bitbake: Add event mask flag support

Add a flag to event handlers which lists the events a given handler wishes to
process. By default event handlers recieve all events but this means
we can stop running code in many cases if we know it doesn't want the event.

This is part of the fix for YOCTO #3812, but implements filtering only
for class event handlers; the other part (events filter for UIs) will be
the subject of a different patch.

Signed-off-by: Bogdan Marinescu <bogdan.a.marinescu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 18 insertions, 5 deletions

diff --git a/lib/bb/event.py b/lib/bb/event.py
index d73067fcf..9c134eed0 100644
--- a/lib/bb/event.py
+++ b/lib/bb/event.py
@@ -64,6 +64,8 @@ def clean_class_handlers():
 _handlers = clean_class_handlers()
 _ui_handlers = {}
 _ui_handler_seq = 0
+_event_handler_map = {}
+_catchall_handlers = {}
 
 def execute_handler(name, handler, event, d):
     event.data = d
@@ -87,11 +89,14 @@ def fire_class_handlers(event, d):
     if isinstance(event, logging.LogRecord):
         return
 
+    eid = str(event.__class__)[8:-2]
+    evt_hmap = _event_handler_map.get(eid, {})
     for name, handler in _handlers.iteritems():
-        try:
-            execute_handler(name, handler, event, d)
-        except Exception:
-            continue
+        if name in _catchall_handlers or name in evt_hmap:
+            try:
+                execute_handler(name, handler, event, d)
+            except Exception:
+                continue
 
 ui_queue = []
 @atexit.register
@@ -160,7 +165,7 @@ def fire_from_worker(event, d):
     fire_ui_handlers(event, d)
 
 noop = lambda _: None
-def register(name, handler):
+def register(name, handler, mask=[]):
     """Register an Event handler"""
 
     # already registered
@@ -185,6 +190,14 @@ def register(name, handler):
         else:
             _handlers[name] = handler
 
+        if not mask:
+            _catchall_handlers[name] = True
+        else:
+            for m in mask:
+                if _event_handler_map.get(m, None) is None:
+                    _event_handler_map[m] = {}
+                _event_handler_map[m][name] = True
+
         return Registered
 
 def remove(name, handler):