** ex.h: exception handling (pre-processor part)
*/
-#ifndef __SG_EX_H__
-#define __SG_EX_H__
+#ifndef __XBT_EX_H__
+#define __XBT_EX_H__
#include <xbt/misc.h>
#include <xbt/sysdep.h>
/* required ISO-C standard facilities */
+#include <errno.h>
#include <stdio.h>
+//#define __EX_MCTX_MCSC__ 1
+#define __EX_MCTX_SSJLJ__ 1
/* the machine context */
#if defined(__EX_MCTX_MCSC__)
#include <ucontext.h> /* POSIX.1 ucontext(3) */
/* 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 TRY \b TRIED_BLOCK [\em CLEANUP \b CLEANUP_BLOCK] \em 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:
+ * - TRY, CLEANUP and 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 CATCH block and not multiple ones (all exceptions are
+ * of the same \em xbt_ex_t C type).
+ * - the variable of CATCH can naturally be reused in subsequent
+ * CATCH clauses.
+ * - it is possible to nest TRY clauses.
+ *
+ * The 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 CLEANUP and CATCH blocks are regular ISO-C language statement
+ * blocks without any restrictions. You are even allowed to throw (and, in the
+ * CATCH block, to re-throw) exceptions.
+ *
+ * There is one subtle detail you should remember about TRY blocks:
+ * Variables used in the CLEANUP or 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 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 TRY and the THROW may be discarded if you forget the
+ * "volatile" keyword.
+ *
+ * \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 CLEANUP or CATCH clauses must be
+ * declared before the TRY clause, otherwise they only exist inside the
+ * TRY block. In the example above, cp1, cp2 and cp3 only exist in the
+ * TRY block and are invisible from the CLEANUP and CATCH
+ * blocks.
+ * -# \b variable \b initialization \n
+ * Variables which are used in the CLEANUP or CATCH clauses must
+ * be initialized before the point of the first possible THROW is
+ * reached. In the example above, 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 CLEANUP or 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 CLEANUP clause is not only place before the CATCH clause in
+ * the source code, it also occures before in the control flow. So,
+ * resources being cleaned up cannot be used in the CATCH block. In the
+ * example, c3 gets freed before the printf placed in CATCH.
+ * -# \b variable \b uninitialization \n
+ * If resources are passed out of the scope of the
+ * TRY/CLEANUP/CATCH construct, they naturally shouldn't get
+ * cleaned up. The example above does free(3) cp1 in 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
+ *
+ * @{
+ */
+
+typedef enum {
+ unknown_error=0, /**< unknown error */
+ arg_error, /**< Invalid argument */
+ mismatch_error, /**< The provided ID does not match */
+ not_found_error, /**< The searched element was not found */
+
+ system_error, /**< a syscall did fail */
+ network_error, /**< error while sending/receiving data */
+ timeout_error, /**< not quick enough, dude */
+ thread_error /**< error while [un]locking */
+} xbt_errcat_t;
+
+const char *xbt_errcat_name(xbt_errcat_t errcode);
-/** Content of an exception */
+/** @brief Structure describing an exception */
typedef struct {
- char *msg; /*< human readable message; to be freed */
- int code; /*< category like HTTP (what went wrong) */
- int value; /*< like errno (why did it went wrong) */
+ char *msg; /**< human readable message; to be freed */
+ xbt_errcat_t 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 *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;
+ char *file; /**< to be freed only for remote exceptions */
+ int line;
+ char *func; /**< to be freed only for remote exceptions */
+ /* Backtrace */
+ void *bt[10];
+ int used;
+} xbt_ex_t;
/* declare the context type (private) */
typedef struct {
__ex_mctx_t *ctx_mctx; /* permanent machine context of enclosing try/catch */
- int ctx_deferred; /* permanent flag whether exception is deferred */
- int ctx_deferring;/* permanent counter of exception deferring level */
- int ctx_defer; /* temporary flag for exception deferring macro */
- int ctx_shielding;/* permanent counter of exception shielding level */
- int ctx_shield; /* temporary flag for exception shielding macro */
int ctx_caught; /* temporary flag whether exception was caught */
- volatile ex_t ctx_ex; /* temporary exception storage */
+ volatile xbt_ex_t ctx_ex; /* temporary exception storage */
} ex_ctx_t;
/* the static and dynamic initializers for a context structure */
-#define SG_CTX_INITIALIZER \
- { NULL, 0, 0, 0, 0, 0, 0, { /* content */ NULL, 0, 0, \
- /*throw point*/ NULL, NULL, NULL, 0, NULL } }
-#define SG_CTX_INITIALIZE(ctx) \
+#define XBT_CTX_INITIALIZER \
+ { NULL, 0, { /* content */ NULL, 0, 0, \
+ /* throw point*/ NULL, NULL, NULL, 0, NULL,\
+ /* backtrace */ {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL},0 } }
+#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.msg = NULL; \
- (ctx)->ctx_ex.code = 0; \
+ (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; \
+ (ctx)->ctx_ex.bt[0] = NULL; \
+ (ctx)->ctx_ex.bt[1] = NULL; \
+ (ctx)->ctx_ex.bt[2] = NULL; \
+ (ctx)->ctx_ex.bt[3] = NULL; \
+ (ctx)->ctx_ex.bt[4] = NULL; \
+ (ctx)->ctx_ex.bt[5] = NULL; \
+ (ctx)->ctx_ex.bt[6] = NULL; \
+ (ctx)->ctx_ex.bt[7] = NULL; \
+ (ctx)->ctx_ex.bt[8] = NULL; \
+ (ctx)->ctx_ex.bt[9] = NULL; \
+ (ctx)->ctx_ex.used = 0; \
} while (0)
/* the exception context */
extern ex_ctx_t *__xbt_ex_ctx_default(void);
/* the termination handler */
-typedef void (*ex_term_cb_t)(ex_t *);
+typedef void (*ex_term_cb_t)(xbt_ex_t *);
extern ex_term_cb_t __xbt_ex_terminate;
-extern void __xbt_ex_terminate_default(ex_t *e);
+extern void __xbt_ex_terminate_default(xbt_ex_t *e) __attribute__((__noreturn__));
-/* the block for trying execution */
-#define sg_try \
+/** @brief Introduce a block where exception may be dealed with
+ * @hideinitializer
+ */
+#define TRY \
{ \
ex_ctx_t *__xbt_ex_ctx_ptr = __xbt_ex_ctx(); \
int __ex_cleanup = 0; \
if (__ex_mctx_save(&__ex_mctx_me)) { \
if (1)
-/* the optional(!) block for cleanup */
-#define sg_cleanup \
+/** @brief optional(!) block for cleanup
+ * @hideinitializer
+ */
+#define CLEANUP \
else { \
} \
__xbt_ex_ctx_ptr->ctx_caught = 0; \
- } \
- else { \
+ } else { \
__ex_mctx_restored(&__ex_mctx_me); \
__xbt_ex_ctx_ptr->ctx_caught = 1; \
} \
if (1) { \
if (1)
-/* the block for catching an exception */
-#define sg_catch(e) \
+/** @brief the block for catching (ie, deal with) an exception
+ * @hideinitializer
+ */
+#define CATCH(e) \
else { \
} \
if (!(__ex_cleanup)) \
__xbt_ex_ctx_ptr->ctx_caught = 0; \
- } \
- else { \
+ } else { \
if (!(__ex_cleanup)) { \
__ex_mctx_restored(&__ex_mctx_me); \
__xbt_ex_ctx_ptr->ctx_caught = 1; \
} \
else
-/* the throwing of a new exception */
-#define sg_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.code = (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) ))))
-
-/* the re-throwing of an already caught exception */
-#define sg_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) ))
-
-/* shield an operation from exception handling */
-#define sg_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--)
-
-/* defer immediate exception handling */
-#define sg_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) ? sg_rethrow : 0))
-
-/* exception handling tests */
-#define sg_catching \
- (__xbt_ex_ctx()->ctx_mctx != NULL)
-#define sg_shielding \
- (__xbt_ex_ctx()->ctx_shielding > 0)
-#define sg_deferring \
- (__xbt_ex_ctx()->ctx_deferring > 0)
-
-/* optional namespace mapping */
-#if defined(__EX_NS_UCCXX__)
-#define Try sg_try
-#define Cleanup sg_cleanup
-#define Catch sg_catch
-#define Throw sg_throw
-#define Rethrow sg_rethrow
-#define Shield sg_shield
-#define Defer sg_defer
-#elif defined(__EX_NS_CXX__) || (!defined(__cplusplus) && !defined(__EX_NS_CUSTOM__))
-#define try sg_try
-#define cleanup sg_cleanup
-#define catch sg_catch
-#define throw sg_throw
-#define rethrow sg_rethrow
-#define shield sg_shield
-#define defer sg_defer
-#endif
+/** @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 TRY/CATCH construct, this exception
+ * is copied into the CATCH relevant variable program control flow
+ * is derouted to the CATCH (after the optional sg_cleanup).
+ *
+ * If no TRY/CATCH construct embeeds this call, the program calls
+ * abort(3).
+ *
+ * The THROW can be performed everywhere, including inside TRY,
+ * CLEANUP and CATCH blocks.
+ */
+#include <execinfo.h>
+#define _THROW(c,v,m) \
+ do { /* change this sequence into one block */ \
+ /* build the exception */ \
+ __xbt_ex_ctx()->ctx_ex.msg = (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_ex.used = backtrace((void**)__xbt_ex_ctx()->ctx_ex.bt,10);\
+ /* deal with the exception */ \
+ if (__xbt_ex_ctx()->ctx_mctx == NULL) \
+ __xbt_ex_terminate((xbt_ex_t *)&(__xbt_ex_ctx()->ctx_ex)); /* not catched */\
+ else \
+ __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); /* catched somewhere */ \
+ abort();/* nope, stupid GCC, we won't survive a THROW (this won't be reached) */ \
+ } while (0)
+
+#define THROW0(c,v,m) _THROW(c,v,bprintf(m))
+#define THROW1(c,v,m,a1) _THROW(c,v,bprintf(m,a1))
+#define THROW2(c,v,m,a1,a2) _THROW(c,v,bprintf(m,a1,a2))
+#define THROW3(c,v,m,a1,a2,a3) _THROW(c,v,bprintf(m,a1,a2,a3))
+#define THROW4(c,v,m,a1,a2,a3,a4) _THROW(c,v,bprintf(m,a1,a2,a3,a4))
+#define THROW5(c,v,m,a1,a2,a3,a4,a5) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5))
+#define THROW6(c,v,m,a1,a2,a3,a4,a5,a6) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5,a6))
+
+#define THROW_IMPOSSIBLE THROW0(unknown_error,0,"The Impossible Did Happen (yet again)")
+#define DIE_IMPOSSIBLE xbt_assert0(0,"The Impossible Did Happen (yet again)")
+#define THROW_UNIMPLEMENTED THROW1(unknown_error,0,"Function %s unimplemented",__FUNCTION__)
+
+/** @brief re-throwing of an already caught exception (ie, pass it to the upper catch block)
+ * @hideinitializer
+ */
+#define RETHROW \
+ do { \
+ if (__xbt_ex_ctx()->ctx_mctx == NULL) \
+ __xbt_ex_terminate((xbt_ex_t *)&(__xbt_ex_ctx()->ctx_ex)); \
+ else \
+ __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); \
+ abort();\
+ } while(0)
+
+/** @brief like RETHROW, but adding some details to the message
+ * @hideinitializer
+ */
+
+
+#define _XBT_PRE_RETHROW \
+ do { \
+ char *_xbt_ex_internal_msg = __xbt_ex_ctx()->ctx_ex.msg; \
+ __xbt_ex_ctx()->ctx_ex.msg = bprintf(
+#define _XBT_POST_RETHROW \
+ _xbt_ex_internal_msg); \
+ free(_xbt_ex_internal_msg); \
+ RETHROW; \
+ } while (0)
+
+#define RETHROW0(msg) _XBT_PRE_RETHROW msg, _XBT_POST_RETHROW
+#define RETHROW1(msg,a) _XBT_PRE_RETHROW msg,a, _XBT_POST_RETHROW
+#define RETHROW2(msg,a,b) _XBT_PRE_RETHROW msg,a,b, _XBT_POST_RETHROW
+#define RETHROW3(msg,a,b,c) _XBT_PRE_RETHROW msg,a,b,c, _XBT_POST_RETHROW
+#define RETHROW4(msg,a,b,c,d) _XBT_PRE_RETHROW msg,a,b,c, _XBT_POST_RETHROW
+#define RETHROW5(msg,a,b,c,d,e) _XBT_PRE_RETHROW msg,a,b,c,d,e _XBT_POST_RETHROW
+
+void xbt_ex_free(xbt_ex_t e);
+const char * xbt_ex_catname(xbt_errcat_t cat);
-#endif /* __SG_EX_H__ */
+/** @} */
+#endif /* __XBT_EX_H__ */