1 files changed, 103 insertions, 0 deletions
diff --git a/tensorflow/python/util/tf_stack.py b/tensorflow/python/util/tf_stack.py
new file mode 100644
index 0000000000..fe4f4a63eb
--- /dev/null
+++ b/tensorflow/python/util/tf_stack.py
@@ -0,0 +1,103 @@
+# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Functions used to extract and analyze stacks.  Faster than Python libs."""
+# pylint: disable=g-bad-name
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import linecache
+import sys
+
+# Names for indices into TF traceback tuples.
+TB_FILENAME = 0
+TB_LINENO = 1
+TB_FUNCNAME = 2
+TB_CODEDICT = 3  # Dictionary of Python interpreter state.
+
+
+def extract_stack(extract_frame_info_fn=None):
+  """A lightweight, extensible re-implementation of traceback.extract_stack.
+
+  NOTE(mrry): traceback.extract_stack eagerly retrieves the line of code for
+      each stack frame using linecache, which results in an abundance of stat()
+      calls. This implementation does not retrieve the code, and any consumer
+      should apply _convert_stack to the result to obtain a traceback that can
+      be formatted etc. using traceback methods.
+
+  Args:
+    extract_frame_info_fn: Optional callable fn(stack_frame) applied to each
+        stack frame.  This callable's return value is stored as the sixth (last)
+        element of the returned tuples.  If not provided, the returned tuples
+        will have None as their sixth value.
+
+  Returns:
+    A list of 6-tuples
+        (filename, lineno, name, frame_globals, func_start_lineno, custom_info)
+    corresponding to the call stack of the current thread.  The returned tuples
+    have the innermost stack frame at the end, unlike the Python inspect
+    module's stack() function.
+  """
+  default_fn = lambda f: None
+  extract_frame_info_fn = extract_frame_info_fn or default_fn
+  try:
+    raise ZeroDivisionError
+  except ZeroDivisionError:
+    f = sys.exc_info()[2].tb_frame.f_back
+  ret = []
+  while f is not None:
+    lineno = f.f_lineno
+    co = f.f_code
+    filename = co.co_filename
+    name = co.co_name
+    frame_globals = f.f_globals
+    func_start_lineno = co.co_firstlineno
+    frame_info = extract_frame_info_fn(f)
+    ret.append((filename, lineno, name, frame_globals, func_start_lineno,
+                frame_info))
+    f = f.f_back
+  ret.reverse()
+  return ret
+
+
+def convert_stack(stack, include_func_start_lineno=False):
+  """Converts a stack extracted using extract_stack() to a traceback stack.
+
+  Args:
+    stack: A list of n 5-tuples,
+      (filename, lineno, name, frame_globals, func_start_lineno).
+    include_func_start_lineno: True if function start line number should be
+      included as the 5th entry in return tuples.
+
+  Returns:
+    A list of n 4-tuples or 5-tuples
+    (filename, lineno, name, code, [optional: func_start_lineno]), where the
+    code tuple element is calculated from the corresponding elements of the
+    input tuple.
+  """
+  ret = []
+  for (filename, lineno, name, frame_globals, func_start_lineno,
+       unused_frame_info) in stack:
+    linecache.checkcache(filename)
+    line = linecache.getline(filename, lineno, frame_globals)
+    if line:
+      line = line.strip()
+    else:
+      line = None
+    if include_func_start_lineno:
+      ret.append((filename, lineno, name, line, func_start_lineno))
+    else:
+      ret.append((filename, lineno, name, line))
+  return ret