X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/9f0e00fec83a9a1f7053f504e48173afb146331e..0f04e364d7fbc468666a577249d3520794930d1b:/include/xbt/ex.h diff --git a/include/xbt/ex.h b/include/xbt/ex.h index 11a9cd858b..5ae667dfb3 100644 --- a/include/xbt/ex.h +++ b/include/xbt/ex.h @@ -1,5 +1,6 @@ /* -** OSSP ex - Exception Handling +** OSSP ex - Exception Handling (modified to fit into SimGrid) +** Copyright (c) 2005 Martin Quinson. ** Copyright (c) 2002-2004 Ralf S. Engelschall ** Copyright (c) 2002-2004 The OSSP Project ** Copyright (c) 2002-2004 Cable & Wireless @@ -28,31 +29,15 @@ ** ex.h: exception handling (pre-processor part) */ -#ifndef __EX_H__ -#define __EX_H__ +#ifndef __XBT_EX_H__ +#define __XBT_EX_H__ + +#include +#include /* required ISO-C standard facilities */ #include -/* convenience define */ -#ifndef NULL -#define NULL (void *)0 -#endif - -/* determine how the current function name can be fetched */ -#if ( defined(__STDC__) \ - && defined(__STDC_VERSION__) \ - && __STDC_VERSION__ >= 199901L) -#define __EX_FUNC__ __func__ /* ISO-C99 compliant */ -#elif ( defined(__GNUC__) \ - && defined(__GNUC_MINOR__) \ - && ( __GNUC__ > 2 \ - || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8))) -#define __EX_FUNC__ __FUNCTION__ /* gcc >= 2.8 */ -#else -#define __EX_FUNC__ "#NA#" /* not available */ -#endif - /* the machine context */ #if defined(__EX_MCTX_MCSC__) #include /* POSIX.1 ucontext(3) */ @@ -78,17 +63,180 @@ /* declare the machine context type */ typedef struct { __ex_mctx_struct } __ex_mctx_t; +/** @addtogroup XBT_ex + * + * This module is a small ISO-C++ style exception handling library + * for use in the ISO-C language. It allows you to use the paradigm + * of throwing and catching exceptions in order to reduce the amount + * of error handling code without hindering program robustness. + * + * This is achieved by directly transferring exceptional return codes + * (and the program control flow) from the location where the exception + * is raised (throw point) to the location where it is handled (catch + * point) -- usually from a deeply nested sub-routine to a parent + * routine. All intermediate routines no longer have to make sure that + * the exceptional return codes from sub-routines are correctly passed + * back to the parent. + * + * These features are brought to you by a modified version of the libex + * library, one of the numerous masterpiece of Ralf S. Engelschall. + * + * @section XBT_ex_intro DESCRIPTION + * + * In SimGrid, exceptions is a triple <\a msg , \a category , \a value> + * where \a msg is a human-readable text describing the exceptional + * condition, \a code an integer describing what went wrong and \a value + * providing a sort of sub-category. (this is different in the original libex). + * + * @section XBT_ex_base BASIC USAGE + * + * \em xbt_try \b TRIED_BLOCK [\em xbt_cleanup \b CLEANUP_BLOCK] \em xbt_catch (variable) \b CATCH_BLOCK + * + * This is the primary syntactical construct provided. It is modeled after the + * ISO-C++ try-catch clause and should sound familiar to most of you. + * + * Any exception thrown directly from the TRIED_BLOCK block or from called + * subroutines is caught. Cleanups which must be done after this block + * (whenever an exception arised or not) should be placed into the optionnal + * CLEANUP_BLOCK. The code dealing with the exceptions when they arise should + * be placed into the (mandatory) CATCH_BLOCK. + * + * + * In absence of exception, the control flow goes into the blocks TRIED_BLOCK + * and CLEANUP_BLOCK (if present); The CATCH_BLOCK block is then ignored. + * + * When an exception is thrown, the control flow goes through the following + * blocks: TRIED_BLOCK (up to the statement throwing the exception), + * CLEANUP_BLOCK (if any) and CATCH_BLOCK. The exception is stored in a + * variable for inspection inside the CATCH_BLOCK. This variable must be + * declared in the outter scope, but its value is only valid within the + * CATCH_BLOCK block. + * + * Some notes: + * - xbt_try, xbt_cleanup and xbt_catch cannot be used separately, they work + * only in combination and form a language clause as a whole. + * - In contrast to the syntax of other languages (such as C++ or Jave) there + * is only one xbt_catch block and not multiple ones (all exceptions are + * of the same C type xbt_t). + * - the variable of xbt_catch can naturally be reused in subsequent + * xbt_catch clauses. + * - it is possible to nest xbt_try clauses. + * + * The xbt_try block is a regular ISO-C language statement block, but it is not + * allowed to jump into it via "goto" or longjmp(3) or out of it via "break", + * "return", "goto" or longjmp(3) because there is some hidden setup and + * cleanup that needs to be done regardless of whether an exception is + * caught. Bypassing these steps will break the exception handling facility. + * + * The xbt_cleanup and xbt_catch blocks are regular ISO-C language statement + * blocks without any restrictions. You are even allowed to throw (and in the + * xbt_catch block to re-throw) exceptions. + * + * There is one subtle detail you should remember about xbt_try blocks: + * Variables used in the xbt_cleanup or xbt_catch clauses must be declared with + * the storage class "volatile", otherwise they might contain outdated + * information if an exception it thrown. + * + * + * This is because you usually do not know which commands in the xbt_try + * were already successful before the exception was thrown (logically speaking) + * and because the underlying ISO-C setjmp(3) facility applies those + * restrictions (technically speaking). As a matter of fact, value changes + * between the xbt_try and the xbt_throw may be discarded if you forget the + * "volatile" keyword. + * + * @section XBT_ex_advanced ADVANCED USAGE + * + * @subsection xbt_defer DEFERING_BLOCK XBT_ex_defer + * + * This directive executes DEFERING_BLOCK while deferring the throwing of + * exceptions, i.e., exceptions thrown within this block are remembered, but + * the control flow still continues until the end of the block. At its end, the + * first exception which occured within the block (if any) is rethrown (any + * subsequent exceptions are ignored). + * + * DEFERING_BLOCK is a regular ISO-C language statement block, but it is not + * allowed to jump into it via "goto" or longjmp(3) or out of it via "break", + * "return", "goto" or longjmp(3). It is however allowed to nest xbt_defer + * clauses. + * + * @subsection XBT_ex_shield xbt_shield SHIELDED_BLOCK + * + * This directive executes SHIELDED_BLOCK while shielding it against the + * throwing of exceptions, i.e., any exception thrown from this block or its + * subroutines are silently ignored. + * + * SHIELDED_BLOCK is a regular ISO-C language statement block, but it is not + * allowed to jump into it via "goto" or longjmp(3) or out of it via "break", + * "return", "goto" or longjmp(3). It is however allowed to nest xbt_shield + * clauses. + * + * @subsection XBT_ex_conditions Retrieving the current execution condition + * + * \a xbt_catching, \a xbt_deferred and \a xbt_shielding return a boolean + * indicating whether the current scope is within a TRYIED_BLOCK, + * DEFERING_BLOCK and SHIELDED_BLOCK (respectively) + * + * \section XBT_ex_pitfalls PROGRAMMING PITFALLS + * + * Exception handling is a very elegant and efficient way of dealing with + * exceptional situation. Nevertheless it requires additional discipline in + * programming and there are a few pitfalls one must be aware of. Look the + * following code which shows some pitfalls and contains many errors (assuming + * a mallocex() function which throws an exception if malloc(3) fails): + * + * \dontinclude ex_test.c + * \skip BAD_EXAMPLE + * \until end_of_bad_example + * + * This example raises a few issues: + * -# \b variable \b scope \n + * Variables which are used in the xbt_cleanup or xbt_catch clauses must be + * declared before the xbt_try clause, otherwise they only exist inside the + * xbt_try block. In the example above, cp1, cp2 and cp3 only exist in the + * xbt_try block and are invisible from the xbt_cleanup and xbt_catch + * blocks. + * -# \b variable \b initialization \n + * Variables which are used in the xbt_cleanup or xbt_catch clauses must + * be initialized before the point of the first possible xbt_throw is + * reached. In the example above, xbt_cleanup would have trouble using cp3 + * if mallocex() throws a exception when allocating a TOOBIG buffer. + * -# \b volatile \b variable \n + * Variables which are used in the xbt_cleanup or xbt_catch clauses MUST BE + * DECLARED AS "volatile", otherwise they might contain outdated + * information when an exception is thrown. + * -# \b clean \b before \b catch \n + * The xbt_cleanup clause is not only place before the xbt_catch clause in + * the source code, it also occures before in the control flow. So, + * resources being cleaned up cannot be used in the xbt_catch block. In the + * example, c3 gets freed before the printf placed in xbt_catch. + * -# \b variable \b uninitialization \n + * If resources are passed out of the scope of the + * xbt_try/xbt_cleanup/xbt_catch construct, they naturally shouldn't get + * cleaned up. The example above does free(3) cp1 in xbt_cleanup although + * its value was affected to globalcontext->first, invalidating this + * pointer. + + * The following is fixed version of the code (annotated with the pitfall items + * for reference): + * + * \skip GOOD_EXAMPLE + * \until end_of_good_example + * + * @{ + */ -/* declare the exception type (public) */ +/** @brief Structure describing an exception */ typedef struct { - /* throw value */ - void *ex_class; - void *ex_object; - void *ex_value; - /* throw point */ - const char *ex_file; - int ex_line; - const char *ex_func; + char *msg; /**< human readable message; to be freed */ + int category; /**< category like HTTP (what went wrong) */ + int value; /**< like errno (why did it went wrong) */ + /* throw point */ + char *host; /* NULL for localhost; hostname:port if remote */ + char *procname; + char *file; /**< to be freed only for remote exceptions */ + int line; + char *func; /**< to be freed only for remote exceptions */ } ex_t; /* declare the context type (private) */ @@ -104,148 +252,190 @@ typedef struct { } ex_ctx_t; /* the static and dynamic initializers for a context structure */ -#define EX_CTX_INITIALIZER \ - { NULL, 0, 0, 0, 0, 0, 0, { NULL, NULL, NULL, NULL, 0, NULL } } -#define EX_CTX_INITIALIZE(ctx) \ +#define XBT_CTX_INITIALIZER \ + { NULL, 0, 0, 0, 0, 0, 0, { /* content */ NULL, 0, 0, \ + /*throw point*/ NULL, NULL, NULL, 0, NULL } } +#define XBT_CTX_INITIALIZE(ctx) \ do { \ - (ctx)->ctx_mctx = NULL; \ - (ctx)->ctx_deferred = 0; \ - (ctx)->ctx_deferring = 0; \ - (ctx)->ctx_defer = 0; \ - (ctx)->ctx_shielding = 0; \ - (ctx)->ctx_shield = 0; \ - (ctx)->ctx_caught = 0; \ - (ctx)->ctx_ex.ex_class = NULL; \ - (ctx)->ctx_ex.ex_object = NULL; \ - (ctx)->ctx_ex.ex_value = NULL; \ - (ctx)->ctx_ex.ex_file = NULL; \ - (ctx)->ctx_ex.ex_line = 0; \ - (ctx)->ctx_ex.ex_func = NULL; \ + (ctx)->ctx_mctx = NULL; \ + (ctx)->ctx_deferred = 0; \ + (ctx)->ctx_deferring = 0; \ + (ctx)->ctx_defer = 0; \ + (ctx)->ctx_shielding = 0; \ + (ctx)->ctx_shield = 0; \ + (ctx)->ctx_caught = 0; \ + (ctx)->ctx_ex.msg = NULL; \ + (ctx)->ctx_ex.category = 0; \ + (ctx)->ctx_ex.value = 0; \ + (ctx)->ctx_ex.host = NULL; \ + (ctx)->ctx_ex.procname = NULL; \ + (ctx)->ctx_ex.file = NULL; \ + (ctx)->ctx_ex.line = 0; \ + (ctx)->ctx_ex.func = NULL; \ } while (0) /* the exception context */ typedef ex_ctx_t *(*ex_ctx_cb_t)(void); -extern ex_ctx_cb_t __ex_ctx; -extern ex_ctx_t *__ex_ctx_default(void); +extern ex_ctx_cb_t __xbt_ex_ctx; +extern ex_ctx_t *__xbt_ex_ctx_default(void); /* the termination handler */ typedef void (*ex_term_cb_t)(ex_t *); -extern ex_term_cb_t __ex_terminate; -extern void __ex_terminate_default(ex_t *e); +extern ex_term_cb_t __xbt_ex_terminate; +extern void __xbt_ex_terminate_default(ex_t *e); -/* the block for trying execution */ -#define ex_try \ +/** @brief Introduce a block where exception may be dealed with + * @hideinitializer + */ +#define xbt_try \ { \ - ex_ctx_t *__ex_ctx_ptr = __ex_ctx(); \ + ex_ctx_t *__xbt_ex_ctx_ptr = __xbt_ex_ctx(); \ int __ex_cleanup = 0; \ __ex_mctx_t *__ex_mctx_en; \ __ex_mctx_t __ex_mctx_me; \ - __ex_mctx_en = __ex_ctx_ptr->ctx_mctx; \ - __ex_ctx_ptr->ctx_mctx = &__ex_mctx_me; \ + __ex_mctx_en = __xbt_ex_ctx_ptr->ctx_mctx; \ + __xbt_ex_ctx_ptr->ctx_mctx = &__ex_mctx_me; \ if (__ex_mctx_save(&__ex_mctx_me)) { \ if (1) -/* the optional(!) block for cleanup */ -#define ex_cleanup \ +/** @brief optional(!) block for cleanup + * @hideinitializer + */ +#define xbt_cleanup \ else { \ } \ - __ex_ctx_ptr->ctx_caught = 0; \ + __xbt_ex_ctx_ptr->ctx_caught = 0; \ } \ else { \ __ex_mctx_restored(&__ex_mctx_me); \ - __ex_ctx_ptr->ctx_caught = 1; \ + __xbt_ex_ctx_ptr->ctx_caught = 1; \ } \ - __ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \ + __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \ __ex_cleanup = 1; \ if (1) { \ if (1) -/* the block for catching an exception */ -#define ex_catch(e) \ +/** @brief the block for catching (ie, deal with) an exception + * @hideinitializer + */ +#define xbt_catch(e) \ else { \ } \ if (!(__ex_cleanup)) \ - __ex_ctx_ptr->ctx_caught = 0; \ + __xbt_ex_ctx_ptr->ctx_caught = 0; \ } \ else { \ if (!(__ex_cleanup)) { \ __ex_mctx_restored(&__ex_mctx_me); \ - __ex_ctx_ptr->ctx_caught = 1; \ + __xbt_ex_ctx_ptr->ctx_caught = 1; \ } \ } \ - __ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \ + __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \ } \ - if ( !(__ex_ctx()->ctx_caught) \ - || ((e) = __ex_ctx()->ctx_ex, 0)) { \ + if ( !(__xbt_ex_ctx()->ctx_caught) \ + || ((e) = __xbt_ex_ctx()->ctx_ex, 0)) { \ } \ else -/* the throwing of a new exception */ -#define ex_throw(c,o,v) \ - (( __ex_ctx()->ctx_shielding > 0 \ - || (__ex_ctx()->ctx_deferring > 0 && __ex_ctx()->ctx_deferred == 1)) ? 0 : \ - (__ex_ctx()->ctx_ex.ex_class = (void *)(c), \ - __ex_ctx()->ctx_ex.ex_object = (void *)(o), \ - __ex_ctx()->ctx_ex.ex_value = (void *)(v), \ - __ex_ctx()->ctx_ex.ex_file = __FILE__, \ - __ex_ctx()->ctx_ex.ex_line = __LINE__, \ - __ex_ctx()->ctx_ex.ex_func = __EX_FUNC__, \ - __ex_ctx()->ctx_deferred = 1, \ - (__ex_ctx()->ctx_deferring > 0 ? 0 : \ - (__ex_ctx()->ctx_mctx == NULL \ - ? (__ex_terminate((ex_t *)&(__ex_ctx()->ctx_ex)), -1) \ - : (__ex_mctx_restore(__ex_ctx()->ctx_mctx), 1) )))) - -/* the re-throwing of an already caught exception */ -#define ex_rethrow \ - (( __ex_ctx()->ctx_shielding > 0 \ - || __ex_ctx()->ctx_deferring > 0) ? 0 : \ - ( __ex_ctx()->ctx_mctx == NULL \ - ? (__ex_terminate((ex_t *)&(__ex_ctx()->ctx_ex)), -1) \ - : (__ex_mctx_restore(__ex_ctx()->ctx_mctx), 1) )) - -/* shield an operation from exception handling */ -#define ex_shield \ - for (__ex_ctx()->ctx_shielding++, \ - __ex_ctx()->ctx_shield = 1; \ - __ex_ctx()->ctx_shield == 1; \ - __ex_ctx()->ctx_shield = 0, \ - __ex_ctx()->ctx_shielding--) - -/* defer immediate exception handling */ -#define ex_defer \ - for (((__ex_ctx()->ctx_deferring)++ == 0 ? __ex_ctx()->ctx_deferred = 0 : 0), \ - __ex_ctx()->ctx_defer = 1; \ - __ex_ctx()->ctx_defer == 1; \ - __ex_ctx()->ctx_defer = 0, \ - ((--(__ex_ctx()->ctx_deferring) == 0 && __ex_ctx()->ctx_deferred == 1) ? ex_rethrow : 0)) - -/* exception handling tests */ -#define ex_catching \ - (__ex_ctx()->ctx_mctx != NULL) -#define ex_shielding \ - (__ex_ctx()->ctx_shielding > 0) -#define ex_deferring \ - (__ex_ctx()->ctx_deferring > 0) +/** @brief Build an exception from the supplied arguments and throws it + * @hideinitializer + * + * @param c: category code (integer) + * @param v: value (integer) + * @param m: message text + * + * If called from within a sg_try/sg_catch construct, this exception + * is copied into the sg_catch relevant variable program control flow + * is derouted to the sg_catch (after the optional sg_cleanup). + * + * If no sg_try/sg_catch conctruct embeeds this call, the program calls + * abort(3). + * + * The sg_throw can be performed everywhere, including inside sg_try, + * sg_cleanup and sg_catch blocks. + */ +#define xbt_throw(c,v,m) \ + (( __xbt_ex_ctx()->ctx_shielding > 0 \ + || (__xbt_ex_ctx()->ctx_deferring > 0 && __xbt_ex_ctx()->ctx_deferred == 1)) ? 0 : \ + (__xbt_ex_ctx()->ctx_ex.msg = bprintf(m), \ + __xbt_ex_ctx()->ctx_ex.category = (c), \ + __xbt_ex_ctx()->ctx_ex.value = (v), \ + __xbt_ex_ctx()->ctx_ex.host = (char*)NULL, \ + __xbt_ex_ctx()->ctx_ex.procname = strdup(xbt_procname()), \ + __xbt_ex_ctx()->ctx_ex.file = (char*)__FILE__, \ + __xbt_ex_ctx()->ctx_ex.line = __LINE__, \ + __xbt_ex_ctx()->ctx_ex.func = (char*)_XBT_FUNCTION, \ + __xbt_ex_ctx()->ctx_deferred = 1, \ + (__xbt_ex_ctx()->ctx_deferring > 0 ? 0 : \ + (__xbt_ex_ctx()->ctx_mctx == NULL \ + ? (__xbt_ex_terminate((ex_t *)&(__xbt_ex_ctx()->ctx_ex)), -1) \ + : (__ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx), 1) )))) + +/** @brief re-throwing of an already caught exception (ie, pass it to the upper catch block) + * @hideinitializer + */ +#define xbt_rethrow \ + (( __xbt_ex_ctx()->ctx_shielding > 0 \ + || __xbt_ex_ctx()->ctx_deferring > 0) ? 0 : \ + ( __xbt_ex_ctx()->ctx_mctx == NULL \ + ? (__xbt_ex_terminate((ex_t *)&(__xbt_ex_ctx()->ctx_ex)), -1) \ + : (__ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx), 1) )) + +/** @brief shield an operation from exception handling + * @hideinitializer + */ +#define xbt_shield \ + for (__xbt_ex_ctx()->ctx_shielding++, \ + __xbt_ex_ctx()->ctx_shield = 1; \ + __xbt_ex_ctx()->ctx_shield == 1; \ + __xbt_ex_ctx()->ctx_shield = 0, \ + __xbt_ex_ctx()->ctx_shielding--) + +/** @brief defer immediate exception handling + * @hideinitializer + */ +#define xbt_defer \ + for (((__xbt_ex_ctx()->ctx_deferring)++ == 0 ? __xbt_ex_ctx()->ctx_deferred = 0 : 0), \ + __xbt_ex_ctx()->ctx_defer = 1; \ + __xbt_ex_ctx()->ctx_defer == 1; \ + __xbt_ex_ctx()->ctx_defer = 0, \ + ((--(__xbt_ex_ctx()->ctx_deferring) == 0 && __xbt_ex_ctx()->ctx_deferred == 1) ? xbt_rethrow : 0)) + +/** @brief exception handling tests + * @hideinitializer + */ +#define xbt_catching \ + (__xbt_ex_ctx()->ctx_mctx != NULL) +/** @brief exception handling tests + * @hideinitializer + */ +#define xbt_shielding \ + (__xbt_ex_ctx()->ctx_shielding > 0) +/** @brief exception handling tests + * @hideinitializer + */ +#define xbt_deferring \ + (__xbt_ex_ctx()->ctx_deferring > 0) /* optional namespace mapping */ #if defined(__EX_NS_UCCXX__) -#define Try ex_try -#define Cleanup ex_cleanup -#define Catch ex_catch -#define Throw ex_throw -#define Rethrow ex_rethrow -#define Shield ex_shield -#define Defer ex_defer +#define Try xbt_try +#define Cleanup xbt_cleanup +#define Catch xbt_catch +#define Throw xbt_throw +#define Rethrow xbt_rethrow +#define Shield xbt_shield +#define Defer xbt_defer #elif defined(__EX_NS_CXX__) || (!defined(__cplusplus) && !defined(__EX_NS_CUSTOM__)) -#define try ex_try -#define cleanup ex_cleanup -#define catch ex_catch -#define throw ex_throw -#define rethrow ex_rethrow -#define shield ex_shield -#define defer ex_defer +#define try xbt_try +#define cleanup xbt_cleanup +#define catch xbt_catch +#define throw xbt_throw +#define rethrow xbt_rethrow +#define shield xbt_shield +#define defer xbt_defer #endif -#endif /* __EX_H__ */ - +/** @} */ +#endif /* __XBT_EX_H__ */ +