MinGW readdir reimplementation to support d_type

The original readdir implementation was fast, but didn't
support the d_type. This means that git would do additional
lstats for each entry, to figure out if the entry was a
directory or not. This unneedingly slowed down many
operations, since Windows API provides this information
directly when walking the directories.

By running this implementation on Moe's repo structure:
  mkdir bummer && cd bummer; for ((i=0;i<100;i++)); do
    mkdir $i && pushd $i;
      for ((j=0;j<1000;j++)); do echo "$j" >$j; done;
    popd;
  done

We see the following speedups:
  git add .
  -------------------
  old: 00:00:23(.087)
  new: 00:00:21(.512) 1.07x

  git status
  -------------------
  old: 00:00:03(.306)
  new: 00:00:01(.684) 1.96x

  git clean -dxf
  -------------------
  old: 00:00:01(.918)
  new: 00:00:00(.295) 6.50x

Signed-off-by: Marius Storm-Olsen <marius@trolltech.com>
Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/compat/mingw.c b/compat/mingw.c
index 12d0c2fd8d1edd54e381fbd670a5ee8d34da286f..bed417875e1344690977fd6aa41b955f127b74b4 100644 (file)
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1172,3 +1172,62 @@ char *getpass(const char *prompt)
        fputs("\n", stderr);
        return strbuf_detach(&buf, NULL);
 }
+
+#ifndef NO_MINGW_REPLACE_READDIR
+/* MinGW readdir implementation to avoid extra lstats for Git */
+struct mingw_DIR
+{
+       struct _finddata_t      dd_dta;         /* disk transfer area for this dir */
+       struct mingw_dirent     dd_dir;         /* Our own implementation, including d_type */
+       long                    dd_handle;      /* _findnext handle */
+       int                     dd_stat;        /* 0 = next entry to read is first entry, -1 = off the end, positive = 0 based index of next entry */
+       char                    dd_name[1];     /* given path for dir with search pattern (struct is extended) */
+};
+
+struct dirent *mingw_readdir(DIR *dir)
+{
+       WIN32_FIND_DATAA buf;
+       HANDLE handle;
+       struct mingw_DIR *mdir = (struct mingw_DIR*)dir;
+
+       if (!dir->dd_handle) {
+               errno = EBADF; /* No set_errno for mingw */
+               return NULL;
+       }
+
+       if (dir->dd_handle == (long)INVALID_HANDLE_VALUE && dir->dd_stat == 0)
+       {
+               handle = FindFirstFileA(dir->dd_name, &buf);
+               DWORD lasterr = GetLastError();
+               dir->dd_handle = (long)handle;
+               if (handle == INVALID_HANDLE_VALUE && (lasterr != ERROR_NO_MORE_FILES)) {
+                       errno = err_win_to_posix(lasterr);
+                       return NULL;
+               }
+       } else if (dir->dd_handle == (long)INVALID_HANDLE_VALUE) {
+               return NULL;
+       } else if (!FindNextFileA((HANDLE)dir->dd_handle, &buf)) {
+               DWORD lasterr = GetLastError();
+               FindClose((HANDLE)dir->dd_handle);
+               dir->dd_handle = (long)INVALID_HANDLE_VALUE;
+               /* POSIX says you shouldn't set errno when readdir can't
+                  find any more files; so, if another error we leave it set. */
+               if (lasterr != ERROR_NO_MORE_FILES)
+                       errno = err_win_to_posix(lasterr);
+               return NULL;
+       }
+
+       /* We get here if `buf' contains valid data.  */
+       strcpy(dir->dd_dir.d_name, buf.cFileName);
+       ++dir->dd_stat;
+
+       /* Set file type, based on WIN32_FIND_DATA */
+       mdir->dd_dir.d_type = 0;
+       if (buf.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+               mdir->dd_dir.d_type |= DT_DIR;
+       else
+               mdir->dd_dir.d_type |= DT_REG;
+
+       return (struct dirent*)&dir->dd_dir;
+}
+#endif // !NO_MINGW_REPLACE_READDIR

diff --git a/compat/mingw.h b/compat/mingw.h
index 4c50f5b1bca1e161b7e6cf0635b57f5e8d741c13..4f7ba4c13f9d0086acf9d1cfadf6912b1d641033 100644 (file)
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -235,3 +235,32 @@ int main(int argc, const char **argv) \
        return mingw_main(argc, argv); \
 } \
 static int mingw_main(c,v)
+
+#ifndef NO_MINGW_REPLACE_READDIR
+/*
+ * A replacement of readdir, to ensure that it reads the file type at
+ * the same time. This avoid extra unneeded lstats in git on MinGW
+ */
+#undef DT_UNKNOWN
+#undef DT_DIR
+#undef DT_REG
+#undef DT_LNK
+#define DT_UNKNOWN     0
+#define DT_DIR         1
+#define DT_REG         2
+#define DT_LNK         3
+
+struct mingw_dirent
+{
+       long            d_ino;                  /* Always zero. */
+       union {
+               unsigned short  d_reclen;       /* Always zero. */
+               unsigned char   d_type;         /* Reimplementation adds this */
+       };
+       unsigned short  d_namlen;               /* Length of name in d_name. */
+       char            d_name[FILENAME_MAX];   /* File name. */
+};
+#define dirent mingw_dirent
+#define readdir(x) mingw_readdir(x)
+struct dirent *mingw_readdir(DIR *dir);
+#endif // !NO_MINGW_REPLACE_READDIR