support dot product relative fast decode

tensor2tensor/models/common_attention.py

@@ -470,13 +470,18 @@ def multihead_attention(query_antecedent,
     x = common_layers.conv1d(x, output_depth, 1, name="output_transform")
     return x
 
-def _generate_relative_positions_matrix(length, max_relative_position):
+def _generate_relative_positions_matrix(length, max_relative_position,
+                                        cache=False):
   """Generates matrix of relative positions between inputs."""
-  range_vec = tf.range(length)
-  range_mat = tf.reshape(tf.tile(range_vec, [length]), [length, length])
-  #range_mat = tf.Print(range_mat, [range_mat], message="range_mat:", summarize=100)
-  distance_mat = range_mat - tf.transpose(range_mat)
-  #distance_mat = tf.Print(distance_mat, [distance_mat], message="distance_mat:", summarize=100)
+  if not cache:
+    #training process
+    range_vec = tf.range(length)
+    range_mat = tf.reshape(tf.tile(range_vec, [length]), [length, length])
+    # range_mat = tf.Print(range_mat, [range_mat], message="range_mat:", summarize=100)
+    distance_mat = range_mat - tf.transpose(range_mat)
+    # distance_mat = tf.Print(distance_mat, [distance_mat], message="distance_mat:", summarize=100)
+  else:
+    distance_mat = tf.expand_dims(tf.range(-length+1, 1, 1), 0)
 
   distance_mat_clipped = tf.clip_by_value(distance_mat, -max_relative_position,
                                           max_relative_position)
@@ -490,12 +495,14 @@ def _generate_relative_positions_matrix(length, max_relative_position):
   return final_mat
 
 def _generate_relative_positions_embeddings(length, depth,
-                                            max_relative_position, name, debug_flag=None):
-  """Generates tensor of size [length, length, depth]."""
+                                            max_relative_position, name,
+                                            debug_flag=None,
+                                            cache=False):
+  """Generates tensor of size [1 if cache else length, length, depth]."""
   with tf.variable_scope(name):
-    # wq: relative_positions_matrix shape is (L, L), value range is 0 ~ 2K (total 2K+1)
+    # libei: relative_positions_matrix shape is (L, L), value range is 0 ~ 2K (total 2K+1)
     relative_positions_matrix = _generate_relative_positions_matrix(
-        length, max_relative_position)
+        length, max_relative_position,cache=cache)
     vocab_size = max_relative_position * 2 + 1
     # Generates embedding for each relative position of dimension depth.
     embeddings_table = tf.get_variable("embeddings", [vocab_size, depth])
@@ -562,7 +569,8 @@ def dot_product_attention_relative(q,
                                    name=None,
                                    make_image_summary=False,
                                    dropout_broadcast_dims=None,
-                                   debug_flag=None):
+                                   debug_flag=None,
+                                   cache=False):
   """Calculate relative position-aware dot-product self-attention.
 
   The attention calculation is augmented with learned representations for the
@@ -595,8 +603,9 @@ def dot_product_attention_relative(q,
     # This calculation only works for self attention.
     # q, k and v must therefore have the same shape.
     # wq: compatible means same shape
-    q.get_shape().assert_is_compatible_with(k.get_shape())
-    q.get_shape().assert_is_compatible_with(v.get_shape())
+    if not cache:
+      q.get_shape().assert_is_compatible_with(k.get_shape())
+      q.get_shape().assert_is_compatible_with(v.get_shape())
 
     # Use separate embeddings suitable for keys and values.
     depth = q.get_shape().as_list()[3]
@@ -604,10 +613,12 @@ def dot_product_attention_relative(q,
     # wq: relations_keys: (L, L, H), where H is hidden size of head
     relations_keys = _generate_relative_positions_embeddings(
         length, depth, max_relative_position, "relative_positions_keys",
-        debug_flag=debug_flag+"+rp-key" if debug_flag is not None else None)
+        debug_flag=debug_flag+"+rp-key" if debug_flag is not None else None,
+        cache=cache)
     relations_values = _generate_relative_positions_embeddings(
         length, depth, max_relative_position, "relative_positions_values",
-        debug_flag=debug_flag + "+rp-value" if debug_flag is not None else None)
+        debug_flag=debug_flag + "+rp-value" if debug_flag is not None else None,
+        cache=cache)
 
     if debug_flag is not None:
         q = tf.Print(q, [q], summarize=100, message="%s+q" % debug_flag)