# HG changeset patch

# User Gregory Szorc <[email protected]>

# Date 1430931130 25200

#      Wed May 06 09:52:10 2015 -0700

# Branch stable

# Node ID 44b054c3a46eac63d5fed06ffb8fffc38d5668f6

# Parent  41cd8171e58f991373dcd0b4897dc1e5978d42dd

extensions: clear aftercallbacks after execution (issue4646)

It was reported that enabling pager without color could cause a hang.

Inserting print statements revealed that the callbacks in

extensions._aftercallbacks were being invoked twice.

extensions.loadall can be called multiple times. If entries in

extensions._aftercallbacks linger between calls, this could result

in double execution of the callbacks. This can lead to unwanted

behavior.

The reproduce steps in the bug seem to only occur when the output of

a command is less than the size of the current screen. This is not

something that can easily be tested. I verified the test case works

with this patch and that pager and color interaction continues to

work. Since we have no existing automated tests for pager, this sadly

appears to be the best testing I can do.

diff --git a/mercurial/extensions.py b/mercurial/extensions.py

--- a/mercurial/extensions.py

+++ b/mercurial/extensions.py

@@ -133,8 +133,12 @@ def loadall(ui):

         for fn in _aftercallbacks[shortname]:

             fn(loaded=False)

+    # loadall() is called multiple times and lingering _aftercallbacks

+    # entries could result in double execution. See issue4646.

+    _aftercallbacks.clear()

+

 def afterloaded(extension, callback):

     '''Run the specified function after a named extension is loaded.

     If the named extension is already loaded, the callback will be called

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