Hotfix supervisor infinite log recursion if no LogMonitor

Console

lib/tfw/components/__init__.py

@@ -7,3 +7,4 @@ from .terminal_event_handler import TerminalEventHandler
 from .ide_event_handler import IdeEventHandler
 from .history_monitor import HistoryMonitor, BashMonitor, GDBMonitor
 from .terminal_commands import TerminalCommands
+from .log_monitoring_event_handler import LogMonitoringEventHandler

lib/tfw/components/log_monitor.py

@@ -0,0 +1,52 @@
+# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
+# All Rights Reserved. See LICENSE file for details.
+
+import logging
+from os.path import dirname
+
+from watchdog.events import PatternMatchingEventHandler as PatternMatchingWatchdogEventHandler
+
+from tfw.networking.event_handlers import ServerUplinkConnector
+from tfw.decorators import RateLimiter
+from tfw.mixins import ObserverMixin, SupervisorLogMixin
+
+
+class LogMonitor(ObserverMixin):
+    def __init__(self, process_name, log_tail=0):
+        self.prevent_log_recursion()
+        ObserverMixin.__init__(self)
+        event_handler = SendLogWatchdogEventHandler(process_name, log_tail=log_tail)
+        self.observer.schedule(
+            event_handler,
+            event_handler.path
+        )
+
+    @staticmethod
+    def prevent_log_recursion():
+        # This is done to prevent inotify event logs triggering themselves (infinite log recursion)
+        logging.getLogger('watchdog.observers.inotify_buffer').propagate = False
+
+
+class SendLogWatchdogEventHandler(PatternMatchingWatchdogEventHandler, SupervisorLogMixin):
+    def __init__(self, process_name, log_tail=0):
+        self.acquire_own_supervisor_instance()  # This thread-localises the xmlrpc client
+        self.process_name = process_name
+        self.procinfo = self.supervisor.getProcessInfo(self.process_name)
+        super().__init__([self.procinfo['stdout_logfile'], self.procinfo['stderr_logfile']])
+        self.uplink = ServerUplinkConnector()
+        self.log_tail = log_tail
+
+    @property
+    def path(self):
+        return dirname(self.procinfo['stdout_logfile'])
+
+    @RateLimiter(rate_per_second=5)
+    def on_modified(self, event):
+        self.uplink.send({
+            'key': 'processlog',
+            'data': {
+                'command': 'new_log',
+                'stdout': self.read_stdout(self.process_name, tail=self.log_tail),
+                'stderr': self.read_stderr(self.process_name, tail=self.log_tail)
+            }
+        })

lib/tfw/components/log_monitoring_event_handler.py

@@ -0,0 +1,37 @@
+# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
+# All Rights Reserved. See LICENSE file for details.
+
+
+from tfw import EventHandlerBase
+from tfw.mixins import MonitorManagerMixin
+from tfw.config.logs import logging
+from .log_monitor import LogMonitor
+
+LOG = logging.getLogger(__name__)
+
+
+class LogMonitoringEventHandler(EventHandlerBase, MonitorManagerMixin):
+    def __init__(self, key, process_name, log_tail=0):
+        super().__init__(key)
+        self.process_name = process_name
+        self.log_tail = log_tail
+        MonitorManagerMixin.__init__(self, LogMonitor, self.process_name, self.log_tail)
+
+        self.command_handlers = {
+            'process_name': self.handle_process_name,
+            'log_tail':     self.handle_log_tail
+        }
+
+    def handle_event(self, message):
+        try:
+            data = message['data']
+            self.command_handlers[data['command']](data)
+            self.reload_monitor()
+        except KeyError:
+            LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
+
+    def handle_process_name(self, data):
+        self.set_monitor_args(data['process_name'], self.log_tail)
+
+    def handle_log_tail(self, data):
+        self.set_monitor_args(self.process_name, data['log_tail'])

lib/tfw/components/process_managing_event_handler.py

@@ -4,14 +4,14 @@
 from xmlrpc.client import Fault as SupervisorFault
 
 from tfw import EventHandlerBase
-from tfw.mixins import SupervisorMixin
+from tfw.mixins import SupervisorMixin, SupervisorLogMixin
 from tfw.config.logs import logging
 from .directory_monitor import with_monitor_paused
 
 LOG = logging.getLogger(__name__)
 
 
-class ProcessManager(SupervisorMixin):
+class ProcessManager(SupervisorMixin, SupervisorLogMixin):
     def __init__(self):
         self.commands = {'start':      self.start_process,
                          'stop':       self.stop_process,
@@ -34,22 +34,24 @@ class ProcessManagingEventHandler(EventHandlerBase):
     Commands available: start, stop, restart, readlog
     (the names are as self-documenting as it gets)
     """
-    def __init__(self, key, dirmonitor=None):
+    def __init__(self, key, dirmonitor=None, log_tail=0):
         super().__init__(key)
         self.key = key
         self.monitor = dirmonitor
         self.processmanager = ProcessManager()
+        self.log_tail = log_tail
 
     @with_monitor_paused
     def handle_event(self, message):
         try:
             data = message['data']
-            self.processmanager(data['command'], data['process_name'])
-            message['data']['log'] = self.processmanager.read_log_stdout(message['data']['process_name'])
+            try:
+                self.processmanager(data['command'], data['process_name'])
+            except SupervisorFault as fault:
+                message['data']['error'] = fault.faultString
+            finally:
+                message['data']['stdout'] = self.processmanager.read_stdout(data['process_name'], self.log_tail)
+                message['data']['stderr'] = self.processmanager.read_stderr(data['process_name'], self.log_tail)
             return message
         except KeyError:
             LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
-        except SupervisorFault as fault:
-            message['data']['error'] = fault.faultString
-            message['data']['log'] = self.processmanager.read_log_stderr(message['data']['process_name'])
-            return message

lib/tfw/mixins/__init__.py

@@ -1,7 +1,7 @@
 # Copyright (C) 2018 Avatao.com Innovative Learning Kft.
 # All Rights Reserved. See LICENSE file for details.
 
-from .supervisor_mixin import SupervisorMixin
+from .supervisor_mixin import SupervisorMixin, SupervisorLogMixin
 from .callback_mixin import CallbackMixin
 from .observer_mixin import ObserverMixin
 from .monitor_manager_mixin import MonitorManagerMixin

lib/tfw/mixins/monitor_manager_mixin.py

@@ -7,21 +7,24 @@ LOG = logging.getLogger(__name__)
 
 
 class MonitorManagerMixin:
-    def __init__(self, monitor_type, directories):
+    def __init__(self, monitor_type, *monitor_args):
         self._monitor_type = monitor_type
         self._monitor = None
-        self._monitored_directories = directories
+        self.monitor_args = monitor_args
         self.reload_monitor()
 
     @property
     def monitor(self):
         return self._monitor
 
+    def set_monitor_args(self, *monitor_args):
+        self.monitor_args = monitor_args
+
     def reload_monitor(self):
         if self._monitor:
             try:
                 self._monitor.stop()
             except KeyError:
                 LOG.debug('Working directory was removed – ignoring...')
-        self._monitor = self._monitor_type(self._monitored_directories)
+        self._monitor = self._monitor_type(*self.monitor_args)
         self._monitor.watch()   # This runs on a separate thread

lib/tfw/mixins/supervisor_mixin.py

@@ -9,9 +9,21 @@ from os import remove
 from tfw.config import TFWENV
 
 
-class SupervisorMixin:
-    supervisor = xmlrpc.client.ServerProxy(TFWENV.SUPERVISOR_HTTP_URI).supervisor
+def get_supervisor_instance():
+    return xmlrpc.client.ServerProxy(TFWENV.SUPERVISOR_HTTP_URI).supervisor
 
+
+class SupervisorBaseMixin:
+    supervisor = get_supervisor_instance()
+
+    def acquire_own_supervisor_instance(self):
+        """
+        Give this instance non-static, local xmlrpc client
+        """
+        self.supervisor = get_supervisor_instance()
+
+
+class SupervisorMixin(SupervisorBaseMixin):
     def stop_process(self, process_name):
         with suppress(SupervisorFault):
             self.supervisor.stopProcess(process_name)
@@ -19,22 +31,20 @@ class SupervisorMixin:
     def start_process(self, process_name):
         self.supervisor.startProcess(process_name)
 
-    def read_log_stdout(self, process_name):
-        return self._read_log_internal(self.supervisor.readProcessStdoutLog, process_name)
-
-    def read_log_stderr(self, process_name):
-        return self._read_log_internal(self.supervisor.readProcessStderrLog, process_name)
-
-    def _read_log_internal(self, read_method, process_name):
-        log = read_method(process_name, 0, 0)
-        self.clear_logs(process_name)
-        return log
-
-    def clear_logs(self, process_name):
-        for logfile in ('stdout_logfile', 'stderr_logfile'):
-            remove(self.supervisor.getProcessInfo(process_name)[logfile])
-        self.supervisor.clearProcessLogs(process_name)
-
     def restart_process(self, process_name):
         self.stop_process(process_name)
         self.start_process(process_name)
+
+
+class SupervisorLogMixin(SupervisorBaseMixin):
+    def read_stdout(self, process_name, tail=0):
+        return self.supervisor.readProcessStdoutLog(process_name, -tail, 0)
+
+    def read_stderr(self, process_name, tail=0):
+        return self.supervisor.readProcessStderrLog(process_name, -tail, 0)
+
+    def clear_logs(self, process_name):
+        for logfile in ('stdout_logfile', 'stderr_logfile'):
+            with suppress(FileNotFoundError):
+                remove(self.supervisor.getProcessInfo(process_name)[logfile])
+        self.supervisor.clearProcessLogs(process_name)

supervisor/supervisord.conf

@@ -1,6 +1,7 @@
 [supervisord]
 user=root
-logfile = /tmp/supervisord.log
+logfile=/dev/null
+logfile_maxbytes=0
 loglevel = debug
 pidfile = /tmp/supervisord.pid