gc: make it safer by only activating by use of certain flags

dvc/command/gc.py

@@ -12,6 +12,16 @@
 
 class CmdGC(CmdBase):
     def run(self):
+        from dvc.repo.gc import _raise_error_if_all_disabled
+
+        _raise_error_if_all_disabled(
+            all_branches=self.args.all_branches,
+            all_tags=self.args.all_tags,
+            all_commits=self.args.all_commits,
+            workspace=self.args.workspace,
+            cloud=self.args.cloud,
+        )
+
         msg = "This will remove all cache except items used in "
 
         msg += "the working tree"
@@ -47,6 +57,7 @@ def run(self):
             force=self.args.force,
             jobs=self.args.jobs,
             repos=self.args.repos,
+            workspace=self.args.workspace,
         )
         return 0
 
@@ -64,6 +75,13 @@ def add_parser(subparsers, parent_parser):
         help=GC_HELP,
         formatter_class=argparse.RawDescriptionHelpFormatter,
     )
+    gc_parser.add_argument(
+        "-w",
+        "--workspace",
+        action="store_true",
+        default=False,
+        help="Keep data files used in the current workspace.",
+    )
     gc_parser.add_argument(
         "-a",
         "--all-branches",

dvc/exceptions.py

@@ -7,6 +7,10 @@ class DvcException(Exception):
     """Base class for all dvc exceptions."""
 
 
+class InvalidArgumentError(ValueError, DvcException):
+    """Thrown if arguments are invalid."""
+
+
 class OutputDuplicationError(DvcException):
     """Thrown if a file/directory is specified as an output in more than one
     stage.

dvc/repo/gc.py

@@ -2,6 +2,7 @@
 
 from . import locked
 from dvc.cache import NamedCache
+from dvc.exceptions import InvalidArgumentError
 
 
 logger = logging.getLogger(__name__)
@@ -13,6 +14,15 @@ def _do_gc(typ, func, clist):
         logger.info("No unused '{}' cache to remove.".format(typ))
 
 
+def _raise_error_if_all_disabled(**kwargs):
+    if not any(kwargs.values()):
+        raise InvalidArgumentError(
+            "Invalid Arguments. Either of ({}) needs to be enabled.".format(
+                ", ".join(kwargs.keys())
+            )
+        )
+
+
 @locked
 def gc(
     self,
@@ -25,7 +35,20 @@ def gc(
     force=False,
     jobs=None,
     repos=None,
+    workspace=False,
 ):
+
+    # require `workspace` to be true to come into effect.
+    # assume `workspace` to be enabled if any of `all_tags`, `all_commits`,
+    # or `all_branches` are enabled.
+    _raise_error_if_all_disabled(
+        workspace=workspace,
+        all_tags=all_tags,
+        all_commits=all_commits,
+        all_branches=all_branches,
+        cloud=cloud,
+    )
+
     from contextlib import ExitStack
     from dvc.repo import Repo
 

tests/func/test_gc.py

@@ -1,9 +1,11 @@
+import logging
 import os
 
 import configobj
 import pytest
 from git import Repo
 
+from dvc.compat import fspath
 from dvc.exceptions import CollectCacheError
 from dvc.main import main
 from dvc.repo import Repo as DvcRepo
@@ -28,11 +30,11 @@ def setUp(self):
             self.bad_cache.append(path)
 
     def test_api(self):
-        self.dvc.gc()
+        self.dvc.gc(workspace=True)
         self._test_gc()
 
     def test_cli(self):
-        ret = main(["gc", "-f"])
+        ret = main(["gc", "-wf"])
         self.assertEqual(ret, 0)
         self._test_gc()
 
@@ -169,10 +171,10 @@ def test(self):
 
         self._check_cache(3)
 
-        self.dvc.gc(repos=[self.additional_path])
+        self.dvc.gc(repos=[self.additional_path], workspace=True)
         self._check_cache(3)
 
-        self.dvc.gc()
+        self.dvc.gc(workspace=True)
         self._check_cache(2)
 
 
@@ -196,10 +198,10 @@ def test_gc_no_dir_cache(tmp_dir, dvc):
     os.unlink(dir_stage.outs[0].cache_path)
 
     with pytest.raises(CollectCacheError):
-        dvc.gc()
+        dvc.gc(workspace=True)
 
     assert _count_files(dvc.cache.local.cache_dir) == 4
-    dvc.gc(force=True)
+    dvc.gc(force=True, workspace=True)
     assert _count_files(dvc.cache.local.cache_dir) == 2
 
 
@@ -218,5 +220,59 @@ def test_gc_no_unpacked_dir(tmp_dir, dvc):
 
     assert os.path.exists(unpackeddir)
 
-    dvc.gc(force=True)
+    dvc.gc(force=True, workspace=True)
     assert not os.path.exists(unpackeddir)
+
+
+def test_gc_without_workspace_raises_error(tmp_dir, dvc):
+    dvc.gc(force=True, workspace=True)  # works without error
+
+    from dvc.exceptions import InvalidArgumentError
+
+    with pytest.raises(InvalidArgumentError):
+        dvc.gc(force=True)
+
+    with pytest.raises(InvalidArgumentError):
+        dvc.gc(force=True, workspace=False)
+
+
+def test_gc_without_workspace_on_tags_branches_commits(tmp_dir, dvc):
+    dvc.gc(force=True, all_tags=True)
+    dvc.gc(force=True, all_commits=True)
+    dvc.gc(force=False, all_branches=True)
+
+    # even if workspace is disabled, and others are enabled, assume as if
+    # workspace is enabled.
+    dvc.gc(force=False, all_branches=True, all_commits=False, workspace=False)
+
+
+def test_gc_without_workspace(tmp_dir, dvc, caplog):
+    with caplog.at_level(logging.WARNING, logger="dvc"):
+        assert main(["gc", "-vf"]) == 255
+
+    assert "Invalid Arguments" in caplog.text
+
+
+def test_gc_with_possible_args_positive(tmp_dir, dvc):
+    for flag in [
+        "-w",
+        "-a",
+        "-T",
+        "--all-commits",
+        "-aT",
+        "-wa",
+        "-waT",
+    ]:
+        assert main(["gc", "-vf", flag]) == 0
+
+
+def test_gc_cloud_positive(tmp_dir, dvc, tmp_path_factory):
+    with dvc.config.edit() as conf:
+        storage = fspath(tmp_path_factory.mktemp("test_remote_base"))
+        conf["remote"]["local_remote"] = {"url": storage}
+        conf["core"]["remote"] = "local_remote"
+
+    dvc.push()
+
+    for flag in ["-c", "-ca", "-cT", "-caT", "-cwT"]:
+        assert main(["gc", "-vf", flag]) == 0

tests/func/test_repro.py

@@ -949,7 +949,7 @@ def test(self, mock_prompt):
         self.assertEqual(self.dvc.status([cmd_stage.path]), {})
 
         self.assertEqual(self.dvc.status(), {})
-        self.dvc.gc()
+        self.dvc.gc(workspace=True)
         self.assertEqual(self.dvc.status(), {})
 
         self.dvc.remove(cmd_stage.path, outs_only=True)