Add form log formating options

The 'wallclock-us' is a option that we thought we already had.

The base64 option is not human redable but should be quicker and dose
not lose infomation converting back and forth from human redable.

buildstream/_frontend/widget.py

@@ -17,6 +17,7 @@
 #  Authors:
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 import datetime
+import base64
 import os
 from collections import defaultdict, OrderedDict
 from contextlib import ExitStack
@@ -94,12 +95,27 @@ class FixedText(Widget):
 
 # Used to add the wallclock time this message was created at
 class WallclockTime(Widget):
+    def __init__(self, context, content_profile, format_profile, output_format=False):
+        self._output_format = output_format 
+        super(WallclockTime, self).__init__(context, content_profile, format_profile)
+
     def render(self, message):
+        if self._output_format == "base64":
+            return self.format_profile.fmt(base64.b64encode(message.creation_time.timestamp()))
+
         fields = [self.content_profile.fmt("{:02d}".format(x)) for x in
                   [message.creation_time.hour,
                    message.creation_time.minute,
                    message.creation_time.second]]
-        return self.format_profile.fmt(":").join(fields)
+
+        text = self.format_profile.fmt(':').join(fields)
+
+        if self._output_format=='us':
+            if elapsed is not None:
+                text += self.content_profile.fmt(".{0:06d}".format(elapsed.microseconds))
+            else:
+                text += self.content_profile.fmt(".------")
+        return text
 
 
 # A widget for rendering the debugging column
@@ -326,6 +342,8 @@ class LogLine(Widget):
             "elapsed": TimeCode(context, content_profile, format_profile, microseconds=False),
             "elapsed-us": TimeCode(context, content_profile, format_profile, microseconds=True),
             "wallclock": WallclockTime(context, content_profile, format_profile),
+            "wallclock-us": WallclockTime(context, content_profile, format_profile, output_format='us'),
+            "wallclock-base64": WallclockTime(context, content_profile, format_profile, output_format='base64'),
             "key": CacheKey(context, content_profile, format_profile, err_profile),
             "element": ElementName(context, content_profile, format_profile),
             "action": TypeName(context, content_profile, format_profile),