[PATCH] bb.event: fix infinite loop on print_ui_queue

["Aníbal Limón" <anibal.limon@linux.intel.com>]

If bitbake ends before _uiready and bb.event.LogHandler was add
to the bitbake logger it causes an infinite loop when logging
something.

The scenario is print_ui_queue is called at exit and executes
the log handlers [2] one of them is bb.event.LogHandler this handler
appends the same entry to ui_queue causing the inifine loop [3].

In order to fix we need to keep track of events already handled to
avoid the infinite loop.

[YOCTO #10399]

[1] https://bugzilla.yoctoproject.org/show_bug.cgi?id=10399#c0
[2] http://git.openembedded.org/bitbake/tree/lib/bb/event.py?id=41d9cd41d40b04746c82b4a940dca47df02514fc#n156
[3]
http://git.openembedded.org/bitbake/tree/lib/bb/event.py?id=41d9cd41d40b04746c82b4a940dca47df02514fc#n164

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
---
 lib/bb/event.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/bb/event.py b/lib/bb/event.py
index c5a5f94..8464e06 100644
--- a/lib/bb/event.py
+++ b/lib/bb/event.py
@@ -139,7 +139,11 @@ def print_ui_queue():
 
         # First check to see if we have any proper messages
         msgprint = False
+        events_handled = []
         for event in ui_queue:
+            if event in events_handled:
+                continue
+
             if isinstance(event, logging.LogRecord):
                 if event.levelno > logging.DEBUG:
                     if event.levelno >= logging.WARNING:
@@ -148,14 +152,20 @@ def print_ui_queue():
                         logger.addHandler(stdout)
                     logger.handle(event)
                     msgprint = True
+            events_handled.append(event)
         if msgprint:
             return
 
         # Nope, so just print all of the messages we have (including debug messages)
         logger.addHandler(stdout)
+        events_handled = []
         for event in ui_queue:
+            if event in events_handled:
+                continue
+
             if isinstance(event, logging.LogRecord):
                 logger.handle(event)
+            events_handled.append(event)
 
 def fire_ui_handlers(event, d):
     global _thread_lock
-- 
2.1.4