ramdiskFactory.py

"""
Factory for creating ramdisks.

@note: may be of more use in the tests/testFramework, or example directories

@author: Roy Nielsen
"""
#--- Native python libraries
import re
from tempfile import mkdtemp
from subprocess import Popen, PIPE, STDOUT

#--- non-native python libraries in this source tree
from lib.loggers import CyLogger
from lib.loggers import LogPriority as lp
from lib.run_commands import RunWith


def BadRamdiskTypeException(Exception):
    """
    Custom Exception
    """
    def __init__(self,*args,**kwargs):
        Exception.__init__(self,*args,**kwargs)

def OSNotValidForRamdiskHelper(Exception):
    """
    Custom Exception
    """
    def __init__(self, *args, **kwargs):
        Exception.__init__(self, *args, **kwargs)

class RamDiskFactory(object):
    """
    Retrieve and OS specific ramdisk, and provide an interface to manage it.

    Keeps a reference to a list of ramdisks.  When calling getRamdisk(new), if
    "new" is true, the method will add the ramdisk to the list of ramdisks.

    @parameter message_level: Level of logging a person wishes to log at.
                              see logMessage in the log_message module.

    @method: getRamdisk: Will return either a new ramdisk, or make the
                         self.activeRamdisk the ramdisk with the name of the
                         passed in mountpoint (if found).  Otherwise, the
                         self.activeRamdisk is initialized to None.

    @method getModuleVersion: gets the version of this module.

    @method unmountActiveRamdisk: Unmounts the active ramdisk.

    @method unmountRamdisk: Unmounts the mountpoint that is passed in.

    @author: Roy Nielsen
    """
    def __init__(self, environ, logger=None):
        """
        Identify OS and instantiate an instance of a ramdisk
        """
        self.module_version = '20160224.203258.288119'

        self.size = 0
        self.environ = environ
        self.mountpoint = None
        self.ramdiskType = None
        if not logger:
            self.logger = CyLogger()
        else:
            self.logger = logger
        self.activeRamdisk = None
        self.ramdisks = []
        self.validRamdiskTypes = ["loop", "tmpfs"]
        self.validOSFamilies = ["macos", "linux"]

        self.myosfamily = self.environ.getosfamily()

        if not self.myosfamily in self.validOSFamilies:
            raise OSNotValidForRamdiskHelper("Needs to be MacOS or Linux...")

    ############################################################################
    
    def getRamdisk(self, size=0, mountpoint="", ramdiskType=""):
        """
        Getter for the ramdisk instance.
        
        @var: ramdisks - a list of ramdisks this factory has created
        
        @param: size - size of the ramdisk to create. If zero, it looks for 
        @author: Roy Nielsen
        """
        if not ramdiskType in self.validRamdiskTypes:
            raise BadRamdiskTypeException("Not a valid ramdisk type")
    
        if size and mountpoint and ramdiskType:
            #####
            # Determine OS and ramdisk type, create ramdisk accordingly
            if self.myosfamily == "darwin":
                #####
                # Found MacOS
                from macRamdisk import RamDisk
                self.activeRamdisk = RamDisk(size, mountpoint, self.logger)

            elif self.myosfamily == "linux" and ramdiskType == "loop":
                #####
                # Found Linux with a loopback ramdisk request
                from linuxLoopRamdisk import RamDisk
                self.activeRamdisk = RamDisk(mountpoint, self.logger)

            elif self.myosfamily == "linux" and ramdiskType == "tmpfs":
                #####
                # Found Linux with a tmpfs ramdisk request.
                from linuxTmpfsRamdisk import RamDisk
                self.activeRamdisk = RamDisk(size, mountpoint, self.logger)

            else:
                #####
                # Bad method input parameters...
                self.activeRamdisk = None

            #####
            # Append the newly assigned self.activeRamdisk to the self.ramdisks
            # list
            self.ramdisks.append(self.activeRamdisk)

        elif not size and mountpoint:
            #####
            # Look for the ramdisk with "mountpoint" and return that instance.
            for ramdisk in self.ramdisks:
                if re.match("^%s$"%mountpoint, ramdisk.getMountPoint()):
                    self.activeRamdisk = ramdisk
                    break

        return self.activeRamdisk

    ############################################################################

    def getModuleVersion(self):
        """
        Getter for the version of this  module.

        @author: Roy Nielsen
        """
        return self.module_version

    ############################################################################

    def unmountActiveRamdisk(self):
        """
        Eject the currently active ramdisk in the Factory.

        @return: success - successful = True, unsuccessful = False

        @author: Roy Nielsen
        """
        success = False

        success = self.activeRamdisk.unmount(self.logger)

        return success

    ############################################################################

    def unmountRamdisk(self, mountpoint=""):
        """
        Eject the ramdisk in the list with the passed in mountpoint.

        @param mountpoint: the mountpoint to eject.

        @return: True if successful, False if not successful

        @author: Roy Nielsen
        """
        success = False
        if mountpoint:
            for ramdisk in self.ramdisks:
                if re.match("^%s$"%mountpoint, ramdisk.getMountPoint()):
                    self.activeRamdisk = ramdisk
                    success = self.unmountActiveRamdisk()
                    break

        return success

    ############################################################################

    ############################################################################

    ############################################################################