From: Nicholas Clark <nick@ccl4.org>
Date: Sat, 7 Feb 2004 19:50:10 +0000 (+0000)
Subject: hv_clear_placeholders now manipulates the linked lists directly, rather
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=d36773897a6f30fc5c947e9ed9a2e06b2e7f3b74;p=p5sagit%2Fp5-mst-13.2.git

hv_clear_placeholders now manipulates the linked lists directly, rather
than using the iterator interface and calling hv_delete
This will allow hv_delete to be simplified to remove most of the
special casing related to placeholders.

p4raw-id: //depot/perl@22278
---

diff --git a/hv.c b/hv.c
index b7415ec..849154c 100644
--- a/hv.c
+++ b/hv.c
@@ -1495,42 +1495,45 @@ See Hash::Util::lock_keys() for an example of its use.
 void
 Perl_hv_clear_placeholders(pTHX_ HV *hv)
 {
-    I32 items;
-    items = (I32)HvPLACEHOLDERS(hv);
-    if (items) {
-        HE *entry;
-        I32 riter = HvRITER(hv);
-        HE *eiter = HvEITER(hv);
-        hv_iterinit(hv);
-        /* This may look suboptimal with the items *after* the iternext, but
-           it's quite deliberate. We only get here with items==0 if we've
-           just deleted the last placeholder in the hash. If we've just done
-           that then it means that the hash is in lazy delete mode, and the
-           HE is now only referenced in our iterator. If we just quit the loop
-           and discarded our iterator then the HE leaks. So we do the && the
-           other way to ensure iternext is called just one more time, which
-           has the side effect of triggering the lazy delete.  */
-        while ((entry = hv_iternext_flags(hv, HV_ITERNEXT_WANTPLACEHOLDERS))
-            && items) {
-            SV *val = hv_iterval(hv, entry);
-
-            if (val == &PL_sv_placeholder) {
-
-                /* It seems that I have to go back in the front of the hash
-                   API to delete a hash, even though I have a HE structure
-                   pointing to the very entry I want to delete, and could hold
-                   onto the previous HE that points to it. And it's easier to
-                   go in with SVs as I can then specify the precomputed hash,
-                   and don't have fun and games with utf8 keys.  */
-                SV *key = hv_iterkeysv(entry);
-
-                hv_delete_ent (hv, key, G_DISCARD, HeHASH(entry));
-                items--;
-            }
-        }
-        HvRITER(hv) = riter;
-        HvEITER(hv) = eiter;
-    }
+    I32 items = (I32)HvPLACEHOLDERS(hv);
+    I32 i = HvMAX(hv);
+
+    if (items == 0)
+	return;
+
+    do {
+	/* Loop down the linked list heads  */
+	int first = 1;
+	HE **oentry = &(HvARRAY(hv))[i];
+	HE *entry = *oentry;
+
+	if (!entry)
+	    continue;
+
+	for (; entry; first=0, oentry = &HeNEXT(entry), entry = *oentry) {
+	    if (HeVAL(entry) == &PL_sv_placeholder) {
+		*oentry = HeNEXT(entry);
+		if (first && !*oentry)
+		    HvFILL(hv)--; /* This linked list is now empty.  */
+		if (HvEITER(hv))
+		    HvLAZYDEL_on(hv);
+		else
+		    hv_free_ent(hv, entry);
+
+		if (--items == 0) {
+		    /* Finished.  */
+		    HvTOTALKEYS(hv) -= HvPLACEHOLDERS(hv);
+		    if (HvKEYS(hv) == 0)
+			HvHASKFLAGS_off(hv);
+		    HvPLACEHOLDERS(hv) = 0;
+		    return;
+		}
+	    }
+	}
+    } while (--i >= 0);
+    /* You can't get here, hence assertion should always fail.  */
+    assert (items == 0);
+    assert (0);
 }
 
 STATIC void