fs: add cat/cat_file/cat_ranges/pipe/pipe_file/touch methods

dvc/data/db/reference.py

@@ -1,4 +1,3 @@
-import io
 import logging
 import os
 from typing import TYPE_CHECKING, Dict
@@ -37,10 +36,10 @@ class ReferenceObjectDB(ObjectDB):
             pass
         fs_path = self.hash_to_path(hash_info.value)
         try:
-            with self.fs.open(fs_path, "rb") as fobj:
-                ref_file = ReferenceHashFile.from_bytes(
-                    fobj.read(), fs_cache=self._fs_cache
-                )
+            ref_file = ReferenceHashFile.from_bytes(
+                self.fs.cat_file(fs_path),
+                fs_cache=self._fs_cache,
+            )
         except OSError:
             raise FileNotFoundError
         try:
@@ -70,10 +69,8 @@ class ReferenceObjectDB(ObjectDB):
             )
         ref_file = ReferenceHashFile(from_info, from_fs, hash_info)
         self._obj_cache[hash_info] = ref_file
-        ref_fobj = io.BytesIO(ref_file.to_bytes())
-        ref_fobj.seek(0)
         try:
-            self.fs.upload(ref_fobj, to_info)
+            self.fs.pipe_file(to_info, ref_file.to_bytes())
         except OSError as exc:
             if isinstance(exc, FileExistsError) or (
                 os.name == "nt"

dvc/data/tree.py

@@ -62,8 +62,7 @@ class Tree(HashFile):
 
         memfs = MemoryFileSystem()
         fs_path = "memory://{}".format(tmp_fname(""))
-        with memfs.open(fs_path, "wb") as fobj:
-            fobj.write(self.as_bytes())
+        memfs.pipe_file(fs_path, self.as_bytes())
         self.fs = memfs
         self.fs_path = fs_path
         if hash_info:

dvc/fs/base.py

@@ -188,6 +188,54 @@ class FileSystem:
     ) -> "IO":  # pylint: disable=arguments-differ
         return self.fs.open(path, mode=mode, encoding=encoding, **kwargs)
 
+    def cat(
+        self,
+        path: Union[AnyFSPath, List[AnyFSPath]],
+        recursive: bool = False,
+        on_error: "Literal['raise', 'omit', 'return']" = "raise",
+        **kwargs: Any,
+    ) -> Union[bytes, Dict[AnyFSPath, bytes]]:
+        return self.fs.cat(
+            path, recursive=recursive, on_error=on_error, **kwargs
+        )
+
+    def cat_ranges(
+        self,
+        paths: List[AnyFSPath],
+        starts: List[int],
+        ends: List[int],
+        max_gap: int = None,
+        **kwargs,
+    ) -> List[bytes]:
+        return self.fs.cat_ranges(
+            paths, starts, ends, max_gap=max_gap, **kwargs
+        )
+
+    def cat_file(
+        self,
+        path: AnyFSPath,
+        start: int = None,
+        end: int = None,
+        **kwargs: Any,
+    ) -> bytes:
+        return self.fs.cat_file(path, start=start, end=end, **kwargs)
+
+    def pipe_file(self, path: AnyFSPath, value: bytes, **kwargs: Any) -> None:
+        return self.fs.pipe_file(path, value, **kwargs)
+
+    def pipe(
+        self,
+        path: Union[AnyFSPath, Dict[AnyFSPath, bytes]],
+        value: Optional[bytes] = None,
+        **kwargs: Any,
+    ) -> None:
+        return self.fs.pipe(path, value=value, **kwargs)
+
+    def touch(
+        self, path: AnyFSPath, truncate: bool = True, **kwargs: Any
+    ) -> None:
+        return self.fs.touch(path, truncate=truncate, **kwargs)
+
     def checksum(self, path: AnyFSPath) -> str:
         return self.fs.checksum(path)
 

dvc/fs/memory.py

@@ -10,8 +10,6 @@ from .base import FileSystem
 class MemoryFileSystem(FileSystem):  # pylint:disable=abstract-method
     scheme = Schemes.MEMORY
     PARAM_CHECKSUM = "md5"
-    TRAVERSE_PREFIX_LEN = 2
-    DEFAULT_BLOCKSIZE = 4096
 
     def __eq__(self, other):
         # NOTE: all fsspec MemoryFileSystem instances are equivalent and use a
@@ -26,8 +24,3 @@ class MemoryFileSystem(FileSystem):  # pylint:disable=abstract-method
         from fsspec.implementations.memory import MemoryFileSystem as MemFS
 
         return MemFS(**self.fs_args)
-
-    def open(self, *args, **kwargs):
-        with super().open(*args, **kwargs) as fobj:
-            fobj.blocksize = self.DEFAULT_BLOCKSIZE
-            return fobj

dvc/repo/experiments/init.py

@@ -177,8 +177,7 @@ def init_deps(stage: PipelineStage) -> List["Dependency"]:
         localfs.makedirs(path)
     for path in files:
         localfs.makedirs(localfs.path.parent(path), exist_ok=True)
-        with localfs.open(path, "w", encoding="utf-8"):
-            pass
+        localfs.touch(path)
 
     return new_deps