Avoid updating a variable in a loop.

Only calculate the number of links in a hash bucket chain if we really
need it.

p4raw-id: //depot/perl@24648

diff --git a/hv.c b/hv.c
index 215bcc3..521d1ff 100644 (file)
--- a/hv.c
+++ b/hv.c
@@ -413,7 +413,6 @@ S_hv_fetch_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
 {
     dVAR;
     XPVHV* xhv;
-    U32 n_links;
     HE *entry;
     HE **oentry;
     SV *sv;
@@ -654,7 +653,6 @@ S_hv_fetch_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
     }
 
     masked_flags = (flags & HVhek_MASK);
-    n_links = 0;
 
 #ifdef DYNAMIC_ENV_FETCH
     if (!HvARRAY(hv)) entry = Null(HE*);
@@ -663,7 +661,7 @@ S_hv_fetch_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
     {
        entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)];
     }
-    for (; entry; ++n_links, entry = HeNEXT(entry)) {
+    for (; entry; entry = HeNEXT(entry)) {
        if (HeHASH(entry) != hash)              /* strings can't be equal */
            continue;
        if (HeKLEN(entry) != (I32)klen)
@@ -798,18 +796,30 @@ S_hv_fetch_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
     if (masked_flags & HVhek_ENABLEHVKFLAGS)
        HvHASKFLAGS_on(hv);
 
-    xhv->xhv_keys++; /* HvKEYS(hv)++ */
-    if (!n_links) {                            /* initial entry? */
-       xhv->xhv_fill++; /* HvFILL(hv)++ */
-    } else if ((xhv->xhv_keys > (IV)xhv->xhv_max)
-              || ((n_links > HV_MAX_LENGTH_BEFORE_SPLIT) && !HvREHASH(hv))) {
-       /* Use only the old HvKEYS(hv) > HvMAX(hv) condition to limit bucket
-          splits on a rehashed hash, as we're not going to split it again,
-          and if someone is lucky (evil) enough to get all the keys in one
-          list they could exhaust our memory as we repeatedly double the
-          number of buckets on every entry. Linear search feels a less worse
-          thing to do.  */
-        hsplit(hv);
+    {
+       const HE *counter = HeNEXT(entry);
+
+       xhv->xhv_keys++; /* HvKEYS(hv)++ */
+       if (!counter) {                         /* initial entry? */
+           xhv->xhv_fill++; /* HvFILL(hv)++ */
+       } else if (xhv->xhv_keys > (IV)xhv->xhv_max) {
+           hsplit(hv);
+       } else if(!HvREHASH(hv)) {
+           U32 n_links = 1;
+
+           while ((counter = HeNEXT(counter)))
+               n_links++;
+
+           if (n_links > HV_MAX_LENGTH_BEFORE_SPLIT) {
+               /* Use only the old HvKEYS(hv) > HvMAX(hv) condition to limit
+                  bucket splits on a rehashed hash, as we're not going to
+                  split it again, and if someone is lucky (evil) enough to
+                  get all the keys in one list they could exhaust our memory
+                  as we repeatedly double the number of buckets on every
+                  entry. Linear search feels a less worse thing to do.  */
+               hsplit(hv);
+           }
+       }
     }
 
     return entry;