[2/3] unbound-dhcp-leases-bridge: Fix inotify handling
Commit Message
This patch changes that the script will listen to changes to the
directory instead of the file which got complicated when files got
renamed.
It also processes all changes at the same time and tries finding out
what actions have to be performed in order to avoid unnecessary
iterations.
The script is also limited to process any changes only once every five
seconds to keep resource usage in check on busy systems.
Suggested-by: Anthony Heading <ajrh@ajrh.net>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---
config/unbound/unbound-dhcp-leases-bridge | 70 +++++++++++++++--------
1 file changed, 47 insertions(+), 23 deletions(-)
@@ -32,6 +32,7 @@ import stat
import subprocess
import sys
import tempfile
+import time
import inotify.adapters
@@ -82,6 +83,12 @@ class UnboundDHCPLeasesBridge(object):
self.fix_leases_file = fix_leases_file
self.hosts_file = hosts_file
+ self.watches = {
+ self.leases_file : inotify.constants.IN_MODIFY,
+ self.fix_leases_file : 0,
+ self.hosts_file : 0,
+ }
+
self.unbound = UnboundConfigWriter(unbound_leases_file)
self.running = False
@@ -89,37 +96,54 @@ class UnboundDHCPLeasesBridge(object):
log.info("Unbound DHCP Leases Bridge started on %s" % self.leases_file)
self.running = True
- # Initial setup
- self.hosts = self.read_static_hosts()
- self.update_dhcp_leases()
+ i = inotify.adapters.Inotify()
- i = inotify.adapters.Inotify([
- self.leases_file,
- self.fix_leases_file,
- self.hosts_file,
- ])
+ # Add watches for the directories of every relevant file
+ for f, mask in self.watches.items():
+ i.add_watch(
+ os.path.dirname(f),
+ mask | inotify.constants.IN_CLOSE_WRITE | inotify.constants.IN_MOVED_TO,
+ )
- for event in i.event_gen():
- # End if we are requested to terminate
- if not self.running:
- break
+ # Enabled so that we update hosts and leases on startup
+ update_hosts = update_leases = True
- if event is None:
- continue
+ while self.running:
+ log.debug("Wakeup of main loop")
+
+ # Process the entire inotify queue and identify what we need to do
+ for event in i.event_gen():
+ # Nothing to do
+ if event is None:
+ break
+
+ # Decode the event
+ header, type_names, path, filename = event
- header, type_names, watch_path, filename = event
+ file = os.path.join(path, filename)
- # Update leases after leases file has been modified
- if "IN_MODIFY" in type_names:
- # Reload hosts
- if watch_path == self.hosts_file:
- self.hosts = self.read_static_hosts()
+ log.debug("inotify event received for %s: %s", file, " ".join(type_names))
+ # Did the hosts file change?
+ if self.hosts_file == file:
+ update_hosts = True
+
+ # We will need to update the leases on any change
+ update_leases = True
+
+ # Update hosts (if needed)
+ if update_hosts:
+ self.hosts = self.read_static_hosts()
+
+ # Update leases (if needed)
+ if update_leases:
self.update_dhcp_leases()
- # If the file is deleted, we re-add the watcher
- if "IN_IGNORED" in type_names:
- i.add_watch(watch_path)
+ # Reset
+ update_hosts = update_leases = False
+
+ # Wait a moment before we start the next iteration
+ time.sleep(5)
log.info("Unbound DHCP Leases Bridge terminated")