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- zymb.sched.Agent
-
- File
class File(zymb.sched.Agent) |
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File: An Agent which reads from a file or file object.
As is common for agents, File does not actually do any work
until you start it and begin calling sched.process(). Also, it does
not (by default) do anything with received data. Incoming data
triggers a 'handle' event, but there is no preregistered handler for
this event. You can write your own, or install the basichandle()
handler. See below.
File(file) -- constructor.
The *file* can be a string (filename) or a file object which is open
for reading (such as sys.stdin).
If you pass a string, the agent will open the file. In this mode,
the agent will almost certainly read the whole file in a single gulp,
and then close it immediately. I don't know if this is useful, but you
can do it.
If you pass a file object, the agent sets it to non-blocking mode.
Again, if the file refers to an actual disk file, you'll probably
get the whole contents at once. If it's stdin or some other stream,
you'll receive the data as it arrives. In this mode, since the agent
did not open the file, it will not presume to close it.
Agent states and events:
state 'start': Open the file (if appropriate), set it non-blocking.
state 'connected': The file is open and ready.
event 'handle' (str): Data has been received from the file.
event 'error' (exc, agent): A low-level error has been detected.
Errors detected when the file is being opened will stop the
agent; read/write errors will not.
event 'closed': Reached the end of the file, or (for a stdin-like
file) the file was closed from the other side. This will be
immediately followed by a jump to the 'end' state.
state 'end': Close the file (if this agent was responsible for opening
it).
Public methods:
basichandle(str) -- a simple event handler for 'handle'.
Internal methods:
connect() -- 'start' state handler.
gotactivity() -- handler for socket activity.
disconnect() -- 'end' state handler.
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Methods defined here:
- __init__(self, fl)
- __str__(self)
- basichandle(self, dat)
- basichandle(dat) -> None
A simple event handler for 'handle'. This simply writes the
received data to stdout:
sys.stdout.write(dat)
This handler is not installed by default. You can enable it by
calling:
fileag.addhandler('handle', fileag.basichandle)
- connect(self)
- connect() -- internal 'start' state handler. Do not call.
Open the file (if a filename was provided) and set it nonblocking.
If successful, jump to state 'connected'. On error, jump to
state 'end'.
- disconnect(self)
- disconnect() -- internal 'end' state handler. Do not call.
Close the file, if this agent was responsible for opening it.
- gotactivity(self)
- gotactivity() -- internal handler for file activity. Do not call.
Pull as much data from the file as is currently available.
Perform a 'handle' event. If the file has closed, perform 'closed'
and then jump to state 'end'.
Data and other attributes defined here:
- logprefix = 'zymb.file'
Methods inherited from zymb.sched.Agent:
- addcleanupaction(self, ac)
- addcleanupaction(action) -> None
Add *action* to the list of actions to be removed when the agent
stops (i.e., jumps to the 'end' state).
This is intended for actions that an agent adds as handlers to
other agents. For example:
ac = otheragent.addhandler('event', self.foreigneventhandler)
# Ensure that ac is removed when *self* shuts down.
addcleanupaction(ac)
You do not need to list pollers or socket-checkers as cleanup
actions. Nor do you need to list handlers that an agent adds
to itself. (All these are automatically removed when the agent
shuts down.) You also don't have to worry about the case of
*otheragent* shutting down; when that happens, all handlers added
to it are removed.
- addhandler(self, state, op, *args)
- addhandler(eventname, op, *args) -> action
Add a state or event handler. The *eventname* is a string naming
the state or event you want to handle. The *op* and *args* are
the operation to perform when that state or event occurs.
(See queueaction() for the use of *op* and *args*.)
Handlers are invoked in last-added-first-run order. If an agent
has a built-in handler, it is added first, so it runs last. Handlers
that you add on later run earlier.
Returns the Action. (You can cancel the handler by calling
ac.remove().)
- addtimer(self, op, *args, **dic)
- addtimer(op, *args, delay=num, when=num, periodic=bool) -> action
Add a timed event. You must supply exactly one of the keyword
arguments *delay* and *when*. A *when* is an absolute time,
expressed as a number of seconds since the epoch (e.g., the kind
of value returned by time.time()). A *delay* is a relative time,
expressed as a number of seconds in the future.
It is legal to give a time in the past (or a negative *delay*).
In that case, this is similar to queueaction() -- the operation
will occur very soon. (Although it's still a "low priority"
action.)
If you supply *periodic*=True, the event will occur repeatedly,
every *delay* seconds. (The interval is inferred if you give
*when*.) In this case, you may NOT give a negative *delay* or
a time in the past -- it is meaningless for a periodic event to
have a period less than or equal to zero.
You can also create a periodic timer by calling addtimer with
a PeriodicAction, which is a subclass of Action. This is slightly
more flexible; the interval between calls is specified when
you create the PeriodicAction, but the delay before the first
call may be specified with *delay* or *when*.
See queueaction() for the use of *op* and *args*.
Returns the Action. (You can cancel the timer by calling
ac.remove().)
- basicerror(self, exc, agent)
- basicerror(exc, agent) -> None
A simple event handler for 'error'. This simply writes the
received data to stdout:
sys.stdout.write('Error: ' + str(agent) + ': ' + str(exc) + '
')
This handler is not installed by default. You can enable it by
calling:
ag.addhandler('error', ag.basicerror)
- jump(self, st, *exargs)
- jump(state, *args) -> None
Jump to a different operating state. (If the agent is already
in the given state, nothing happens.)
This queues up all the state transition handlers registered
for the new state. If you provide *args*, they are passed to the
handlers when they are called.
- perform(self, name, *exargs)
- perform(eventname, *args) -> None
Trigger an event.
This queues up all the event handlers registered for the given
event. If you provide *args*, they are passed to the handlers when
they are called.
- queueaction(self, op, *args)
- queueaction(op, *args) -> action
Invoke an action. The action will be handed to the scheduler, which
will run it very soon.
("Very soon" means "before the next timed event or network message
is handled." However, if you queue several actions, they will be
handled in the order you queued them.)
You can pass any callable as *op*; the (optional) *args* will be
passed to it as arguments. You can also, if you like, create
an Action object and pass it as *op*. You can still pass *args*
in this case; they'll be appended to the arguments bound into
the Action.
Returns the Action.
- registerpoll(self, op, *args, **dic)
- registerpoll(op, *args, interval=num) -> action
Add a repeating activity check. *interval* is a (mandatory) keyword
argument; the scheduler will invoke your operation at least every
*interval* seconds. (And at least once per sched.process() call.)
See queueaction() for the use of *op* and *args*. Your operation
should not do any work except for absorbing input and queueing
actions. Typically, it will collect the input and then call
perform(), triggering an event, so that the agent's event
handlers can do something with the input.
Returns the Action. (You can cancel it by calling ac.remove().)
- registersocket(self, fileno, op, *args)
- registersocket(socket, op, *args) -> action
Add a socket-based activity check. The *socket* may be a socket
object, or a number representing a fileno, or any object which
provides a fileno() method.
See queueaction() for the use of *op* and *args*. Your operation
should not do any work except for absorbing input and queueing
actions. Typically, it will collect the input and then call
perform(), triggering an event, so that the agent's event
handlers can do something with the input.
Returns the Action. (You can cancel it by calling ac.remove().)
- shutdown(self)
- shutdown() -- internal 'end' state handler. Do not call.
This is the final 'end' handler. It removes the agent from the
scheduler, and cancels all its remaining actions, timed events,
etc.
- start(self)
- start() -> None
Begin activity. The agent adds itself to the scheduler and moves
to the 'start' state. It does not actually begin doing work in
this call; that happens the next time the scheduler is invoked
(sched.process).
You should only call this once per agent.
- stop(self)
- stop() -> None
Stop activity. The agent moves to the 'end' state. Its 'end'
state handlers will take care of shutting it down and removing
it from the scheduler.
It is safe to call this on an agent which is already in 'end',
or which is completely shut down. (Nothing further will happen.)
(Remember, state handlers are not called as part of the stop()
method. They are run by the scheduler "soon" after stop() is
called. If you want to be sure the agent is completely stopped,
you can check the agent.live field. However, it is better to
register your own 'end' state handler, and consider the agent
stopped when that it called.)
Data and other attributes inherited from zymb.sched.Agent:
- agentcounter = 1
- hidden = False
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