From 45df9023c05891ca1b056b1babfa382db95aa8ec Mon Sep 17 00:00:00 2001
From: Per Hedbor <ph@opera.com>
Date: Fri, 17 May 2013 18:04:28 +0200
Subject: [PATCH] Changed worst-case ordo of replace(array,item1,item2) from
O(n^2) to O(n).
Replace uses search_array, which in turn calls
check_array_for_destruct. So, if you had an array where all elements
were replaced by the replace containing at least one object replace()
was O(n^2), not O(n).
In general check_array_for_destruct is rather unneeded, since the
comparison functions already checks for destructed objects, but I
guess that it might cause objects to be free:d slightly sooner.
---
src/array.c | 53 +++++++++++++++++++++++------------------------------
1 file changed, 23 insertions(+), 30 deletions(-)
diff --git a/src/array.c b/src/array.c
index 562c73e6ef..1939261286 100644
--- a/src/array.c
+++ b/src/array.c
@@ -646,6 +646,25 @@ PMOD_EXPORT struct array *array_remove(struct array *v,INT32 index)
}
}
+static ptrdiff_t fast_array_search( struct array *v, struct svalue *s, ptrdiff_t start )
+{
+ ptrdiff_t e;
+ /* Why search for something that is not there?
+ * however, we must explicitly check for searches
+ * for destructed objects/functions
+ */
+ if((v->type_field & (1 << TYPEOF(*s))) ||
+ (UNSAFE_IS_ZERO(s) && (v->type_field & (BIT_FUNCTION|BIT_OBJECT))) ||
+ ( (v->type_field | (1<<TYPEOF(*s))) & BIT_OBJECT )) /* for overloading */
+ {
+ struct svalue *ip = ITEM(v);
+ for(e=start;e<v->size;e++)
+ if(is_eq(ip+e,s))
+ return e;
+ }
+ return -1;
+}
+
/**
* Search for in svalue in an array.
* @param v the array to search
@@ -656,41 +675,15 @@ PMOD_EXPORT struct array *array_remove(struct array *v,INT32 index)
PMOD_EXPORT ptrdiff_t array_search(struct array *v, struct svalue *s,
ptrdiff_t start)
{
- ptrdiff_t e;
-
#ifdef PIKE_DEBUG
if(start<0)
Pike_fatal("Start of find_index is less than zero.\n");
#endif
-
- check_destructed(s);
-
#ifdef PIKE_DEBUG
if(d_flag > 1) array_check_type_field(v);
#endif
- /* Why search for something that is not there?
- * however, we must explicitly check for searches
- * for destructed objects/functions
- */
- if((v->type_field & (1 << TYPEOF(*s))) ||
- (UNSAFE_IS_ZERO(s) && (v->type_field & (BIT_FUNCTION|BIT_OBJECT))) ||
- ( (v->type_field | (1<<TYPEOF(*s))) & BIT_OBJECT )) /* for overloading */
- {
- if(start)
- {
- for(e=start;e<v->size;e++)
- if(is_eq(ITEM(v)+e,s)) return e;
- }else{
- TYPE_FIELD t=0;
- for(e=0;e<v->size;e++)
- {
- if(is_eq(ITEM(v)+e,s)) return e;
- t |= 1<<TYPEOF(ITEM(v)[e]);
- }
- v->type_field=t;
- }
- }
- return -1;
+ check_destructed(s);
+ return fast_array_search( v, s, start );
}
/**
@@ -2626,8 +2619,8 @@ void array_replace(struct array *a,
struct svalue *to)
{
ptrdiff_t i = -1;
-
- while((i=array_search(a,from,i+1)) >= 0) array_set_index(a,i,to);
+ check_array_for_destruct(a);
+ while((i=fast_array_search(a,from,i+1)) >= 0) array_set_index(a,i,to);
}
#ifdef PIKE_DEBUG
--
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