bitbake: cooker: Improve pyinotify performance

Benchmarks show that the introduction of pyinotify regressed
performance. This patch ensures we only call the add_watch() function
for new entries, not ones we've already processed which does improve
performance as measured by "time bitbake -p".

This doesn't completely remove the overhead but it does substantially
reduce it.

(Bitbake rev: 493361f35f6cc332d4ea359a2695622c2c91a9c2)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/cooker.py

@@ -122,11 +122,13 @@ class BBCooker:
         self.configuration = configuration
 
         self.configwatcher = pyinotify.WatchManager()
+        self.configwatcher.bbseen = []
         self.confignotifier = pyinotify.Notifier(self.configwatcher, self.config_notifications)
         self.watchmask = pyinotify.IN_CLOSE_WRITE | pyinotify.IN_CREATE | pyinotify.IN_DELETE | \
                          pyinotify.IN_DELETE_SELF | pyinotify.IN_MODIFY | pyinotify.IN_MOVE_SELF | \
                          pyinotify.IN_MOVED_FROM | pyinotify.IN_MOVED_TO 
         self.watcher = pyinotify.WatchManager()
+        self.watcher.bbseen = []
         self.notifier = pyinotify.Notifier(self.watcher, self.notifications)
 
 
@@ -181,6 +183,9 @@ class BBCooker:
             watcher = self.watcher
         for i in deps:
             f = i[0]
+            if f in watcher.bbseen:
+                continue
+            watcher.bbseen.append(f)
             while True:
                 # We try and add watches for files that don't exist but if they did, would influence
                 # the parser. The parent directory of these files may not exist, in which case we need 
@@ -191,6 +196,7 @@ class BBCooker:
                 except pyinotify.WatchManagerError as e:
                     if 'ENOENT' in str(e):
                         f = os.path.dirname(f)
+                        watcher.bbseen.append(f)
                         continue
                     raise