[Feature] Add hook msg for checkpoint hook (#635)

* [Feature] Add hook msg for ckpt_hook

* [Feature] Add hook msg for ckpt_hook

* add test

mmcv/runner/hooks/checkpoint.py

@@ -60,6 +60,16 @@ class CheckpointHook(Hook):
             self.out_dir = runner.work_dir
         runner.save_checkpoint(
             self.out_dir, save_optimizer=self.save_optimizer, **self.args)
+        if runner.meta is not None:
+            if self.by_epoch:
+                cur_ckpt_filename = self.args.get(
+                    'filename_tmpl', 'epoch_{}.pth').format(runner.epoch + 1)
+            else:
+                cur_ckpt_filename = self.args.get(
+                    'filename_tmpl', 'iter_{}.pth').format(runner.iter + 1)
+            runner.meta.setdefault('hook_msgs', dict())
+            runner.meta['hook_msgs']['last_ckpt'] = os.path.join(
+                self.out_dir, cur_ckpt_filename)
         # remove other checkpoints
         if self.max_keep_ckpts > 0:
             if self.by_epoch:

tests/test_runner/test_hooks.py

@@ -23,6 +23,32 @@ from mmcv.runner import (CheckpointHook, EMAHook, IterTimerHook,
 from mmcv.runner.hooks.lr_updater import CosineRestartLrUpdaterHook
 
 
+def test_checkpoint_hook():
+    """xdoctest -m tests/test_runner/test_hooks.py test_checkpoint_hook."""
+
+    # test epoch based runner
+    loader = DataLoader(torch.ones((5, 2)))
+    runner = _build_demo_runner('EpochBasedRunner', max_epochs=1)
+    runner.meta = dict()
+    checkpointhook = CheckpointHook(interval=1, by_epoch=True)
+    runner.register_hook(checkpointhook)
+    runner.run([loader], [('train', 1)])
+    assert runner.meta['hook_msgs']['last_ckpt'] == osp.join(
+        runner.work_dir, 'epoch_1.pth')
+    shutil.rmtree(runner.work_dir)
+
+    # test iter based runner
+    runner = _build_demo_runner(
+        'IterBasedRunner', max_iters=1, max_epochs=None)
+    runner.meta = dict()
+    checkpointhook = CheckpointHook(interval=1, by_epoch=False)
+    runner.register_hook(checkpointhook)
+    runner.run([loader], [('train', 1)])
+    assert runner.meta['hook_msgs']['last_ckpt'] == osp.join(
+        runner.work_dir, 'iter_1.pth')
+    shutil.rmtree(runner.work_dir)
+
+
 def test_ema_hook():
     """xdoctest -m tests/test_hooks.py test_ema_hook."""