Remove third_party/twisted_8_1

third_party/twisted_8_1/twisted/persisted/journal/base.py

-# -*- test-case-name: twisted.test.test_journal -*-
-#
-# Copyright (c) 2001-2004 Twisted Matrix Laboratories.
-# See LICENSE for details.
-
-# 
-
-
-"""Basic classes and interfaces for journal."""
-
-from __future__ import nested_scopes
-
-# system imports
-import os, time
-
-try:
-    import cPickle as pickle
-except ImportError:
-    import pickle
-
-# twisted imports
-from zope.interface import implements, Interface
-
-
-class Journal:
-    """All commands to the system get routed through here.
-
-    Subclasses should implement the actual snapshotting capability.
-    """
-
-    def __init__(self, log, journaledService):
-        self.log = log
-        self.journaledService = journaledService
-        self.latestIndex = self.log.getCurrentIndex()
-
-    def updateFromLog(self):
-        """Run all commands from log that haven't been run yet.
-
-        This method should be run on startup to ensure the snapshot
-        is up-to-date.
-        """
-        snapshotIndex = self.getLastSnapshot()
-        if snapshotIndex < self.latestIndex:
-            for cmdtime, command in self.log.getCommandsSince(snapshotIndex + 1):
-                command.execute(self.journaledService, cmdtime)
-
-    def executeCommand(self, command):
-        """Log and execute a command."""
-        runTime = time.time()
-        d = self.log.logCommand(command, runTime)
-        d.addCallback(self._reallyExecute, command, runTime)
-        return d
-
-    def _reallyExecute(self, index, command, runTime):
-        """Callback called when logging command is done."""
-        result = command.execute(self.journaledService, runTime)
-        self.latestIndex = index
-        return result
-    
-    def getLastSnapshot(self):
-        """Return command index of the last snapshot taken."""
-        raise NotImplementedError
-
-    def sync(self, *args, **kwargs):
-        """Save journal to disk, returns Deferred of finish status.
-
-        Subclasses may choose whatever signature is appropriate, or may
-        not implement this at all.
-        """
-        raise NotImplementedError
-
-
-
-class MemoryJournal(Journal):
-    """Prevayler-like journal that dumps from memory to disk."""
-
-    def __init__(self, log, journaledService, path, loadedCallback):
-        self.path = path
-        if os.path.exists(path):
-            try:
-                self.lastSync, obj = pickle.load(open(path, "rb"))
-            except (IOError, OSError, pickle.UnpicklingError):
-                self.lastSync, obj = 0, None
-            loadedCallback(obj)
-        else:
-            self.lastSync = 0
-            loadedCallback(None)
-        Journal.__init__(self, log, journaledService)
-
-    def getLastSnapshot(self):
-        return self.lastSync
-
-    def sync(self, obj):
-        # make this more reliable at some point
-        f = open(self.path, "wb")
-        pickle.dump((self.latestIndex, obj), f, 1)
-        f.close()
-        self.lastSync = self.latestIndex
-
-
-class ICommand(Interface):
-    """A serializable command which interacts with a journaled service."""
-
-    def execute(journaledService, runTime):
-        """Run the command and return result."""
-
-
-class ICommandLog(Interface):
-    """Interface for command log."""
-
-    def logCommand(command, runTime):
-        """Add a command and its run time to the log.
-
-        @return: Deferred of command index.
-        """
-
-    def getCurrentIndex():
-        """Return index of last command that was logged."""
-
-    def getCommandsSince(index):
-        """Return commands who's index >= the given one.
-
-        @return: list of (time, command) tuples, sorted with ascending times.
-        """
-
-
-class LoadingService:
-    """Base class for journalled service used with Wrappables."""
-
-    def loadObject(self, objType, objId):
-        """Return object of specified type and id."""
-        raise NotImplementedError
-
-
-class Wrappable:
-    """Base class for objects used with LoadingService."""
-
-    objectType = None # override in base class
-
-    def getUid(self):
-        """Return uid for loading with LoadingService.loadObject"""
-        raise NotImplementedError
-
-
-class WrapperCommand:
-    
-    implements(ICommand)
-
-    def __init__(self, methodName, obj, args=(), kwargs={}):
-        self.obj = obj
-        self.objId = obj.getUid()
-        self.objType = obj.objectType
-        self.methodName = methodName
-        self.args = args
-        self.kwargs = kwargs
-
-    def execute(self, svc, commandTime):
-        if not hasattr(self, "obj"):
-            obj = svc.loadObject(self.objType, self.objId)
-        else:
-            obj = self.obj
-        return getattr(obj, self.methodName)(*self.args, **self.kwargs)
-
-    def __getstate__(self):
-        d = self.__dict__.copy()
-        del d["obj"]
-        return d
-
-
-def command(methodName, cmdClass=WrapperCommand):
-    """Wrap a method so it gets turned into command automatically.
-
-    For use with Wrappables.
-
-    Usage::
-
-        | class Foo(Wrappable):
-        |     objectType = "foo"
-        |     def getUid(self):
-        |         return self.id
-        |     def _bar(self, x):
-        |         return x + 1
-        |
-        |     bar = command('_bar')
-
-    The resulting callable will have signature identical to wrapped
-    function, except that it expects journal as first argument, and
-    returns a Deferred.
-    """
-    def wrapper(obj, journal, *args, **kwargs):
-        return journal.executeCommand(cmdClass(methodName, obj, args, kwargs))
-    return wrapper
-
-
-class ServiceWrapperCommand:
-
-    implements(ICommand)
-
-    def __init__(self, methodName, args=(), kwargs={}):
-        self.methodName = methodName
-        self.args = args
-        self.kwargs = kwargs
-
-    def execute(self, svc, commandTime):
-        return getattr(svc, self.methodName)(*self.args, **self.kwargs)
-
-    def __repr__(self):
-        return "<ServiceWrapperCommand: %s, %s, %s>" % (self.methodName, self.args, self.kwargs)
-    
-    def __cmp__(self, other):
-        if hasattr(other, "__dict__"):
-            return cmp(self.__dict__, other.__dict__)
-        else:
-            return 0
-
-
-def serviceCommand(methodName, cmdClass=ServiceWrapperCommand):
-    """Wrap methods into commands for a journalled service.
-
-    The resulting callable will have signature identical to wrapped
-    function, except that it expects journal as first argument, and
-    returns a Deferred.
-    """
-    def wrapper(obj, journal, *args, **kwargs):
-        return journal.executeCommand(cmdClass(methodName, args, kwargs))
-    return wrapper