X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=hv.c;h=eb2a1a5aa71e98b0c47a259ff90a433e4b44f811;hb=89e33a0587050e7ef2e88ba45c87444d8506f821;hp=2b00650fe7016fd3efa1b615b7ca916a0c11542f;hpb=66a1b24beb76ea873ad4caa57ee3ab9df945afbf;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/hv.c b/hv.c
index 2b00650..eb2a1a5 100644
--- a/hv.c
+++ b/hv.c
@@ -33,6 +33,9 @@ holds the key and hash value.
 
 #define HV_MAX_LENGTH_BEFORE_SPLIT 14
 
+static const char *const S_strtab_error
+    = "Cannot modify shared string table in hv_%s";
+
 STATIC void
 S_more_he(pTHX)
 {
@@ -126,19 +129,20 @@ Perl_free_tied_hv_pool(pTHX)
 HEK *
 Perl_hek_dup(pTHX_ HEK *source, CLONE_PARAMS* param)
 {
-    HE *shared = (HE*)ptr_table_fetch(PL_shared_hek_table, source);
+    HEK *shared = (HEK*)ptr_table_fetch(PL_ptr_table, source);
     (void)param;
 
     if (shared) {
 	/* We already shared this hash key.  */
-	++HeVAL(shared);
+	(void)share_hek_hek(shared);
     }
     else {
-	shared = share_hek_flags(HEK_KEY(source), HEK_LEN(source),
-				 HEK_HASH(source), HEK_FLAGS(source));
-	ptr_table_store(PL_shared_hek_table, source, shared);
+	shared
+	    = share_hek_flags(HEK_KEY(source), HEK_LEN(source),
+			      HEK_HASH(source), HEK_FLAGS(source));
+	ptr_table_store(PL_ptr_table, source, shared);
     }
-    return HeKEY_hek(shared);
+    return shared;
 }
 
 HE *
@@ -168,18 +172,19 @@ Perl_he_dup(pTHX_ HE *e, bool shared, CLONE_PARAMS* param)
 	/* This is hek_dup inlined, which seems to be important for speed
 	   reasons.  */
 	HEK *source = HeKEY_hek(e);
-	HE *shared = (HE*)ptr_table_fetch(PL_shared_hek_table, source);
+	HEK *shared = (HEK*)ptr_table_fetch(PL_ptr_table, source);
 
 	if (shared) {
 	    /* We already shared this hash key.  */
-	    ++HeVAL(shared);
+	    (void)share_hek_hek(shared);
 	}
 	else {
-	    shared = share_hek_flags(HEK_KEY(source), HEK_LEN(source),
-				     HEK_HASH(source), HEK_FLAGS(source));
-	    ptr_table_store(PL_shared_hek_table, source, shared);
+	    shared
+		= share_hek_flags(HEK_KEY(source), HEK_LEN(source),
+				  HEK_HASH(source), HEK_FLAGS(source));
+	    ptr_table_store(PL_ptr_table, source, shared);
 	}
-	HeKEY_hek(ret) = HeKEY_hek(shared);
+	HeKEY_hek(ret) = shared;
     }
     else
 	HeKEY_hek(ret) = save_hek_flags(HeKEY(e), HeKLEN(e), HeHASH(e),
@@ -685,11 +690,19 @@ S_hv_fetch_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
 		    /* Need to swap the key we have for a key with the flags we
 		       need. As keys are shared we can't just write to the
 		       flag, so we share the new one, unshare the old one.  */
-		    HEK *new_hek = HeKEY_hek(share_hek_flags(key, klen, hash,
-							     masked_flags));
+		    HEK *new_hek = share_hek_flags(key, klen, hash,
+						   masked_flags);
 		    unshare_hek (HeKEY_hek(entry));
 		    HeKEY_hek(entry) = new_hek;
 		}
+		else if (hv == PL_strtab) {
+		    /* PL_strtab is usually the only hash without HvSHAREKEYS,
+		       so putting this test here is cheap  */
+		    if (flags & HVhek_FREEKEY)
+			Safefree(key);
+		    Perl_croak(aTHX_ S_strtab_error,
+			       action & HV_FETCH_LVALUE ? "fetch" : "store");
+		}
 		else
 		    HeKFLAGS(entry) = masked_flags;
 		if (masked_flags & HVhek_ENABLEHVKFLAGS)
@@ -790,7 +803,15 @@ S_hv_fetch_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
     /* share_hek_flags will do the free for us.  This might be considered
        bad API design.  */
     if (HvSHAREKEYS(hv))
-	HeKEY_hek(entry) = HeKEY_hek(share_hek_flags(key, klen, hash, flags));
+	HeKEY_hek(entry) = share_hek_flags(key, klen, hash, flags);
+    else if (hv == PL_strtab) {
+	/* PL_strtab is usually the only hash without HvSHAREKEYS, so putting
+	   this test here is cheap  */
+	if (flags & HVhek_FREEKEY)
+	    Safefree(key);
+	Perl_croak(aTHX_ S_strtab_error,
+		   action & HV_FETCH_LVALUE ? "fetch" : "store");
+    }
     else                                       /* gotta do the real thing */
 	HeKEY_hek(entry) = save_hek_flags(key, klen, hash, flags);
     HeVAL(entry) = val;
@@ -1034,6 +1055,12 @@ S_hv_delete_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
 	if ((HeKFLAGS(entry) ^ masked_flags) & HVhek_UTF8)
 	    continue;
 
+	if (hv == PL_strtab) {
+	    if (k_flags & HVhek_FREEKEY)
+		Safefree(key);
+	    Perl_croak(aTHX_ S_strtab_error, "delete");
+	}
+
 	/* if placeholder is here, it's already been deleted.... */
 	if (HeVAL(entry) == &PL_sv_placeholder)
 	{
@@ -1417,7 +1444,7 @@ Perl_newHVhv(pTHX_ HV *ohv)
 		ent = new_HE();
 		HeVAL(ent)     = newSVsv(HeVAL(oent));
 		HeKEY_hek(ent)
-                    = shared ? HeKEY_hek(share_hek_flags(key, len, hash, flags))
+                    = shared ? share_hek_flags(key, len, hash, flags)
                              :  save_hek_flags(key, len, hash, flags);
 		if (prev)
 		    HeNEXT(prev) = ent;
@@ -2149,7 +2176,7 @@ Perl_unshare_hek(pTHX_ HEK *hek)
    are used.  If so, len and hash must both be valid for str.
  */
 STATIC void
-S_unshare_hek_or_pvn(pTHX_ HEK *hek, const char *str, I32 len, U32 hash)
+S_unshare_hek_or_pvn(pTHX_ const HEK *hek, const char *str, I32 len, U32 hash)
 {
     register XPVHV* xhv;
     register HE *entry;
@@ -2159,8 +2186,26 @@ S_unshare_hek_or_pvn(pTHX_ HEK *hek, const char *str, I32 len, U32 hash)
     bool is_utf8 = FALSE;
     int k_flags = 0;
     const char *save = str;
+    struct shared_he *he = 0;
 
     if (hek) {
+	/* Find the shared he which is just before us in memory.  */
+	he = (struct shared_he *)(((char *)hek)
+				  - STRUCT_OFFSET(struct shared_he,
+						  shared_he_hek));
+
+	/* Assert that the caller passed us a genuine (or at least consistent)
+	   shared hek  */
+	assert (he->shared_he_he.hent_hek == hek);
+
+	LOCK_STRTAB_MUTEX;
+	if (he->shared_he_he.hent_val - 1) {
+	    --he->shared_he_he.hent_val;
+	    UNLOCK_STRTAB_MUTEX;
+	    return;
+	}
+	UNLOCK_STRTAB_MUTEX;
+
         hash = HEK_HASH(hek);
     } else if (len < 0) {
         STRLEN tmplen = -len;
@@ -2183,9 +2228,10 @@ S_unshare_hek_or_pvn(pTHX_ HEK *hek, const char *str, I32 len, U32 hash)
     /* assert(xhv_array != 0) */
     LOCK_STRTAB_MUTEX;
     first = oentry = &(HvARRAY(PL_strtab))[hash & (I32) HvMAX(PL_strtab)];
-    if (hek) {
+    if (he) {
+	const HE *const he_he = &(he->shared_he_he);
         for (entry = *oentry; entry; oentry = &HeNEXT(entry), entry = *oentry) {
-            if (HeKEY_hek(entry) != hek)
+            if (entry != he_he)
                 continue;
             found = 1;
             break;
@@ -2213,8 +2259,7 @@ S_unshare_hek_or_pvn(pTHX_ HEK *hek, const char *str, I32 len, U32 hash)
 		/* There are now no entries in our slot.  */
                 xhv->xhv_fill--; /* HvFILL(hv)-- */
 	    }
-            Safefree(HeKEY_hek(entry));
-            del_HE(entry);
+            Safefree(entry);
             xhv->xhv_keys--; /* HvKEYS(hv)-- */
         }
     }
@@ -2258,10 +2303,10 @@ Perl_share_hek(pTHX_ const char *str, I32 len, register U32 hash)
           flags |= HVhek_WASUTF8 | HVhek_FREEKEY;
     }
 
-    return HeKEY_hek(share_hek_flags (str, len, hash, flags));
+    return share_hek_flags (str, len, hash, flags);
 }
 
-STATIC HE *
+STATIC HEK *
 S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags)
 {
     register XPVHV* xhv;
@@ -2299,11 +2344,35 @@ S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags)
 	   If this is NULL, then we're the first entry for this slot, which
 	   means we need to increate fill.  */
 	const HE *old_first = *oentry;
-	entry = new_HE();
-	HeKEY_hek(entry) = save_hek_flags(str, len, hash, flags_masked);
+	struct shared_he *new_entry;
+	HEK *hek;
+	char *k;
+
+	/* We don't actually store a HE from the arena and a regular HEK.
+	   Instead we allocate one chunk of memory big enough for both,
+	   and put the HEK straight after the HE. This way we can find the
+	   HEK directly from the HE.
+	*/
+
+	New(0, k, STRUCT_OFFSET(struct shared_he,
+				shared_he_hek.hek_key[0]) + len + 2, char);
+	new_entry = (struct shared_he *)k;
+	entry = &(new_entry->shared_he_he);
+	hek = &(new_entry->shared_he_hek);
+
+	Copy(str, HEK_KEY(hek), len, char);
+	HEK_KEY(hek)[len] = 0;
+	HEK_LEN(hek) = len;
+	HEK_HASH(hek) = hash;
+	HEK_FLAGS(hek) = (unsigned char)flags_masked;
+
+	/* Still "point" to the HEK, so that other code need not know what
+	   we're up to.  */
+	HeKEY_hek(entry) = hek;
 	HeVAL(entry) = Nullsv;
 	HeNEXT(entry) = *oentry;
 	*oentry = entry;
+
 	xhv->xhv_keys++; /* HvKEYS(hv)++ */
 	if (!old_first) {			/* initial entry? */
 	    xhv->xhv_fill++; /* HvFILL(hv)++ */
@@ -2318,7 +2387,7 @@ S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags)
     if (flags & HVhek_FREEKEY)
 	Safefree(str);
 
-    return entry;
+    return HeKEY_hek(entry);
 }
 
 I32 *