Created working static fam infrastructure for Ticket #536

git-svn-id: https://svn.mcs.anl.gov/repos/bcfg/trunk/bcfg2@4875 ce84e21b-d406-0410-9b95-82705330c041

1 files changed, 235 insertions, 0 deletions

diff --git a/src/lib/Server/FileMonitor.py b/src/lib/Server/FileMonitor.py
new file mode 100644
index 000000000..347e37b7b
--- /dev/null
+++ b/src/lib/Server/FileMonitor.py
@@ -0,0 +1,235 @@
+from time import time
+import logging, os, stat
+
+logger = logging.getLogger('Bcfg2.Server.FileMonitor')
+
+def ShouldIgnore(event):
+    '''Test if the event should be suppresed'''
+    # FIXME should move event suppression out of the core
+    if event.filename.split('/')[-1] == '.svn':
+        return True
+    if event.filename.endswith('~') or event.filename.endswith('.tmp') \
+    or event.filename.startswith('#') or event.filename.startswith('.#'):
+        logger.error("Suppressing event for file %s" % (event.filename))
+        return True
+    return False
+
+class FamFam(object):
+    '''The fam object is a set of callbacks for file alteration events (FAM support)'''
+    
+    def __init__(self):
+        object.__init__(self)
+        self.fm = _fam.open()
+        self.users = {}
+        self.handles = {}
+        self.debug = False
+
+    def fileno(self):
+        '''return fam file handle number'''
+        return self.fm.fileno()
+
+    def AddMonitor(self, path, obj):
+        '''add a monitor to path, installing a callback to obj.HandleEvent'''
+        mode = os.stat(path)[stat.ST_MODE]
+        if stat.S_ISDIR(mode):
+            handle = self.fm.monitorDirectory(path, None)
+        else:
+            handle = self.fm.monitorFile(path, None)
+        self.handles[handle.requestID()] = handle
+        if obj != None:
+            self.users[handle.requestID()] = obj
+        return handle.requestID()
+
+    def Service(self):
+        '''Handle all fam work'''
+        count = 0
+        collapsed = 0
+        rawevents = []
+        start = time()
+        now = time()
+        while (time() - now) < 0.10:
+            if self.fm.pending():
+                while self.fm.pending():
+                    count += 1
+                    rawevents.append(self.fm.nextEvent())
+                now = time()
+        unique = []
+        bookkeeping = []
+        for event in rawevents:
+            if ShouldIgnore(event):
+                continue
+            if event.code2str() != 'changed':
+                # process all non-change events
+                unique.append(event)
+            else:
+                if (event.filename, event.requestID) not in bookkeeping:
+                    bookkeeping.append((event.filename, event.requestID))
+                    unique.append(event)
+                else:
+                    collapsed += 1
+        for event in unique:
+            if self.users.has_key(event.requestID):
+                try:
+                    self.users[event.requestID].HandleEvent(event)
+                except:
+                    logger.error("handling event for file %s" % (event.filename), exc_info=1)
+        end = time()
+        logger.info("Processed %s fam events in %03.03f seconds. %s coalesced" %
+                    (count, (end - start), collapsed))
+        return count
+
+class Event(object):
+    def __init(self, request_id, filename, code):
+        self.requestID = request_id
+        self.filename = filename
+        self.action = code
+
+    def code2str(self):
+        '''return static code for event'''
+        return self.action
+
+
+class GaminEvent(Event):
+    '''This class provides an event analogous to python-fam events based on gamin sources'''
+    def __init__(self, request_id, filename, code):
+        Event.__init__(self, request_id, filename, code)
+        action_map = {GAMCreated: 'created', GAMExists: 'exists', GAMChanged: 'changed',
+                      GAMDeleted: 'deleted', GAMEndExist: 'endExist', GAMMoved: 'moved'}
+        if action_map.has_key(code):
+            self.action = action_map[code]
+
+class GaminFam(object):
+    '''The fam object is a set of callbacks for file alteration events (Gamin support)'''
+    def __init__(self):
+        object.__init__(self)
+        self.mon = WatchMonitor()
+        self.handles = {}
+        self.counter = 0
+        self.events = []
+        self.debug = False
+
+    def fileno(self):
+        '''return fam file handle number'''
+        return self.mon.get_fd()
+
+    def queue(self, path, action, request_id):
+        '''queue up the event for later handling'''
+        self.events.append(GaminEvent(request_id, path, action))
+
+    def AddMonitor(self, path, obj):
+        '''add a monitor to path, installing a callback to obj.HandleEvent'''
+        handle = self.counter
+        self.counter += 1
+        mode = os.stat(path)[stat.ST_MODE]
+        if stat.S_ISDIR(mode):
+            self.mon.watch_directory(path, self.queue, handle)
+        else:
+            self.mon.watch_file(path, self.queue, handle)
+        self.handles[handle] = obj
+        return handle
+
+    def Service(self):
+        '''Handle all gamin work'''
+        count = 0
+        collapsed = 0
+        start = time()
+        now = time()
+        while (time() - now) < 0.10:
+            if self.mon.event_pending():
+                while self.mon.event_pending():
+                    count += 1
+                    self.mon.handle_one_event()
+                now = time()
+        unique = []
+        bookkeeping = []
+        for event in self.events:
+            if ShouldIgnore(event):
+                continue
+            if event.code2str() != 'changed':
+                # process all non-change events
+                unique.append(event)
+            else:
+                if (event.filename, event.requestID) not in bookkeeping:
+                    bookkeeping.append((event.filename, event.requestID))
+                    unique.append(event)
+                else:
+                    collapsed += 1
+        self.events = []
+        for event in unique:
+            if event.requestID not in self.handles:
+                logger.info("Got event for unexpected id %s, file %s" %
+                            (event.requestID, event.filename))
+                continue
+            if self.debug:
+                logger.info("Dispatching event %s %s to obj %s" \
+                            % (event.code2str(), event.filename,
+                               self.handles[event.requestID]))
+            try:
+                self.handles[event.requestID].HandleEvent(event)
+            except:
+                logger.error("error in handling of gamin event for %s" % \
+                             (event.filename), exc_info=1)
+        end = time()
+        logger.info("Processed %s gamin events in %03.03f seconds. %s collapsed" %
+                    (count, (end - start), collapsed))
+        return count
+
+class PseudoFam(object):
+    '''The fam object is a set of callbacks for file alteration events (FAM support)'''
+    
+    def __init__(self):
+        object.__init__(self)
+        self.users = {}
+        self.handles = {}
+        self.debug = False
+        self.pending = []
+
+    def AddMonitor(self, path, obj):
+        '''add a monitor to path, installing a callback to obj.HandleEvent'''
+        handleID = len(self.handles.keys())
+        mode = os.stat(path)[stat.ST_MODE]
+        handle = GaminEvent(handleID, path, 'exists')
+        if stat.S_ISDIR(mode):
+            dirList = os.listdir(path)
+            self.pending.append(handle)
+            for includedFile in dirList:
+                self.pending.append(GaminEvent(handleID, includedFile, 'exists'))
+            self.pending.append(GaminEvent(handleID, path, 'endExist'))
+        else:
+            self.pending.append(GaminEvent(handleID, path, 'exists'))
+        self.handles[handleID] = handle
+        if obj != None:
+            self.users[handleID] = obj
+        return handleID
+
+    def Service(self):
+        '''Handle all fam work'''
+        count = 0
+        rawevents = []
+        for event in self.pending:
+            count += 1
+            rawevents.append(event)
+        self.pending = []
+        for event in rawevents:
+            if self.users.has_key(event.requestID):
+                self.users[event.requestID].HandleEvent(event)
+        return count
+        
+available = {}
+try:
+    from gamin import WatchMonitor, GAMCreated, GAMExists, GAMEndExist, GAMChanged, GAMDeleted, GAMMoved
+    available['gamin'] = GaminFam
+except ImportError:
+    # fall back to _fam
+    pass
+try:
+    import _fam
+    available['fam'] = FamFam
+except ImportError:
+    pass
+available['pseudo'] = PseudoFam
+
+for fdrv in ['gamin', 'fam', 'pseudo']:
+    if fdrv in available:
+        default = available[fdrv]
+        break