DOS drive cache: Fix directory listing performance issues by deferrin…

…g filename sort until after all entries have been added. [#5039]
joncampbell123 · Jun 17, 2024 · 3ff38b6 · 3ff38b6
1 parent 0f38f55
commit 3ff38b6
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Showing 3 changed files with 11 additions and 5 deletions.
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,4 +1,7 @@
 Next:
+  - DOS drive cache: When listing a directory, defer the filename sort until
+    the entire list is built. This improves directory listing performance
+    in directories with many files. (joncampbell123).
   - INT 10h, if instructed, will now use the video parameter table to set
     standard VGA modes instead of internal logic. (joncampbell123).
   - Removed erroneous VGA display compensation code for certain EGA/VGA

diff --git a/include/dos_system.h b/include/dos_system.h
@@ -270,7 +270,7 @@ class DOS_Drive_Cache {
 	CFileInfo*	FindDirInfo		(const char* path, char* expandedPath);
 	bool		RemoveSpaces		(char* str);
 	bool		OpenDir			(CFileInfo* dir, const char* expand, uint16_t& id);
-    char*       CreateEntry     (CFileInfo* dir, const char* name, const char* sname, bool is_directory);
+    char*       CreateEntry     (CFileInfo* dir, const char* name, const char* sname, bool is_directory, bool skipSort=false);
 	void		CopyEntry		(CFileInfo* dir, CFileInfo* from);
 	uint16_t		GetFreeID		(CFileInfo* dir);
 	void		Clear			(void);

diff --git a/src/dos/drive_cache.cpp b/src/dos/drive_cache.cpp
@@ -824,7 +824,7 @@ bool DOS_Drive_Cache::OpenDir(CFileInfo* dir, const char* expand, uint16_t& id)
     return false;
 }
 
-char* DOS_Drive_Cache::CreateEntry(CFileInfo* dir, const char* name, const char* sname, bool is_directory) {
+char* DOS_Drive_Cache::CreateEntry(CFileInfo* dir, const char* name, const char* sname, bool is_directory, bool skipSort) {
     CFileInfo* info = new CFileInfo;
     strcpy(info->shortname, sname);
 	strcpy(info->orgname, name);
@@ -835,7 +835,7 @@ char* DOS_Drive_Cache::CreateEntry(CFileInfo* dir, const char* name, const char*
     if (sname[0]==0) CreateShortName(dir, info);
 
     // keep list sorted (so GetLongName works correctly, used by CreateShortName in this routine)
-    if (dir->fileList.size()>0) {
+    if (dir->fileList.size()>0 && !skipSort) {
         if (!(strcmp(info->shortname,dir->fileList.back()->shortname)<0)) {
             // append at end of list
             dir->fileList.push_back(info);
@@ -891,12 +891,15 @@ bool DOS_Drive_Cache::ReadDir(uint16_t id, char* &result, char * &lresult) {
         char dir_name[CROSS_LEN], dir_sname[DOS_NAMELENGTH+1];
         bool is_directory;
         if (drive->read_directory_first(dirp, dir_name, dir_sname, is_directory)) {
-            CreateEntry(dirSearch[id], dir_name, dir_sname, is_directory);
+            CreateEntry(dirSearch[id], dir_name, dir_sname, is_directory, /*skip search*/true);
             while (drive->read_directory_next(dirp, dir_name, dir_sname, is_directory)) {
-                CreateEntry(dirSearch[id], dir_name, dir_sname, is_directory);
+                CreateEntry(dirSearch[id], dir_name, dir_sname, is_directory, /*skip search*/true);
             }
         }
 
+        // Insertion skipped sorting, now sort in one go, which should be faster when faced with many files
+        std::sort(dirSearch[id]->fileList.begin(), dirSearch[id]->fileList.end(), SortByName);
+
         // close dir
         drive->closedir(dirp);