From def96b25a7cb531d59aa7b57abcf7c77c0d25710 Mon Sep 17 00:00:00 2001
From: Kawe Mazidjatari <48657826+Mauler125@users.noreply.github.com>
Date: Sun, 9 Feb 2025 02:33:37 +0100
Subject: [PATCH] VpkLib: strong optimizations for directory tree builder

- Only lookup the map key once, and construct its name with already known size.
- Store pointers to entry blocks rather than copying it, since by the time we build the tree, the entry block vector is guaranteed to not change. It is also qualified as const.
---
 src/vpklib/packedstore.cpp | 34 ++++++++++------------------------
 src/vpklib/packedstore.h   |  2 +-
 2 files changed, 11 insertions(+), 25 deletions(-)

diff --git a/src/vpklib/packedstore.cpp b/src/vpklib/packedstore.cpp
index 0f8e4583..eec80697 100644
--- a/src/vpklib/packedstore.cpp
+++ b/src/vpklib/packedstore.cpp
@@ -1095,25 +1095,11 @@ void VPKDir_t::CTreeBuilder::BuildTree(const CUtlVector<VPKEntryBlock_t>& entryB
 		* - A file path is only written once per extension tree.
 		* - A file name is only written once per file path tree.
 		**********************************************************************/
-		const char* pFileExt = fileExt.Get();
-		auto extIt = m_FileTree.find(pFileExt);
-
-		if (extIt == m_FileTree.end())
-		{
-			extIt = m_FileTree.insert({ pFileExt, PathContainer_t() }).first;
-		}
-
+		const auto& extIt = m_FileTree.try_emplace({ fileExt.String(), (size_t)fileExt.Length() }, PathContainer_t()).first;
 		PathContainer_t& pathTree = extIt->second;
 
-		const char* pFilePath = filePath.Get();
-		auto pathIt = pathTree.find(pFilePath);
-
-		if (pathIt == pathTree.end())
-		{
-			pathIt = pathTree.insert({ pFilePath, std::list<VPKEntryBlock_t>() }).first;
-		}
-
-		pathIt->second.push_back(entryBlock);
+		const auto& pathIt = pathTree.try_emplace({ filePath.String(), (size_t)filePath.Length() }, std::list<const VPKEntryBlock_t*>()).first;
+		pathIt->second.emplace_back(&entryBlock);
 	}
 }
 
@@ -1134,17 +1120,17 @@ int VPKDir_t::CTreeBuilder::WriteTree(FileHandle_t hDirectoryFile) const
 			FileSystem()->Write(jKeyValue.first.c_str(), jKeyValue.first.length() + 1, hDirectoryFile);
 			for (auto& vEntry : jKeyValue.second)
 			{
-				const CUtlString entryPath = vEntry.m_EntryPath.UnqualifiedFilename().StripExtension();
+				const CUtlString entryPath = vEntry->m_EntryPath.UnqualifiedFilename().StripExtension();
 				FileSystem()->Write(entryPath.Get(), entryPath.Length() + 1, hDirectoryFile);
 
-				FileSystem()->Write(&vEntry.m_nFileCRC, sizeof(uint32_t), hDirectoryFile);
-				FileSystem()->Write(&vEntry.m_iPreloadSize, sizeof(uint16_t), hDirectoryFile);
-				FileSystem()->Write(&vEntry.m_iPackFileIndex, sizeof(uint16_t), hDirectoryFile);
+				FileSystem()->Write(&vEntry->m_nFileCRC, sizeof(uint32_t), hDirectoryFile);
+				FileSystem()->Write(&vEntry->m_iPreloadSize, sizeof(uint16_t), hDirectoryFile);
+				FileSystem()->Write(&vEntry->m_iPackFileIndex, sizeof(uint16_t), hDirectoryFile);
 
-				FOR_EACH_VEC(vEntry.m_Fragments, i)
+				FOR_EACH_VEC(vEntry->m_Fragments, i)
 				{
 					/*Write chunk descriptor*/
-					const VPKChunkDescriptor_t& descriptor = vEntry.m_Fragments[i];
+					const VPKChunkDescriptor_t& descriptor = vEntry->m_Fragments[i];
 
 					FileSystem()->Write(&descriptor.m_nLoadFlags, sizeof(uint32_t), hDirectoryFile);
 					FileSystem()->Write(&descriptor.m_nTextureFlags, sizeof(uint16_t), hDirectoryFile);
@@ -1152,7 +1138,7 @@ int VPKDir_t::CTreeBuilder::WriteTree(FileHandle_t hDirectoryFile) const
 					FileSystem()->Write(&descriptor.m_nCompressedSize, sizeof(uint64_t), hDirectoryFile);
 					FileSystem()->Write(&descriptor.m_nUncompressedSize, sizeof(uint64_t), hDirectoryFile);
 
-					if (i != (vEntry.m_Fragments.Count() - 1))
+					if (i != (vEntry->m_Fragments.Count() - 1))
 					{
 						FileSystem()->Write(&PACKFILEINDEX_SEP, sizeof(uint16_t), hDirectoryFile);
 					}
diff --git a/src/vpklib/packedstore.h b/src/vpklib/packedstore.h
index 288a49df..278a0216 100644
--- a/src/vpklib/packedstore.h
+++ b/src/vpklib/packedstore.h
@@ -158,7 +158,7 @@ struct VPKDir_t
 	class CTreeBuilder
 	{
 	public:
-		typedef std::map<std::string, std::list<VPKEntryBlock_t>> PathContainer_t;
+		typedef std::map<std::string, std::list<const VPKEntryBlock_t*>> PathContainer_t;
 		typedef std::map<std::string, PathContainer_t> TypeContainer_t;
 
 		void BuildTree(const CUtlVector<VPKEntryBlock_t>& entryBlocks);