From d14a3f64db7833acf19b4560dc78a7a0be3f0984 Mon Sep 17 00:00:00 2001
From: Alug <alufoliehorst@gmail.com>
Date: Sun, 7 Dec 2025 15:55:25 -0500
Subject: [PATCH] w_wad: optimize W_LumpExists

in two parts:
- Use our lumpcache lookup first (our unordered map), BUT since it is case insensitive we extract our lump out of it to do another case sensitive name compare
- In the manual lump seach falltthrough case, we can also check against the string lenghts and hash (its case insensitive but will still reject differing names, same with stringlenght)

this improves the performance of the leaderboard map browser quite a bit and everything else using v.patchExists
---
 src/w_wad.cpp | 66 +++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 53 insertions(+), 13 deletions(-)

diff --git a/src/w_wad.cpp b/src/w_wad.cpp
index fd504872a..c672962ff 100644
--- a/src/w_wad.cpp
+++ b/src/w_wad.cpp
@@ -1423,6 +1423,20 @@ UINT16 W_CheckNumForFullNamePK3(const char *name, UINT16 wad, UINT16 startlump)
 	return INT16_MAX;
 }
 
+static lumpnum_t CheckLumpInCache(const char *name)
+{
+	auto it = lumpnumcache.find(name);
+	if (it != lumpnumcache.end())
+		return it->second;
+
+	return LUMPERROR;
+}
+
+static void AddLumpToCache(lumpnum_t lumpnum, const char *name)
+{
+	lumpnumcache.insert({name, lumpnum});
+}
+
 //
 // W_CheckNumForName
 // Returns LUMPERROR if name not found.
@@ -1438,11 +1452,10 @@ lumpnum_t W_CheckNumForName(const char *name)
 	if (!*name) // some doofus gave us an empty string?
 		return LUMPERROR;
 
-	// Check the lumpnumcache first. Loop backwards so that we check
-	// most recent entries first
-	auto it = lumpnumcache.find(name);
-	if (it != lumpnumcache.end())
-		return it->second;
+	// Check the lumpnumcache first.
+	lumpnum_t cachenum = CheckLumpInCache(name);
+	if (cachenum != LUMPERROR)
+		return cachenum;
 
 	// scan wad files backwards so patch lump files take precedence
 	for (i = numwadfiles - 1; i >= 0; i--)
@@ -1481,10 +1494,9 @@ lumpnum_t W_CheckNumForLongName(const char *name)
 
 	// Check the lumpnumcache first. Loop backwards so that we check
 	// most recent entries first
-	auto it = lumpnumcache.find(name);
-	if (it != lumpnumcache.end())
-		return it->second;
-
+	lumpnum_t cachenum = CheckLumpInCache(name);
+	if (cachenum != LUMPERROR)
+		return cachenum;
 
 	// scan wad files backwards so patch lump files take precedence
 	for (i = numwadfiles - 1; i >= 0; i--)
@@ -1501,7 +1513,8 @@ lumpnum_t W_CheckNumForLongName(const char *name)
 		{
 			// Update the cache.
 			lumpnum_t lumpnum = (i << 16) | check;
-			lumpnumcache.insert({name, lumpnum});
+			AddLumpToCache(lumpnum, name);
+
 			return lumpnum;
 		}
 
@@ -1544,7 +1557,8 @@ lumpnum_t W_CheckNumForMap(const char *name, boolean checktofirst)
 		{
 			// Update the cache.
 			lumpnum_t lumpnum = (i << 16) | check;
-			lumpnumcache.insert({name, lumpnum});
+			AddLumpToCache(lumpnum, name);
+
 			return lumpnum;
 		}
 
@@ -1659,13 +1673,39 @@ lumpnum_t W_CheckNumForNameInFolder(const char *lump, const char *folder)
 #include "fastcmp.h"
 UINT8 W_LumpExists(const char *name)
 {
-	INT32 i,j;
+	INT32 i, j;
+	UINT32 hash;
+	size_t namelen;
+
+	lumpnum_t cachenum = CheckLumpInCache(name);
+	if (cachenum != LUMPERROR)
+	{
+		// ok ok, we did find a lump in our lumpcache BUTT
+		// the lumpcache map is case insensitive
+		// extract the lumpinfo out of the lumpnum
+		// so we can do one more extra case ~sensitive~ name compare
+		// otherwise we gotta fall through to our manual lump search below
+		// lumpnum == (i << 16) | check
+		UINT16 wadnum = (cachenum >> 16) & 0xFFFF;
+		UINT16 lumpid = cachenum & 0xFFFF;
+		lumpinfo_t *lump_p = &wadfiles[wadnum]->lumpinfo[lumpid];
+		if (fastcmp(lump_p->longname, name))
+			return true;
+	}
+
+	namelen = strlen(name);
+	hash = W_HashLumpName(name, namelen);
+
 	for (i = numwadfiles - 1; i >= 0; i--)
 	{
 		lumpinfo_t *lump_p = wadfiles[i]->lumpinfo;
 		for (j = 0; j < wadfiles[i]->numlumps; ++j, ++lump_p)
-			if (fastcmp(lump_p->longname, name))
+		{
+			if (lump_p->longnamelength == namelen
+			 && lump_p->hash.longname == hash
+			 && fastcmp(lump_p->longname, name))
 				return true;
+		}
 	}
 	return false;
 }