hparams: write valid tensor summaries

tensorboard/BUILD

@@ -491,6 +491,7 @@ py_library(
         "//tensorboard/compat/proto:protos_all_py_pb2",
         "//tensorboard/plugins/graph:metadata",
         "//tensorboard/plugins/histogram:metadata",
+        "//tensorboard/plugins/hparams:metadata",
         "//tensorboard/plugins/image:metadata",
         "//tensorboard/plugins/scalar:metadata",
         "//tensorboard/plugins/text:metadata",
@@ -512,6 +513,8 @@ py_test(
         "//tensorboard/plugins/graph:metadata",
         "//tensorboard/plugins/histogram:metadata",
         "//tensorboard/plugins/histogram:summary",
+        "//tensorboard/plugins/hparams:metadata",
+        "//tensorboard/plugins/hparams:summary_v2",
         "//tensorboard/plugins/scalar:metadata",
         "//tensorboard/plugins/scalar:summary",
         "//tensorboard/util:tensor_util",

tensorboard/dataclass_compat.py

@@ -27,8 +27,10 @@
 
 from tensorboard.compat.proto import event_pb2
 from tensorboard.compat.proto import summary_pb2
+from tensorboard.compat.proto import types_pb2
 from tensorboard.plugins.graph import metadata as graphs_metadata
 from tensorboard.plugins.histogram import metadata as histograms_metadata
+from tensorboard.plugins.hparams import metadata as hparams_metadata
 from tensorboard.plugins.image import metadata as images_metadata
 from tensorboard.plugins.scalar import metadata as scalars_metadata
 from tensorboard.plugins.text import metadata as text_metadata
@@ -95,6 +97,8 @@ def _migrate_value(value):
         return _migrate_scalar_value(value)
     if plugin_name == text_metadata.PLUGIN_NAME:
         return _migrate_text_value(value)
+    if plugin_name == hparams_metadata.PLUGIN_NAME:
+        return _migrate_hparams_value(value)
     return (value,)
 
 
@@ -116,3 +120,10 @@ def _migrate_image_value(value):
 def _migrate_text_value(value):
     value.metadata.data_class = summary_pb2.DATA_CLASS_TENSOR
     return (value,)
+
+
+def _migrate_hparams_value(value):
+    value.metadata.data_class = summary_pb2.DATA_CLASS_TENSOR
+    if not value.HasField("tensor"):
+        value.tensor.CopyFrom(hparams_metadata.NULL_TENSOR)
+    return (value,)

tensorboard/dataclass_compat_test.py

@@ -31,6 +31,8 @@
 from tensorboard.plugins.graph import metadata as graphs_metadata
 from tensorboard.plugins.histogram import metadata as histogram_metadata
 from tensorboard.plugins.histogram import summary as histogram_summary
+from tensorboard.plugins.hparams import metadata as hparams_metadata
+from tensorboard.plugins.hparams import summary_v2 as hparams_summary
 from tensorboard.plugins.scalar import metadata as scalar_metadata
 from tensorboard.plugins.scalar import summary as scalar_summary
 from tensorboard.util import tensor_util
@@ -138,6 +140,29 @@ def test_histogram(self):
             histogram_metadata.PLUGIN_NAME,
         )
 
+    def test_hparams(self):
+        old_event = event_pb2.Event()
+        old_event.step = 0
+        old_event.wall_time = 456.75
+        hparams_pb = hparams_summary.hparams_pb({"optimizer": "adam"})
+        # Simulate legacy event with no tensor content
+        for v in hparams_pb.value:
+            v.ClearField("tensor")
+        old_event.summary.CopyFrom(hparams_pb)
+
+        new_events = self._migrate_event(old_event)
+        self.assertLen(new_events, 1)
+        self.assertLen(new_events[0].summary.value, 1)
+        value = new_events[0].summary.value[0]
+        self.assertEqual(value.tensor, hparams_metadata.NULL_TENSOR)
+        self.assertEqual(
+            value.metadata.data_class, summary_pb2.DATA_CLASS_TENSOR
+        )
+        self.assertEqual(
+            value.metadata.plugin_data,
+            hparams_pb.value[0].metadata.plugin_data,
+        )
+
     def test_graph_def(self):
         # Create a `GraphDef` and write it to disk as an event.
         logdir = self.get_temp_dir()

tensorboard/plugins/hparams/BUILD

@@ -316,6 +316,7 @@ py_library(
         ":error",
         ":protos_all_py_pb2",
         "//tensorboard/compat/proto:protos_all_py_pb2",
+        "//tensorboard/util:tensor_util",
     ],
 )
 

tensorboard/plugins/hparams/metadata.py

@@ -19,13 +19,22 @@
 from __future__ import print_function
 
 from tensorboard.compat.proto import summary_pb2
+from tensorboard.compat.proto import types_pb2
 from tensorboard.plugins.hparams import error
 from tensorboard.plugins.hparams import plugin_data_pb2
+from tensorboard.util import tensor_util
 
 
 PLUGIN_NAME = "hparams"
 PLUGIN_DATA_VERSION = 0
 
+# Tensor value for use in summaries that really only need to store
+# metadata. A length-0 float vector is of minimal serialized length
+# (6 bytes) among valid tensors. Cache this: computing it takes on the
+# order of tens of microseconds.
+NULL_TENSOR = tensor_util.make_tensor_proto(
+    [], dtype=types_pb2.DT_FLOAT, shape=(0,)
+)
 
 EXPERIMENT_TAG = "_hparams_/experiment"
 SESSION_START_INFO_TAG = "_hparams_/session_start_info"

tensorboard/plugins/hparams/summary.py

@@ -193,5 +193,14 @@ def _summary(tag, hparams_plugin_data):
     tb_metadata = metadata.create_summary_metadata(hparams_plugin_data)
     raw_metadata = tb_metadata.SerializeToString()
     tf_metadata = tf.compat.v1.SummaryMetadata.FromString(raw_metadata)
-    summary.value.add(tag=tag, metadata=tf_metadata)
+    summary.value.add(
+        tag=tag, metadata=tf_metadata, tensor=_TF_NULL_TENSOR,
+    )
     return summary
+
+
+# Like `metadata.NULL_TENSOR`, but with the TensorFlow version of the
+# proto. Slight kludge needed to expose the `TensorProto` type.
+_TF_NULL_TENSOR = type(tf.make_tensor_proto(0)).FromString(
+    metadata.NULL_TENSOR.SerializeToString()
+)

tensorboard/plugins/hparams/summary_test.py

@@ -70,6 +70,7 @@ def test_experiment_pb(self):
                 value=[
                     tf.compat.v1.Summary.Value(
                         tag="_hparams_/experiment",
+                        tensor=summary._TF_NULL_TENSOR,
                         metadata=tf.compat.v1.SummaryMetadata(
                             plugin_data=tf.compat.v1.SummaryMetadata.PluginData(
                                 plugin_name="hparams",
@@ -98,6 +99,7 @@ def test_session_end_pb(self):
                 value=[
                     tf.compat.v1.Summary.Value(
                         tag="_hparams_/session_end_info",
+                        tensor=summary._TF_NULL_TENSOR,
                         metadata=tf.compat.v1.SummaryMetadata(
                             plugin_data=tf.compat.v1.SummaryMetadata.PluginData(
                                 plugin_name="hparams",

tensorboard/plugins/hparams/summary_v2.py

@@ -268,7 +268,9 @@ def _summary_pb(tag, hparams_plugin_data):
     """
     summary = summary_pb2.Summary()
     summary_metadata = metadata.create_summary_metadata(hparams_plugin_data)
-    summary.value.add(tag=tag, metadata=summary_metadata)
+    value = summary.value.add(
+        tag=tag, metadata=summary_metadata, tensor=metadata.NULL_TENSOR
+    )
     return summary
 
 

tensorboard/plugins/hparams/summary_v2_test.py

@@ -39,6 +39,7 @@
 from tensorboard import test
 from tensorboard.compat import tf
 from tensorboard.compat.proto import summary_pb2
+from tensorboard.compat.proto import tensor_pb2
 from tensorboard.plugins.hparams import api_pb2
 from tensorboard.plugins.hparams import metadata
 from tensorboard.plugins.hparams import plugin_data_pb2
@@ -108,6 +109,12 @@ def _check_summary(self, summary_pb, check_group_name=False):
         self.assertEqual(
             actual_value.metadata.plugin_data.plugin_name, metadata.PLUGIN_NAME,
         )
+        self.assertEqual(
+            tensor_pb2.TensorProto.FromString(
+                actual_value.tensor.SerializeToString()
+            ),
+            metadata.NULL_TENSOR,
+        )
         plugin_content = actual_value.metadata.plugin_data.content
         info_pb = metadata.parse_session_start_info_plugin_data(plugin_content)
         # Usually ignore the `group_name` field; its properties are checked