Revert "remote: base: don't checkout existing file (iterative#2358)"

This reverts commit 5ec1d27.

Save tests to try make them work, and `_get_cache_type()` to be used
later.

dvc/remote/base.py

@@ -758,45 +758,20 @@ def safe_remove(self, path_info, force=False):
         self.remove(path_info)
 
     def _checkout_file(
-        self,
-        path_info,
-        checksum,
-        force,
-        progress_callback=None,
-        save_link=True,
+        self, path_info, checksum, force, progress_callback=None
     ):
-        # NOTE: In case if path_info is already cached and path_info's
-        # link type matches cache link type, we would like to avoid
-        # relinking.
-        if self.changed(
-            path_info, {self.PARAM_CHECKSUM: checksum}
-        ) or not self._link_matches(path_info):
+        cache_info = self.checksum_to_path_info(checksum)
+        if self.exists(path_info):
+            msg = "data '{}' exists. Removing before checkout."
+            logger.warning(msg.format(str(path_info)))
             self.safe_remove(path_info, force=force)
 
-            cache_info = self.checksum_to_path_info(checksum)
-            self.link(cache_info, path_info)
-
-            if save_link:
-                self.state.save_link(path_info)
-
-            self.state.save(path_info, checksum)
-        else:
-            # NOTE: performing (un)protection costs us +/- the same as checking
-            # if path_info is protected. Instead of implementing logic,
-            # just (un)protect according to self.protected.
-            if self.protected:
-                self.protect(path_info)
-            else:
-                # NOTE dont allow copy, because we checked before that link
-                # type matches cache, and we don't want data duplication
-                self.unprotect(path_info, allow_copy=False)
-
+        self.link(cache_info, path_info)
+        self.state.save_link(path_info)
+        self.state.save(path_info, checksum)
         if progress_callback:
             progress_callback(str(path_info))
 
-    def _link_matches(self, path_info):
-        return True
-
     def makedirs(self, path_info):
         """Optional: Implement only if the remote needs to create
         directories before copying/linking/moving data
@@ -818,14 +793,17 @@ def _checkout_dir(
         for entry in dir_info:
             relative_path = entry[self.PARAM_RELPATH]
             entry_checksum = entry[self.PARAM_CHECKSUM]
+            entry_cache_info = self.checksum_to_path_info(entry_checksum)
             entry_info = path_info / relative_path
-            self._checkout_file(
-                entry_info,
-                entry_checksum,
-                force,
-                progress_callback,
-                save_link=False,
-            )
+
+            entry_checksum_info = {self.PARAM_CHECKSUM: entry_checksum}
+            if self.changed(entry_info, entry_checksum_info):
+                if self.exists(entry_info):
+                    self.safe_remove(entry_info, force=force)
+                self.link(entry_cache_info, entry_info)
+                self.state.save(entry_info, entry_checksum)
+            if progress_callback:
+                progress_callback(str(entry_info))
 
         self._remove_redundant_files(path_info, dir_info, force)
 
@@ -904,7 +882,7 @@ def get_files_number(self, checksum):
         return 1
 
     @staticmethod
-    def unprotect(path_info, allow_copy=True):
+    def unprotect(path_info):
         pass
 
     def _get_unpacked_dir_names(self, checksums):

dvc/remote/local.py

@@ -394,22 +394,19 @@ def _log_missing_caches(checksum_info_dict):
             logger.warning(msg)
 
     @staticmethod
-    def _unprotect_file(path, allow_copy=True):
+    def _unprotect_file(path):
         if System.is_symlink(path) or System.is_hardlink(path):
-            if allow_copy:
-                logger.debug("Unprotecting '{}'".format(path))
-                tmp = os.path.join(os.path.dirname(path), "." + str(uuid()))
-
-                # The operations order is important here - if some application
-                # would access the file during the process of copyfile then it
-                # would get only the part of file. So, at first, the file
-                # should be copied with the temporary name, and then
-                # original file should be replaced by new.
-                copyfile(
-                    path, tmp, name="Unprotecting '{}'".format(relpath(path))
-                )
-                remove(path)
-                os.rename(tmp, path)
+            logger.debug("Unprotecting '{}'".format(path))
+            tmp = os.path.join(os.path.dirname(path), "." + str(uuid()))
+
+            # The operations order is important here - if some application
+            # would access the file during the process of copyfile then it
+            # would get only the part of file. So, at first, the file should be
+            # copied with the temporary name, and then original file should be
+            # replaced by new.
+            copyfile(path, tmp, name="Unprotecting '{}'".format(relpath(path)))
+            remove(path)
+            os.rename(tmp, path)
 
         else:
             logger.debug(
@@ -419,21 +416,21 @@ def _unprotect_file(path, allow_copy=True):
 
         os.chmod(path, os.stat(path).st_mode | stat.S_IWRITE)
 
-    def _unprotect_dir(self, path, allow_copy=True):
+    def _unprotect_dir(self, path):
         for fname in walk_files(path, self.repo.dvcignore):
-            self._unprotect_file(fname, allow_copy)
+            RemoteLOCAL._unprotect_file(fname)
 
-    def unprotect(self, path_info, allow_copy=True):
+    def unprotect(self, path_info):
         path = path_info.fspath
         if not os.path.exists(path):
             raise DvcException(
                 "can't unprotect non-existing data '{}'".format(path)
             )
 
         if os.path.isdir(path):
-            self._unprotect_dir(path, allow_copy)
+            self._unprotect_dir(path)
         else:
-            self._unprotect_file(path, allow_copy)
+            RemoteLOCAL._unprotect_file(path)
 
     @staticmethod
     def protect(path_info):
@@ -525,18 +522,3 @@ def _get_cache_type(self, path_info):
 
         self.cache_type_confirmed = True
         return self.cache_types[0]
-
-    def _link_matches(self, path_info):
-        is_hardlink = System.is_hardlink(path_info)
-        is_symlink = System.is_symlink(path_info)
-        is_copy_or_reflink = not is_hardlink and not is_symlink
-
-        cache_type = self._get_cache_type(path_info)
-
-        if cache_type == "symlink":
-            return is_symlink
-
-        if cache_type == "hardlink":
-            return is_hardlink
-
-        return is_copy_or_reflink