Internal change

PiperOrigin-RevId: 374236491

official/nlp/configs/encoders.py

@@ -18,15 +18,15 @@ Includes configurations and factory methods.
 """
 from typing import Optional
 
-from absl import logging
 import dataclasses
 import gin
 import tensorflow as tf
 
 from official.modeling import hyperparams
 from official.modeling import tf_utils
+from official.nlp.modeling import layers
 from official.nlp.modeling import networks
-from official.nlp.projects.bigbird import encoder as bigbird_encoder
+from official.nlp.projects.bigbird import attention as bigbird_attention
 
 
 @dataclasses.dataclass
@@ -177,15 +177,6 @@ class EncoderConfig(hyperparams.OneOfConfig):
   xlnet: XLNetEncoderConfig = XLNetEncoderConfig()
 
 
-ENCODER_CLS = {
-    "bert": networks.BertEncoder,
-    "mobilebert": networks.MobileBERTEncoder,
-    "albert": networks.AlbertEncoder,
-    "bigbird": bigbird_encoder.BigBirdEncoder,
-    "xlnet": networks.XLNetBase,
-}
-
-
 @gin.configurable
 def build_encoder(config: EncoderConfig,
                   embedding_layer: Optional[tf.keras.layers.Layer] = None,
@@ -205,13 +196,11 @@ def build_encoder(config: EncoderConfig,
   Returns:
     An encoder instance.
   """
-  encoder_type = config.type
-  encoder_cfg = config.get()
-  encoder_cls = encoder_cls or ENCODER_CLS[encoder_type]
-  logging.info("Encoder class: %s to build...", encoder_cls.__name__)
   if bypass_config:
     return encoder_cls()
-  if encoder_cls.__name__ == "EncoderScaffold":
+  encoder_type = config.type
+  encoder_cfg = config.get()
+  if encoder_cls and encoder_cls.__name__ == "EncoderScaffold":
     embedding_cfg = dict(
         vocab_size=encoder_cfg.vocab_size,
         type_vocab_size=encoder_cfg.type_vocab_size,
@@ -243,7 +232,7 @@ def build_encoder(config: EncoderConfig,
     return encoder_cls(**kwargs)
 
   if encoder_type == "mobilebert":
-    return encoder_cls(
+    return networks.MobileBERTEncoder(
         word_vocab_size=encoder_cfg.word_vocab_size,
         word_embed_size=encoder_cfg.word_embed_size,
         type_vocab_size=encoder_cfg.type_vocab_size,
@@ -265,7 +254,7 @@ def build_encoder(config: EncoderConfig,
         input_mask_dtype=encoder_cfg.input_mask_dtype)
 
   if encoder_type == "albert":
-    return encoder_cls(
+    return networks.AlbertEncoder(
         vocab_size=encoder_cfg.vocab_size,
         embedding_width=encoder_cfg.embedding_width,
         hidden_size=encoder_cfg.hidden_size,
@@ -282,26 +271,55 @@ def build_encoder(config: EncoderConfig,
         dict_outputs=True)
 
   if encoder_type == "bigbird":
-    return encoder_cls(
+    # TODO(frederickliu): Support use_gradient_checkpointing.
+    if encoder_cfg.use_gradient_checkpointing:
+      raise ValueError("Gradient checkpointing unsupported at the moment.")
+    embedding_cfg = dict(
         vocab_size=encoder_cfg.vocab_size,
+        type_vocab_size=encoder_cfg.type_vocab_size,
         hidden_size=encoder_cfg.hidden_size,
-        num_layers=encoder_cfg.num_layers,
+        max_seq_length=encoder_cfg.max_position_embeddings,
+        initializer=tf.keras.initializers.TruncatedNormal(
+            stddev=encoder_cfg.initializer_range),
+        dropout_rate=encoder_cfg.dropout_rate)
+    attention_cfg = dict(
+        num_heads=encoder_cfg.num_attention_heads,
+        key_dim=int(encoder_cfg.hidden_size // encoder_cfg.num_attention_heads),
+        kernel_initializer=tf.keras.initializers.TruncatedNormal(
+            stddev=encoder_cfg.initializer_range),
+        max_rand_mask_length=encoder_cfg.max_position_embeddings,
+        num_rand_blocks=encoder_cfg.num_rand_blocks,
+        from_block_size=encoder_cfg.block_size,
+        to_block_size=encoder_cfg.block_size,
+        )
+    hidden_cfg = dict(
         num_attention_heads=encoder_cfg.num_attention_heads,
         intermediate_size=encoder_cfg.intermediate_size,
-        activation=tf_utils.get_activation(encoder_cfg.hidden_activation),
+        intermediate_activation=tf_utils.get_activation(
+            encoder_cfg.hidden_activation),
         dropout_rate=encoder_cfg.dropout_rate,
         attention_dropout_rate=encoder_cfg.attention_dropout_rate,
-        num_rand_blocks=encoder_cfg.num_rand_blocks,
-        block_size=encoder_cfg.block_size,
-        max_position_embeddings=encoder_cfg.max_position_embeddings,
-        type_vocab_size=encoder_cfg.type_vocab_size,
-        initializer=tf.keras.initializers.TruncatedNormal(
+        kernel_initializer=tf.keras.initializers.TruncatedNormal(
             stddev=encoder_cfg.initializer_range),
-        embedding_width=encoder_cfg.embedding_width,
-        use_gradient_checkpointing=encoder_cfg.use_gradient_checkpointing)
+        attention_cls=bigbird_attention.BigBirdAttention,
+        attention_cfg=attention_cfg)
+    kwargs = dict(
+        embedding_cfg=embedding_cfg,
+        hidden_cls=layers.TransformerScaffold,
+        hidden_cfg=hidden_cfg,
+        num_hidden_instances=encoder_cfg.num_layers,
+        mask_cls=bigbird_attention.BigBirdMasks,
+        mask_cfg=dict(block_size=encoder_cfg.block_size),
+        pooled_output_dim=encoder_cfg.hidden_size,
+        pooler_layer_initializer=tf.keras.initializers.TruncatedNormal(
+            stddev=encoder_cfg.initializer_range),
+        return_all_layer_outputs=False,
+        dict_outputs=True,
+        layer_idx_as_attention_seed=True)
+    return networks.EncoderScaffold(**kwargs)
 
   if encoder_type == "xlnet":
-    return encoder_cls(
+    return networks.XLNetBase(
         vocab_size=encoder_cfg.vocab_size,
         num_layers=encoder_cfg.num_layers,
         hidden_size=encoder_cfg.hidden_size,
@@ -325,7 +343,7 @@ def build_encoder(config: EncoderConfig,
 
   # Uses the default BERTEncoder configuration schema to create the encoder.
   # If it does not match, please add a switch branch by the encoder type.
-  return encoder_cls(
+  return networks.BertEncoder(
       vocab_size=encoder_cfg.vocab_size,
       hidden_size=encoder_cfg.hidden_size,
       num_layers=encoder_cfg.num_layers,

official/nlp/modeling/networks/encoder_scaffold.py

@@ -14,6 +14,7 @@
 
 """Transformer-based text encoder network."""
 # pylint: disable=g-classes-have-attributes
+import copy
 import inspect
 
 from absl import logging
@@ -86,12 +87,19 @@ class EncoderScaffold(tf.keras.Model):
         `dropout_rate`: The overall dropout rate for the transformer layers.
         `attention_dropout_rate`: The dropout rate for the attention layers.
         `kernel_initializer`: The initializer for the transformer layers.
+    mask_cls: The class to generate masks passed into hidden_cls() from inputs
+      and 2D mask indicating positions we can attend to. It is the caller's job
+      to make sure the output of the mask_layer can be used by hidden_layer.
+      A mask_cls is usually mapped to a hidden_cls.
+    mask_cfg: A dict of kwargs pass to mask_cls.
     layer_norm_before_pooling: Whether to add a layer norm before the pooling
       layer. You probably want to turn this on if you set `norm_first=True` in
       transformer layers.
     return_all_layer_outputs: Whether to output sequence embedding outputs of
       all encoder transformer layers.
     dict_outputs: Whether to use a dictionary as the model outputs.
+    layer_idx_as_attention_seed: Whether to include layer_idx in
+      attention_cfg in hidden_cfg.
   """
 
   def __init__(self,
@@ -104,9 +112,12 @@ class EncoderScaffold(tf.keras.Model):
                num_hidden_instances=1,
                hidden_cls=layers.Transformer,
                hidden_cfg=None,
+               mask_cls=keras_nlp.layers.SelfAttentionMask,
+               mask_cfg=None,
                layer_norm_before_pooling=False,
                return_all_layer_outputs=False,
                dict_outputs=False,
+               layer_idx_as_attention_seed=False,
                **kwargs):
 
     if embedding_cls:
@@ -169,15 +180,25 @@ class EncoderScaffold(tf.keras.Model):
           tf.keras.layers.Dropout(
               rate=embedding_cfg['dropout_rate'])(embeddings))
 
-      attention_mask = keras_nlp.layers.SelfAttentionMask()(embeddings, mask)
+      mask_cfg = {} if mask_cfg is None else mask_cfg
+      if inspect.isclass(mask_cls):
+        mask_layer = mask_cls(**mask_cfg)
+      else:
+        mask_layer = mask_cls
+      attention_mask = mask_layer(embeddings, mask)
 
     data = embeddings
 
     layer_output_data = []
     hidden_layers = []
-    for _ in range(num_hidden_instances):
+    hidden_cfg = hidden_cfg if hidden_cfg else {}
+    for i in range(num_hidden_instances):
       if inspect.isclass(hidden_cls):
-        layer = hidden_cls(**hidden_cfg) if hidden_cfg else hidden_cls()
+        if hidden_cfg and 'attention_cfg' in hidden_cfg and (
+            layer_idx_as_attention_seed):
+          hidden_cfg = copy.deepcopy(hidden_cfg)
+          hidden_cfg['attention_cfg']['seed'] = i
+        layer = hidden_cls(**hidden_cfg)
       else:
         layer = hidden_cls
       data = layer([data, attention_mask])
@@ -227,6 +248,8 @@ class EncoderScaffold(tf.keras.Model):
 
     self._hidden_cls = hidden_cls
     self._hidden_cfg = hidden_cfg
+    self._mask_cls = mask_cls
+    self._mask_cfg = mask_cfg
     self._num_hidden_instances = num_hidden_instances
     self._pooled_output_dim = pooled_output_dim
     self._pooler_layer_initializer = pooler_layer_initializer
@@ -247,6 +270,7 @@ class EncoderScaffold(tf.keras.Model):
     if self._layer_norm_before_pooling:
       self._output_layer_norm = output_layer_norm
     self._pooler_layer = pooler_layer
+    self._layer_idx_as_attention_seed = layer_idx_as_attention_seed
 
     logging.info('EncoderScaffold configs: %s', self.get_config())
 
@@ -260,32 +284,48 @@ class EncoderScaffold(tf.keras.Model):
         'layer_norm_before_pooling': self._layer_norm_before_pooling,
         'return_all_layer_outputs': self._return_all_layer_outputs,
         'dict_outputs': self._dict_outputs,
+        'layer_idx_as_attention_seed': self._layer_idx_as_attention_seed
+    }
+    cfgs = {
+        'hidden_cfg': self._hidden_cfg,
+        'mask_cfg': self._mask_cfg
     }
-    if self._hidden_cfg:
-      config_dict['hidden_cfg'] = {}
-      for k, v in self._hidden_cfg.items():
+
+    for cfg_name, cfg in cfgs.items():
+      if cfg:
+        config_dict[cfg_name] = {}
+        for k, v in cfg.items():
           # `self._hidden_cfg` may contain `class`, e.g., when `hidden_cfg` is
-        # `TransformerScaffold`, its `attention_cls` argument can be a `class`.
+          # `TransformerScaffold`, `attention_cls` argument can be a `class`.
           if inspect.isclass(v):
-          config_dict['hidden_cfg'][k] = tf.keras.utils.get_registered_name(v)
+            config_dict[cfg_name][k] = tf.keras.utils.get_registered_name(v)
           else:
-          config_dict['hidden_cfg'][k] = v
+            config_dict[cfg_name][k] = v
+
+    clss = {
+        'hidden_cls': self._hidden_cls,
+        'mask_cls': self._mask_cls
+    }
 
-    if inspect.isclass(self._hidden_cls):
-      config_dict['hidden_cls_string'] = tf.keras.utils.get_registered_name(
-          self._hidden_cls)
+    for cls_name, cls in clss.items():
+      if inspect.isclass(cls):
+        key = '{}_string'.format(cls_name)
+        config_dict[key] = tf.keras.utils.get_registered_name(cls)
       else:
-      config_dict['hidden_cls'] = self._hidden_cls
+        config_dict[cls_name] = cls
 
     config_dict.update(self._kwargs)
     return config_dict
 
   @classmethod
   def from_config(cls, config, custom_objects=None):
-    if 'hidden_cls_string' in config:
-      config['hidden_cls'] = tf.keras.utils.get_registered_object(
-          config['hidden_cls_string'], custom_objects=custom_objects)
-      del config['hidden_cls_string']
+    cls_names = ['hidden_cls', 'mask_cls']
+    for cls_name in cls_names:
+      cls_string = '{}_string'.format(cls_name)
+      if cls_string in config:
+        config[cls_name] = tf.keras.utils.get_registered_object(
+            config[cls_string], custom_objects=custom_objects)
+        del config[cls_string]
     return cls(**config)
 
   def get_embedding_table(self):

official/nlp/modeling/networks/encoder_scaffold_test.py

@@ -20,6 +20,7 @@ import tensorflow as tf
 
 from tensorflow.python.keras import keras_parameterized  # pylint: disable=g-direct-tensorflow-import
 from official.modeling import activations
+from official.nlp import keras_nlp
 from official.nlp.modeling import layers
 from official.nlp.modeling.networks import encoder_scaffold
 
@@ -47,6 +48,30 @@ class ValidatedTransformerLayer(layers.Transformer):
     return config
 
 
+# Test class that wraps a standard self attention mask layer.
+# If this layer is called at any point, the list passed to the config
+# object will be filled with a
+# boolean 'True'. We register this class as a Keras serializable so we can
+# test serialization below.
+@tf.keras.utils.register_keras_serializable(package="TestOnly")
+class ValidatedMaskLayer(keras_nlp.layers.SelfAttentionMask):
+
+  def __init__(self, call_list, call_class=None, **kwargs):
+    super(ValidatedMaskLayer, self).__init__(**kwargs)
+    self.list = call_list
+    self.call_class = call_class
+
+  def call(self, inputs, mask):
+    self.list.append(True)
+    return super(ValidatedMaskLayer, self).call(inputs, mask)
+
+  def get_config(self):
+    config = super(ValidatedMaskLayer, self).get_config()
+    config["call_list"] = self.list
+    config["call_class"] = tf.keras.utils.get_registered_name(self.call_class)
+    return config
+
+
 @tf.keras.utils.register_keras_serializable(package="TestLayerOnly")
 class TestLayer(tf.keras.layers.Layer):
   pass
@@ -95,6 +120,11 @@ class EncoderScaffoldLayerClassTest(keras_parameterized.TestCase):
         "call_list":
             call_list
     }
+    mask_call_list = []
+    mask_cfg = {
+        "call_list":
+            mask_call_list
+    }
     # Create a small EncoderScaffold for testing.
     test_network = encoder_scaffold.EncoderScaffold(
         num_hidden_instances=num_hidden_instances,
@@ -103,6 +133,8 @@ class EncoderScaffoldLayerClassTest(keras_parameterized.TestCase):
             stddev=0.02),
         hidden_cls=ValidatedTransformerLayer,
         hidden_cfg=hidden_cfg,
+        mask_cls=ValidatedMaskLayer,
+        mask_cfg=mask_cfg,
         embedding_cfg=embedding_cfg,
         layer_norm_before_pooling=True,
         return_all_layer_outputs=return_all_layer_outputs)
@@ -530,10 +562,15 @@ class EncoderScaffoldHiddenInstanceTest(keras_parameterized.TestCase):
         "call_list":
             call_list
     }
+    mask_call_list = []
+    mask_cfg = {
+        "call_list": mask_call_list
+    }
     # Create a small EncoderScaffold for testing. This time, we pass an already-
     # instantiated layer object.
 
     xformer = ValidatedTransformerLayer(**hidden_cfg)
+    xmask = ValidatedMaskLayer(**mask_cfg)
 
     test_network = encoder_scaffold.EncoderScaffold(
         num_hidden_instances=3,
@@ -541,6 +578,7 @@ class EncoderScaffoldHiddenInstanceTest(keras_parameterized.TestCase):
         pooler_layer_initializer=tf.keras.initializers.TruncatedNormal(
             stddev=0.02),
         hidden_cls=xformer,
+        mask_cls=xmask,
         embedding_cfg=embedding_cfg)
 
     # Create the inputs (note that the first dimension is implicit).
@@ -603,6 +641,8 @@ class EncoderScaffoldHiddenInstanceTest(keras_parameterized.TestCase):
         "call_class":
             TestLayer
     }
+    mask_call_list = []
+    mask_cfg = {"call_list": mask_call_list, "call_class": TestLayer}
     # Create a small EncoderScaffold for testing. This time, we pass an already-
     # instantiated layer object.
     kwargs = dict(
@@ -614,11 +654,16 @@ class EncoderScaffoldHiddenInstanceTest(keras_parameterized.TestCase):
 
     if use_hidden_cls_instance:
       xformer = ValidatedTransformerLayer(**hidden_cfg)
+      xmask = ValidatedMaskLayer(**mask_cfg)
       test_network = encoder_scaffold.EncoderScaffold(
-          hidden_cls=xformer, **kwargs)
+          hidden_cls=xformer, mask_cls=xmask, **kwargs)
     else:
       test_network = encoder_scaffold.EncoderScaffold(
-          hidden_cls=ValidatedTransformerLayer, hidden_cfg=hidden_cfg, **kwargs)
+          hidden_cls=ValidatedTransformerLayer,
+          hidden_cfg=hidden_cfg,
+          mask_cls=ValidatedMaskLayer,
+          mask_cfg=mask_cfg,
+          **kwargs)
 
     # Create another network object from the first object's config.
     new_network = encoder_scaffold.EncoderScaffold.from_config(

official/nlp/projects/bigbird/attention.py

@@ -375,14 +375,15 @@ class BigBirdMasks(tf.keras.layers.Layer):
     super().__init__(**kwargs)
     self._block_size = block_size
 
-  def call(self, inputs):
-    encoder_shape = tf.shape(inputs)
+  def call(self, inputs, mask):
+    encoder_shape = tf.shape(mask)
+    mask = tf.cast(mask, inputs.dtype)
     batch_size, seq_length = encoder_shape[0], encoder_shape[1]
     # reshape for blocking
     blocked_encoder_mask = tf.reshape(
-        inputs, (batch_size, seq_length // self._block_size, self._block_size))
-    encoder_from_mask = tf.reshape(inputs, (batch_size, 1, seq_length, 1))
-    encoder_to_mask = tf.reshape(inputs, (batch_size, 1, 1, seq_length))
+        mask, (batch_size, seq_length // self._block_size, self._block_size))
+    encoder_from_mask = tf.reshape(mask, (batch_size, 1, seq_length, 1))
+    encoder_to_mask = tf.reshape(mask, (batch_size, 1, 1, seq_length))
 
     band_mask = create_band_mask_from_inputs(blocked_encoder_mask,
                                              blocked_encoder_mask)

official/nlp/projects/bigbird/attention_test.py

@@ -29,7 +29,6 @@ class BigbirdAttentionTest(tf.test.TestCase):
     block_size = 64
     mask_layer = attention.BigBirdMasks(block_size=block_size)
     encoder_inputs_mask = tf.zeros((batch_size, seq_length), dtype=tf.int32)
-    masks = mask_layer(tf.cast(encoder_inputs_mask, dtype=tf.float64))
     test_layer = attention.BigBirdAttention(
         num_heads=num_heads,
         key_dim=key_dim,
@@ -38,6 +37,7 @@ class BigbirdAttentionTest(tf.test.TestCase):
         seed=0)
     query = tf.random.normal(
         shape=(batch_size, seq_length, key_dim))
+    masks = mask_layer(query, tf.cast(encoder_inputs_mask, dtype=tf.float64))
     value = query
     output = test_layer(
         query=query,

official/nlp/projects/bigbird/encoder.py

@@ -177,8 +177,7 @@ class BigBirdEncoder(tf.keras.Model):
 
     self._transformer_layers = []
     data = embeddings
-    masks = attention.BigBirdMasks(block_size=block_size)(
-        tf.cast(mask, embeddings.dtype))
+    masks = attention.BigBirdMasks(block_size=block_size)(data, mask)
     encoder_outputs = []
     attn_head_dim = hidden_size // num_attention_heads
     for i in range(num_layers):