specified by the
166 format. This is usualy a good idea.
168 Because some C compilers do not support vararg macros, there is a version of
169 the macro for any number of arguments from 0 to 6. The macro name ends with
170 the total number of arguments.
172 Here is an example of the most basic type of macro. This is a logging
173 request with priority <i>warning</i>.
175 <code>CLOG5(MyCat, gras_log_priority_warning, "Values are: %d and '%s'", 5,
178 A logging request is said to be enabled if its priority is higher than or
179 equal to the threshold priority of its category. Otherwise, the request is
180 said to be disabled. A category without an assigned priority will inherit
181 one from the hierarchy.
183 It is possible to use any non-negative integer as a priority. If, as in the
184 example, one of the standard priorites is used, then there is a convenience
185 macro that is typically used instead. For example, the above example is
186 equivalent to the shorter:
188 <code>CWARN4(MyCat, "Values are: %d and '%s'", 5, "oops");</code>
190 \section log_API_subcat 2.3 Using a default category (the easy interface)
192 If \ref XBT_LOG_NEW_DEFAULT_SUBCATEGORY(MyCat, Parent) or
193 \ref XBT_LOG_NEW_DEFAULT_CATEGORY(MyCat) is used to create the
194 category, then the even shorter form can be used:
196 <code>WARN3("Values are: %d and '%s'", 5, "oops");</code>
198 Only one default category can be created per file, though multiple
199 non-defaults can be created and used.
201 \section log_API_easy 2.4 Putting all together: the easy interface
203 First of all, each module should register its own category into the categories
204 tree using \ref XBT_LOG_NEW_DEFAULT_SUBCATEGORY.
206 Then, logging should be done with the DEBUG<n>, VERB<n>, INFO<n>, WARN<n>,
207 ERROR<n> or CRITICAL<n> macro families. For each group, there is 6 different
208 macros (like DEBUG0, DEBUG1, DEBUG2, DEBUG3, DEBUG4 and DEBUG5), only differing
209 in the number of arguments passed along the format. This is because we want
210 SimGrid itself to keep compilable on ancient compiler not supporting variable
211 number of arguments to macros. But we should provide a macro simpler to use for
212 the users not interested in SP3 machines (FIXME).
214 Under GCC, these macro check there arguments the same way than printf does. So,
215 if you compile with -Wall, the folliwing code will issue a warning:
216 <code>DEBUG2("Found %s (id %f)", some_string, a_double)</code>
218 \section log_API_example 2.5 Example of use
220 Here is a more complete example:
225 / * create a category and a default subcategory * /
226 XBT_LOG_NEW_CATEGORY(VSS);
227 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(SA, VSS);
230 / * Now set the parent's priority. (the string would typcially be a runtime option) * /
231 xbt_log_control_set("SA.thresh=3");
233 / * This request is enabled, because WARNING >= INFO. * /
234 CWARN2(VSS, "Low fuel level.");
236 / * This request is disabled, because DEBUG < INFO. * /
237 CDEBUG2(VSS, "Starting search for nearest gas station.");
239 / * The default category SA inherits its priority from VSS. Thus,
240 the following request is enabled because INFO >= INFO. * /
241 INFO1("Located nearest gas station.");
243 / * This request is disabled, because DEBUG < INFO. * /
244 DEBUG1("Exiting gas station search");
249 \section log_user 3. User interface
251 \section log_use_conf 3.1 Configuration
252 Configuration is typically done during program initialization by invoking
253 the xbt_log_control_set() method. The control string passed to it typically
254 comes from the command line. Look at the documentation for that function for
255 the format of the control string.
257 Any SimGrid program can furthermore be configured at run time by passing a
258 --xbt-log argument on the command line (--gras-log, --msg-log and --surf-log
259 are synonyms provided by aestheticism). You can provide several of those
260 arguments to change the setting of several categories, they will be applied
261 from left to right. So,
262 \verbatim --xbt-log="root.thres=debug root.thres=critical"\endverbatim
263 should disable any logging.
265 Note that the quotes on above line are mandatory because there is a space in
266 the argument, so we are protecting ourselves from the shell, not from SimGrid.
267 We could also reach the same effect with this:
268 \verbatim --xbt-log=root.thres=debug --xbt-log=root.thres=critical\endverbatim
270 \section log_use_misc 3.2 Misc and Caveats
272 - Do not use any of the macros that start with '_'.
273 - Log4J has a 'rolling file appender' which you can select with a run-time
274 option and specify the max file size. This would be a nice default for
275 non-kernel applications.
276 - Careful, category names are global variables.
278 \section log_internals 4. Internal considerations
280 This module is a mess of macro black magic, and when it goes wrong, SimGrid
281 studently loose its ability to explain its problems. When messing around this
282 module, I often find useful to define XBT_LOG_MAYDAY (which turns it back to
283 good old printf) for the time of finding what's going wrong.
285 \section log_in_perf 4.1 Performance
287 Except for the first invocation of a given category, a disabled logging request
288 requires an a single comparison of a static variable to a constant.
290 There is also compile time constant, \ref XBT_LOG_STATIC_THRESHOLD, which
291 causes all logging requests with a lower priority to be optimized to 0 cost
292 by the compiler. By setting it to gras_log_priority_infinite, all logging
293 requests are statically disabled and cost nothing. Released executables
294 might be compiled with
295 \verbatim-DXBT_LOG_STATIC_THRESHOLD=gras_log_priority_infinite\endverbatim
297 Compiling with the \verbatim-DNLOG\endverbatim option disables all logging
298 requests at compilation time while the \verbatim-DNDEBUG\endverbatim disables
299 the requests of priority below INFO.
301 \todo Logging performance *may* be improved further by improving the message
302 propagation from appender to appender in the category tree.
304 \section log_in_app 4.2 Appenders
306 Each category has an optional appender. An appender is a pointer to a
307 structure which starts with a pointer to a doAppend() function. DoAppend()
308 prints a message to a log.
310 When a category is passed a message by one of the logging macros, the
311 category performs the following actions:
313 - if the category has an appender, the message is passed to the
314 appender's doAppend() function,
315 - if 'willLogToParent' is true for the category, the message is passed
316 to the category's parent.
318 By default, only the root category have an appender, and 'willLogToParent'
319 is true for any other category. This situation causes all messages to be
320 logged by the root category's appender.
322 The default appender function currently prints to stderr, and no other one
323 exist, even if more would be needed, like the one able to send the logs to a
324 remote dedicated server, or other ones offering different output formats.
325 This is on our TODO list for quite a while now, but your help would be
334 e_xbt_log_priority_t thresh;
335 } s_xbt_log_setting_t,*xbt_log_setting_t;
337 static xbt_dynar_t xbt_log_settings=NULL;
338 static void _free_setting(void *s) {
339 xbt_log_setting_t set=(xbt_log_setting_t)s;
342 /* free(set); FIXME: uncommenting this leads to segfault when more than one chunk is passed as gras-log */
346 const char *xbt_log_priority_names[8] = {
357 s_xbt_log_category_t _XBT_LOGV(XBT_LOG_ROOT_CAT) = {
359 "root", xbt_log_priority_uninitialized, 0,
363 XBT_LOG_NEW_CATEGORY(xbt,"All XBT categories (simgrid toolbox)");
364 XBT_LOG_NEW_CATEGORY(surf,"All SURF categories");
365 XBT_LOG_NEW_CATEGORY(msg,"All MSG categories");
366 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(log,xbt,"Loggings from the logging mechanism itself");
368 void xbt_log_init(int *argc,char **argv) {
372 /* Set logs and init log submodule */
373 for (i=1; i<*argc; i++) {
374 if (!strncmp(argv[i],"--gras-log=",strlen("--gras-log=")) ||
375 !strncmp(argv[i],"--surf-log=",strlen("--surf-log=")) ||
376 !strncmp(argv[i],"--msg-log=",strlen("--msg-log=")) ||
377 !strncmp(argv[i],"--xbt-log=",strlen("--xbt-log="))) {
378 opt=strchr(argv[i],'=');
380 xbt_log_control_set(opt);
381 DEBUG1("Did apply '%s' as log setting",opt);
382 /*remove this from argv*/
383 for (j=i+1; j<*argc; j++) {
388 i--; /* compensate effect of next loop incrementation */
393 void xbt_log_exit(void) {
394 VERB0("Exiting log");
395 xbt_dynar_free(&xbt_log_settings);
399 static void _apply_control(xbt_log_category_t cat) {
401 xbt_log_setting_t setting=NULL;
404 if (!xbt_log_settings)
407 xbt_assert0(cat,"NULL category");
408 xbt_assert(cat->name);
410 xbt_dynar_foreach(xbt_log_settings,cursor,setting) {
411 xbt_assert0(setting,"Damnit, NULL cat in the list");
412 xbt_assert1(setting->catname,"NULL setting(=%p)->catname",(void*)setting);
414 if (!strcmp(setting->catname,cat->name)) {
417 xbt_log_threshold_set(cat, setting->thresh);
418 xbt_dynar_cursor_rm(xbt_log_settings,&cursor);
420 if (cat->threshold <= xbt_log_priority_debug) {
421 s_xbt_log_event_t _log_ev =
422 {cat,xbt_log_priority_debug,__FILE__,_XBT_FUNCTION,__LINE__};
423 _xbt_log_event_log(&_log_ev,
424 "Apply settings for category '%s': set threshold to %s (=%d)",
426 xbt_log_priority_names[cat->threshold], cat->threshold);
430 if (!found && cat->threshold <= xbt_log_priority_verbose) {
431 s_xbt_log_event_t _log_ev =
432 {cat,xbt_log_priority_verbose,__FILE__,_XBT_FUNCTION,__LINE__};
433 _xbt_log_event_log(&_log_ev,
434 "Category '%s': inherited threshold = %s (=%d)",
436 xbt_log_priority_names[cat->threshold], cat->threshold);
441 void _xbt_log_event_log( xbt_log_event_t ev, const char *fmt, ...) {
442 xbt_log_category_t cat = ev->cat;
443 va_start(ev->ap, fmt);
445 xbt_log_appender_t appender = cat->appender;
446 if (appender != NULL) {
447 appender->do_append(appender, ev, fmt);
449 if (!cat->willLogToParent)
457 static void _cat_init(xbt_log_category_t category) {
458 if (category == &_XBT_LOGV(XBT_LOG_ROOT_CAT)) {
459 category->threshold = xbt_log_priority_info;
460 category->appender = xbt_log_default_appender;
462 xbt_log_parent_set(category, category->parent);
464 _apply_control(category);
468 * This gets called the first time a category is referenced and performs the
470 * Also resets threshold to inherited!
472 int _xbt_log_cat_init(e_xbt_log_priority_t priority,
473 xbt_log_category_t category) {
477 return priority >= category->threshold;
480 void xbt_log_parent_set(xbt_log_category_t cat,
481 xbt_log_category_t parent) {
483 xbt_assert0(cat,"NULL category to be given a parent");
484 xbt_assert1(parent,"The parent category of %s is NULL",cat->name);
486 /* unlink from current parent */
487 if (cat->threshold != xbt_log_priority_uninitialized) {
488 xbt_log_category_t* cpp = &parent->firstChild;
489 while(*cpp != cat && *cpp != NULL) {
490 cpp = &(*cpp)->nextSibling;
492 xbt_assert(*cpp == cat);
493 *cpp = cat->nextSibling;
497 cat->parent = parent;
498 cat->nextSibling = parent->firstChild;
499 parent->firstChild = cat;
501 /* Make sure parent is initialized */
502 if (parent->threshold == xbt_log_priority_uninitialized) {
507 cat->threshold = parent->threshold;
508 cat->isThreshInherited = 1;
509 } /* log_setParent */
511 static void _set_inherited_thresholds(xbt_log_category_t cat) {
512 xbt_log_category_t child = cat->firstChild;
513 for( ; child != NULL; child = child->nextSibling) {
514 if (child->isThreshInherited) {
515 if (cat != &_XBT_LOGV(log))
516 VERB3("Set category threshold of %s to %s (=%d)",
517 child->name,xbt_log_priority_names[cat->threshold],cat->threshold);
518 child->threshold = cat->threshold;
519 _set_inherited_thresholds(child);
524 void xbt_log_threshold_set(xbt_log_category_t cat,
525 e_xbt_log_priority_t threshold) {
526 cat->threshold = threshold;
527 cat->isThreshInherited = 0;
528 _set_inherited_thresholds(cat);
531 static void _xbt_log_parse_setting(const char* control_string,
532 xbt_log_setting_t set) {
533 const char *name, *dot, *eq;
536 if (!*control_string)
538 DEBUG1("Parse log setting '%s'",control_string);
540 control_string += strspn(control_string, " ");
541 name = control_string;
542 control_string += strcspn(control_string, ".= ");
543 dot = control_string;
544 control_string += strcspn(control_string, "= ");
546 control_string += strcspn(control_string, " ");
548 xbt_assert1(*dot == '.' && *eq == '=',
549 "Invalid control string '%s'",control_string);
551 if (!strncmp(dot + 1, "thresh", min((size_t)(eq - dot - 1),strlen("thresh")))) {
553 char *neweq=xbt_strdup(eq+1);
556 while (*(++p) != '\0') {
557 if (*p >= 'a' && *p <= 'z') {
562 DEBUG1("New priority name = %s",neweq);
563 for (i=0; i<xbt_log_priority_infinite-1; i++) {
564 if (!strncmp(xbt_log_priority_names[i],neweq,p-eq)) {
565 DEBUG1("This is priority %d",i);
569 if (i<xbt_log_priority_infinite-1) {
570 set->thresh= (e_xbt_log_priority_t) i;
572 xbt_assert1(FALSE,"Unknown priority name: %s",eq+1);
577 snprintf(buff,min(512,eq - dot - 1),"%s",dot+1);
578 xbt_assert1(FALSE,"Unknown setting of the log category: %s",buff);
580 set->catname=(char*)xbt_malloc(dot - name+1);
582 strncpy(set->catname,name,dot-name);
583 set->catname[dot-name]='\0'; /* Just in case */
584 DEBUG1("This is for cat '%s'", set->catname);
587 static xbt_log_category_t _xbt_log_cat_searchsub(xbt_log_category_t cat,char *name) {
588 xbt_log_category_t child;
590 if (!strcmp(cat->name,name)) {
593 for(child=cat->firstChild ; child != NULL; child = child->nextSibling) {
594 return _xbt_log_cat_searchsub(child,name);
596 THROW0(not_found_error,0,"No such category");
599 static void _cleanup_double_spaces(char *s) {
622 if (e ^ !isspace(*p))
633 * \param control_string What to parse
635 * Typically passed a command-line argument. The string has the syntax:
637 * ( [category] "." [keyword] "=" value (" ")... )...
639 * where [category] is one the category names (see \ref XBT_log_cats for a complete list)
640 * and keyword is one of the following:
642 * - thres: category's threshold priority. Possible values:
643 * TRACE,DEBUG,VERBOSE,INFO,WARNING,ERROR,CRITICAL
647 * This routine may only be called once and that must be before any other
648 * logging command! Typically, this is done from main().
649 * \todo the previous warning seems a bit old and need double checking
651 void xbt_log_control_set(const char* control_string) {
652 xbt_log_setting_t set;
657 DEBUG1("Parse log settings '%s'",control_string);
658 if (control_string == NULL)
660 if (xbt_log_settings == NULL)
661 xbt_log_settings = xbt_dynar_new(sizeof(xbt_log_setting_t),
664 set = xbt_new(s_xbt_log_setting_t,1);
665 cs=xbt_strdup(control_string);
667 _cleanup_double_spaces(cs);
670 xbt_log_category_t cat=NULL;
682 _xbt_log_parse_setting(p,set);
685 cat = _xbt_log_cat_searchsub(&_XBT_LOGV(root),set->catname);
688 if (e.category != not_found_error)
693 DEBUG0("Store for further application");
694 DEBUG1("push %p to the settings",(void*)set);
695 xbt_dynar_push(xbt_log_settings,&set);
696 /* malloc in advance the next slot */
697 set = xbt_new(s_xbt_log_setting_t,1);
701 DEBUG0("Apply directly");
703 xbt_log_threshold_set(cat,set->thresh);
710 void xbt_log_appender_set(xbt_log_category_t cat, xbt_log_appender_t app) {