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from enum import IntEnum, IntFlag
import sys, os, errno, platform
import ctypes, ctypes.util
#bindings
if platform.system() != "Linux":
sys.exit("Not supported")
c_path_libdlm = ctypes.util.find_library("dlm_lt")
if not c_path_libdlm:
print("Unable to find the specified library.")
sys.exit()
try:
c_libdlm = ctypes.CDLL(c_path_libdlm)
except OSError:
print("Unable to load the system C library")
sys.exit()
class C_DLM_LSHANDLE(ctypes.c_void_p):
pass
class C_DLM_LKSB(ctypes.Structure):
_fields_ = [('sb_status', ctypes.c_int),
('sb_lkid', ctypes.c_uint32),
('sb_flags', ctypes.c_char),
('sb_lvbptr', ctypes.c_char_p)]
C_BAST_CB = ctypes.CFUNCTYPE(None, ctypes.py_object)
#dlm_create_lockspace
c_dlm_create_lockspace = c_libdlm.dlm_create_lockspace
c_dlm_create_lockspace.argtypes = [ctypes.c_char_p, #name
ctypes.c_uint, #mode
]
c_dlm_create_lockspace.restype = C_DLM_LSHANDLE
#dlm_release_lockspace
c_dlm_release_lockspace = c_libdlm.dlm_release_lockspace
c_dlm_release_lockspace.argtypes = [ctypes.c_char_p, #name
C_DLM_LSHANDLE, #ls
ctypes.c_int, #force
]
c_dlm_release_lockspace.restype = ctypes.c_int
#dlm_ls_lock_wait
c_dlm_ls_lock_wait = c_libdlm.dlm_ls_lock_wait
c_dlm_ls_lock_wait.argtypes = [C_DLM_LSHANDLE, #ls
ctypes.c_uint32, #mode
ctypes.POINTER(C_DLM_LKSB), #lksb
ctypes.c_uint32, #flags
ctypes.c_char_p, #name
ctypes.c_uint, #namelen
ctypes.c_uint32, #parent
ctypes.py_object, #bastarg
C_BAST_CB, #bastaddr
ctypes.c_void_p, #range
]
c_dlm_ls_lock_wait.restype = ctypes.c_int
#dlm_ls_unlock_wait
c_dlm_ls_unlock_wait = c_libdlm.dlm_ls_unlock_wait
c_dlm_ls_unlock_wait.argtypes = [C_DLM_LSHANDLE, #ls
ctypes.c_uint32, #lkid
ctypes.c_uint32, #flags
ctypes.POINTER(C_DLM_LKSB), #lksb
]
c_dlm_ls_unlock_wait.restype = ctypes.c_int
#classes
class LockMode(IntEnum):
IV = -1
NL = 0
CR = 1
CW = 2
PR = 3
PW = 4
EX = 5
class LockFlag(IntFlag):
NOQUEUE = 0x00000001
CANCEL = 0x00000002
CONVERT = 0x00000004
VALBLK = 0x00000008
QUECVT = 0x00000010
IVVALBLK = 0x00000020
CONVDEADLK = 0x00000040
PERSISTENT = 0x00000080
NODLCKWT = 0x00000100
NODLCKBLK = 0x00000200
EXPEDITE = 0x00000400
NOQUEUEBAST = 0x00000800
HEADQUE = 0x00001000
NOORDER = 0x00002000
ORPHAN = 0x00004000
ALTPR = 0x00008000
ALTCW = 0x00010000
FORCEUNLOCK = 0x00020000
TIMEOUT = 0x00040000
class LockSBFlag(IntFlag):
DEMOTED = 0x01
VALNOTVALID = 0x02
ALTMODE = 0x04
class DLMError(OSError):
def __init__(self, errno):
if not errno < 0:
raise ValueError()
errno = abs(errno)
super().__init__(errno, os.strerror(errno))
DLM_LOCK_TO_STR_FORMAT = \
"""name: {}
last_mode: {}
last_flags: {}
local_locked: {}
last_sb: status: {}, lkid: {}, flags: {}, lvb: {}"""
class Lockspace:
def __init__(self, name="default", mode=0o600):
self.__lsname = name
self.__ls = c_dlm_create_lockspace(self.__lsname.encode(), mode)
if not self.__ls:
raise DLMError(-errno.ENOMEM)
def release(self, force=2):
if not self.__ls:
return
rc = c_dlm_release_lockspace(self.__lsname.encode(), self.__ls,
force)
if rc:
raise DLMError(rc)
self.__ls = None
def __del__(self):
self.release()
def __str__(self):
return "Lockspace: {}".format(self.__lsname)
def get_name(self):
return self.__lsname
# lockspace lock factory
def create_lock(self, name):
class Lock:
#note name should be 8 byte aligned for now
def __init__(self, ls, c_ls, name):
self.__local_locked = False
self.__last_mode = LockMode.IV
self.__last_flags = LockFlag(0)
self.__lk = C_DLM_LKSB()
self.__lk.sb_status = 0
self.__lk.sb_lkid = 0
self.__lk.sb_flags = LockSBFlag(0)
self.__lk.sb_lvbptr = None
self.__ls = ls
self.__c_ls = c_ls
self.__name = name
def __del__(self):
if self.__local_locked:
self.unlock_wait()
def __str__(self):
sb = self.get_sb()
return DLM_LOCK_TO_STR_FORMAT.format(
self.__name,
str(self.__last_mode),
str(self.__last_flags),
self.__local_locked,
str(sb.status),
sb.lkid, str(sb.flags),
str(sb.lvb))
def get_name(self):
return self.__name
def get_ls(self):
return self.__ls
# get a copy of current sb state in high-level python
def get_sb(self):
class LockSB:
def __init__(self, status, lkid,
flags, lvb):
self.status = status
self.lkid = lkid
self.flags = LockSBFlag(flags[0])
self.lvb = lvb
return LockSB(self.__lk.sb_status,
self.__lk.sb_lkid,
self.__lk.sb_flags,
self.__lk.sb_lvbptr)
def lock_wait(self, mode=LockMode.EX,
flags=LockFlag(0), bast=None,
bastarg=None):
if bast:
bast = C_BAST_CB(bast)
else:
bast = ctypes.cast(None, C_BAST_CB)
rc = c_dlm_ls_lock_wait(self.__c_ls, mode,
ctypes.byref(self.__lk),
flags,
self.__name.encode(),
len(self.__name), 0,
bastarg, bast, None)
if rc:
raise DLMError(rc)
self.__last_mode = mode
self.__last_flags = flags
self.__local_locked = True
def unlock_wait(self, flags=0):
rc = c_dlm_ls_unlock_wait(self.__c_ls,
self.__lk.sb_lkid,
flags,
ctypes.byref(self.__lk))
if rc:
raise DLMError(rc)
self.__last_flags = flags
self.__local_locked = False
lock = Lock(self, self.__ls, name)
return lock
# vim: tabstop=8 softtabstop=8 shiftwidth=8 noexpandtab
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