`DvcliveLoggerHook` updates to work with `DVC` (#1208)

* Updates to work with DVC

* Update docstrings

* Updated test

* Updated DVCLiveLoggerHook

* Fix name

* Added missing next_step call

* Fix expected call

* Implicit next_step

* Suggestions from review

* Update test_hooks.py

* Updated to last dvclive version

* Cleaned docstring

* Update mmcv/runner/hooks/logger/dvclive.py
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

* Update dvclive.py
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

mmcv/runner/hooks/logger/dvclive.py

 # Copyright (c) OpenMMLab. All rights reserved.
+from pathlib import Path
+
 from ...dist_utils import master_only
 from ..hook import HOOKS
 from .base import LoggerHook
@@ -11,48 +13,62 @@ class DvcliveLoggerHook(LoggerHook):
     It requires `dvclive`_ to be installed.
 
     Args:
-        path (str): Directory where dvclive will write TSV log files.
+        model_file (str):
+            Default None.
+            If not None, after each epoch the model will
+            be saved to {model_file}.
         interval (int): Logging interval (every k iterations).
             Default 10.
         ignore_last (bool): Ignore the log of last iterations in each epoch
             if less than `interval`.
             Default: True.
         reset_flag (bool): Whether to clear the output buffer after logging.
-            Default: True.
+            Default: False.
         by_epoch (bool): Whether EpochBasedRunner is used.
             Default: True.
+        kwargs:
+            Arguments for instantiating `Live`_
 
     .. _dvclive:
         https://dvc.org/doc/dvclive
+
+    .. _Live:
+        https://dvc.org/doc/dvclive/api-reference/live#parameters
     """
 
     def __init__(self,
-                 path,
+                 model_file=None,
                  interval=10,
                  ignore_last=True,
-                 reset_flag=True,
-                 by_epoch=True):
-
-        super(DvcliveLoggerHook, self).__init__(interval, ignore_last,
-                                                reset_flag, by_epoch)
-        self.path = path
-        self.import_dvclive()
+                 reset_flag=False,
+                 by_epoch=True,
+                 **kwargs):
+        super().__init__(interval, ignore_last, reset_flag, by_epoch)
+        self.model_file = model_file
+        self.import_dvclive(**kwargs)
 
-    def import_dvclive(self):
+    def import_dvclive(self, **kwargs):
         try:
-            import dvclive
+            from dvclive import Live
         except ImportError:
             raise ImportError(
                 'Please run "pip install dvclive" to install dvclive')
-        self.dvclive = dvclive
-
-    @master_only
-    def before_run(self, runner):
-        self.dvclive.init(self.path)
+        self.dvclive = Live(**kwargs)
 
     @master_only
     def log(self, runner):
         tags = self.get_loggable_tags(runner)
         if tags:
+            self.dvclive.set_step(self.get_iter(runner))
             for k, v in tags.items():
-                self.dvclive.log(k, v, step=self.get_iter(runner))
+                self.dvclive.log(k, v)
+
+    @master_only
+    def after_train_epoch(self, runner):
+        super().after_train_epoch(runner)
+        if self.model_file is not None:
+            runner.save_checkpoint(
+                Path(self.model_file).parent,
+                filename_tmpl=Path(self.model_file).name,
+                create_symlink=False,
+            )

tests/test_runner/test_hooks.py

@@ -1226,21 +1226,37 @@ def test_neptune_hook():
     hook.run.stop.assert_called_with()
 
 
-def test_dvclive_hook(tmp_path):
+def test_dvclive_hook():
     sys.modules['dvclive'] = MagicMock()
     runner = _build_demo_runner()
 
-    (tmp_path / 'dvclive').mkdir()
-    hook = DvcliveLoggerHook(str(tmp_path / 'dvclive'))
+    hook = DvcliveLoggerHook()
+    dvclive_mock = hook.dvclive
     loader = DataLoader(torch.ones((5, 2)))
 
     runner.register_hook(hook)
     runner.run([loader, loader], [('train', 1), ('val', 1)])
     shutil.rmtree(runner.work_dir)
 
-    hook.dvclive.init.assert_called_with(str(tmp_path / 'dvclive'))
-    hook.dvclive.log.assert_called_with('momentum', 0.95, step=6)
-    hook.dvclive.log.assert_any_call('learning_rate', 0.02, step=6)
+    dvclive_mock.set_step.assert_called_with(6)
+    dvclive_mock.log.assert_called_with('momentum', 0.95)
+
+
+def test_dvclive_hook_model_file(tmp_path):
+    sys.modules['dvclive'] = MagicMock()
+    runner = _build_demo_runner()
+
+    hook = DvcliveLoggerHook(model_file=osp.join(runner.work_dir, 'model.pth'))
+    runner.register_hook(hook)
+
+    loader = torch.utils.data.DataLoader(torch.ones((5, 2)))
+    loader = DataLoader(torch.ones((5, 2)))
+
+    runner.run([loader, loader], [('train', 1), ('val', 1)])
+
+    assert osp.exists(osp.join(runner.work_dir, 'model.pth'))
+
+    shutil.rmtree(runner.work_dir)
 
 
 def _build_demo_runner_without_hook(runner_type='EpochBasedRunner',