erl_db_util.c

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	buff = erts_alloc(ERTS_ALC_T_DB_TMP,
			  sizeof(Eterm) * num_heads * 3);
    } 

    matches = buff;
    guards = buff + num_heads;
    bodies = buff + (num_heads * 2);

    i = 0;
    for (l = matchexpr; is_list(l); l = CDR(list_val(l))) {
	t = CAR(list_val(l));
	if (!is_tuple(t) || arityval((tp = tuple_val(t))[0]) != 3) {
	    add_dmc_err(err_info, 
			"Match program part is not a tuple of "
			"arity 3.", 
			-1, 0UL, dmcError);
	    goto done;
	}
	if (!(flags & DCOMP_TRACE) || (!is_list(tp[1]) && 
					!is_nil(tp[1]))) {
	    t = tp[1];
	} else {
	    n = 0;
	    for (l2 = tp[1]; is_list(l2); l2 = CDR(list_val(l2))) {
		++n;
	    }
	    if (l2 != NIL) {
		add_dmc_err(err_info, 
			    "Match expression part %T is not a "
			    "proper list.", 
			    -1, tp[1], dmcError);
		
		goto done;
	    }
	    hp = HAlloc(p, n + 1);
	    t = make_tuple(hp);
	    *hp++ = make_arityval((Uint) n);
	    l2 = tp[1];
	    while (n--) {
		*hp++ = CAR(list_val(l2));
		l2 = CDR(list_val(l2));
	    }
	}
	matches[i] = t;
	guards[i] = tp[2];
	bodies[i] = tp[3];
	++i;
    }
    mp = db_match_compile(matches, guards, bodies, num_heads,
			  flags, err_info); 
    if (mp != NULL) {
	erts_match_set_free(mp);
    }
done:
    ret = db_format_dmc_err_info(p, err_info);
    db_free_dmc_err_info(err_info);
    if (buff != sbuff) {
	erts_free(ERTS_ALC_T_DB_TMP, buff);
    }
    return ret;
}
    
Eterm erts_match_set_run(Process *p, Binary *mpsp, 
			 Eterm *args, int num_args, 
			 Uint32 *return_flags) 
{
    Eterm ret;

    ret = db_prog_match(p, mpsp,
			(Eterm) args, 
			num_args, return_flags);
#if defined(HARDDEBUG)
    if (is_non_value(ret)) {
	erts_fprintf(stderr, "Failed\n");
    } else {
	erts_fprintf(stderr, "Returning : %T\n", ret);
    }
#endif
    return ret;
    /* Returns 
     *   THE_NON_VALUE if no match
     *   am_false      if {message,false} has been called,
     *   am_true       if {message,_} has not been called or
     *                 if {message,true} has been called,
     *   Msg           if {message,Msg} has been called.
     */
}

/*
** API Used by other erl_db modules.
*/

void db_initialize_util(void){
    qsort(guard_tab, 
	  sizeof(guard_tab) / sizeof(DMCGuardBif), 
	  sizeof(DMCGuardBif), 
	  (int (*)(const void *, const void *)) &cmp_guard_bif);
    match_pseudo_process_init();
    erts_smp_atomic_init(&trace_control_word, 0);
}



Eterm db_getkey(int keypos, Eterm obj)
{
    if (is_tuple(obj)) {
	Eterm *tptr = tuple_val(obj);
	if (arityval(*tptr) >= keypos)
	    return *(tptr + keypos);
    }
    return THE_NON_VALUE;
}

/*
** Matching compiled (executed by "Pam" :-)
*/

/*
** The actual compiling of the match expression and the guards
*/
Binary *db_match_compile(Eterm *matchexpr, 
			 Eterm *guards, 
			 Eterm *body,
			 int num_progs,
			 Uint flags, 
			 DMCErrInfo *err_info)
{
    DMCHeap heap;
    DMC_STACK_TYPE(Eterm) stack;
    DMC_STACK_TYPE(Uint) text;
    DMC_STACK_TYPE(Uint) labels;
    DMCContext context;
    MatchProg *ret = NULL;
    Eterm t;
    Uint i;
    Uint num_iters;
    int structure_checked;
    DMCRet res;
    int current_try_label;
    Uint max_eheap_need;
    Binary *bp = NULL;
    unsigned clause_start;

    DMC_INIT_STACK(stack);
    DMC_INIT_STACK(text);
    DMC_INIT_STACK(labels);

    context.stack_need = context.stack_used = 0;
    context.save = context.copy = NULL;
    context.num_match = num_progs;
    context.matchexpr = matchexpr;
    context.guardexpr = guards;
    context.bodyexpr = body;
    context.eheap_need = 0;
    context.err_info = err_info;
    context.cflags = flags;
    context.labels = &labels;

    heap.size = DMC_DEFAULT_SIZE;
    heap.data = heap.def;

    /*
    ** Compile the match expression
    */
restart:
    heap.used = 0;
    max_eheap_need = 0;
    for (context.current_match = 0; 
	 context.current_match < num_progs; 
	 ++context.current_match) { /* This loop is long, 
				       too long */
	memset(heap.data, 0, heap.size * sizeof(*heap.data));
	t = context.matchexpr[context.current_match];
	context.stack_used = 0;
	context.eheap_need = 0;
	structure_checked = 0;
	if (context.current_match < num_progs - 1) {
	    DMC_PUSH(text,matchTryMeElse);
	    DMC_PUSH(text,current_try_label = 
		     DMC_STACK_NUM(*(context.labels)));
	    DMC_PUSH(*(context.labels), 0);
	} else {
	    current_try_label = -1;
	}
	clause_start = DMC_STACK_NUM(text); /* the "special" test needs it */
	DMC_PUSH(stack,NIL);
	for (;;) {
	    switch (t & _TAG_PRIMARY_MASK) {
	    case TAG_PRIMARY_BOXED:
		if (!BOXED_IS_TUPLE(t)) {
		    goto simple_term;
		}
		num_iters = arityval(*tuple_val(t));
		if (!structure_checked) { /* i.e. we did not 
					     pop it */
		    DMC_PUSH(text,matchTuple);
		    DMC_PUSH(text,num_iters);
		}
		structure_checked = 0;
		for (i = 1; i <= num_iters; ++i) {
		    if ((res = dmc_one_term(&context, 
					    &heap, 
					    &stack, 
					    &text, 
					    tuple_val(t)[i]))
			!= retOk) {
			if (res == retRestart) {
			    goto restart; /* restart the 
					     surrounding 
					     loop */
			} else goto error;
		    }	    
		}
		break;
	    case TAG_PRIMARY_LIST:
		if (!structure_checked) {
		    DMC_PUSH(text, matchList);
		}
		structure_checked = 0; /* Whatever it is, we did 
					  not pop it */
		if ((res = dmc_one_term(&context, &heap, &stack, 
					&text, CAR(list_val(t))))
		    != retOk) {
		    if (res == retRestart) {
			goto restart;
		    } else goto error;
		}	    
		t = CDR(list_val(t));
		continue;
	    default: /* Nil and non proper tail end's or 
			single terms as match 
			expressions */
	    simple_term:
		structure_checked = 0;
		if ((res = dmc_one_term(&context, &heap, &stack, 
					&text, t))
		    != retOk) {
		    if (res == retRestart) {
			goto restart;
		    } else goto error;
		}	    
		break;
	    }

	    /* The *program's* stack just *grows* while we are 
	       traversing one composite data structure, we can 
	       check the stack usage here */

	    if (context.stack_used > context.stack_need)
		context.stack_need = context.stack_used;

	    /* We are at the end of one composite data structure, 
	       pop sub structures and emit a matchPop instruction 
	       (or break) */
	    if ((t = DMC_POP(stack)) == NIL) {
		break;
	    } else {
		DMC_PUSH(text, matchPop);
		structure_checked = 1; /* 
					* Checked with matchPushT 
					* or matchPushL
					*/
		--(context.stack_used);
	    }
	}
    
	/* 
	** There is one single top variable in the match expression
	** iff the text is tho Uint's and the single instruction 
	** is 'matchBind' or it is only a skip.
	*/
	context.special = 
	    (DMC_STACK_NUM(text) == 2 + clause_start && 
	     DMC_PEEK(text,clause_start) == matchBind) || 
	    (DMC_STACK_NUM(text) == 1 + clause_start && 
	     DMC_PEEK(text, clause_start) == matchSkip);

	if (flags & DCOMP_TRACE) {
	    if (context.special) {
		if (DMC_PEEK(text, clause_start) == matchBind) {
		    DMC_POKE(text, clause_start, matchArrayBind);
		} 
	    } else {
		ASSERT(DMC_STACK_NUM(text) >= 1);
		if (DMC_PEEK(text, clause_start) != matchTuple) {
		    /* If it isn't "special" and the argument is 
		       not a tuple, the expression is not valid 
		       when matching an array*/
		    if (context.err_info) {
			add_dmc_err(context.err_info, 
				    "Match head is invalid in "
				    "this context.", 
				    -1, 0UL,
				    dmcError);
		    }
		    goto error;
		}
		DMC_POKE(text, clause_start, matchArray);
	    }
	}


	/*
	** ... and the guards
	*/
	context.is_guard = 1;
	if (compile_guard_expr
	    (&context,
	     &heap,
	     &text,
	     context.guardexpr[context.current_match]) != retOk) 
	    goto error;
	context.is_guard = 0;
	if ((context.cflags & DCOMP_TABLE) && 
	    !is_list(context.bodyexpr[context.current_match])) {
	    if (context.err_info) {
		add_dmc_err(context.err_info, 
			    "Body clause does not return "
			    "anything.", -1, 0UL,
			    dmcError);
	    }
	    goto error;
	}
	if (compile_guard_expr
	    (&context,
	     &heap,
	     &text,
	     context.bodyexpr[context.current_match]) != retOk) 
	    goto error;

	/*
	 * The compilation does not bail out when error information
	 * is requested, so we need to detect that here...
	 */
	if (context.err_info != NULL && 
	    (context.err_info)->error_added) {
	    goto error;
	}


	/* If the matchprogram comes here, the match is 
	   successfull */
	DMC_PUSH(text,matchHalt);
	/* Fill in try-me-else label if there is one. */ 
	if (current_try_label >= 0) {
	    DMC_POKE(*(context.labels), current_try_label, 
		     DMC_STACK_NUM(text));
	}
	/* So, how much eheap did this part of the match program need? */
	if (context.eheap_need > max_eheap_need) {
	    max_eheap_need = context.eheap_need;
	}
    } /* for (context.current_match = 0 ...) */


    /*
    ** Done compiling
    ** Allocate enough space for the program,
    ** heap size is in 'heap_used', stack size is in 'stack_need'
    ** and text size is simply DMC_STACK_NUM(text).
    ** The "program memory" is allocated like this:
    ** text ----> +-------------+
    **            |             |
    **              ..........
    ** labels --> +             + (labels are offset's from text)
    **              ..........
    **            +-------------+
    **
    **  The heap-eheap-stack block of a MatchProg is nowadays allocated
    **  when the match program is run (see db_prog_match()).
    **
    ** heap ----> +-------------+
    **              ..........
    ** eheap ---> +             +
    **              ..........
    ** stack ---> +             +
    **              ..........
    **            +-------------+
    ** The stack is expected to grow towards *higher* adresses.
    ** A special case is when the match expression is a single binding 
    ** (i.e '$1'), then the field single_variable is set to 1.
    */
    bp = allocate_magic_binary
	((sizeof(MatchProg) - sizeof(Uint)) +
	 (DMC_STACK_NUM(text) * sizeof(Uint)) +
	 (DMC_STACK_NUM(labels) * sizeof(Uint)));
    ret = Binary2MatchProg(bp);
    ret->saved_program_buf = NULL;
    ret->saved_program = NIL;
    ret->term_save = context.save;
    ret->num_bindings = heap.used;
    ret->labels = (Uint *) (ret->text + DMC_STACK_NUM(text));
    ret->single_variable = context.special;
#ifdef DMC_DEBUG
    ret->label_size = DMC_STACK_NUM(labels);
#endif
    sys_memcpy(ret->text, DMC_STACK_DATA(text), 
	       DMC_STACK_NUM(text) * sizeof(Uint));
    sys_memcpy(ret->labels, DMC_STACK_DATA(labels), 
	       DMC_STACK_NUM(labels) * sizeof(Uint));
    ret->heap_size = ((heap.used * sizeof(Eterm)) +
		      (max_eheap_need * sizeof(Eterm)) +
		      (context.stack_need * sizeof(Eterm *)) +
		      (3 * (FENCE_PATTERN_SIZE * sizeof(Eterm *))));
    ret->eheap_offset = heap.used + FENCE_PATTERN_SIZE;
    ret->stack_offset = ret->eheap_offset + max_eheap_need + FENCE_PATTERN_SIZE;
    /* 
     * Fall through to cleanup code, but context.save should not be free'd
     */  
    context.save = NULL;
error: /* Here is were we land when compilation failed. */
    while (context.save != NULL) {
	ErlHeapFragment *ll = context.save->next;
	free_message_buffer(context.save);
	context.save = ll;
    }
    DMC_FREE(stack);
    DMC_FREE(text);
    DMC_FREE(labels);
    if (context.copy != NULL) 
	free_message_buffer(context.copy);
    if (heap.data != heap.def)
	erts_free(ERTS_ALC_T_DB_MS_CMPL_HEAP, (void *) heap.data);
    return bp;
}

/*
** Free a match program (in a binary)
*/
void erts_match_set_free(Binary *bprog)
{
    MatchProg *prog;
    ErlHeapFragment *tmp, *ll;
    if (bprog == NULL)
	return;
    prog = Binary2MatchProg(bprog);
    tmp = prog->term_save; 
    while (tmp != NULL) {
	ll = tmp->next;
	free_message_buffer(tmp);
	tmp = ll;
    }
    if (prog->saved_program_buf != NULL)
	free_message_buffer(prog->saved_program_buf);
    erts_bin_free(bprog);
}

void
erts_match_prog_foreach_offheap(Binary *bprog,
				void (*func)(ErlOffHeap *, void *),
				void *arg)
{
    MatchProg *prog;
    ErlHeapFragment *tmp;
    if (bprog == NULL)
	return;
    prog = Binary2MatchProg(bprog);
    tmp = prog->term_save; 
    while (tmp) {
	(*func)(&(tmp->off_heap), arg);
	tmp = tmp->next;
    }
    if (prog->saved_program_buf)
	(*func)(&(prog->saved_program_buf->off_heap), arg);
}

/*
** This is not the most efficient way to do it, but it's a rare
** and not especially nice case when this is used.
*/
static Eterm dpm_array_to_list(Process *psp, Eterm *arr, int arity)
{
    Eterm *hp = HAlloc(psp, arity * 2);
    Eterm ret = NIL;
    while (--arity >= 0) {
	ret = CONS(hp, arr[arity], ret);
	hp += 2;
    }
    return ret;
}
/*
** Execution of the match program, this is Pam.
** May return THE_NON_VALUE, which is a bailout.
** the para meter 'arity' is only used if 'term' is actually an array,
** i.e. 'DCOMP_TRACE' was specified 
*/
Eterm db_prog_match(Process *c_p, Binary *bprog, Eterm term, 
		    int arity,
		    Uint32 *return_flags)
{
    MatchProg *prog = Binary2MatchProg(bprog);
    Eterm *ep;
    Eterm *tp;
    Eterm t;
    Eterm **sp;
    Eterm *esp;
    Eterm *hp;
    Uint *pc = prog->text;
    Eterm *ehp;
    Eterm ret;
    Uint n = 0; /* To avoid warning. */
    int i;
    unsigned do_catch;
    ErtsMatchPseudoProcess *mpsp;
    Process *psp;
    Process *tmpp;
    Process *current_scheduled;
    ErtsSchedulerData *esdp;
    Eterm (*bif)(Process*, ...);
    int fail_label;
    int atomic_trace;
#ifdef DMC_DEBUG
    unsigned long *heap_fence;
    unsigned long *eheap_fence;
    unsigned long *stack_fence;
    Uint save_op;
#endif /* DMC_DEBUG */

    mpsp = get_match_pseudo_process(c_p, prog->heap_size);
    psp = &mpsp->process;

    /* We need to lure the scheduler into believing in the pseudo process, 
       because of floating point exceptions. Do *after* mpsp is set!!! */

    esdp = ERTS_GET_SCHEDULER_DATA_FROM_PROC(c_p);
    ASSERT(esdp != NULL);
    current_scheduled = esdp->current_process;
    esdp->current_process = psp;
    /* SMP: psp->scheduler_data is set by get_match_pseudo_process */

    atomic_trace = 0;
#define BEGIN_ATOMIC_TRACE(p)                               \
    do {                                                    \
	if (! atomic_trace) {                               \
	    erts_smp_proc_unlock((p), ERTS_PROC_LOCK_MAIN); \
	    erts_smp_block_system(0);                       \
            atomic_trace = !0;                              \
	}                                                   \
    } while (0)
#define END_ATOMIC_TRACE(p)                               \
    do {                                                  \
	if (atomic_trace) {                               \
            erts_smp_release_system();                    \
            erts_smp_proc_lock((p), ERTS_PROC_LOCK_MAIN); \
            atomic_trace = 0;                             \
	}                                                 \
    } while (0)

#ifdef DMC_DEBUG
    save_op = 0;
    heap_fence =  (unsigned long *) mpsp->heap + prog->eheap_offset - 1;
    eheap_fence = (unsigned long *) mpsp->heap + prog->stack_offset - 1;
    stack_fence = (unsigned long *) mpsp->heap + prog->heap_size - 1;
    *heap_fence = FENCE_PATTERN;
    *eheap_fence = FENCE_PATTERN;
    *stack_fence = FENCE_PATTERN;
#endif /* DMC_DEBUG */

#ifdef HARDDEBUG
#define FAIL() {erts_printf("Fail line %d\n",__LINE__); goto fail;}
#else
#define FAIL() goto fail