API Reference ************* Package Layout ============== mitogen Package --------------- .. automodule:: mitogen .. autodata:: mitogen.is_master .. autodata:: mitogen.context_id .. autodata:: mitogen.parent_id .. autodata:: mitogen.parent_ids .. autofunction:: mitogen.main mitogen.core ------------ .. module:: mitogen.core This module implements most package functionality, but remains separate from non-essential code in order to reduce its size, since it is also serves as the bootstrap implementation sent to every new slave context. .. currentmodule:: mitogen.core .. decorator:: takes_econtext Decorator that marks a function or class method to automatically receive a kwarg named `econtext`, referencing the :py:class:`mitogen.core.ExternalContext` active in the context in which the function is being invoked in. The decorator is only meaningful when the function is invoked via :py:data:`CALL_FUNCTION `. When the function is invoked directly, `econtext` must still be passed to it explicitly. .. currentmodule:: mitogen.core .. decorator:: takes_router Decorator that marks a function or class method to automatically receive a kwarg named `router`, referencing the :py:class:`mitogen.core.Router` active in the context in which the function is being invoked in. The decorator is only meaningful when the function is invoked via :py:data:`CALL_FUNCTION `. When the function is invoked directly, `router` must still be passed to it explicitly. mitogen.master -------------- .. module:: mitogen.master This module implements functionality required by master processes, such as starting new contexts via SSH. Its size is also restricted, since it must be sent to any context that will be used to establish additional child contexts. .. currentmodule:: mitogen.master .. class:: Select (receivers=(), oneshot=True) Support scatter/gather asynchronous calls and waiting on multiple receivers, channels, and sub-Selects. Accepts a sequence of :py:class:`mitogen.core.Receiver` or :py:class:`mitogen.master.Select` instances and returns the first value posted to any receiver or select. If `oneshot` is ``True``, then remove each receiver as it yields a result; since :py:meth:`__iter__` terminates once the final receiver is removed, this makes it convenient to respond to calls made in parallel: .. code-block:: python total = 0 recvs = [c.call_async(long_running_operation) for c in contexts] for msg in mitogen.master.Select(recvs): print 'Got %s from %s' % (msg, msg.receiver) total += msg.unpickle() # Iteration ends when last Receiver yields a result. print 'Received total %s from %s receivers' % (total, len(recvs)) :py:class:`Select` may drive a long-running scheduler: .. code-block:: python with mitogen.master.Select(oneshot=False) as select: while running(): for msg in select: process_result(msg.receiver.context, msg.unpickle()) for context, workfunc in get_new_work(): select.add(context.call_async(workfunc)) :py:class:`Select` may be nested: .. code-block:: python subselects = [ mitogen.master.Select(get_some_work()), mitogen.master.Select(get_some_work()), mitogen.master.Select([ mitogen.master.Select(get_some_work()), mitogen.master.Select(get_some_work()) ]) ] for msg in mitogen.master.Select(selects): print msg.unpickle() .. py:classmethod:: all (it) Take an iterable of receivers and retrieve a :py:class:`Message` from each, returning the result of calling `msg.unpickle()` on each in turn. Results are returned in the order they arrived. This is sugar for handling batch :py:class:`Context.call_async` invocations: .. code-block:: python print('Total disk usage: %.02fMiB' % (sum( mitogen.master.Select.all( context.call_async(get_disk_usage) for context in contexts ) / 1048576.0 ),)) However, unlike in a naive comprehension such as: .. code-block:: python sum(context.call_async(get_disk_usage).get().unpickle() for context in contexts) Result processing happens concurrently to new results arriving, so :py:meth:`all` should always be faster. .. py:method:: get (timeout=None) Fetch the next available value from any receiver, or raise :py:class:`mitogen.core.TimeoutError` if no value is available within `timeout` seconds. On success, the message's :py:attr:`receiver ` attribute is set to the receiver. :param float timeout: Timeout in seconds. :return: :py:class:`mitogen.core.Message` :raises mitogen.core.TimeoutError: Timeout was reached. :raises mitogen.core.LatchError: :py:meth:`close` has been called, and the underlying latch is no longer valid. .. py:method:: __bool__ () Return ``True`` if any receivers are registered with this select. .. py:method:: close () Remove the select's notifier function from each registered receiver, mark the associated latch as closed, and cause any thread currently sleeping in :py:meth:`get` to be woken with :py:class:`mitogen.core.LatchError`. This is necessary to prevent memory leaks in long-running receivers. It is called automatically when the Python :keyword:`with` statement is used. .. py:method:: empty () Return ``True`` if calling :py:meth:`get` would block. As with :py:class:`Queue.Queue`, ``True`` may be returned even though a subsequent call to :py:meth:`get` will succeed, since a message may be posted at any moment between :py:meth:`empty` and :py:meth:`get`. :py:meth:`empty` may return ``False`` even when :py:meth:`get` would block if another thread has drained a receiver added to this select. This can be avoided by only consuming each receiver from a single thread. .. py:method:: __iter__ (self) Yield the result of :py:meth:`get` until no receivers remain in the select, either because `oneshot` is ``True``, or each receiver was explicitly removed via :py:meth:`remove`. .. py:method:: add (recv) Add the :py:class:`mitogen.core.Receiver` or :py:class:`mitogen.core.Channel` `recv` to the select. .. py:method:: remove (recv) Remove the :py:class:`mitogen.core.Receiver` or :py:class:`mitogen.core.Channel` `recv` from the select. Note that if the receiver has notified prior to :py:meth:`remove`, then it will still be returned by a subsequent :py:meth:`get`. This may change in a future version. mitogen.fakessh --------------- .. module:: mitogen.fakessh fakessh is a stream implementation that starts a local subprocess with its environment modified such that ``PATH`` searches for `ssh` return an mitogen implementation of the SSH command. When invoked, this tool arranges for the command line supplied by the calling program to be executed in a context already established by the master process, reusing the master's (possibly proxied) connection to that context. This allows tools like `rsync` and `scp` to transparently reuse the connections and tunnels already established by the host program to connect to a target machine, without wasteful redundant SSH connection setup, 3-way handshakes, or firewall hopping configurations, and enables these tools to be used in impossible scenarios, such as over `sudo` with ``requiretty`` enabled. The fake `ssh` command source is written to a temporary file on disk, and consists of a copy of the :py:mod:`mitogen.core` source code (just like any other child context), with a line appended to cause it to connect back to the host process over an FD it inherits. As there is no reliance on an existing filesystem file, it is possible for child contexts to use fakessh. As a consequence of connecting back through an inherited FD, only one SSH invocation is possible, which is fine for tools like `rsync`, however in future this restriction will be lifted. Sequence: 1. ``fakessh`` Context and Stream created by parent context. The stream's buffer has a :py:func:`_fakessh_main` :py:data:`CALL_FUNCTION ` enqueued. 2. Target program (`rsync/scp/sftp`) invoked, which internally executes `ssh` from ``PATH``. 3. :py:mod:`mitogen.core` bootstrap begins, recovers the stream FD inherited via the target program, established itself as the fakessh context. 4. :py:func:`_fakessh_main` :py:data:`CALL_FUNCTION ` is read by fakessh context, a. sets up :py:class:`IoPump` for stdio, registers stdin_handle for local context. b. Enqueues :py:data:`CALL_FUNCTION ` for :py:func:`_start_slave` invoked in target context, i. the program from the `ssh` command line is started ii. sets up :py:class:`IoPump` for `ssh` command line process's stdio pipes iii. returns `(control_handle, stdin_handle)` to :py:func:`_fakessh_main` 5. :py:func:`_fakessh_main` receives control/stdin handles from from :py:func:`_start_slave`, a. registers remote's stdin_handle with local :py:class:`IoPump`. b. sends `("start", local_stdin_handle)` to remote's control_handle c. registers local :py:class:`IoPump` with :py:class:`mitogen.core.Broker`. d. loops waiting for `local stdout closed && remote stdout closed` 6. :py:func:`_start_slave` control channel receives `("start", stdin_handle)`, a. registers remote's stdin_handle with local :py:class:`IoPump` b. registers local :py:class:`IoPump` with :py:class:`mitogen.core.Broker`. c. loops waiting for `local stdout closed && remote stdout closed` .. currentmodule:: mitogen.fakessh .. function:: run (dest, router, args, daedline=None, econtext=None) Run the command specified by the argument vector `args` such that ``PATH`` searches for SSH by the command will cause its attempt to use SSH to execute a remote program to be redirected to use mitogen to execute that program using the context `dest` instead. :param mitogen.core.Context dest: The destination context to execute the SSH command line in. :param mitogen.core.Router router: :param list[str] args: Command line arguments for local program, e.g. ``['rsync', '/tmp', 'remote:/tmp']`` :returns: Exit status of the child process. Message Class ============ .. currentmodule:: mitogen.core .. class:: Message .. attribute:: router The :py:class:`mitogen.core.Router` responsible for routing the message. This is :py:data:`None` for locally originated messages. .. attribute:: receiver The :py:class:`mitogen.core.Receiver` over which the message was last received. Part of the :py:class:`mitogen.master.Select` interface. Defaults to :py:data:`None`. .. attribute:: dst_id .. attribute:: src_id .. attribute:: auth_id .. attribute:: handle .. attribute:: reply_to .. attribute:: data .. py:method:: __init__ (\**kwargs) Construct a message from from the supplied `kwargs`. :py:attr:`src_id` and :py:attr:`auth_id` are always set to :py:data:`mitogen.context_id`. .. py:classmethod:: pickled (obj, \**kwargs) Construct a pickled message, setting :py:attr:`data` to the serialization of `obj`, and setting remaining fields using `kwargs`. :returns: The new message. .. method:: unpickle (throw=True) Unpickle :py:attr:`data`, optionally raising any exceptions present. :param bool throw: If :py:data:`True`, raise exceptions, otherwise it is the caller's responsibility. :raises mitogen.core.CallError: The serialized data contained CallError exception. :raises mitogen.core.ChannelError: The serialized data contained :py:data:`mitogen.core._DEAD`. .. method:: reply (obj, \**kwargs) Compose a pickled reply to this message and send it using :py:attr:`router`. :param obj: Object to serialize. :param kwargs: Optional keyword parameters overriding message fields in the reply. Router Class ============ .. currentmodule:: mitogen.core .. class:: Router Route messages between parent and child contexts, and invoke handlers defined on our parent context. :py:meth:`Router.route() ` straddles the :py:class:`Broker ` and user threads, it is safe to call anywhere. **Note:** This is the somewhat limited core version of the Router class used by child contexts. The master subclass is documented below this one. .. method:: stream_by_id (dst_id) Return the :py:class:`mitogen.core.Stream` that should be used to communicate with `dst_id`. If a specific route for `dst_id` is not known, a reference to the parent context's stream is returned. .. method:: add_route (target_id, via_id) Arrange for messages whose `dst_id` is `target_id` to be forwarded on the directly connected stream for `via_id`. This method is called automatically in response to ``ADD_ROUTE`` messages, but remains public for now while the design has not yet settled, and situations may arise where routing is not fully automatic. .. method:: register (context, stream) Register a new context and its associated stream, and add the stream's receive side to the I/O multiplexer. This This method remains public for now while hte design has not yet settled. .. method:: add_handler (fn, handle=None, persist=True, respondent=None) Invoke `fn(msg)` for each Message sent to `handle` from this context. Unregister after one invocation if `persist` is ``False``. If `handle` is ``None``, a new handle is allocated and returned. :param int handle: If not ``None``, an explicit handle to register, usually one of the ``mitogen.core.*`` constants. If unspecified, a new unused handle will be allocated. :param bool persist: If ``False``, the handler will be unregistered after a single message has been received. :param mitogen.core.Context respondent: Context that messages to this handle are expected to be sent from. If specified, arranges for :py:data:`_DEAD` to be delivered to `fn` when disconnection of the context is detected. In future `respondent` will likely also be used to prevent other contexts from sending messages to the handle. :return: `handle`, or if `handle` was ``None``, the newly allocated handle. .. method:: _async_route(msg, stream=None) Arrange for `msg` to be forwarded towards its destination. If its destination is the local context, then arrange for it to be dispatched using the local handlers. This is a lower overhead version of :py:meth:`route` that may only be called from the I/O multiplexer thread. :param mitogen.core.Stream stream: If not ``None``, a reference to the stream the message arrived on. Used for performing source route verification, to ensure sensitive messages such as ``CALL_FUNCTION`` arrive only from trusted contexts. .. method:: route(msg) Arrange for the :py:class:`Message` `msg` to be delivered to its destination using any relevant downstream context, or if none is found, by forwarding the message upstream towards the master context. If `msg` is destined for the local context, it is dispatched using the handles registered with :py:meth:`add_handler`. This may be called from any thread. .. currentmodule:: mitogen.master .. class:: Router (broker=None) Extend :py:class:`mitogen.core.Router` with functionality useful to masters, and child contexts who later become masters. Currently when this class is required, the target context's router is upgraded at runtime. .. note:: You may construct as many routers as desired, and use the same broker for multiple routers, however usually only one broker and router need exist. Multiple routers may be useful when dealing with separate trust domains, for example, manipulating infrastructure belonging to separate customers or projects. :param mitogen.master.Broker broker: :py:class:`Broker` instance to use. If not specified, a private :py:class:`Broker` is created. .. data:: profiling When enabled, causes the broker thread and any subsequent broker and main threads existing in any child to write ``/tmp/mitogen.stats...log`` containing a :py:mod:`cProfile` dump on graceful exit. Must be set prior to any :py:class:`Broker` being constructed, e.g. via: .. code:: mitogen.master.Router.profiling = True .. method:: enable_debug Cause this context and any descendant child contexts to write debug logs to /tmp/mitogen..log. .. method:: allocate_id Arrange for a unique context ID to be allocated and associated with a route leading to the active context. In masters, the ID is generated directly, in children it is forwarded to the master via an ``ALLOCATE_ID`` message that causes the master to emit matching ``ADD_ROUTE`` messages prior to replying. .. method:: context_by_id (context_id, via_id=None) Messy factory/lookup function to find a context by its ID, or construct it. In future this will be replaced by a much more sensible interface. .. _context-factories: **Context Factories** .. method:: local (remote_name=None, python_path=None, debug=False, connect_timeout=None, profiling=False, via=None) Arrange for a context to be constructed on the local machine, as an immediate subprocess of the current process. The associated stream implementation is :py:class:`mitogen.master.Stream`. :param str remote_name: The ``argv[0]`` suffix for the new process. If `remote_name` is ``test``, the new process ``argv[0]`` will be ``mitogen:test``. If unspecified, defaults to ``@:``. This variable cannot contain slash characters, as the resulting ``argv[0]`` must be presented in such a way as to allow Python to determine its installation prefix. This is required to support virtualenv. :param str python_path: Path to the Python interpreter to use for bootstrap. Defaults to ``python2.7``. In future this may default to ``sys.executable``. :param bool debug: If ``True``, arrange for debug logging (:py:meth:`enable_debug`) to be enabled in the new context. Automatically ``True`` when :py:meth:`enable_debug` has been called, but may be used selectively otherwise. :param float connect_timeout: Fractional seconds to wait for the subprocess to indicate it is healthy. Defaults to 30 seconds. :param bool profiling: If ``True``, arrange for profiling (:py:data:`profiling`) to be enabled in the new context. Automatically ``True`` when :py:data:`profiling` is ``True``, but may be used selectively otherwise. :param mitogen.core.Context via: If not ``None``, arrange for construction to occur via RPCs made to the context `via`, and for :py:data:`ADD_ROUTE ` messages to be generated as appropriate. .. code-block:: python # SSH to the remote machine. remote_machine = router.ssh(hostname='mybox.com') # Use the SSH connection to create a sudo connection. remote_root = router.sudo(username='root', via=remote_machine) .. method:: docker (container=None, image=None, docker_path=None, \**kwargs) Arrange for a context to be constructed in an existing or temporary new Docker container. One of `container` or `image` must be specified. Accepts all parameters accepted by :py:meth:`local`, in addition to: :param str container: Existing container to connect to. Defaults to ``None``. :param str image: Image tag to use to construct a temporary container. Defaults to ``None``. :param str docker_path: Filename or complete path to the Docker binary. ``PATH`` will be searched if given as a filename. Defaults to ``docker``. .. method:: sudo (username=None, sudo_path=None, password=None, \**kwargs) Arrange for a context to be constructed over a ``sudo`` invocation. The ``sudo`` process is started in a newly allocated pseudo-terminal, and supports typing interactive passwords. Accepts all parameters accepted by :py:meth:`local`, in addition to: :param str username: Username to pass to sudo as the ``-u`` parameter, defaults to ``root``. :param str sudo_path: Filename or complete path to the sudo binary. ``PATH`` will be searched if given as a filename. Defaults to ``sudo``. :param str password: The password to use if/when sudo requests it. Depending on the sudo configuration, this is either the current account password or the target account password. :py:class:`mitogen.sudo.PasswordError` will be raised if sudo requests a password but none is provided. :param bool set_home: If :py:data:`True`, request ``sudo`` set the ``HOME`` environment variable to match the target UNIX account. :param bool preserve_env: If :py:data:`True`, request ``sudo`` to preserve the environment of the parent process. :param list sudo_args: Arguments in the style of :py:data:`sys.argv` that would normally be passed to ``sudo``. The arguments are parsed in-process to set equivalent parameters. Re-parsing ensures unsupported options cause :py:class:`mitogen.core.StreamError` to be raised, and that attributes of the stream match the actual behaviour of ``sudo``. .. method:: ssh (hostname, username=None, ssh_path=None, port=None, check_host_keys=True, password=None, identity_file=None, compression=True, \**kwargs) Arrange for a context to be constructed over a ``ssh`` invocation. The ``ssh`` process is started in a newly allocated pseudo-terminal, and supports typing interactive passwords. Accepts all parameters accepted by :py:meth:`local`, in addition to: :param str username: The SSH username; default is unspecified, which causes SSH to pick the username to use. :param str ssh_path: Absolute or relative path to ``ssh``. Defaults to ``ssh``. :param int port: Port number to connect to; default is unspecified, which causes SSH to pick the port number. :param bool check_host_keys: If ``False``, arrange for SSH to perform no verification of host keys. If ``True``, cause SSH to pick the default behaviour, which is usually to verify host keys. :param str password: Password to type if/when ``ssh`` requests it. If not specified and a password is requested, :py:class:`mitogen.ssh.PasswordError` is raised. :param str identity_file: Path to an SSH private key file to use for authentication. Default is unspecified, which causes SSH to pick the identity file. When this option is specified, only `identity_file` will be used by the SSH client to perform authenticaion; agent authentication is automatically disabled, as is reading the default private key from ``~/.ssh/id_rsa``, or ``~/.ssh/id_dsa``. :param bool compression: If :py:data:`True`, enable ``ssh`` compression support. Compression has a minimal effect on the size of modules transmitted, as they are already compressed, however it has a large effect on every remaining message in the otherwise uncompressed stream protocol, such as function call arguments and return values. Context Class ============= .. currentmodule:: mitogen.core .. class:: Context Represent a remote context regardless of connection method. **Note:** This is the somewhat limited core version of the Context class used by child contexts. The master subclass is documented below this one. .. method:: send (msg) Arrange for `msg` to be delivered to this context. Updates the message's `dst_id` prior to routing it via the associated router. :param mitogen.core.Message msg: The message. .. method:: send_async (msg, persist=False) Arrange for `msg` to be delivered to this context, with replies delivered to a newly constructed Receiver. Updates the message's `dst_id` prior to routing it via the associated router and registers a handle which is placed in the message's `reply_to`. :param bool persist: If ``False``, the handler will be unregistered after a single message has been received. :param mitogen.core.Message msg: The message. :returns: :py:class:`mitogen.core.Receiver` configured to receive any replies sent to the message's `reply_to` handle. .. method:: send_await (msg, deadline=None) As with :py:meth:`send_async`, but expect a single reply (`persist=False`) delivered within `deadline` seconds. :param mitogen.core.Message msg: The message. :param float deadline: If not ``None``, seconds before timing out waiting for a reply. :raises mitogen.core.TimeoutError: No message was received and `deadline` passed. .. currentmodule:: mitogen.master .. class:: Context Extend :py:class:`mitogen.core.Router` with functionality useful to masters, and child contexts who later become masters. Currently when this class is required, the target context's router is upgraded at runtime. .. method:: call_async (fn, \*args, \*\*kwargs) Arrange for the context's ``CALL_FUNCTION`` handle to receive a message that causes `fn(\*args, \**kwargs)` to be invoked on the context's main thread. :param fn: A free function in module scope, or a classmethod or staticmethod of a class directly reachable from module scope: .. code-block:: python # mymodule.py def my_func(): """A free function reachable as mymodule.my_func""" class MyClass: @staticmethod def my_staticmethod(): """Reachable as mymodule.MyClass.my_staticmethod""" @classmethod def my_classmethod(cls): """Reachable as mymodule.MyClass.my_classmethod""" def my_instancemethod(self): """Unreachable: requires a class instance!""" class MyEmbeddedClass: @classmethod def my_classmethod(cls): """Not directly reachable from module scope!""" :param tuple args: Function arguments, if any. See :ref:`serialization-rules` for permitted types. :param dict kwargs: Function keyword arguments, if any. See :ref:`serialization-rules` for permitted types. :returns: :py:class:`mitogen.core.Receiver` configured to receive the result of the invocation: .. code-block:: python recv = context.call_async(os.check_output, 'ls /tmp/') try: # Prints output once it is received. msg = recv.get() print msg.unpickle() except mitogen.core.CallError, e: print 'Call failed:', str(e) Asynchronous calls may be dispatched in parallel to multiple contexts and consumed as they complete using :py:class:`mitogen.master.Select`. .. method:: call (fn, \*args, \*\*kwargs) Equivalent to :py:meth:`call_async(fn, \*args, \**kwargs).get_data() `. :returns: The function's return value. :raises mitogen.core.CallError: An exception was raised in the remote context during execution. Receiver Class -------------- .. currentmodule:: mitogen.core .. class:: Receiver (router, handle=None, persist=True, respondent=None) Receivers are used to wait for pickled responses from another context to be sent to a handle registered in this context. A receiver may be single-use (as in the case of :py:meth:`mitogen.master.Context.call_async`) or multiple use. :param mitogen.core.Router router: Router to register the handler on. :param int handle: If not ``None``, an explicit handle to register, otherwise an unused handle is chosen. :param bool persist: If ``True``, do not unregister the receiver's handler after the first message. :param mitogen.core.Context respondent: Reference to the context this receiver is receiving from. If not ``None``, arranges for the receiver to receive :py:data:`_DEAD` if messages can no longer be routed to the context, due to disconnection or exit. .. attribute:: notify = None If not ``None``, a reference to a function invoked as `notify(receiver)` when a new message is delivered to this receiver. Used by :py:class:`mitogen.master.Select` to implement waiting on multiple receivers. .. py:method:: empty () Return ``True`` if calling :py:meth:`get` would block. As with :py:class:`Queue.Queue`, ``True`` may be returned even though a subsequent call to :py:meth:`get` will succeed, since a message may be posted at any moment between :py:meth:`empty` and :py:meth:`get`. :py:meth:`empty` is only useful to avoid a race while installing :py:attr:`notify`: .. code-block:: python recv.notify = _my_notify_function if not recv.empty(): _my_notify_function(recv) # It is guaranteed the receiver was empty after the notification # function was installed, or that it was non-empty and the # notification function was invoked at least once. .. py:method:: close () Cause :py:class:`mitogen.core.ChannelError` to be raised in any thread waiting in :py:meth:`get` on this receiver. .. py:method:: get (timeout=None) Sleep waiting for a message to arrive on this receiver. :param float timeout: If not ``None``, specifies a timeout in seconds. :raises mitogen.core.ChannelError: The remote end indicated the channel should be closed, or communication with its parent context was lost. :raises mitogen.core.TimeoutError: Timeout was reached. :returns: `(msg, data)` tuple, where `msg` is the :py:class:`mitogen.core.Message` that was received, and `data` is its unpickled data part. .. py:method:: get_data (timeout=None) Like :py:meth:`get`, except only return the data part. .. py:method:: __iter__ () Block and yield `(msg, data)` pairs delivered to this receiver until :py:class:`mitogen.core.ChannelError` is raised. Sender Class ------------ .. currentmodule:: mitogen.core .. class:: Sender (context, dst_handle) Senders are used to send pickled messages to a handle in another context, it is the inverse of :py:class:`mitogen.core.Sender`. :param mitogen.core.Context context: Context to send messages to. :param int dst_handle: Destination handle to send messages to. .. py:method:: close () Send :py:data:`_DEAD` to the remote end, causing :py:meth:`ChannelError` to be raised in any waiting thread. .. py:method:: put (data) Send `data` to the remote end. Channel Class ------------- .. currentmodule:: mitogen.core .. class:: Channel (router, context, dst_handle, handle=None) A channel inherits from :py:class:`mitogen.core.Sender` and `mitogen.core.Receiver` to provide bidirectional functionality. Since all handles aren't known until after both ends are constructed, for both ends to communicate through a channel, it is necessary for one end to retrieve the handle allocated to the other and reconfigure its own channel to match. Currently this is a manual task. Broker Class ============ .. currentmodule:: mitogen.core .. class:: Broker Responsible for handling I/O multiplexing in a private thread. **Note:** This is the somewhat limited core version of the Broker class used by child contexts. The master subclass is documented below this one. .. attribute:: shutdown_timeout = 3.0 Seconds grace to allow :py:class:`streams ` to shutdown gracefully before force-disconnecting them during :py:meth:`shutdown`. .. method:: defer (func, \*args, \*kwargs) Arrange for `func(\*args, \**kwargs)` to be executed on the broker thread, or immediately if the current thread is the broker thread. Safe to call from any thread. .. method:: start_receive (stream) Mark the :py:attr:`receive_side ` on `stream` as ready for reading. Safe to call from any thread. When the associated file descriptor becomes ready for reading, :py:meth:`BasicStream.on_receive` will be called. .. method:: stop_receive (stream) Mark the :py:attr:`receive_side ` on `stream` as not ready for reading. Safe to call from any thread. .. method:: start_transmit (stream) Mark the :py:attr:`transmit_side ` on `stream` as ready for writing. Safe to call from any thread. When the associated file descriptor becomes ready for writing, :py:meth:`BasicStream.on_transmit` will be called. .. method:: stop_receive (stream) Mark the :py:attr:`transmit_side ` on `stream` as not ready for writing. Safe to call from any thread. .. method:: shutdown Request broker gracefully disconnect streams and stop. .. method:: join Wait for the broker to stop, expected to be called after :py:meth:`shutdown`. .. method:: keep_alive Return ``True`` if any reader's :py:attr:`Side.keep_alive` attribute is ``True``, or any :py:class:`Context` is still registered that is not the master. Used to delay shutdown while some important work is in progress (e.g. log draining). **Internal Methods** .. method:: _broker_main Handle events until :py:meth:`shutdown`. On shutdown, invoke :py:meth:`Stream.on_shutdown` for every active stream, then allow up to :py:attr:`shutdown_timeout` seconds for the streams to unregister themselves before forcefully calling :py:meth:`Stream.on_disconnect`. .. currentmodule:: mitogen.master .. class:: Broker (install_watcher=True) .. note:: You may construct as many brokers as desired, and use the same broker for multiple routers, however usually only one broker need exist. Multiple brokers may be useful when dealing with sets of children with differing lifetimes. For example, a subscription service where non-payment results in termination for one customer. :param bool install_watcher: If ``True``, an additional thread is started to monitor the lifetime of the main thread, triggering :py:meth:`shutdown` automatically in case the user forgets to call it, or their code crashed. You should not rely on this functionality in your program, it is only intended as a fail-safe and to simplify the API for new users. In particular, alternative Python implementations may not be able to support watching the main thread. .. attribute:: shutdown_timeout = 5.0 Seconds grace to allow :py:class:`streams ` to shutdown gracefully before force-disconnecting them during :py:meth:`shutdown`. Utility Functions ================= .. module:: mitogen.utils A random assortment of utility functions useful on masters and children. .. currentmodule:: mitogen.utils .. function:: cast (obj) Many tools love to subclass built-in types in order to implement useful functionality, such as annotating the safety of a Unicode string, or adding additional methods to a dict. However, cPickle loves to preserve those subtypes during serialization, resulting in CallError during :py:meth:`call ` in the target when it tries to deserialize the data. This function walks the object graph `obj`, producing a copy with any custom sub-types removed. The functionality is not default since the resulting walk may be computationally expensive given a large enough graph. See :ref:`serialization-rules` for a list of supported types. :param obj: Object to undecorate. :returns: Undecorated object. .. currentmodule:: mitogen.utils .. function:: disable_site_packages Remove all entries mentioning ``site-packages`` or ``Extras`` from the system path. Used primarily for testing on OS X within a virtualenv, where OS X bundles some ancient version of the :py:mod:`six` module. .. currentmodule:: mitogen.utils .. function:: log_to_file (path=None, io=False, usec=False, level='INFO') Install a new :py:class:`logging.Handler` writing applications logs to the filesystem. Useful when debugging slave IO problems. Parameters to this function may be overridden at runtime using environment variables. See :ref:`logging-env-vars`. :param str path: If not ``None``, a filesystem path to write logs to. Otherwise, logs are written to :py:data:`sys.stderr`. :param bool io: If ``True``, include extremely verbose IO logs in the output. Useful for debugging hangs, less useful for debugging application code. :parm bool usec: If ``True``, include microsecond timestamps. This greatly helps when debugging races and similar determinism issues. :param str level: Name of the :py:mod:`logging` package constant that is the minimum level to log at. Useful levels are ``DEBUG``, ``INFO``, ``WARNING``, and ``ERROR``. .. currentmodule:: mitogen.utils .. function:: run_with_router(func, \*args, \**kwargs) Arrange for `func(router, \*args, \**kwargs)` to run with a temporary :py:class:`mitogen.master.Router`, ensuring the Router and Broker are correctly shut down during normal or exceptional return. :returns: `func`'s return value. .. currentmodule:: mitogen.utils .. decorator:: with_router Decorator version of :py:func:`run_with_router`. Example: .. code-block:: python @with_router def do_stuff(router, arg): pass do_stuff(blah, 123) Exceptions ========== .. currentmodule:: mitogen.core .. class:: Error (fmt, \*args) Base for all exceptions raised by Mitogen. .. class:: CallError (e) Raised when :py:meth:`Context.call() ` fails. A copy of the traceback from the external context is appended to the exception message. .. class:: ChannelError (fmt, \*args) Raised when a channel dies or has been closed. .. class:: LatchError (fmt, \*args) Raised when an attempt is made to use a :py:class:`mitogen.core.Latch` that has been marked closed. .. class:: StreamError (fmt, \*args) Raised when a stream cannot be established. .. class:: TimeoutError (fmt, \*args) Raised when a timeout occurs on a stream.