add last_duration attribute to progress bar

dask/diagnostics/progress.py

@@ -54,6 +54,15 @@ class ProgressBar(Callback):
     ...     out = some_slow_computation.compute()
     [########################################] | 100% Completed | 10.4 s
 
+    The duration of the last computation is available as an attribute
+
+    >>> pbar = ProgressBar()
+    >>> with pbar:                          # doctest: +SKIP
+    ...     out = some_computation.compute()
+    [########################################] | 100% Completed | 10.4 s
+    >>> pbar.last_duration                  # doctest: +SKIP
+    10.4
+
     You can also register a progress bar so that it displays for all
     computations:
 
@@ -67,6 +76,7 @@ def __init__(self, minimum=0, width=40, dt=0.1):
         self._minimum = minimum
         self._width = width
         self._dt = dt
+        self.last_duration = 0
 
     def _start(self, dsk):
         self._state = None
@@ -84,6 +94,7 @@ def _finish(self, dsk, state, errored):
         self._running = False
         self._timer.join()
         elapsed = default_timer() - self._start_time
+        self.last_duration = elapsed
         if elapsed < self._minimum:
             return
         if not errored:

dask/diagnostics/tests/test_progress.py

@@ -107,3 +107,11 @@ def test_with_alias(capsys):
     with ProgressBar():
         get(dsk, 'f')
     check_bar_completed(capsys)
+
+
+def test_store_time():
+    p = ProgressBar()
+    with p:
+        get({'x': 1}, 'x')
+
+    assert isinstance(p.last_duration, float)