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+# -*- coding: utf-8 -*-
+# safezmqhandler.py
+# Copyright (C) 2013, 2014, 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+A thread-safe zmq handler for LogBook.
+"""
+import json
+import threading
+
+from logbook.queues import ZeroMQHandler
+from logbook import NOTSET
+
+import zmq
+
+
+class SafeZMQHandler(ZeroMQHandler):
+ """
+ A ZMQ log handler for LogBook that is thread-safe.
+
+ This log handler makes use of the existing zmq handler and if the user
+ tries to log something from a different thread than the one used to
+ create the handler a new socket is created for that thread.
+
+ Note: In ZMQ, Contexts are threadsafe objects, but Sockets are not.
+ """
+
+ def __init__(self, uri=None, level=NOTSET, filter=None, bubble=False,
+ context=None, multi=False):
+
+ ZeroMQHandler.__init__(self, uri, level, filter, bubble, context,
+ multi)
+
+ current_id = self._get_caller_id()
+ # we store the socket created on the parent
+ self._sockets = {current_id: self.socket}
+
+ # store the settings for new socket creation
+ self._multi = multi
+ self._uri = uri
+
+ def _get_caller_id(self):
+ """
+ Return an id for the caller that depends on the current thread.
+ Thanks to this we can detect if we are running in a thread different
+ than the one who created the socket and create a new one for it.
+
+ :rtype: int
+ """
+ # NOTE it makes no sense to use multiprocessing id since the sockets
+ # list can't/shouldn't be shared between processes. We only use
+ # thread id. The user needs to make sure that the handler is created
+ # inside each process.
+ return threading.current_thread().ident
+
+ def _get_new_socket(self):
+ """
+ Return a new socket using the `uri` and `multi` parameters given in the
+ constructor.
+
+ :rtype: zmq.Socket
+ """
+ socket = None
+
+ if self._multi:
+ socket = self.context.socket(zmq.PUSH)
+ if self._uri is not None:
+ socket.connect(self._uri)
+ else:
+ socket = self.context.socket(zmq.PUB)
+ if self._uri is not None:
+ socket.bind(self._uri)
+
+ return socket
+
+ def emit(self, record):
+ """
+ Emit the given `record` through the socket.
+
+ :param record: the record to emit
+ :type record: Logbook.LogRecord
+ """
+ current_id = self._get_caller_id()
+ socket = None
+
+ if current_id in self._sockets:
+ socket = self._sockets[current_id]
+ else:
+ # TODO: create new socket
+ socket = self._get_new_socket()
+ self._sockets[current_id] = socket
+
+ socket.send(json.dumps(self.export_record(record)).encode("utf-8"))
+
+ def close(self, linger=-1):
+ """
+ Close all the sockets and linger `linger` time.
+
+ This reimplements the ZeroMQHandler.close method that is used by
+ context methods.
+
+ :param linger: time to linger, -1 to not to.
+ :type linger: int
+ """
+ for socket in self._sockets.values():
+ socket.close(linger)