Add LogDog / annotation protobuf support.

recipe_engine/util.py

 # Copyright 2013 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 import contextlib
 import functools
 import os
 import sys
 import traceback
 import urllib
@@ skipping 172 matching lines @@
         self.lines[-1].write(s)
         break
       self.lines[-1].write(s[:i])
       self.lines[-1] = self.lines[-1].getvalue()
       self.lines.append(StringIO())
       s = s[i+1:]
 
   def close(self):
     if not isinstance(self.lines[-1], basestring):
       self.lines[-1] = self.lines[-1].getvalue()
+
+
+class MultiException(Exception):
+  """An exception that aggregates multiple exceptions and summarizes them."""
+
+  def __init__(self):
+    self._inner = []
+
+  def append(self, exc):
+    assert isinstance(exc, BaseException)
+    self._inner.append(exc)
+
+  def __nonzero__(self):
+    return bool(self._inner)
+
+  def __str__(self):
+    if len(self._inner) == 0:
+      text = 'No exceptions'
+    elif len(self._inner) == 1:
+      text = str(self._inner[0])
+    else:
+      text = str(self._inner[0]) + ', and %d more...' % (len(self._inner)-1)
+    return '%s(%s)' % (type(self).__name__, text)
+
+  def raise_if_any(self):
+    if self:

[martiniss, 2016/09/01 21:59:48]

Shouldn't this be "if self._inner"?

[dnj, 2016/09/07 17:54:58]

Done.

+      raise self
+
+  @contextlib.contextmanager
+  def catch(self):
+    try:
+      yield
+    except Exception as e:

[martiniss, 2016/09/01 21:59:48]

Can you make the exception class a required parameter? I don't like try-catches
which catch Exception as a rule, so I'd like the person calling this to feel the
shame

[dnj, 2016/09/07 17:54:58]

Sure.

However, note the only user ("defer_exceptions_for") raises whatever it catches,
so the exception type is not too interesting.

Also fixed and added some unit tests.

+      self.append(e)
+
+
+def defer_exceptions_for(gen):
+  mexc = MultiException()
+  for e in gen:
+    try:
+      yield e
+    except Exception as e:
+      exc.append(e)
+  mexc.raise_if_any()