caches: improved locking problems with distributed lock new cache backend

vcsserver/lib/_vendor/redis_lock/__init__.py

@@ -1,389 +1,390 b''
 import sys
 import threading
 import weakref
 from base64 import b64encode
 from logging import getLogger
 from os import urandom
 
 from redis import StrictRedis
 
 __version__ = '3.7.0'
 
 loggers = {
-    k: getLogger("vcsserver" + ".".join((__name__, k)))
+    k: getLogger("vcsserver." + ".".join((__name__, k)))
     for k in [
         "acquire",
         "refresh.thread.start",
         "refresh.thread.stop",
         "refresh.thread.exit",
         "refresh.start",
         "refresh.shutdown",
         "refresh.exit",
         "release",
     ]
 }
 
 PY3 = sys.version_info[0] == 3
 
 if PY3:
     text_type = str
     binary_type = bytes
 else:
     text_type = unicode  # noqa
     binary_type = str
 
 
 # Check if the id match. If not, return an error code.
 UNLOCK_SCRIPT = b"""
     if redis.call("get", KEYS[1]) ~= ARGV[1] then
         return 1
     else
         redis.call("del", KEYS[2])
         redis.call("lpush", KEYS[2], 1)
         redis.call("pexpire", KEYS[2], ARGV[2])
         redis.call("del", KEYS[1])
         return 0
     end
 """
 
 # Covers both cases when key doesn't exist and doesn't equal to lock's id
 EXTEND_SCRIPT = b"""
     if redis.call("get", KEYS[1]) ~= ARGV[1] then
         return 1
     elseif redis.call("ttl", KEYS[1]) < 0 then
         return 2
     else
         redis.call("expire", KEYS[1], ARGV[2])
         return 0
     end
 """
 
 RESET_SCRIPT = b"""
     redis.call('del', KEYS[2])
     redis.call('lpush', KEYS[2], 1)
     redis.call('pexpire', KEYS[2], ARGV[2])
     return redis.call('del', KEYS[1])
 """
 
 RESET_ALL_SCRIPT = b"""
     local locks = redis.call('keys', 'lock:*')
     local signal
     for _, lock in pairs(locks) do
         signal = 'lock-signal:' .. string.sub(lock, 6)
         redis.call('del', signal)
         redis.call('lpush', signal, 1)
         redis.call('expire', signal, 1)
         redis.call('del', lock)
     end
     return #locks
 """
 
 
 class AlreadyAcquired(RuntimeError):
     pass
 
 
 class NotAcquired(RuntimeError):
     pass
 
 
 class AlreadyStarted(RuntimeError):
     pass
 
 
 class TimeoutNotUsable(RuntimeError):
     pass
 
 
 class InvalidTimeout(RuntimeError):
     pass
 
 
 class TimeoutTooLarge(RuntimeError):
     pass
 
 
 class NotExpirable(RuntimeError):
     pass
 
 
 class Lock(object):
     """
     A Lock context manager implemented via redis SETNX/BLPOP.
     """
     unlock_script = None
     extend_script = None
     reset_script = None
     reset_all_script = None
 
     def __init__(self, redis_client, name, expire=None, id=None, auto_renewal=False, strict=True, signal_expire=1000):
         """
         :param redis_client:
             An instance of :class:`~StrictRedis`.
         :param name:
             The name (redis key) the lock should have.
         :param expire:
             The lock expiry time in seconds. If left at the default (None)
             the lock will not expire.
         :param id:
             The ID (redis value) the lock should have. A random value is
             generated when left at the default.
 
             Note that if you specify this then the lock is marked as "held". Acquires
             won't be possible.
         :param auto_renewal:
             If set to ``True``, Lock will automatically renew the lock so that it
             doesn't expire for as long as the lock is held (acquire() called
             or running in a context manager).
 
             Implementation note: Renewal will happen using a daemon thread with
             an interval of ``expire*2/3``. If wishing to use a different renewal
             time, subclass Lock, call ``super().__init__()`` then set
             ``self._lock_renewal_interval`` to your desired interval.
         :param strict:
             If set ``True`` then the ``redis_client`` needs to be an instance of ``redis.StrictRedis``.
         :param signal_expire:
             Advanced option to override signal list expiration in milliseconds. Increase it for very slow clients. Default: ``1000``.
         """
         if strict and not isinstance(redis_client, StrictRedis):
             raise ValueError("redis_client must be instance of StrictRedis. "
                              "Use strict=False if you know what you're doing.")
         if auto_renewal and expire is None:
             raise ValueError("Expire may not be None when auto_renewal is set")
 
         self._client = redis_client
 
         if expire:
             expire = int(expire)
             if expire < 0:
                 raise ValueError("A negative expire is not acceptable.")
         else:
             expire = None
         self._expire = expire
 
         self._signal_expire = signal_expire
         if id is None:
             self._id = b64encode(urandom(18)).decode('ascii')
         elif isinstance(id, binary_type):
             try:
                 self._id = id.decode('ascii')
             except UnicodeDecodeError:
                 self._id = b64encode(id).decode('ascii')
         elif isinstance(id, text_type):
             self._id = id
         else:
             raise TypeError("Incorrect type for `id`. Must be bytes/str not %s." % type(id))
         self._name = 'lock:' + name
         self._signal = 'lock-signal:' + name
         self._lock_renewal_interval = (float(expire) * 2 / 3
                                        if auto_renewal
                                        else None)
         self._lock_renewal_thread = None
 
         self.register_scripts(redis_client)
 
     @classmethod
     def register_scripts(cls, redis_client):
         global reset_all_script
         if reset_all_script is None:
             reset_all_script = redis_client.register_script(RESET_ALL_SCRIPT)
             cls.unlock_script = redis_client.register_script(UNLOCK_SCRIPT)
             cls.extend_script = redis_client.register_script(EXTEND_SCRIPT)
             cls.reset_script = redis_client.register_script(RESET_SCRIPT)
             cls.reset_all_script = redis_client.register_script(RESET_ALL_SCRIPT)
 
     @property
     def _held(self):
         return self.id == self.get_owner_id()
 
     def reset(self):
         """
         Forcibly deletes the lock. Use this with care.
         """
         self.reset_script(client=self._client, keys=(self._name, self._signal), args=(self.id, self._signal_expire))
 
     @property
     def id(self):
         return self._id
 
     def get_owner_id(self):
         owner_id = self._client.get(self._name)
         if isinstance(owner_id, binary_type):
             owner_id = owner_id.decode('ascii', 'replace')
         return owner_id
 
     def acquire(self, blocking=True, timeout=None):
         """
         :param blocking:
             Boolean value specifying whether lock should be blocking or not.
         :param timeout:
             An integer value specifying the maximum number of seconds to block.
         """
         logger = loggers["acquire"]
 
-        logger.debug("Getting %r ...", self._name)
+        logger.debug("Getting acquire on %r ...", self._name)
 
         if self._held:
-            raise AlreadyAcquired("Already acquired from this Lock instance.")
+            owner_id = self.get_owner_id()
+            raise AlreadyAcquired("Already acquired from this Lock instance. Lock id: {}".format(owner_id))
 
         if not blocking and timeout is not None:
             raise TimeoutNotUsable("Timeout cannot be used if blocking=False")
 
         if timeout:
             timeout = int(timeout)
             if timeout < 0:
                 raise InvalidTimeout("Timeout (%d) cannot be less than or equal to 0" % timeout)
 
             if self._expire and not self._lock_renewal_interval and timeout > self._expire:
                 raise TimeoutTooLarge("Timeout (%d) cannot be greater than expire (%d)" % (timeout, self._expire))
 
         busy = True
         blpop_timeout = timeout or self._expire or 0
         timed_out = False
         while busy:
             busy = not self._client.set(self._name, self._id, nx=True, ex=self._expire)
             if busy:
                 if timed_out:
                     return False
                 elif blocking:
                     timed_out = not self._client.blpop(self._signal, blpop_timeout) and timeout
                 else:
                     logger.warning("Failed to get %r.", self._name)
                     return False
 
         logger.info("Got lock for %r.", self._name)
         if self._lock_renewal_interval is not None:
             self._start_lock_renewer()
         return True
 
     def extend(self, expire=None):
         """Extends expiration time of the lock.
 
         :param expire:
             New expiration time. If ``None`` - `expire` provided during
             lock initialization will be taken.
         """
         if expire:
             expire = int(expire)
             if expire < 0:
                 raise ValueError("A negative expire is not acceptable.")
         elif self._expire is not None:
             expire = self._expire
         else:
             raise TypeError(
                 "To extend a lock 'expire' must be provided as an "
                 "argument to extend() method or at initialization time."
             )
 
         error = self.extend_script(client=self._client, keys=(self._name, self._signal), args=(self._id, expire))
         if error == 1:
             raise NotAcquired("Lock %s is not acquired or it already expired." % self._name)
         elif error == 2:
             raise NotExpirable("Lock %s has no assigned expiration time" % self._name)
         elif error:
             raise RuntimeError("Unsupported error code %s from EXTEND script" % error)
 
     @staticmethod
     def _lock_renewer(lockref, interval, stop):
         """
         Renew the lock key in redis every `interval` seconds for as long
         as `self._lock_renewal_thread.should_exit` is False.
         """
         while not stop.wait(timeout=interval):
             loggers["refresh.thread.start"].debug("Refreshing lock")
             lock = lockref()
             if lock is None:
                 loggers["refresh.thread.stop"].debug(
                     "The lock no longer exists, stopping lock refreshing"
                 )
                 break
             lock.extend(expire=lock._expire)
             del lock
         loggers["refresh.thread.exit"].debug("Exit requested, stopping lock refreshing")
 
     def _start_lock_renewer(self):
         """
         Starts the lock refresher thread.
         """
         if self._lock_renewal_thread is not None:
             raise AlreadyStarted("Lock refresh thread already started")
 
         loggers["refresh.start"].debug(
             "Starting thread to refresh lock every %s seconds",
             self._lock_renewal_interval
         )
         self._lock_renewal_stop = threading.Event()
         self._lock_renewal_thread = threading.Thread(
             group=None,
             target=self._lock_renewer,
             kwargs={'lockref': weakref.ref(self),
                     'interval': self._lock_renewal_interval,
                     'stop': self._lock_renewal_stop}
         )
         self._lock_renewal_thread.setDaemon(True)
         self._lock_renewal_thread.start()
 
     def _stop_lock_renewer(self):
         """
         Stop the lock renewer.
 
         This signals the renewal thread and waits for its exit.
         """
         if self._lock_renewal_thread is None or not self._lock_renewal_thread.is_alive():
             return
         loggers["refresh.shutdown"].debug("Signalling the lock refresher to stop")
         self._lock_renewal_stop.set()
         self._lock_renewal_thread.join()
         self._lock_renewal_thread = None
         loggers["refresh.exit"].debug("Lock refresher has stopped")
 
     def __enter__(self):
         acquired = self.acquire(blocking=True)
         assert acquired, "Lock wasn't acquired, but blocking=True"
         return self
 
     def __exit__(self, exc_type=None, exc_value=None, traceback=None):
         self.release()
 
     def release(self):
         """Releases the lock, that was acquired with the same object.
 
         .. note::
 
             If you want to release a lock that you acquired in a different place you have two choices:
 
             * Use ``Lock("name", id=id_from_other_place).release()``
             * Use ``Lock("name").reset()``
         """
         if self._lock_renewal_thread is not None:
             self._stop_lock_renewer()
         loggers["release"].debug("Releasing %r.", self._name)
         error = self.unlock_script(client=self._client, keys=(self._name, self._signal), args=(self._id, self._signal_expire))
         if error == 1:
             raise NotAcquired("Lock %s is not acquired or it already expired." % self._name)
         elif error:
             raise RuntimeError("Unsupported error code %s from EXTEND script." % error)
 
     def locked(self):
         """
         Return true if the lock is acquired.
 
         Checks that lock with same name already exists. This method returns true, even if
         lock have another id.
         """
         return self._client.exists(self._name) == 1
 
 
 reset_all_script = None
 
 
 def reset_all(redis_client):
     """
     Forcibly deletes all locks if its remains (like a crash reason). Use this with care.
 
     :param redis_client:
         An instance of :class:`~StrictRedis`.
     """
     Lock.register_scripts(redis_client)
 
     reset_all_script(client=redis_client)  # noqa

vcsserver/lib/rc_cache/backends.py

@@ -1,260 +1,307 b''
 # RhodeCode VCSServer provides access to different vcs backends via network.
 # Copyright (C) 2014-2020 RhodeCode GmbH
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation; either version 3 of the License, or
 # (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program; if not, write to the Free Software Foundation,
 # Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
 
 import time
 import errno
 import logging
 
 import msgpack
 import redis
 
 from dogpile.cache.api import CachedValue
 from dogpile.cache.backends import memory as memory_backend
 from dogpile.cache.backends import file as file_backend
 from dogpile.cache.backends import redis as redis_backend
 from dogpile.cache.backends.file import NO_VALUE, compat, FileLock
 from dogpile.cache.util import memoized_property
 
 from vcsserver.lib.memory_lru_dict import LRUDict, LRUDictDebug
 
 
 _default_max_size = 1024
 
 log = logging.getLogger(__name__)
 
 
 class LRUMemoryBackend(memory_backend.MemoryBackend):
     key_prefix = 'lru_mem_backend'
     pickle_values = False
 
     def __init__(self, arguments):
         max_size = arguments.pop('max_size', _default_max_size)
 
         LRUDictClass = LRUDict
         if arguments.pop('log_key_count', None):
             LRUDictClass = LRUDictDebug
 
         arguments['cache_dict'] = LRUDictClass(max_size)
         super(LRUMemoryBackend, self).__init__(arguments)
 
     def delete(self, key):
         try:
             del self._cache[key]
         except KeyError:
             # we don't care if key isn't there at deletion
             pass
 
     def delete_multi(self, keys):
         for key in keys:
             self.delete(key)
 
 
 class PickleSerializer(object):
 
     def _dumps(self, value, safe=False):
         try:
             return compat.pickle.dumps(value)
         except Exception:
             if safe:
                 return NO_VALUE
             else:
                 raise
 
     def _loads(self, value, safe=True):
         try:
             return compat.pickle.loads(value)
         except Exception:
             if safe:
                 return NO_VALUE
             else:
                 raise
 
 
 class MsgPackSerializer(object):
 
     def _dumps(self, value, safe=False):
         try:
             return msgpack.packb(value)
         except Exception:
             if safe:
                 return NO_VALUE
             else:
                 raise
 
     def _loads(self, value, safe=True):
         """
         pickle maintained the `CachedValue` wrapper of the tuple
         msgpack does not, so it must be added back in.
        """
         try:
             value = msgpack.unpackb(value, use_list=False)
             return CachedValue(*value)
         except Exception:
             if safe:
                 return NO_VALUE
             else:
                 raise
 
 
 import fcntl
 flock_org = fcntl.flock
 
 
 class CustomLockFactory(FileLock):
 
     pass
 
 
 class FileNamespaceBackend(PickleSerializer, file_backend.DBMBackend):
     key_prefix = 'file_backend'
 
     def __init__(self, arguments):
         arguments['lock_factory'] = CustomLockFactory
-        super(FileNamespaceBackend, self).__init__(arguments)
+        db_file = arguments.get('filename')
+
+        log.debug('initialing %s DB in %s', self.__class__.__name__, db_file)
+        try:
+            super(FileNamespaceBackend, self).__init__(arguments)
+        except Exception:
+            log.error('Failed to initialize db at: %s', db_file)
+            raise
 
     def __repr__(self):
         return '{} `{}`'.format(self.__class__, self.filename)
 
     def list_keys(self, prefix=''):
         prefix = '{}:{}'.format(self.key_prefix, prefix)
 
         def cond(v):
             if not prefix:
                 return True
 
             if v.startswith(prefix):
                 return True
             return False
 
         with self._dbm_file(True) as dbm:
-
-            return filter(cond, dbm.keys())
+            try:
+                return filter(cond, dbm.keys())
+            except Exception:
+                log.error('Failed to fetch DBM keys from DB: %s', self.get_store())
+                raise
 
     def get_store(self):
         return self.filename
 
-    def get(self, key):
+    def _dbm_get(self, key):
         with self._dbm_file(False) as dbm:
             if hasattr(dbm, 'get'):
                 value = dbm.get(key, NO_VALUE)
             else:
                 # gdbm objects lack a .get method
                 try:
                     value = dbm[key]
                 except KeyError:
                     value = NO_VALUE
             if value is not NO_VALUE:
                 value = self._loads(value)
             return value
 
+    def get(self, key):
+        try:
+            return self._dbm_get(key)
+        except Exception:
+            log.error('Failed to fetch DBM key %s from DB: %s', key, self.get_store())
+            raise
+
     def set(self, key, value):
         with self._dbm_file(True) as dbm:
             dbm[key] = self._dumps(value)
 
     def set_multi(self, mapping):
         with self._dbm_file(True) as dbm:
             for key, value in mapping.items():
                 dbm[key] = self._dumps(value)
 
 
 class BaseRedisBackend(redis_backend.RedisBackend):
 
     def _create_client(self):
         args = {}
 
         if self.url is not None:
             args.update(url=self.url)
 
         else:
             args.update(
                 host=self.host, password=self.password,
                 port=self.port, db=self.db
             )
 
         connection_pool = redis.ConnectionPool(**args)
 
         return redis.StrictRedis(connection_pool=connection_pool)
 
     def list_keys(self, prefix=''):
         prefix = '{}:{}*'.format(self.key_prefix, prefix)
         return self.client.keys(prefix)
 
     def get_store(self):
         return self.client.connection_pool
 
     def get(self, key):
         value = self.client.get(key)
         if value is None:
             return NO_VALUE
         return self._loads(value)
 
     def get_multi(self, keys):
         if not keys:
             return []
         values = self.client.mget(keys)
         loads = self._loads
         return [
             loads(v) if v is not None else NO_VALUE
             for v in values]
 
     def set(self, key, value):
         if self.redis_expiration_time:
             self.client.setex(key, self.redis_expiration_time,
                               self._dumps(value))
         else:
             self.client.set(key, self._dumps(value))
 
     def set_multi(self, mapping):
         dumps = self._dumps
         mapping = dict(
             (k, dumps(v))
             for k, v in mapping.items()
         )
 
         if not self.redis_expiration_time:
             self.client.mset(mapping)
         else:
             pipe = self.client.pipeline()
             for key, value in mapping.items():
                 pipe.setex(key, self.redis_expiration_time, value)
             pipe.execute()
 
     def get_mutex(self, key):
         if self.distributed_lock:
-            import redis_lock
             lock_key = redis_backend.u('_lock_{0}').format(key)
             log.debug('Trying to acquire Redis lock for key %s', lock_key)
-            lock = redis_lock.Lock(
-                redis_client=self.client,
-                name=lock_key,
-                expire=self.lock_timeout,
-                auto_renewal=False,
-                strict=True,
-            )
-            return lock
+
+            auto_renewal = True
+            lock_timeout = self.lock_timeout
+            if auto_renewal and not self.lock_timeout:
+                # set default timeout for auto_renewal
+                lock_timeout = 10
+            return get_mutex_lock(self.client, lock_key, lock_timeout,
+                                  auto_renewal=auto_renewal)
         else:
             return None
 
 
 class RedisPickleBackend(PickleSerializer, BaseRedisBackend):
     key_prefix = 'redis_pickle_backend'
     pass
 
 
 class RedisMsgPackBackend(MsgPackSerializer, BaseRedisBackend):
     key_prefix = 'redis_msgpack_backend'
     pass
+
+
+def get_mutex_lock(client, lock_key, lock_timeout, auto_renewal=False):
+    import redis_lock
+
+    class _RedisLockWrapper(object):
+        """LockWrapper for redis_lock"""
+
+        def __init__(self):
+            pass
+
+        @property
+        def lock(self):
+            return redis_lock.Lock(
+                redis_client=client,
+                name=lock_key,
+                expire=lock_timeout,
+                auto_renewal=auto_renewal,
+                strict=True,
+            )
+
+        def acquire(self, wait=True):
+            return self.lock.acquire(wait)
+
+        def release(self):
+            try:
+                self.lock.release()
+            except redis_lock.NotAcquired:
+                pass
+
+    return _RedisLockWrapper()