Add optional semaphore to protect integrity of persistent storage backend
This commit is contained in:
lash
parent
fe00eaf3c8
commit
53da59c06e
GPG Key ID:
21D2E7BB88C2A746
|
|
@ -1,3 +1,5 @@
|
|||
- 0.2.4
|
||||
* Add optional concurrency lock for persistence store, implemented for file store
|
||||
- 0.2.3
|
||||
* Add noop-store, for convenience for code using persist constructor but will only use memory state
|
||||
- 0.2.2
|
||||
|
|
|
|||
|
|
@ -1,6 +1,6 @@
|
|||
[metadata]
|
||||
name = shep
|
||||
version = 0.2.3
|
||||
version = 0.2.4
|
||||
description = Multi-state key stores using bit masks
|
||||
author = Louis Holbrook
|
||||
author_email = dev@holbrook.no
|
||||
|
|
@ -22,7 +22,7 @@ licence_files =
|
|||
|
||||
[options]
|
||||
include_package_data = True
|
||||
python_requires = >= 3.6
|
||||
python_requires = >= 3.7
|
||||
packages =
|
||||
shep
|
||||
shep.store
|
||||
|
|
|
|||
|
|
@ -32,3 +32,9 @@ class StateTransitionInvalid(Exception):
|
|||
"""Raised if state transition verification fails
|
||||
"""
|
||||
pass
|
||||
|
||||
|
||||
class StateLockedKey(Exception):
|
||||
"""Attempt to write to a state key that is being written to by another client
|
||||
"""
|
||||
pass
|
||||
|
|
|
|||
|
|
@ -3,7 +3,10 @@ import datetime
|
|||
|
||||
# local imports
|
||||
from .state import State
|
||||
from .error import StateItemExists
|
||||
from .error import (
|
||||
StateItemExists,
|
||||
StateLockedKey,
|
||||
)
|
||||
|
||||
|
||||
class PersistedState(State):
|
||||
|
|
@ -34,13 +37,14 @@ class PersistedState(State):
|
|||
|
||||
See shep.state.State.put
|
||||
"""
|
||||
to_state = super(PersistedState, self).put(key, state=state, contents=contents)
|
||||
|
||||
k = self.name(to_state)
|
||||
k = self.to_name(state)
|
||||
|
||||
self.__ensure_store(k)
|
||||
|
||||
self.__stores[k].put(key, contents)
|
||||
|
||||
super(PersistedState, self).put(key, state=state, contents=contents)
|
||||
|
||||
self.register_modify(key)
|
||||
|
||||
|
||||
|
|
@ -56,10 +60,15 @@ class PersistedState(State):
|
|||
k_to = self.name(to_state)
|
||||
self.__ensure_store(k_to)
|
||||
|
||||
contents = self.__stores[k_from].get(key)
|
||||
self.__stores[k_to].put(key, contents)
|
||||
self.__stores[k_from].remove(key)
|
||||
|
||||
contents = None
|
||||
try:
|
||||
contents = self.__stores[k_from].get(key)
|
||||
self.__stores[k_to].put(key, contents)
|
||||
self.__stores[k_from].remove(key)
|
||||
except StateLockedKey as e:
|
||||
super(PersistedState, self).unset(key, or_state, allow_base=True)
|
||||
raise e
|
||||
|
||||
self.sync(to_state)
|
||||
|
||||
return to_state
|
||||
|
|
@ -143,6 +152,7 @@ class PersistedState(State):
|
|||
:raises StateItemExists: A content key is already recorded with a different state in memory than in persisted store.
|
||||
# :todo: if sync state is none, sync all
|
||||
"""
|
||||
|
||||
states = []
|
||||
if state == None:
|
||||
states = list(self.all())
|
||||
|
|
@ -208,10 +218,11 @@ class PersistedState(State):
|
|||
|
||||
See shep.state.State.replace
|
||||
"""
|
||||
super(PersistedState, self).replace(key, contents)
|
||||
state = self.state(key)
|
||||
k = self.name(state)
|
||||
return self.__stores[k].replace(key, contents)
|
||||
r = self.__stores[k].replace(key, contents)
|
||||
super(PersistedState, self).replace(key, contents)
|
||||
return r
|
||||
|
||||
|
||||
def modified(self, key):
|
||||
|
|
|
|||
|
|
@ -185,6 +185,12 @@ class State:
|
|||
self.__set(k, v)
|
||||
|
||||
|
||||
def to_name(self, k):
|
||||
if k == None:
|
||||
k = 0
|
||||
return self.name(k)
|
||||
|
||||
|
||||
def __alias(self, k, *args):
|
||||
v = 0
|
||||
for a in args:
|
||||
|
|
@ -436,7 +442,7 @@ class State:
|
|||
return self.__move(key, current_state, to_state)
|
||||
|
||||
|
||||
def unset(self, key, not_state):
|
||||
def unset(self, key, not_state, allow_base=False):
|
||||
"""Unset a single bit, moving to a pure or alias state.
|
||||
|
||||
The resulting state cannot be State.base_state_name (0).
|
||||
|
|
@ -462,7 +468,7 @@ class State:
|
|||
if to_state == current_state:
|
||||
raise ValueError('invalid change for state {}: {}'.format(key, not_state))
|
||||
|
||||
if to_state == getattr(self, self.base_state_name):
|
||||
if to_state == getattr(self, self.base_state_name) and not allow_base:
|
||||
raise ValueError('State {} for {} cannot be reverted to {}'.format(current_state, key, self.base_state_name))
|
||||
|
||||
new_state = self.__reverse.get(to_state)
|
||||
|
|
|
|||
|
|
@ -7,6 +7,7 @@ from .base import (
|
|||
re_processedname,
|
||||
StoreFactory,
|
||||
)
|
||||
from shep.error import StateLockedKey
|
||||
|
||||
|
||||
class SimpleFileStore:
|
||||
|
|
@ -15,15 +16,47 @@ class SimpleFileStore:
|
|||
:param path: Filesystem base path for all state directory
|
||||
:type path: str
|
||||
"""
|
||||
def __init__(self, path, binary=False):
|
||||
def __init__(self, path, binary=False, lock_path=None):
|
||||
self.__path = path
|
||||
os.makedirs(self.__path, exist_ok=True)
|
||||
if binary:
|
||||
self.__m = ['rb', 'wb']
|
||||
else:
|
||||
self.__m = ['r', 'w']
|
||||
self.__lock_path = lock_path
|
||||
if self.__lock_path != None:
|
||||
os.makedirs(lock_path, exist_ok=True)
|
||||
|
||||
|
||||
def __is_locked(self, k):
|
||||
if self.__lock_path == None:
|
||||
return False
|
||||
for v in os.listdir(self.__lock_path):
|
||||
if k == v:
|
||||
return True
|
||||
return False
|
||||
|
||||
|
||||
def __lock(self, k):
|
||||
if self.__lock_path == None:
|
||||
return
|
||||
if self.__is_locked(k):
|
||||
raise StateLockedKey(k)
|
||||
fp = os.path.join(self.__lock_path, k)
|
||||
f = open(fp, 'w')
|
||||
f.close()
|
||||
|
||||
|
||||
def __unlock(self, k):
|
||||
if self.__lock_path == None:
|
||||
return
|
||||
fp = os.path.join(self.__lock_path, k)
|
||||
try:
|
||||
os.unlink(fp)
|
||||
except FileNotFoundError:
|
||||
pass
|
||||
|
||||
|
||||
def put(self, k, contents=None):
|
||||
"""Add a new key and optional contents
|
||||
|
||||
|
|
@ -32,6 +65,7 @@ class SimpleFileStore:
|
|||
:param contents: Optional contents to assign for content key
|
||||
:type contents: any
|
||||
"""
|
||||
self.__lock(k)
|
||||
fp = os.path.join(self.__path, k)
|
||||
if contents == None:
|
||||
if self.__m[1] == 'wb':
|
||||
|
|
@ -42,6 +76,7 @@ class SimpleFileStore:
|
|||
f = open(fp, self.__m[1])
|
||||
f.write(contents)
|
||||
f.close()
|
||||
self.__unlock(k)
|
||||
|
||||
|
||||
def remove(self, k):
|
||||
|
|
@ -51,8 +86,10 @@ class SimpleFileStore:
|
|||
:type k: str
|
||||
:raises FileNotFoundError: Content key does not exist in the state
|
||||
"""
|
||||
self.__lock(k)
|
||||
fp = os.path.join(self.__path, k)
|
||||
os.unlink(fp)
|
||||
self.__unlock(k)
|
||||
|
||||
|
||||
def get(self, k):
|
||||
|
|
@ -64,10 +101,12 @@ class SimpleFileStore:
|
|||
:rtype: any
|
||||
:return: Contents
|
||||
"""
|
||||
self.__lock(k)
|
||||
fp = os.path.join(self.__path, k)
|
||||
f = open(fp, self.__m[0])
|
||||
r = f.read()
|
||||
f.close()
|
||||
self.__unlock(k)
|
||||
return r
|
||||
|
||||
|
||||
|
|
@ -77,6 +116,7 @@ class SimpleFileStore:
|
|||
:rtype: list of str
|
||||
:return: Content keys in state
|
||||
"""
|
||||
self.__lock('.list')
|
||||
files = []
|
||||
for p in os.listdir(self.__path):
|
||||
fp = os.path.join(self.__path, p)
|
||||
|
|
@ -86,6 +126,7 @@ class SimpleFileStore:
|
|||
if len(r) == 0:
|
||||
r = None
|
||||
files.append((p, r,))
|
||||
self.__unlock('.list')
|
||||
return files
|
||||
|
||||
|
||||
|
|
@ -110,16 +151,20 @@ class SimpleFileStore:
|
|||
:param contents: Contents
|
||||
:type contents: any
|
||||
"""
|
||||
self.__lock(k)
|
||||
fp = os.path.join(self.__path, k)
|
||||
os.stat(fp)
|
||||
f = open(fp, self.__m[1])
|
||||
r = f.write(contents)
|
||||
f.close()
|
||||
self.__unlock(k)
|
||||
|
||||
|
||||
def modified(self, k):
|
||||
self.__lock(k)
|
||||
path = self.path(k)
|
||||
st = os.stat(path)
|
||||
self.__unlock(k)
|
||||
return st.st_ctime
|
||||
|
||||
|
||||
|
|
@ -133,9 +178,10 @@ class SimpleFileStoreFactory(StoreFactory):
|
|||
:param path: Filesystem path as base path for states
|
||||
:type path: str
|
||||
"""
|
||||
def __init__(self, path, binary=False):
|
||||
def __init__(self, path, binary=False, use_lock=False):
|
||||
self.__path = path
|
||||
self.__binary = binary
|
||||
self.__use_lock = use_lock
|
||||
|
||||
|
||||
def add(self, k):
|
||||
|
|
@ -146,9 +192,13 @@ class SimpleFileStoreFactory(StoreFactory):
|
|||
:rtype: SimpleFileStore
|
||||
:return: A filesystem persistence instance with the given identifier as subdirectory
|
||||
"""
|
||||
lock_path = None
|
||||
if self.__use_lock:
|
||||
lock_path = os.path.join(self.__path, '.lock')
|
||||
|
||||
k = str(k)
|
||||
store_path = os.path.join(self.__path, k)
|
||||
return SimpleFileStore(store_path, binary=self.__binary)
|
||||
return SimpleFileStore(store_path, binary=self.__binary, lock_path=lock_path)
|
||||
|
||||
|
||||
def ls(self):
|
||||
|
|
|
|||
|
|
@ -11,6 +11,7 @@ from shep.error import (
|
|||
StateExists,
|
||||
StateInvalid,
|
||||
StateItemExists,
|
||||
StateLockedKey,
|
||||
)
|
||||
|
||||
|
||||
|
|
@ -257,5 +258,52 @@ class TestFileStore(unittest.TestCase):
|
|||
self.assertEqual(len(r), 3)
|
||||
|
||||
|
||||
def test_lock(self):
|
||||
factory = SimpleFileStoreFactory(self.d, use_lock=True)
|
||||
states = PersistedState(factory.add, 3)
|
||||
states.add('foo')
|
||||
states.add('bar')
|
||||
states.add('baz')
|
||||
states.alias('xyzzy', states.FOO | states.BAR)
|
||||
states.alias('plugh', states.FOO | states.BAR | states.BAZ)
|
||||
states.put('abcd')
|
||||
|
||||
lock_path = os.path.join(self.d, '.lock')
|
||||
os.stat(lock_path)
|
||||
|
||||
fp = os.path.join(self.d, '.lock', 'xxxx')
|
||||
f = open(fp, 'w')
|
||||
f.close()
|
||||
|
||||
with self.assertRaises(StateLockedKey):
|
||||
states.put('xxxx')
|
||||
|
||||
os.unlink(fp)
|
||||
states.put('xxxx')
|
||||
|
||||
states.set('xxxx', states.FOO)
|
||||
states.set('xxxx', states.BAR)
|
||||
states.replace('xxxx', contents='zzzz')
|
||||
|
||||
fp = os.path.join(self.d, '.lock', 'xxxx')
|
||||
f = open(fp, 'w')
|
||||
f.close()
|
||||
|
||||
with self.assertRaises(StateLockedKey):
|
||||
states.set('xxxx', states.BAZ)
|
||||
|
||||
v = states.state('xxxx')
|
||||
self.assertEqual(v, states.XYZZY)
|
||||
|
||||
with self.assertRaises(StateLockedKey):
|
||||
states.unset('xxxx', states.FOO)
|
||||
|
||||
with self.assertRaises(StateLockedKey):
|
||||
states.replace('xxxx', contents='yyyy')
|
||||
|
||||
v = states.get('xxxx')
|
||||
self.assertEqual(v, 'zzzz')
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
unittest.main()
|
||||
|
|
|
|||
Loading…
Reference in New Issue