import socket, pickle, struct, select, threading
-__all__ = ["client", "replclient"]
+__all__ = ["client", "replclient", "perfclient"]
class protoerr(Exception):
+ """Raised on protocol errors"""
pass
def resolve(spec):
return rv
class client(object):
+ """PDM client
+
+ This class provides general facilities to speak to PDM servers,
+ and is mainly intended to be subclassed to provide for the
+ specific protocols, such as replclient and perfclient do.
+
+ `client' instances can be passed as arguments to select.select(),
+ and can be used in `with' statements.
+ """
def __init__(self, sk, proto = None):
+ """Create a client object connected to the specified
+ server. `sk' can either be a socket object, which is used as
+ it is, or a string specification very similar to the
+ specification for pdm.srv.listen, so see its documentation for
+ details. The differences are only that this function does not
+ take arguments specific to socket creation, like the mode and
+ group arguments for Unix sockets. If `proto' is given, that
+ subprotocol will negotiated with the server (by calling the
+ select() method).
+ """
self.sk = resolve(sk)
self.buf = b""
line = self.readline()
self.select(proto)
def close(self):
+ """Close this connection"""
self.sk.close()
def fileno(self):
+ """Return the file descriptor of the underlying socket."""
return self.sk.fileno()
def readline(self):
+ """Read a single NL-terminated line and return it."""
while True:
p = self.buf.find(b"\n")
if p >= 0:
self.buf += ret
def select(self, proto):
+ """Negotiate the given subprotocol with the server"""
if isinstance(proto, str):
proto = proto.encode("ascii")
if b"\n" in proto:
return False
class replclient(client):
+ """REPL protocol client
+
+ Implements the client side of the REPL protocol; see pdm.srv.repl
+ for details on the protocol and its functionality.
+ """
def __init__(self, sk):
+ """Create a connected client as documented in the `client' class."""
super().__init__(sk, "repl")
def run(self, code):
+ """Run a single block of Python code on the server. Returns
+ the output of the command (as documented in pdm.srv.repl) as a
+ string.
+ """
while True:
ncode = code.replace("\n\n", "\n")
if ncode == code: break
except: pass
def close(self):
- self.cl.run("unbind", self.id)
- del self.cl.proxies[self.id]
+ if self.id is not None:
+ self.cl.run("unbind", self.id)
+ del self.cl.proxies[self.id]
+ self.id = None
+
+ def __del__(self):
+ self.close()
def __enter__(self):
return self
return False
class perfclient(client):
+ """PERF protocol client
+
+ Implements the client side of the PERF protocol; see pdm.srv.perf
+ for details on the protocol and its functionality.
+
+ This client class implements functions for finding PERF objects on
+ the server, and returns, for each server-side object looked up, a
+ proxy object that mimics exactly the PERF interfaces that the
+ object implements. As the proxy objects reference live objects on
+ the server, they should be released when they are no longer used;
+ they implement a close() method for that purpose, and can also be
+ used in `with' statements.
+
+ See pdm.srv.perf for details on the various PERF interfaces that
+ the proxy objects might implement.
+ """
def __init__(self, sk):
+ """Create a connected client as documented in the `client' class."""
super().__init__(sk, "perf")
self.nextid = 0
self.lock = threading.Lock()
proxy.notify(ev)
def dispatch(self, timeout = None):
+ """Wait for an incoming notification from the server, and
+ dispatch it to the callback functions that have been
+ registered for it. If `timeout' is specified, wait no longer
+ than so many seconds; otherwise, wait forever. This client
+ object may also be used as argument to select.select().
+ """
rfd, wfd, efd = select.select([self.sk], [], [], timeout)
if self.sk in rfd:
msg = self.recv()
self.lock.release()
def lookup(self, module, obnm):
+ """Look up a single server-side object by the given name in
+ the given module. Will return a new proxy object for each
+ call when called multiple times for the same name.
+ """
self.lock.acquire()
try:
id = self.nextid
return proxy
def find(self, name):
+ """Convenience function for looking up server-side objects
+ through PERF directories and for multiple uses. The object
+ name can be given as "MODULE.OBJECT", which will look up the
+ named OBJECT in the named MODULE, and can be followed by any
+ number of slash-separated names, which will assume that the
+ object to the left of the slash is a PERF directory, and will
+ return the object in that directory by the name to the right
+ of the slash. For instance, find("pdm.perf.sysres/cputime")
+ will return the built-in attribute for reading the CPU time
+ used by the server process.
+ """
ret = self.names.get(name)
if ret is None:
if "/" in name:
-"""Management for daemon processes
+"""Python Daemon Management -- Server functions
-This module contains a utility to listen for management commands on a
-socket, lending itself to managing daemon processes.
+This module implements the server part of the PDM protocols. The
+primary object of interest herein is the listen() function, which is
+the most generic way to create PDM listeners based on user
+configuration, and the documentation for the repl and perf classes,
+which describes the functioning of the REPL and PERF protocols.
"""
import os, sys, socket, threading, grp, select
import types, pprint, traceback
import pickle, struct
-__all__ = ["listener", "unixlistener", "tcplistener", "listen"]
+__all__ = ["repl", "perf", "listener", "unixlistener", "tcplistener", "listen"]
protocols = {}
class repl(object):
+ """REPL protocol handler
+
+ Provides a read-eval-print loop. The primary client-side interface
+ is the pdm.cli.replclient class. Clients can send arbitrary code,
+ which is compiled and run on its own thread in the server process,
+ and output responses that are echoed back to the client.
+
+ Each client is provided with its own module, in which the code
+ runs. The module is prepared with a function named `echo', which
+ takes a single object and pretty-prints it as part of the command
+ response. If a command can be parsed as an expression, the value
+ it evaluates to is automatically echoed to the client. If the
+ evalution of the command terminates with an exception, its
+ traceback is echoed to the client.
+
+ The REPL protocol is only intended for interactive usage. In order
+ to interact programmatically with the server process, see the PERF
+ protocol instead.
+ """
def __init__(self, cl):
self.cl = cl
self.mod = types.ModuleType("repl")
protocols["repl"] = repl
class perf(object):
+ """PERF protocol handler
+
+ The PERF protocol provides an interface for program interaction
+ with the server process. It allows limited remote interactions
+ with Python objects over a few defined interfaces.
+
+ All objects that wish to be available for interaction need to
+ implement a method named `pdm_protocols' which, when called with
+ no arguments, should return a list of strings, each indicating a
+ PERF interface that the object implements. For each such
+ interface, the object must implement additional methods as
+ described below.
+
+ A client can find PERF objects to interact with either by
+ specifying the name of such an object in an existing module, or by
+ using the `dir' interface, described below. Thus, to make a PERF
+ object available for clients, it needs only be bound to a global
+ variable in a module and implement the `pdm_protocols'
+ method. When requesting an object from a module, the module must
+ already be imported. PDM will not import new modules for clients;
+ rather, the daemon process needs to import all modules that
+ clients should be able to interact with. PDM itself always imports
+ the pdm.perf module, which contains a few basic PERF objects. See
+ its documentation for details.
+
+ The following interfaces are currently known to PERF.
+
+ * attr:
+ An object that implements the `attr' interface models an
+ attribute that can be read by clients. The attribute can be
+ anything, as long as its representation can be
+ pickled. Examples of attributes could be such things as the CPU
+ time consumed by the server process, or the number of active
+ connections to whatever clients the program serves. To
+ implement the `attr' interface, an object must implement
+ methods called `readattr' and `attrinfo'. `readattr' is called
+ with no arguments to read the current value of the attribute,
+ and `attrinfo' is called with no arguments to read a
+ description of the attribute. Both should be
+ idempotent. `readattr' can return any pickleable object, and
+ `attrinfo' should return either None to indicate that it has no
+ description, or an instance of the pdm.perf.attrinfo class.
+
+ * dir:
+ The `dir' interface models a directory of other PERF
+ objects. An object implementing it must implement methods
+ called `lookup' and `listdir'. `lookup' is called with a single
+ string argument that names an object, and should either return
+ another PERF object based on the name, or raise KeyError if it
+ does not recognize the name. `listdir' is called with no
+ arguments, and should return a list of known names that can be
+ used as argument to `lookup', but the list is not required to
+ be exhaustive and may also be empty.
+
+ * invoke:
+ The `invoke' interface allows a more arbitrary form of method
+ calls to objects implementing it. Such objects must implement a
+ method called `invoke', which is called with one positional
+ argument naming a method to be called (which it is free to
+ interpret however it wishes), and with any additional
+ positional and keyword arguments that the client wishes to pass
+ to it. Whatever `invoke' returns is pickled and sent back to
+ the client. In case the method name is not recognized, `invoke'
+ should raise an AttributeError.
+
+ * event:
+ The `event' interface allows PERF objects to notify clients of
+ events asynchronously. Objects implementing it must implement
+ methods called `subscribe' and `unsubscribe'. `subscribe' will
+ be called with a single argument, which is a callable of one
+ argument, which should be registered to be called when an event
+ pertaining to the `event' object in question occurs. The
+ `event' object should then call all such registered callables
+ with a single argument describing the event. The argument could
+ be any object that can be pickled, but should be an instance of
+ a subclass of the pdm.perf.event class. If `subscribe' is
+ called with a callback object that it has already registered,
+ it should raise a ValueError. `unsubscribe' is called with a
+ single argument, which is a previously registered callback
+ object, which should then be unregistered to that it is no
+ longer called when an event occurs. If the given callback
+ object is not, in fact, registered, a ValueError should be
+ raised.
+
+ The pdm.perf module contains a few convenience classes which
+ implements the interfaces, but PERF objects are not required to be
+ instances of them. Any object can implement a PERF interface, as
+ long as it does so as described above.
+
+ The pdm.cli.perfclient class is the client-side implementation.
+ """
def __init__(self, cl):
self.cl = cl
self.odtab = {}
class listener(threading.Thread):
+ """PDM listener
+
+ This subclass of a thread listens to PDM connections and handles
+ client connections properly. It is intended to be subclassed by
+ providers of specific domains, such as unixlistener and
+ tcplistener.
+ """
def __init__(self):
super().__init__(name = "Management listener")
self.setDaemon(True)
def listen(self, sk):
+ """Listen for and accept connections."""
self.running = True
while self.running:
rfd, wfd, efd = select.select([sk], [], [sk], 1)
self.accept(nsk, addr)
def stop(self):
+ """Stop listening for client connections
+
+ Tells the listener thread to stop listening, and then waits
+ for it to terminate.
+ """
self.running = False
self.join()
cl.start()
class unixlistener(listener):
+ """Unix socket listener"""
def __init__(self, name, mode = 0o600, group = None):
+ """Create a listener that will bind to the Unix socket named
+ by `name'. The socket will not actually be bound until the
+ listener is started. The socket will be chmodded to `mode',
+ and if `group' is given, the named group will be set as the
+ owner of the socket.
+ """
super().__init__()
self.name = name
self.mode = mode
os.unlink(self.name)
class tcplistener(listener):
+ """TCP socket listener"""
def __init__(self, port, bindaddr = "127.0.0.1"):
+ """Create a listener that will bind to the given TCP port, and
+ the given local interface. The socket will not actually be
+ bound until the listener is started.
+ """
super().__init__()
self.port = port
self.bindaddr = bindaddr
sk.close()
def listen(spec):
+ """Create and start a listener according to a string
+ specification. The string specifications can easily be passed from
+ command-line options, user configuration or the like. Currently,
+ the two following specification formats are recognized:
+
+ PATH[:MODE[:GROUP]] -- PATH must contain at least one slash. A
+ Unix socket listener will be created listening to that path, and
+ the socket will be chmodded to MODE and owned by GROUP. If MODE is
+ not given, it defaults to 0600, and if GROUP is not given, the
+ process' default group is used.
+
+ ADDRESS:PORT -- PORT must be entirely numeric. A TCP socket
+ listener will be created listening to that port, bound to the
+ given local interface address. Since PDM has no authentication
+ support, ADDRESS should probably be localhost.
+ """
if ":" in spec:
first = spec[:spec.index(":")]
last = spec[spec.rindex(":") + 1:]
Dolda2000 GitWeb / pdm.git / commitdiff