progress: clear progress bar when locking to suspend

Summary:
The recent changes to the progress engine to work around locking bugs removed
the `clear` step of `progress.suspend`.  This leads to garbled output when
a progress bar is ongoing.  Restore it by adding a new lock method to the
engine.

Also add a `--with-output` option to `hg debugprogress` to test this.

Reviewed By: mitrandir77

Differential Revision: D12838415

fbshipit-source-id: 83ed516b528d0b0bbe37945141d50b50da00ac8e

mercurial/debugcommands.py

@@ -3053,11 +3053,14 @@ def debugdrawdag(ui, repo, **opts):
         ("s", "spinner", False, _("use a progress spinner")),
         ("n", "nototal", False, _("don't include the total")),
         ("b", "bytes", False, _("use a bytes format function")),
+        ("", "with-output", False, _("also print output every 10%")),
     ],
     _("NUMBER"),
     norepo=True,
 )
-def debugprogress(ui, number, spinner=False, nototal=False, bytes=False):
+def debugprogress(
+    ui, number, spinner=False, nototal=False, bytes=False, with_output=False
+):
     """
     Initiate a progress bar and increment the progress NUMBER times.
 
@@ -3069,18 +3072,30 @@ def debugprogress(ui, number, spinner=False, nototal=False, bytes=False):
 
     formatfunc = util.bytecount if bytes else None
 
+    if with_output:
+        outputfreq = num // 10
+        if outputfreq == 0:
+            outputfreq = 1
+    else:
+        outputfreq = None
+
     if spinner:
         with progress.spinner(ui, _spinning):
             for i in xrange(num):
-                pass
+                if outputfreq and i % outputfreq == 0:
+                    ui.write(("processed %d items") % i)
     elif nototal:
         with progress.bar(ui, _spinning, formatfunc=formatfunc) as p:
             for i in xrange(num):
                 p.value = (i, "item %s" % i)
+                if outputfreq and i % outputfreq == 0:
+                    ui.write(("processed %d items") % i)
     else:
         with progress.bar(ui, _spinning, total=num, formatfunc=formatfunc) as p:
             for i in xrange(num):
                 p.value = (i, "item %s" % i)
+                if outputfreq and i % outputfreq == 0:
+                    ui.write(("processed %d items\n") % i)
 
 
 def _findtreemanifest(ctx):

mercurial/progress.py

@@ -432,6 +432,14 @@ class engine(object):
         with b, b, b, b, b, b:
             yield
 
+    @contextlib.contextmanager
+    def _lockclear(self):
+        with self.lock():
+            bar = self._currentbar()
+            if bar is not None:
+                bar._enginerenderer.clear()
+            yield
+
     def resetstate(self):
         with self.lock():
             self._clear()
@@ -449,7 +457,7 @@ class engine(object):
             self._bars.append(bar)
             self._recalculatedisplay(now)
             global suspend
-            suspend = self.lock
+            suspend = self._lockclear
             self._cond.notify_all()
 
     def unregister(self, bar):

tests/test-completion.t

@@ -306,7 +306,7 @@ Show all commands + options
   debugpathcomplete: full, normal, added, removed
   debugpickmergetool: rev, changedelete, include, exclude, tool
   debugprocesstree: 
-  debugprogress: spinner, nototal, bytes
+  debugprogress: spinner, nototal, bytes, with-output
   debugpushkey: 
   debugpvec: 
   debugrebuilddirstate: rev, minimal