############################################################################## # # Copyright (c) 2001, 2002, 2003 Zope Corporation and Contributors. # All Rights Reserved. # # This software is subject to the provisions of the Zope Public License, # Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution. # THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED # WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED # WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS # FOR A PARTICULAR PURPOSE # ############################################################################## """The ClientStorage class and the exceptions that it may raise. Public contents of this module: ClientStorage -- the main class, implementing the Storage API """ import cPickle import os import socket import stat import sys import tempfile import threading import time import types import logging import weakref import zope.interface from ZEO import ServerStub from ZEO.cache import ClientCache from ZEO.TransactionBuffer import TransactionBuffer from ZEO.Exceptions import ClientStorageError, ClientDisconnected, AuthError from ZEO.auth import get_module from ZEO.zrpc.client import ConnectionManager import ZODB.interfaces import zc.lockfile import ZODB.BaseStorage from ZODB import POSException from ZODB import utils from ZODB.loglevels import BLATHER from ZODB.blob import rename_or_copy_blob from persistent.TimeStamp import TimeStamp logger = logging.getLogger('ZEO.ClientStorage') _pid = str(os.getpid()) def log2(msg, level=logging.INFO, subsys=_pid, exc_info=False): message = "(%s) %s" % (subsys, msg) logger.log(level, message, exc_info=exc_info) try: from ZODB.ConflictResolution import ResolvedSerial except ImportError: ResolvedSerial = 'rs' def tid2time(tid): return str(TimeStamp(tid)) def get_timestamp(prev_ts=None): """Internal helper to return a unique TimeStamp instance. If the optional argument is not None, it must be a TimeStamp; the return value is then guaranteed to be at least 1 microsecond later the argument. """ t = time.time() t = TimeStamp(*time.gmtime(t)[:5] + (t % 60,)) if prev_ts is not None: t = t.laterThan(prev_ts) return t class DisconnectedServerStub: """Internal helper class used as a faux RPC stub when disconnected. This raises ClientDisconnected on all attribute accesses. This is a singleton class -- there should be only one instance, the global disconnected_stub, so it can be tested by identity. """ def __getattr__(self, attr): raise ClientDisconnected() # Singleton instance of DisconnectedServerStub disconnected_stub = DisconnectedServerStub() MB = 1024**2 class ClientStorage(object): """A storage class that is a network client to a remote storage. This is a faithful implementation of the Storage API. This class is thread-safe; transactions are serialized in tpc_begin(). """ # ClientStorage does not declare any interfaces here. Interfaces are # declared according to the server's storage once a connection is # established. # Classes we instantiate. A subclass might override. TransactionBufferClass = TransactionBuffer ClientCacheClass = ClientCache ConnectionManagerClass = ConnectionManager StorageServerStubClass = ServerStub.StorageServer def __init__(self, addr, storage='1', cache_size=20 * MB, name='', client=None, debug=0, var=None, min_disconnect_poll=5, max_disconnect_poll=300, wait_for_server_on_startup=None, # deprecated alias for wait wait=None, wait_timeout=None, read_only=0, read_only_fallback=0, drop_cache_rather_verify=False, username='', password='', realm=None, blob_dir=None, shared_blob_dir=False): """ClientStorage constructor. This is typically invoked from a custom_zodb.py file. All arguments except addr should be keyword arguments. Arguments: addr -- The server address(es). This is either a list of addresses or a single address. Each address can be a (hostname, port) tuple to signify a TCP/IP connection or a pathname string to signify a Unix domain socket connection. A hostname may be a DNS name or a dotted IP address. Required. storage -- The storage name, defaulting to '1'. The name must match one of the storage names supported by the server(s) specified by the addr argument. The storage name is displayed in the Zope control panel. cache_size -- The disk cache size, defaulting to 20 megabytes. This is passed to the ClientCache constructor. name -- The storage name, defaulting to ''. If this is false, str(addr) is used as the storage name. client -- A name used to construct persistent cache filenames. Defaults to None, in which case the cache is not persistent. See ClientCache for more info. debug -- Ignored. This is present only for backwards compatibility with ZEO 1. var -- When client is not None, this specifies the directory where the persistent cache files are created. It defaults to None, in whichcase the current directory is used. min_disconnect_poll -- The minimum delay in seconds between attempts to connect to the server, in seconds. Defaults to 5 seconds. max_disconnect_poll -- The maximum delay in seconds between attempts to connect to the server, in seconds. Defaults to 300 seconds. wait_for_server_on_startup -- A backwards compatible alias for the wait argument. wait -- A flag indicating whether to wait until a connection with a server is made, defaulting to true. wait_timeout -- Maximum time to wait for a connection before giving up. Only meaningful if wait is True. read_only -- A flag indicating whether this should be a read-only storage, defaulting to false (i.e. writing is allowed by default). read_only_fallback -- A flag indicating whether a read-only remote storage should be acceptable as a fallback when no writable storages are available. Defaults to false. At most one of read_only and read_only_fallback should be true. username -- string with username to be used when authenticating. These only need to be provided if you are connecting to an authenticated server storage. password -- string with plaintext password to be used when authenticated. realm -- not documented. drop_cache_rather_verify -- a flag indicating that the cache should be dropped rather than expensively verified. blob_dir -- directory path for blob data. 'blob data' is data that is retrieved via the loadBlob API. shared_blob_dir -- Flag whether the blob_dir is a server-shared filesystem that should be used instead of transferring blob data over zrpc. Note that the authentication protocol is defined by the server and is detected by the ClientStorage upon connecting (see testConnection() and doAuth() for details). """ log2("%s (pid=%d) created %s/%s for storage: %r" % (self.__class__.__name__, os.getpid(), read_only and "RO" or "RW", read_only_fallback and "fallback" or "normal", storage)) if debug: log2("ClientStorage(): debug argument is no longer used") # Remember some parameters for "_setupCache" self._var_ = var self._storage_ = storage self._client_ = client self._cache_size_ = cache_size self._drop_cache_rather_verify = drop_cache_rather_verify # wait defaults to True, but wait_for_server_on_startup overrides # if not None if wait_for_server_on_startup is not None: if wait is not None and wait != wait_for_server_on_startup: log2("ClientStorage(): conflicting values for wait and " "wait_for_server_on_startup; wait prevails", level=logging.WARNING) else: log2("ClientStorage(): wait_for_server_on_startup " "is deprecated; please use wait instead") wait = wait_for_server_on_startup elif wait is None: wait = 1 self._addr = addr # For tests # A ZEO client can run in disconnected mode, using data from # its cache, or in connected mode. Several instance variables # are related to whether the client is connected. # _server: All method calls are invoked through the server # stub. When not connect, set to disconnected_stub an # object that raises ClientDisconnected errors. # _ready: A threading Event that is set only if _server # is set to a real stub. # _connection: The current zrpc connection or None. # _connection is set as soon as a connection is established, # but _server is set only after cache verification has finished # and clients can safely use the server. _pending_server holds # a server stub while it is being verified. self._server = disconnected_stub self._connection = None self._pending_server = None self._ready = threading.Event() # _is_read_only stores the constructor argument self._is_read_only = read_only self._storage = storage self._read_only_fallback = read_only_fallback self._username = username self._password = password self._realm = realm self._iterators = weakref.WeakValueDictionary() self._iterator_ids = set() # Flag tracking disconnections in the middle of a transaction. This # is reset in tpc_begin() and set in notifyDisconnected(). self._midtxn_disconnect = 0 # _server_addr is used by sortKey() self._server_addr = None self._pickler = self._tfile = None self._info = {'length': 0, 'size': 0, 'name': 'ZEO Client', 'supportsUndo': 0, 'interfaces': ()} self._tbuf = self.TransactionBufferClass() self._db = None self._ltid = None # the last committed transaction # _serials: stores (oid, serialno) as returned by server # _seriald: _check_serials() moves from _serials to _seriald, # which maps oid to serialno # TODO: If serial number matches transaction id, then there is # no need to have all this extra infrastructure for handling # serial numbers. The vote call can just return the tid. # If there is a conflict error, we can't have a special method # called just to propagate the error. self._serials = [] self._seriald = {} self.__name__ = name or str(addr) # Standard convention for storages # A ClientStorage only allows one thread to commit at a time. # Mutual exclusion is achieved using _tpc_cond, which # protects _transaction. A thread that wants to assign to # self._transaction must acquire _tpc_cond first. A thread # that decides it's done with a transaction (whether via success # or failure) must set _transaction to None and do # _tpc_cond.notify() before releasing _tpc_cond. self._tpc_cond = threading.Condition() self._transaction = None # Prevent multiple new_oid calls from going out. The _oids # variable should only be modified while holding the # _oid_lock. self._oid_lock = threading.Lock() self._oids = [] # Object ids retrieved from new_oids() # load() and tpc_finish() must be serialized to guarantee # that cache modifications from each occur atomically. # It also prevents multiple load calls occuring simultaneously, # which simplifies the cache logic. self._load_lock = threading.Lock() # _load_oid and _load_status are protected by _lock self._load_oid = None self._load_status = None # Can't read data in one thread while writing data # (tpc_finish) in another thread. In general, the lock # must prevent access to the cache while _update_cache # is executing. self._lock = threading.Lock() # XXX need to check for POSIX-ness here self.blob_dir = blob_dir self.shared_blob_dir = shared_blob_dir if blob_dir is not None: # Avoid doing this import unless we need it, as it # currently requires pywin32 on Windows. import ZODB.blob self.fshelper = ZODB.blob.FilesystemHelper(blob_dir) self.fshelper.create() self.fshelper.checkSecure() else: self.fshelper = None self._setupCache() self._rpc_mgr = self.ConnectionManagerClass(addr, self, tmin=min_disconnect_poll, tmax=max_disconnect_poll) if wait: self._wait(wait_timeout) else: # attempt_connect() will make an attempt that doesn't block # "too long," for a very vague notion of too long. If that # doesn't succeed, call connect() to start a thread. if not self._rpc_mgr.attempt_connect(): self._rpc_mgr.connect() def _setupCache(self): '''create and open the cache.''' # Decide whether to use non-temporary files storage = self._storage_ client = self._client_ cache_size = self._cache_size_ if client is not None: dir = self._var_ or os.getcwd() cache_path = os.path.join(dir, "%s-%s.zec" % (client, storage)) else: cache_path = None self._cache = self.ClientCacheClass(cache_path, size=cache_size) def _wait(self, timeout=None): if timeout is not None: deadline = time.time() + timeout log2("Setting deadline to %f" % deadline, level=BLATHER) else: deadline = None # Wait for a connection to be established. self._rpc_mgr.connect(sync=1) # When a synchronous connect() call returns, there is # a valid _connection object but cache validation may # still be going on. This code must wait until validation # finishes, but if the connection isn't a zrpc async # connection it also needs to poll for input. while 1: self._ready.wait(30) if self._ready.isSet(): break if timeout and time.time() > deadline: log2("Timed out waiting for connection", level=logging.WARNING) break log2("Waiting for cache verification to finish") def close(self): """Storage API: finalize the storage, releasing external resources.""" if self._rpc_mgr is not None: self._rpc_mgr.close() self._rpc_mgr = None if self._connection is not None: self._connection.register_object(None) # Don't call me! self._connection.close() self._connection = None self._tbuf.close() if self._cache is not None: self._cache.close() self._cache = None if self._tfile is not None: self._tfile.close() def registerDB(self, db): """Storage API: register a database for invalidation messages. This is called by ZODB.DB (and by some tests). The storage isn't really ready to use until after this call. """ self._db = db def is_connected(self): """Return whether the storage is currently connected to a server.""" # This function is used by clients, so we only report that a # connection exists when the connection is ready to use. return self._ready.isSet() def sync(self): # The separate async thread should keep us up to date pass def doAuth(self, protocol, stub): if not (self._username and self._password): raise AuthError("empty username or password") module = get_module(protocol) if not module: log2("%s: no such an auth protocol: %s" % (self.__class__.__name__, protocol), level=logging.WARNING) return storage_class, client, db_class = module if not client: log2("%s: %s isn't a valid protocol, must have a Client class" % (self.__class__.__name__, protocol), level=logging.WARNING) raise AuthError("invalid protocol") c = client(stub) # Initiate authentication, returns boolean specifying whether OK return c.start(self._username, self._realm, self._password) def testConnection(self, conn): """Internal: test the given connection. This returns: 1 if the connection is an optimal match, 0 if it is a suboptimal but acceptable match. It can also raise DisconnectedError or ReadOnlyError. This is called by ZEO.zrpc.ConnectionManager to decide which connection to use in case there are multiple, and some are read-only and others are read-write. This works by calling register() on the server. In read-only mode, register() is called with the read_only flag set. In writable mode and in read-only fallback mode, register() is called with the read_only flag cleared. In read-only fallback mode only, if the register() call raises ReadOnlyError, it is retried with the read-only flag set, and if this succeeds, this is deemed a suboptimal match. In all other cases, a succeeding register() call is deemed an optimal match, and any exception raised by register() is passed through. """ log2("Testing connection %r" % conn) # TODO: Should we check the protocol version here? conn._is_read_only = self._is_read_only stub = self.StorageServerStubClass(conn) auth = stub.getAuthProtocol() log2("Server authentication protocol %r" % auth) if auth: skey = self.doAuth(auth, stub) if skey: log2("Client authentication successful") conn.setSessionKey(skey) else: log2("Authentication failed") raise AuthError("Authentication failed") try: stub.register(str(self._storage), self._is_read_only) return 1 except POSException.ReadOnlyError: if not self._read_only_fallback: raise log2("Got ReadOnlyError; trying again with read_only=1") stub.register(str(self._storage), read_only=1) conn._is_read_only = True return 0 def notifyConnected(self, conn): """Internal: start using the given connection. This is called by ConnectionManager after it has decided which connection should be used. """ if self._cache is None: # the storage was closed, but the connect thread called # this method before it was stopped. return if self._connection is not None: # If we are upgrading from a read-only fallback connection, # we must close the old connection to prevent it from being # used while the cache is verified against the new connection. self._connection.register_object(None) # Don't call me! self._connection.close() self._connection = None self._ready.clear() reconnect = 1 else: reconnect = 0 self.set_server_addr(conn.get_addr()) self._connection = conn # invalidate our db cache if self._db is not None: self._db.invalidateCache() if reconnect: log2("Reconnected to storage: %s" % self._server_addr) else: log2("Connected to storage: %s" % self._server_addr) stub = self.StorageServerStubClass(conn) self._oids = [] self.verify_cache(stub) # It's important to call get_info after calling verify_cache. # If we end up doing a full-verification, we need to wait till # it's done. By doing a synchonous call, we are guarenteed # that the verification will be done because operations are # handled in order. self._info.update(stub.get_info()) self._handle_extensions() for iface in ( ZODB.interfaces.IStorageRestoreable, ZODB.interfaces.IStorageIteration, ZODB.interfaces.IStorageUndoable, ZODB.interfaces.IStorageCurrentRecordIteration, ZODB.interfaces.IBlobStorage, ): if (iface.__module__, iface.__name__) in self._info.get('interfaces', ()): zope.interface.alsoProvides(self, iface) def _handle_extensions(self): for name in self.getExtensionMethods().keys(): if not hasattr(self, name): setattr(self, name, self._server.extensionMethod(name)) def set_server_addr(self, addr): # Normalize server address and convert to string if isinstance(addr, types.StringType): self._server_addr = addr else: assert isinstance(addr, types.TupleType) # If the server is on a remote host, we need to guarantee # that all clients used the same name for the server. If # they don't, the sortKey() may be different for each client. # The best solution seems to be the official name reported # by gethostbyaddr(). host = addr[0] try: canonical, aliases, addrs = socket.gethostbyaddr(host) except socket.error, err: log2("Error resolving host: %s (%s)" % (host, err), level=BLATHER) canonical = host self._server_addr = str((canonical, addr[1])) def sortKey(self): # If the client isn't connected to anything, it can't have a # valid sortKey(). Raise an error to stop the transaction early. if self._server_addr is None: raise ClientDisconnected else: return '%s:%s' % (self._storage, self._server_addr) ### Is there a race condition between notifyConnected and ### notifyDisconnected? In Particular, what if we get ### notifyDisconnected in the middle of notifyConnected? ### The danger is that we'll proceed as if we were connected ### without worrying if we were, but this would happen any way if ### notifyDisconnected had to get the instance lock. There's ### nothing to gain by getting the instance lock. def notifyDisconnected(self): """Internal: notify that the server connection was terminated. This is called by ConnectionManager when the connection is closed or when certain problems with the connection occur. """ log2("Disconnected from storage: %s" % repr(self._server_addr)) self._connection = None self._ready.clear() self._server = disconnected_stub self._midtxn_disconnect = 1 self._iterator_gc() def __len__(self): """Return the size of the storage.""" # TODO: Is this method used? return self._info['length'] def getName(self): """Storage API: return the storage name as a string. The return value consists of two parts: the name as determined by the name and addr argments to the ClientStorage constructor, and the string 'connected' or 'disconnected' in parentheses indicating whether the storage is (currently) connected. """ return "%s (%s)" % ( self.__name__, self.is_connected() and "connected" or "disconnected") def getSize(self): """Storage API: an approximate size of the database, in bytes.""" return self._info['size'] def getExtensionMethods(self): """getExtensionMethods This returns a dictionary whose keys are names of extra methods provided by this storage. Storage proxies (such as ZEO) should call this method to determine the extra methods that they need to proxy in addition to the standard storage methods. Dictionary values should be None; this will be a handy place for extra marshalling information, should we need it """ return self._info.get('extensionMethods', {}) def supportsUndo(self): """Storage API: return whether we support undo.""" return self._info['supportsUndo'] def isReadOnly(self): """Storage API: return whether we are in read-only mode.""" if self._is_read_only: return True else: # If the client is configured for a read-write connection # but has a read-only fallback connection, conn._is_read_only # will be True. If self._connection is None, we'll behave as # read_only try: return self._connection._is_read_only except AttributeError: return True def _check_trans(self, trans): """Internal helper to check a transaction argument for sanity.""" if self._is_read_only: raise POSException.ReadOnlyError() if self._transaction is not trans: raise POSException.StorageTransactionError(self._transaction, trans) def history(self, oid, size=1): """Storage API: return a sequence of HistoryEntry objects. """ return self._server.history(oid, size) def record_iternext(self, next=None): """Storage API: get the next database record. This is part of the conversion-support API. """ return self._server.record_iternext(next) def getTid(self, oid): """Storage API: return current serial number for oid.""" return self._server.getTid(oid) def loadSerial(self, oid, serial): """Storage API: load a historical revision of an object.""" return self._server.loadSerial(oid, serial) def load(self, oid, version=''): """Storage API: return the data for a given object. This returns the pickle data and serial number for the object specified by the given object id, if they exist; otherwise a KeyError is raised. """ self._lock.acquire() # for atomic processing of invalidations try: t = self._cache.load(oid) if t: return t finally: self._lock.release() if self._server is None: raise ClientDisconnected() self._load_lock.acquire() try: self._lock.acquire() try: self._load_oid = oid self._load_status = 1 finally: self._lock.release() data, tid = self._server.loadEx(oid) self._lock.acquire() # for atomic processing of invalidations try: if self._load_status: self._cache.store(oid, tid, None, data) self._load_oid = None finally: self._lock.release() finally: self._load_lock.release() return data, tid def loadBefore(self, oid, tid): self._lock.acquire() try: t = self._cache.loadBefore(oid, tid) if t is not None: return t finally: self._lock.release() t = self._server.loadBefore(oid, tid) if t is None: return None data, start, end = t if end is None: # This method should not be used to get current data. It # doesn't use the _load_lock, so it is possble to overlap # this load with an invalidation for the same object. # If we call again, we're guaranteed to get the # post-invalidation data. But if the data is still # current, we'll still get end == None. # Maybe the best thing to do is to re-run the test with # the load lock in the case. That's slow performance, but # I don't think real application code will ever care about # it. return data, start, end self._lock.acquire() try: self._cache.store(oid, start, end, data) finally: self._lock.release() return data, start, end def new_oid(self): """Storage API: return a new object identifier.""" if self._is_read_only: raise POSException.ReadOnlyError() # avoid multiple oid requests to server at the same time self._oid_lock.acquire() try: if not self._oids: self._oids = self._server.new_oids() self._oids.reverse() return self._oids.pop() finally: self._oid_lock.release() def pack(self, t=None, referencesf=None, wait=1, days=0): """Storage API: pack the storage. Deviations from the Storage API: the referencesf argument is ignored; two additional optional arguments wait and days are provided: wait -- a flag indicating whether to wait for the pack to complete; defaults to true. days -- a number of days to subtract from the pack time; defaults to zero. """ # TODO: Is it okay that read-only connections allow pack()? # rf argument ignored; server will provide its own implementation if t is None: t = time.time() t = t - (days * 86400) return self._server.pack(t, wait) def _check_serials(self): """Internal helper to move data from _serials to _seriald.""" # serials are always going to be the same, the only # question is whether an exception has been raised. if self._serials: l = len(self._serials) r = self._serials[:l] del self._serials[:l] for oid, s in r: if isinstance(s, Exception): raise s self._seriald[oid] = s return r def store(self, oid, serial, data, version, txn): """Storage API: store data for an object.""" assert not version self._check_trans(txn) self._server.storea(oid, serial, data, id(txn)) self._tbuf.store(oid, data) return self._check_serials() def storeBlob(self, oid, serial, data, blobfilename, version, txn): """Storage API: store a blob object.""" assert not version serials = self.store(oid, serial, data, '', txn) if self.shared_blob_dir: self._storeBlob_shared(oid, serial, data, blobfilename, txn) else: self._server.storeBlob(oid, serial, data, blobfilename, txn) self._tbuf.storeBlob(oid, blobfilename) return serials def _storeBlob_shared(self, oid, serial, data, filename, txn): # First, move the blob into the blob directory self.fshelper.getPathForOID(oid, create=True) fd, target = self.fshelper.blob_mkstemp(oid, serial) os.close(fd) if sys.platform == 'win32': # On windows, we can't rename to an existing file. We'll # use a slightly different file name. We keep the old one # until we're done to avoid conflicts. Then remove the old name. target += 'w' rename_or_copy_blob(filename, target) os.remove(target[:-1]) else: rename_or_copy_blob(filename, target) # Now tell the server where we put it self._server.storeBlobShared( oid, serial, data, os.path.basename(target), id(txn)) def _have_blob(self, blob_filename, oid, serial): if os.path.exists(blob_filename): log2("Found blob %s/%s in cache." % (utils.oid_repr(oid), utils.tid_repr(serial)), level=BLATHER) return True return False def receiveBlobStart(self, oid, serial): blob_filename = self.fshelper.getBlobFilename(oid, serial) assert not os.path.exists(blob_filename) assert os.path.exists(blob_filename+'.lock') blob_filename += '.dl' assert not os.path.exists(blob_filename) f = open(blob_filename, 'wb') f.close() def receiveBlobChunk(self, oid, serial, chunk): blob_filename = self.fshelper.getBlobFilename(oid, serial)+'.dl' assert os.path.exists(blob_filename) f = open(blob_filename, 'ab') f.write(chunk) f.close() def receiveBlobStop(self, oid, serial): blob_filename = self.fshelper.getBlobFilename(oid, serial) os.rename(blob_filename+'.dl', blob_filename) os.chmod(blob_filename, stat.S_IREAD) def loadBlob(self, oid, serial): # Load a blob. If it isn't present and we have a shared blob # directory, then assume that it doesn't exist on the server # and return None. if self.fshelper is None: raise POSException.Unsupported("No blob cache directory is " "configured.") blob_filename = self.fshelper.getBlobFilename(oid, serial) # Case 1: Blob is available already, just use it if self._have_blob(blob_filename, oid, serial): return blob_filename if self.shared_blob_dir: # We're using a server shared cache. If the file isn't # here, it's not anywhere. raise POSException.POSKeyError("No blob file", oid, serial) # First, we'll create the directory for this oid, if it doesn't exist. self.fshelper.createPathForOID(oid) # OK, it's not here and we (or someone) needs to get it. We # want to avoid getting it multiple times. We want to avoid # getting it multiple times even accross separate client # processes on the same machine. We'll use file locking. lockfilename = blob_filename+'.lock' try: lock = zc.lockfile.LockFile(lockfilename) except zc.lockfile.LockError: # Someone is already downloading the Blob. Wait for the # lock to be freed. How long should we be willing to wait? # TODO: maybe find some way to assess download progress. while 1: time.sleep(0.1) try: lock = zc.lockfile.LockFile(lockfilename) except zc.lockfile.LockError: pass else: # We have the lock. We should be able to get the file now. lock.close() try: os.remove(lockfilename) except OSError: pass break if self._have_blob(blob_filename, oid, serial): return blob_filename return None try: # We got the lock, so it's our job to download it. First, # we'll double check that someone didn't download it while we # were getting the lock: if self._have_blob(blob_filename, oid, serial): return blob_filename # Ask the server to send it to us. When this function # returns, it will have been sent. (The recieving will # have been handled by the asyncore thread.) self._server.sendBlob(oid, serial) if self._have_blob(blob_filename, oid, serial): return blob_filename raise POSException.POSKeyError("No blob file", oid, serial) finally: lock.close() try: os.remove(lockfilename) except OSError: pass def temporaryDirectory(self): return self.fshelper.temp_dir def tpc_vote(self, txn): """Storage API: vote on a transaction.""" if txn is not self._transaction: return self._server.vote(id(txn)) return self._check_serials() def tpc_transaction(self): return self._transaction def tpc_begin(self, txn, tid=None, status=' '): """Storage API: begin a transaction.""" if self._is_read_only: raise POSException.ReadOnlyError() self._tpc_cond.acquire() self._midtxn_disconnect = 0 while self._transaction is not None: # It is allowable for a client to call two tpc_begins in a # row with the same transaction, and the second of these # must be ignored. if self._transaction == txn: self._tpc_cond.release() return self._tpc_cond.wait(30) self._transaction = txn self._tpc_cond.release() try: self._server.tpc_begin(id(txn), txn.user, txn.description, txn._extension, tid, status) except: # Client may have disconnected during the tpc_begin(). if self._server is not disconnected_stub: self.end_transaction() raise self._tbuf.clear() self._seriald.clear() del self._serials[:] def end_transaction(self): """Internal helper to end a transaction.""" # the right way to set self._transaction to None # calls notify() on _tpc_cond in case there are waiting threads self._tpc_cond.acquire() self._transaction = None self._tpc_cond.notify() self._tpc_cond.release() def lastTransaction(self): return self._cache.getLastTid() def tpc_abort(self, txn): """Storage API: abort a transaction.""" if txn is not self._transaction: return try: # Caution: Are there any exceptions that should prevent an # abort from occurring? It seems wrong to swallow them # all, yet you want to be sure that other abort logic is # executed regardless. try: self._server.tpc_abort(id(txn)) except ClientDisconnected: log2("ClientDisconnected in tpc_abort() ignored", level=BLATHER) finally: self._tbuf.clear() self._seriald.clear() del self._serials[:] self._iterator_gc() self.end_transaction() def tpc_finish(self, txn, f=None): """Storage API: finish a transaction.""" if txn is not self._transaction: return self._load_lock.acquire() try: if self._midtxn_disconnect: raise ClientDisconnected( 'Calling tpc_finish() on a disconnected transaction') # The calls to tpc_finish() and _update_cache() should # never run currently with another thread, because the # tpc_cond condition variable prevents more than one # thread from calling tpc_finish() at a time. tid = self._server.tpc_finish(id(txn)) try: self._lock.acquire() # for atomic processing of invalidations try: self._update_cache(tid) if f is not None: f(tid) finally: self._lock.release() r = self._check_serials() assert r is None or len(r) == 0, "unhandled serialnos: %s" % r except: # The server successfully committed. If we get a failure # here, our own state will be in question, so reconnect. self._connection.close() raise self.end_transaction() finally: self._load_lock.release() self._iterator_gc() def _update_cache(self, tid): """Internal helper to handle objects modified by a transaction. This iterates over the objects in the transaction buffer and update or invalidate the cache. """ # Must be called with _lock already acquired. # Not sure why _update_cache() would be called on a closed storage. if self._cache is None: return for oid, data in self._tbuf: self._cache.invalidate(oid, tid, False) # If data is None, we just invalidate. if data is not None: s = self._seriald[oid] if s != ResolvedSerial: assert s == tid, (s, tid) self._cache.store(oid, s, None, data) if self.fshelper is not None: blobs = self._tbuf.blobs while blobs: oid, blobfilename = blobs.pop() targetpath = self.fshelper.getPathForOID(oid, create=True) rename_or_copy_blob(blobfilename, self.fshelper.getBlobFilename(oid, tid), ) self._tbuf.clear() def undo(self, trans_id, txn): """Storage API: undo a transaction. This is executed in a transactional context. It has no effect until the transaction is committed. It can be undone itself. Zope uses this to implement undo unless it is not supported by a storage. """ self._check_trans(txn) tid, oids = self._server.undo(trans_id, id(txn)) for oid in oids: self._tbuf.invalidate(oid) return tid, oids def undoInfo(self, first=0, last=-20, specification=None): """Storage API: return undo information.""" return self._server.undoInfo(first, last, specification) def undoLog(self, first=0, last=-20, filter=None): """Storage API: return a sequence of TransactionDescription objects. The filter argument should be None or left unspecified, since it is impossible to pass the filter function to the server to be executed there. If filter is not None, an empty sequence is returned. """ if filter is not None: return [] return self._server.undoLog(first, last) # Recovery support def copyTransactionsFrom(self, other, verbose=0): """Copy transactions from another storage. This is typically used for converting data from one storage to another. `other` must have an .iterator() method. """ ZODB.BaseStorage.copy(other, self, verbose) def restore(self, oid, serial, data, version, prev_txn, transaction): """Write data already committed in a separate database.""" assert not version self._check_trans(transaction) self._server.restorea(oid, serial, data, prev_txn, id(transaction)) # Don't update the transaction buffer, because current data are # unaffected. return self._check_serials() # Below are methods invoked by the StorageServer def serialnos(self, args): """Server callback to pass a list of changed (oid, serial) pairs.""" self._serials.extend(args) def info(self, dict): """Server callback to update the info dictionary.""" self._info.update(dict) def verify_cache(self, server): """Internal routine called to verify the cache. The return value (indicating which path we took) is used by the test suite. """ self._pending_server = server # setup tempfile to hold zeoVerify results and interim # invalidation results self._tfile = tempfile.TemporaryFile(suffix=".inv") self._pickler = cPickle.Pickler(self._tfile, 1) self._pickler.fast = 1 # Don't use the memo # allow incoming invalidations: self._connection.register_object(self) # If verify_cache() finishes the cache verification process, # it should set self._server. If it goes through full cache # verification, then endVerify() should self._server. ltid = server.lastTransaction() if not self._cache: log2("No verification necessary -- empty cache") if ltid and ltid != utils.z64: self._cache.setLastTid(ltid) self.finish_verification() return "full verification" last_inval_tid = self._cache.getLastTid() if last_inval_tid is not None: if ltid == last_inval_tid: log2("No verification necessary (last_inval_tid up-to-date)") self.finish_verification() return "no verification" elif ltid < last_inval_tid: message = "Client has seen newer transactions than server!" log2(message, level=logging.CRITICAL) raise ClientStorageError(message) # log some hints about last transaction log2("last inval tid: %r %s\n" % (last_inval_tid, tid2time(last_inval_tid))) log2("last transaction: %r %s" % (ltid, ltid and tid2time(ltid))) pair = server.getInvalidations(last_inval_tid) if pair is not None: log2("Recovering %d invalidations" % len(pair[1])) self.finish_verification(pair) return "quick verification" elif ltid and ltid != utils.z64: self._cache.setLastTid(ltid) # From this point on, we do not have complete information about # the missed transactions. The reason is that cache # verification only checks objects in the client cache and # there may be objects in the object caches that aren't in the # client cach that would need verification too. We avoid that # problem by just invalidating the objects in the object caches. if self._db is not None: self._db.invalidateCache() if self._cache and self._drop_cache_rather_verify: log2("dropping cache") self._cache.close() self._setupCache() # creates a new cache self._server = server self._ready.set() return "cache dropped" log2("Verifying cache") for oid, tid in self._cache.contents(): server.verify(oid, tid) server.endZeoVerify() return "full verification" def invalidateVerify(self, args): """Server callback to invalidate an (oid, '') pair. This is called as part of cache validation. """ # Invalidation as result of verify_cache(). # Queue an invalidate for the end the verification procedure. if self._pickler is None: # This should never happen. log2("invalidateVerify with no _pickler", level = logging.ERROR) return self._pickler.dump((None, [args[0]])) def endVerify(self): """Server callback to signal end of cache validation.""" log2("endVerify finishing") self.finish_verification() log2("endVerify finished") def finish_verification(self, catch_up=None): self._lock.acquire() try: if catch_up: # process catch-up invalidations tid, invalidations = catch_up self._process_invalidations( tid, (arg[0] for arg in invalidations) ) if self._pickler is None: return # write end-of-data marker self._pickler.dump((None, None)) self._pickler = None self._tfile.seek(0) unpickler = cPickle.Unpickler(self._tfile) min_tid = self._cache.getLastTid() while 1: tid, oids = unpickler.load() if oids is None: break if ((tid is None) or (min_tid is None) or (tid > min_tid) ): self._process_invalidations(tid, oids) self._tfile.close() self._tfile = None finally: self._lock.release() self._server = self._pending_server self._ready.set() self._pending_server = None def invalidateTransaction(self, tid, args): """Server callback: Invalidate objects modified by tid.""" self._lock.acquire() try: if self._pickler is not None: log2("Transactional invalidation during cache verification", level=BLATHER) self._pickler.dump((tid, [arg[0] for arg in args])) else: self._process_invalidations(tid, (arg[0] for arg in args)) finally: self._lock.release() def _process_invalidations(self, tid, oids): oids = list(oids) for oid in oids: if oid == self._load_oid: self._load_status = 0 self._cache.invalidate(oid, tid) if self._db is not None: self._db.invalidate(tid, oids) # The following are for compatibility with protocol version 2.0.0 def invalidateTrans(self, args): return self.invalidateTransaction(None, args) invalidate = invalidateVerify end = endVerify Invalidate = invalidateTrans # IStorageIteration def iterator(self, start=None, stop=None): """Return an IStorageTransactionInformation iterator.""" # iids are "iterator IDs" that can be used to query an iterator whose # status is held on the server. iid = self._server.iterator_start(start, stop) return self._setup_iterator(TransactionIterator, iid) def _setup_iterator(self, factory, iid, *args): self._iterators[iid] = iterator = factory(self, iid, *args) self._iterator_ids.add(iid) return iterator def _forget_iterator(self, iid): self._iterators.pop(iid, None) self._iterator_ids.remove(iid) def _iterator_gc(self): iids = self._iterator_ids - set(self._iterators) try: self._server.iterator_gc(list(iids)) except ClientDisconnected: # We could not successfully garbage-collect iterators. # The server might have been restarted, so the IIDs might mean # something different now. We simply forget our unused IIDs to # avoid gc'ing foreign iterators. # In the case that the server was not restarted, we accept the # risk of leaking resources on the ZEO server. pass self._iterator_ids -= iids class TransactionIterator(object): def __init__(self, storage, iid, *args): self._storage = storage self._iid = iid self._ended = False def __iter__(self): return self def next(self): if self._ended: raise ZODB.interfaces.StorageStopIteration() tx_data = self._storage._server.iterator_next(self._iid) if tx_data is None: # The iterator is exhausted, and the server has already # disposed it. self._ended = True self._storage._forget_iterator(self._iid) raise ZODB.interfaces.StorageStopIteration() return ClientStorageTransactionInformation(self._storage, self, *tx_data) class ClientStorageTransactionInformation(ZODB.BaseStorage.TransactionRecord): def __init__(self, storage, txiter, tid, status, user, description, extension): self._storage = storage self._txiter = txiter self._completed = False self._riid = None self.tid = tid self.status = status self.user = user self.description = description self.extension = extension def __iter__(self): riid = self._storage._server.iterator_record_start(self._txiter._iid, self.tid) return self._storage._setup_iterator(RecordIterator, riid) class RecordIterator(object): def __init__(self, storage, riid): self._riid = riid self._completed = False self._storage = storage def __iter__(self): return self def next(self): if self._completed: # We finished iteration once already and the server can't know # about the iteration anymore. raise ZODB.interfaces.StorageStopIteration() item = self._storage._server.iterator_record_next(self._riid) if item is None: # The iterator is exhausted, and the server has already # disposed it. self._completed = True raise ZODB.interfaces.StorageStopIteration() return ZODB.BaseStorage.DataRecord(*item)