Revert "[config] Implement a process level lock (sonic-net#857)" (son…

…ic-net#882)

This reverts commit 3f651dc.

config/main.py

@@ -529,98 +529,7 @@ def is_ipaddress(val):
         return False
     return True
 
-# class for locking entire config process
-class ConfigDbLock():
-    def __init__(self):
-        self.lockName = "LOCK|configDbLock"
-        self.timeout = 10
-        self.pid = os.getpid()
-        self.client = None
-
-        self._acquireLock()
-        return
-
-    def _acquireLock(self):
-        try:
-            # connect to db
-            db_kwargs = dict()
-            configdb = ConfigDBConnector(**db_kwargs)
-            configdb.connect()
-
-            self.client = configdb.get_redis_client('CONFIG_DB')
-            # Set lock and expire time. Process may get killed b/w set lock and
-            # expire call.
-            if self.client.hsetnx(self.lockName, "PID", self.pid):
-                self.client.expire(self.lockName, self.timeout)
-            # if lock exists but expire timer not running, run expire time and
-            # abort.
-            elif not self.client.ttl(self.lockName):
-                click.echo(":::Unable to acquire lock. Resetting timer and aborting:::");
-                self.client.expire(self.lockName, self.timeout)
-                sys.exit(1)
-            else:
-                click.echo(":::Unable to acquire lock. Aborting:::");
-                sys.exit(1)
-        except Exception as e:
-            click.echo(":::Exception: {}:::".format(e))
-            sys.exit(1)
-        return
-
-    def reacquireLock(self):
-        try:
-            # Try to set lock first
-            if self.client.hsetnx(self.lockName, "PID", self.pid):
-                self.client.expire(self.lockName, self.timeout)
-            # if lock exists, check who owns it
-            else:
-                p = self.client.pipeline(True)
-                # watch, we do not want to work on modified lock
-                p.watch(self.lockName)
-                # if current process holding then extend the timer
-                if p.hget(self.lockName, "PID") == str(self.pid):
-                    self.client.expire(self.lockName, self.timeout)
-                    p.unwatch()
-                    return
-                else:
-                    # some other process is holding the lock.
-                    click.echo(":::Unable to reacquire lock (lock PID: {}, self.pid: {}):::".\
-                        format(p.hget(self.lockName, "PID"), self.pid))
-                    p.unwatch()
-                    sys.exit(1)
-        except Exception as e:
-            click.echo(":::Exception: {}:::".format(e))
-            sys.exit(1)
-        return
-
-    def _releaseLock(self):
-        try:
-            p = self.client.pipeline(True)
-            # watch, we do not want to work on modified lock
-            p.watch(self.lockName)
-            # if current process holding the lock then release it.
-            if p.hget(self.lockName, "PID") == str(self.pid):
-                p.multi()
-                p.delete(self.lockName)
-                p.execute()
-                return
-            # lock may be None, if timer has expired before releasing lock.
-            elif not self.lockName:
-                return
-            else:
-                # some other process is holding the lock.
-                click.echo(":::Unable to release lock (lock PID: {}, self.pid: {}):::".\
-                    format(p.hget(self.lockName, "PID"), self.pid))
-            p.unwatch()
-        except Exception as e:
-            click.echo(":::Exception: {}:::".format(e))
-        return
-
-    def __del__(self):
-        self._releaseLock()
-        return
-# end of class configdblock
 
-configdb_lock = ConfigDbLock()
 # This is our main entrypoint - the main 'config' command
 @click.group(context_settings=CONTEXT_SETTINGS)
 def config():
@@ -638,8 +547,6 @@ def config():
 @click.argument('filename', default='/etc/sonic/config_db.json', type=click.Path())
 def save(filename):
     """Export current config DB to a file on disk."""
-    # reacquire lock after prompt
-    configdb_lock.reacquireLock()
     command = "{} -d --print-data > {}".format(SONIC_CFGGEN_PATH, filename)
     run_command(command, display_cmd=True)
 
@@ -650,9 +557,6 @@ def load(filename, yes):
     """Import a previous saved config DB dump file."""
     if not yes:
         click.confirm('Load config from the file %s?' % filename, abort=True)
-        # reacquire lock after prompt
-        configdb_lock.reacquireLock()
-
     command = "{} -j {} --write-to-db".format(SONIC_CFGGEN_PATH, filename)
     run_command(command, display_cmd=True)
 
@@ -664,8 +568,6 @@ def reload(filename, yes, load_sysinfo):
     """Clear current configuration and import a previous saved config DB dump file."""
     if not yes:
         click.confirm('Clear current config and reload config from the file %s?' % filename, abort=True)
-        # reacquire lock after prompt
-        configdb_lock.reacquireLock()
 
     log_info("'reload' executing...")
 
@@ -715,8 +617,6 @@ def reload(filename, yes, load_sysinfo):
 @click.argument('filename', default='/etc/sonic/device_desc.xml', type=click.Path(exists=True))
 def load_mgmt_config(filename):
     """Reconfigure hostname and mgmt interface based on device description file."""
-    # reacquire lock after prompt
-    configdb_lock.reacquireLock()
     command = "{} -M {} --write-to-db".format(SONIC_CFGGEN_PATH, filename)
     run_command(command, display_cmd=True)
     #FIXME: After config DB daemon for hostname and mgmt interface is implemented, we'll no longer need to do manual configuration here
@@ -739,10 +639,7 @@ def load_mgmt_config(filename):
 @click.option('-y', '--yes', is_flag=True, callback=_abort_if_false,
                 expose_value=False, prompt='Reload config from minigraph?')
 def load_minigraph():
-
     """Reconfigure based on minigraph."""
-    # reacquire lock after prompt
-    configdb_lock.reacquireLock()
     log_info("'load_minigraph' executing...")
 
     # get the device type
@@ -2407,8 +2304,6 @@ def ztp():
 @click.argument('run', required=False, type=click.Choice(["run"]))
 def run(run):
     """Restart ZTP of the device."""
-    # reacquire lock after prompt
-    configdb_lock.reacquireLock()
     command = "ztp run -y"
     run_command(command, display_cmd=True)
 
@@ -2418,8 +2313,6 @@ def run(run):
 @click.argument('disable', required=False, type=click.Choice(["disable"]))
 def disable(disable):
     """Administratively Disable ZTP."""
-    # reacquire lock after prompt
-    configdb_lock.reacquireLock()
     command = "ztp disable -y"
     run_command(command, display_cmd=True)