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[SV 45728] Detect changes in .VARIABLES more accurately.

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For performance, we only recompute .VARIABLES when (a) it's expanded
and (b) when its value will change from a previous expansion.  To
determine (b) we were checking the number of entries in the hash
table which used to work until we started undefining entries: now if
you undefine and redefine the same number of entries in between
expanding .VARIABLES, it doesn't detect any change.  Instead, keep
an increasing change number.
* variables.c: Add variable_changenum.
(define_variable_in_set, merge_variable_sets): Increment
variable_changenum if adding a new variable to the global set.
(undefine_variable_in_set): Increment variable_changenum if
undefining a variable from the global set.
(lookup_special_var): Test variable_changenum not the hash table.
* tests/scripts/variables/special: Test undefining variables.
This commit is contained in:
Paul Smith
2016-03-13 18:13:00 -04:00
parent 247b71e690
commit 9ae02b7916
2 changed files with 49 additions and 32 deletions
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31
variable.c
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@@ -29,6 +29,9 @@ this program. If not, see <http://www.gnu.org/licenses/>. */
#endif
#include "hash.h"
/* Incremented every time we add or remove a global variable. */
static unsigned int variable_changenum;
/* Chain of all pattern-specific variables. */
static struct pattern_var *pattern_vars;
@@ -268,6 +271,9 @@ define_variable_in_set (const char *name, unsigned int length,
v->name = xstrndup (name, length);
v->length = length;
hash_insert_at (&set->table, v, var_slot);
if (set == &global_variable_set)
++variable_changenum;
v->value = xstrdup (value);
if (flocp != 0)
v->fileinfo = *flocp;
@@ -350,12 +356,14 @@ undefine_variable_in_set (const char *name, unsigned int length,
before the switches were parsed, it wasn't affected by -e. */
v->origin = o_env_override;
/* If the definition is from a stronger source than this one, don't
undefine it. */
/* Undefine only if this undefinition is from an equal or stronger
source than the variable definition. */
if ((int) origin >= (int) v->origin)
{
hash_delete_at (&set->table, var_slot);
free_variable_name_and_value (v);
if (set == &global_variable_set)
++variable_changenum;
}
}
}
@@ -373,7 +381,7 @@ undefine_variable_in_set (const char *name, unsigned int length,
static struct variable *
lookup_special_var (struct variable *var)
{
static unsigned long last_var_count = 0;
static unsigned long last_changenum = 0;
/* This one actually turns out to be very hard, due to the way the parser
@@ -401,8 +409,7 @@ lookup_special_var (struct variable *var)
else
*/
if (streq (var->name, ".VARIABLES")
&& global_variable_set.table.ht_fill != last_var_count)
if (variable_changenum != last_changenum && streq (var->name, ".VARIABLES"))
{
unsigned long max = EXPANSION_INCREMENT (strlen (var->value));
unsigned long len;
@@ -438,11 +445,8 @@ lookup_special_var (struct variable *var)
}
*(p-1) = '\0';
/* Remember how many variables are in our current count. Since we never
remove variables from the list, this is a reliable way to know whether
the list is up to date or needs to be recomputed. */
last_var_count = global_variable_set.table.ht_fill;
/* Remember the current variable change number. */
last_changenum = variable_changenum;
}
return var;
@@ -753,6 +757,8 @@ merge_variable_sets (struct variable_set *to_set,
struct variable **from_var_slot = (struct variable **) from_set->table.ht_vec;
struct variable **from_var_end = from_var_slot + from_set->table.ht_size;
int inc = to_set == &global_variable_set ? 1 : 0;
for ( ; from_var_slot < from_var_end; from_var_slot++)
if (! HASH_VACANT (*from_var_slot))
{
@@ -760,7 +766,10 @@ merge_variable_sets (struct variable_set *to_set,
struct variable **to_var_slot
= (struct variable **) hash_find_slot (&to_set->table, *from_var_slot);
if (HASH_VACANT (*to_var_slot))
hash_insert_at (&to_set->table, from_var, to_var_slot);
{
hash_insert_at (&to_set->table, from_var, to_var_slot);
variable_changenum += inc;
}
else
{
/* GKM FIXME: delete in from_set->table */