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Commit 3fd474e7 authored by Jeremy Hylton's avatar Jeremy Hylton
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Removed on one branch, but restored in the merge.

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##############################################################################
#
# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.0 (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
#
##############################################################################
#
# File-based ZODB storage
#
# Files are arranged as follows.
#
# - The first 4 bytes are a file identifier.
#
# - The rest of the file consists of a sequence of transaction
# "records".
#
# A transaction record consists of:
#
# - 8-byte transaction id, which is also a time stamp.
#
# - 8-byte transaction record length - 8.
#
# - 1-byte status code
#
# - 2-byte length of user name
#
# - 2-byte length of description
#
# - 2-byte length of extension attributes
#
# - user name
#
# - description
#
# - extension attributes
#
# * A sequence of data records
#
# - 8-byte redundant transaction length -8
#
# A data record consists of
#
# - 8-byte oid.
#
# - 8-byte serial, which is a type stamp that matches the
# transaction timestamp.
#
# - 8-byte previous-record file-position.
#
# - 8-byte beginning of transaction record file position.
#
# - 2-byte version length
#
# - 8-byte data length
#
# ? 8-byte position of non-version data
# (if version length > 0)
#
# ? 8-byte position of previous record in this version
# (if version length > 0)
#
# ? version string
# (if version length > 0)
#
# ? data
# (data length > 0)
#
# ? 8-byte position of data record containing data
# (data length == 0)
#
# Note that the lengths and positions are all big-endian.
# Also, the object ids time stamps are big-endian, so comparisons
# are meaningful.
#
# Version handling
#
# There isn't a separate store for versions. Each record has a
# version field, indicating what version it is in. The records in a
# version form a linked list. Each record that has a non-empty
# version string has a pointer to the previous record in the version.
# Version back pointers are retained *even* when versions are
# committed or aborted or when transactions are undone.
#
# There is a notion of "current" version records, which are the
# records in a version that are the current records for their
# respective objects. When a version is comitted, the current records
# are committed to the destination version. When a version is
# aborted, the current records are aborted.
#
# When committing or aborting, we search backward through the linked
# list until we find a record for an object that does not have a
# current record in the version. If we find a record for which the
# non-version pointer is the same as the previous pointer, then we
# forget that the corresponding object had a current record in the
# version. This strategy allows us to avoid searching backward through
# previously committed or aborted version records.
#
# Of course, we ignore records in undone transactions when committing
# or aborting.
#
# Backpointers
#
# When we commit or abort a version, we don't copy (or delete)
# and data. Instead, we write records with back pointers.
#
# A version record *never* has a back pointer to a non-version
# record, because we never abort to a version. A non-version record
# may have a back pointer to a version record or to a non-version
# record.
#
__version__='$Revision: 1.140 $'[11:-2]
import base64
from cPickle import Pickler, Unpickler, loads
import errno
import os
import struct
import sys
import time
from types import StringType, DictType
from struct import pack, unpack
# Not all platforms have fsync
fsync = getattr(os, "fsync", None)
from persistent.TimeStamp import TimeStamp
from ZODB import BaseStorage, ConflictResolution, POSException
from ZODB.POSException import UndoError, POSKeyError, MultipleUndoErrors
from ZODB.lock_file import LockFile
from ZODB.utils import p64, u64, cp, z64
from ZODB.fspack import FileStoragePacker
try:
from ZODB.fsIndex import fsIndex
except ImportError:
def fsIndex():
return {}
from zLOG import LOG, BLATHER, WARNING, ERROR, PANIC
t32 = 1L << 32
# the struct formats for the headers
TRANS_HDR = ">8s8scHHH"
DATA_HDR = ">8s8s8s8sH8s"
# constants to support various header sizes
TRANS_HDR_LEN = 23
DATA_HDR_LEN = 42
DATA_VERSION_HDR_LEN = 58
assert struct.calcsize(TRANS_HDR) == TRANS_HDR_LEN
assert struct.calcsize(DATA_HDR) == DATA_HDR_LEN
def blather(message, *data):
LOG('ZODB FS', BLATHER, "%s blather: %s\n" % (packed_version,
message % data))
def warn(message, *data):
LOG('ZODB FS', WARNING, "%s warn: %s\n" % (packed_version,
message % data))
def error(message, *data):
LOG('ZODB FS', ERROR, "%s ERROR: %s\n" % (packed_version,
message % data))
def nearPanic(message, *data):
LOG('ZODB FS', PANIC, "%s ERROR: %s\n" % (packed_version,
message % data))
def panic(message, *data):
message = message % data
LOG('ZODB FS', PANIC, "%s ERROR: %s\n" % (packed_version, message))
raise CorruptedTransactionError(message)
class FileStorageError(POSException.StorageError):
pass
class PackError(FileStorageError):
pass
class FileStorageFormatError(FileStorageError):
"""Invalid file format
The format of the given file is not valid.
"""
class CorruptedFileStorageError(FileStorageError,
POSException.StorageSystemError):
"""Corrupted file storage."""
class CorruptedTransactionError(CorruptedFileStorageError):
pass
class CorruptedDataError(CorruptedFileStorageError):
pass
class FileStorageQuotaError(FileStorageError,
POSException.StorageSystemError):
"""File storage quota exceeded."""
packed_version='FS21'
class FileStorage(BaseStorage.BaseStorage,
ConflictResolution.ConflictResolvingStorage):
# default pack time is 0
_packt = z64
_records_before_save = 10000
def __init__(self, file_name, create=0, read_only=0, stop=None,
quota=None):
if read_only:
self._is_read_only = 1
if create:
raise ValueError, "can't create a read-only file"
elif stop is not None:
raise ValueError, "time-travel is only supported in read-only mode"
if stop is None:
stop='\377'*8
# Lock the database and set up the temp file.
if not read_only:
# Create the lock file
self._lock_file = LockFile(file_name + '.lock')
self._tfile = open(file_name + '.tmp', 'w+b')
else:
self._tfile = None
self._file_name = file_name
BaseStorage.BaseStorage.__init__(self, file_name)
(index, vindex, tindex, tvindex,
oid2serial, toid2serial, toid2serial_delete) = self._newIndexes()
self._initIndex(index, vindex, tindex, tvindex,
oid2serial, toid2serial, toid2serial_delete)
# Now open the file
self._file = None
if not create:
try:
self._file = open(file_name, read_only and 'rb' or 'r+b')
except IOError, exc:
if exc.errno == errno.EFBIG:
# The file is too big to open. Fail visibly.
raise
if exc.errno == errno.ENOENT:
# The file doesn't exist. Create it.
create = 1
# If something else went wrong, it's hard to guess
# what the problem was. If the file does not exist,
# create it. Otherwise, fail.
if os.path.exists(file_name):
raise
else:
create = 1
if self._file is None and create:
if os.path.exists(file_name):
os.remove(file_name)
self._file = open(file_name, 'w+b')
self._file.write(packed_version)
r = self._restore_index()
if r is not None:
self._used_index = 1 # Marker for testing
index, vindex, start, maxoid, ltid = r
self._initIndex(index, vindex, tindex, tvindex,
oid2serial, toid2serial, toid2serial_delete)
self._pos, self._oid, tid = read_index(
self._file, file_name, index, vindex, tindex, stop,
ltid=ltid, start=start, maxoid=maxoid,
read_only=read_only,
)
else:
self._used_index = 0 # Marker for testing
self._pos, self._oid, tid = read_index(
self._file, file_name, index, vindex, tindex, stop,
read_only=read_only,
)
self._save_index()
self._records_before_save = max(self._records_before_save,
len(self._index))
self._ltid = tid
# self._pos should always point just past the last
# transaction. During 2PC, data is written after _pos.
# invariant is restored at tpc_abort() or tpc_finish().
self._ts = tid = TimeStamp(tid)
t = time.time()
t = TimeStamp(*time.gmtime(t)[:5] + (t % 60,))
if tid > t:
warn("%s Database records in the future", file_name);
if tid.timeTime() - t.timeTime() > 86400*30:
# a month in the future? This is bogus, use current time
self._ts = t
self._quota = quota
# Serialno cache statistics.
self._oid2serial_nlookups = self._oid2serial_nhits = 0
def _initIndex(self, index, vindex, tindex, tvindex,
oid2serial, toid2serial, toid2serial_delete):
self._index=index
self._vindex=vindex
self._tindex=tindex
self._tvindex=tvindex
self._index_get=index.get
self._vindex_get=vindex.get
# .store() needs to compare the passed-in serial to the current
# serial in the database. _oid2serial caches the oid -> current
# serial mapping for non-version data (if the current record for
# oid is version data, the oid is not a key in _oid2serial).
# The point is that otherwise seeking into the storage is needed
# to extract the current serial, and that's an expensive operation.
# For example, if a transaction stores 4000 objects, and each
# random seek + read takes 7ms (that was approximately true on
# Linux and Windows tests in mid-2003), that's 28 seconds just to
# find the old serials.
# XXX Probably better to junk this and redefine _index as mapping
# XXX oid to (offset, serialno) pair, via a new memory-efficient
# XXX BTree type.
self._oid2serial = oid2serial
# oid->serialno map to transactionally add to _oid2serial.
self._toid2serial = toid2serial
# Set of oids to transactionally delete from _oid2serial (e.g.,
# oids reverted by undo, or for which the most recent record
# becomes version data).
self._toid2serial_delete = toid2serial_delete
def __len__(self):
return len(self._index)
def _newIndexes(self):
# hook to use something other than builtin dict
return fsIndex(), {}, {}, {}, {}, {}, {}
_saved = 0
def _save_index(self):
"""Write the database index to a file to support quick startup."""
index_name = self.__name__ + '.index'
tmp_name = index_name + '.index_tmp'
f=open(tmp_name,'wb')
p=Pickler(f,1)
info={'index': self._index, 'pos': self._pos,
'oid': self._oid, 'vindex': self._vindex}
p.dump(info)
f.flush()
f.close()
try:
try:
os.remove(index_name)
except OSError:
pass
os.rename(tmp_name, index_name)
except: pass
self._saved += 1
def _clear_index(self):
index_name = self.__name__ + '.index'
if os.path.exists(index_name):
try:
os.remove(index_name)
except OSError:
pass
def _sane(self, index, pos):
"""Sanity check saved index data by reading the last undone trans
Basically, we read the last not undone transaction and
check to see that the included records are consistent
with the index. Any invalid record records or inconsistent
object positions cause zero to be returned.
"""
if pos < 100:
return 0 # insane
file = self._file
seek = file.seek
read = file.read
seek(0,2)
if file.tell() < pos:
return 0 # insane
ltid = None
max_checked = 5
checked = 0
while checked < max_checked:
seek(pos-8)
rstl = read(8)
tl = u64(rstl)
pos = pos-tl-8
if pos < 4:
return 0 # insane
seek(pos)
s = read(TRANS_HDR_LEN)
tid, stl, status, ul, dl, el = unpack(TRANS_HDR, s)
if not ltid:
ltid = tid
if stl != rstl:
return 0 # inconsistent lengths
if status == 'u':
continue # undone trans, search back
if status not in ' p':
return 0 # insane
if tl < (TRANS_HDR_LEN + ul + dl + el):
return 0 # insane
tend = pos+tl
opos = pos+(TRANS_HDR_LEN + ul + dl + el)
if opos == tend:
continue # empty trans
while opos < tend and checked < max_checked:
# Read the data records for this transaction
seek(opos)
h = read(DATA_HDR_LEN)
oid, serial, sprev, stloc, vlen, splen = unpack(DATA_HDR, h)
tloc = u64(stloc)
plen = u64(splen)
dlen = DATA_HDR_LEN+(plen or 8)
if vlen:
dlen = dlen+(16+vlen)
if opos+dlen > tend or tloc != pos:
return 0 # insane
if index.get(oid, 0) != opos:
return 0 # insane
checked += 1
opos = opos+dlen
return ltid
def _restore_index(self):
"""Load database index to support quick startup."""
file_name=self.__name__
index_name=file_name+'.index'
try: f=open(index_name,'rb')
except: return None
p=Unpickler(f)
try:
info=p.load()
except:
exc, err = sys.exc_info()[:2]
warn("Failed to load database index: %s: %s" %
(exc, err))
return None
index = info.get('index')
pos = info.get('pos')
oid = info.get('oid')
vindex = info.get('vindex')
if index is None or pos is None or oid is None or vindex is None:
return None
pos = long(pos)
if isinstance(index, DictType) and not self._is_read_only:
# Convert to fsIndex
newindex = fsIndex()
if type(newindex) is not type(index):
# And we have fsIndex
newindex.update(index)
# Now save the index
f = open(index_name, 'wb')
p = Pickler(f, 1)
info['index'] = newindex
p.dump(info)
f.close()
# Now call this method again to get the new data
return self._restore_index()
tid = self._sane(index, pos)
if not tid:
return None
return index, vindex, pos, oid, tid
def close(self):
self._file.close()
if hasattr(self,'_lock_file'):
self._lock_file.close()
if self._tfile:
self._tfile.close()
try:
self._save_index()
except:
# XXX should log the error, though
pass # We don't care if this fails.
# Return serial number of most recent record for oid if that's in
# the _oid2serial cache. Else return None. It's important to use
# this instead of indexing _oid2serial directly so that cache
# statistics can be logged.
def _get_cached_serial(self, oid):
self._oid2serial_nlookups += 1
result = self._oid2serial.get(oid)
if result is not None:
self._oid2serial_nhits += 1
# Log a msg every ~8000 tries, and prevent overflow.
if self._oid2serial_nlookups & 0x1fff == 0:
if self._oid2serial_nlookups >> 30:
# In older Pythons, we may overflow if we keep it an int.
self._oid2serial_nlookups = long(self._oid2serial_nlookups)
self._oid2serial_nhits = long(self._oid2serial_nhits)
blather("_oid2serial size %s lookups %s hits %s rate %.1f%%",
len(self._oid2serial),
self._oid2serial_nlookups,
self._oid2serial_nhits,
100.0 * self._oid2serial_nhits /
self._oid2serial_nlookups)
return result
def abortVersion(self, src, transaction):
return self.commitVersion(src, '', transaction, abort=1)
def commitVersion(self, src, dest, transaction, abort=None):
# We are going to commit by simply storing back pointers.
if self._is_read_only:
raise POSException.ReadOnlyError()
if not (src and isinstance(src, StringType)
and isinstance(dest, StringType)):
raise POSException.VersionCommitError('Invalid source version')
if src == dest:
raise POSException.VersionCommitError(
"Can't commit to same version: %s" % repr(src))
if dest and abort:
raise POSException.VersionCommitError(
"Internal error, can't abort to a version")
if transaction is not self._transaction:
raise POSException.StorageTransactionError(self, transaction)
self._lock_acquire()
try:
return self._commitVersion(src, dest, transaction, abort)
finally:
self._lock_release()
def _commitVersion(self, src, dest, transaction, abort=None):
# call after checking arguments and acquiring lock
srcpos = self._vindex_get(src, 0)
spos = p64(srcpos)
# middle holds bytes 16:34 of a data record:
# pos of transaction, len of version name, data length
# commit version never writes data, so data length is always 0
middle = struct.pack(">8sH8s", p64(self._pos), len(dest), z64)
if dest:
sd = p64(self._vindex_get(dest, 0))
heredelta = 66 + len(dest)
else:
sd = ''
heredelta = 50
here = self._pos + (self._tfile.tell() + self._thl)
oids = []
current_oids = {}
t = None
tstatus = ' '
if abort is None:
newserial = self._serial
while srcpos:
self._file.seek(srcpos)
h = self._file.read(DATA_VERSION_HDR_LEN)
# h -> oid, serial, prev(oid), tloc, vlen, plen, pnv, pv
oid = h[:8]
pnv = h[-16:-8]
if abort:
# If we are aborting, the serialno in the new data
# record should be the same as the serialno in the last
# non-version data record.
# XXX This might be the only time that the serialno
# of a data record does not match the transaction id.
self._file.seek(u64(pnv))
h_pnv = self._file.read(DATA_VERSION_HDR_LEN)
newserial = h_pnv[8:16]
if self._index.get(oid) == srcpos:
# This is a current record!
self._tindex[oid] = here
oids.append(oid)
self._tfile.write(oid + newserial + spos + middle)
if dest:
self._tvindex[dest] = here
self._tfile.write(pnv + sd + dest)
sd = p64(here)
self._tfile.write(abort and pnv or spos)
# data backpointer to src data
here += heredelta
current_oids[oid] = 1
else:
# Hm. This is a non-current record. Is there a
# current record for this oid?
if not current_oids.has_key(oid):
# Nope. We're done *if* this transaction wasn't undone.
tloc = h[24:32]
if t != tloc:
# We haven't checked this transaction before,
# get its status.
t = tloc
self._file.seek(u64(t) + 16)
tstatus = self._file.read(1)
if tstatus != 'u':
# Yee ha! We can quit
break
spos = h[-8:]
srcpos = u64(spos)
self._toid2serial_delete.update(current_oids)
return oids
def getSize(self):
return self._pos
def _load(self, oid, version, _index, file):
try:
pos = _index[oid]
except KeyError:
raise POSKeyError(oid)
except TypeError:
raise TypeError, 'invalid oid %r' % (oid,)
file.seek(pos)
read = file.read
h = read(DATA_HDR_LEN)
doid, serial, prev, tloc, vlen, plen = unpack(DATA_HDR, h)
if doid != oid:
raise CorruptedDataError, h
if vlen:
pnv = read(8) # Read location of non-version data
if (not version or len(version) != vlen or
(read(8) # skip past version link
and version != read(vlen))):
return _loadBack(file, oid, pnv)
else:
# The most recent record is for non-version data -- cache
# the serialno.
self._oid2serial[oid] = serial
# If we get here, then either this was not a version record,
# or we've already read past the version data!
if plen != z64:
return read(u64(plen)), serial
pnv = read(8)
# We use the current serial, since that is the one that
# will get checked when we store.
return _loadBack(file, oid, pnv)[0], serial
def load(self, oid, version):
self._lock_acquire()
try:
return self._load(oid, version, self._index, self._file)
finally:
self._lock_release()
def loadSerial(self, oid, serial):
self._lock_acquire()
try:
file=self._file
seek=file.seek
read=file.read
try:
pos = self._index[oid]
except KeyError:
raise POSKeyError(oid)
except TypeError:
raise TypeError, 'invalid oid %r' % (oid,)
while 1:
seek(pos)
h=read(DATA_HDR_LEN)
doid,dserial,prev,tloc,vlen,plen = unpack(DATA_HDR, h)
if doid != oid: raise CorruptedDataError(h)
if dserial == serial: break # Yeee ha!
# Keep looking for serial
pos = u64(prev)
if not pos:
raise POSKeyError(serial)
continue
if vlen:
pnv=read(8) # Read location of non-version data
read(8) # skip past version link
read(vlen) # skip version
if plen != z64: return read(u64(plen))
# We got a backpointer, probably from a commit.
pnv=read(8)
return _loadBack(file, oid, pnv)[0]
finally: self._lock_release()
def modifiedInVersion(self, oid):
self._lock_acquire()
try:
try:
pos = self._index[oid]
except KeyError:
raise POSKeyError(oid)
except TypeError:
raise TypeError, 'invalid oid %r' % (oid,)
file=self._file
file.seek(pos)
doid,serial,prev,tloc,vlen = unpack(">8s8s8s8sH", file.read(34))
if doid != oid:
raise CorruptedDataError(pos)
if vlen:
file.read(24) # skip plen, pnv, and pv
return file.read(vlen)
return ''
finally: self._lock_release()
def store(self, oid, serial, data, version, transaction):
if self._is_read_only:
raise POSException.ReadOnlyError()
if transaction is not self._transaction:
raise POSException.StorageTransactionError(self, transaction)
self._lock_acquire()
try:
old = self._index_get(oid, 0)
cached_serial = None
pnv = None
if old:
cached_serial = self._get_cached_serial(oid)
if cached_serial is None:
self._file.seek(old)
h=self._file.read(DATA_HDR_LEN)
doid,oserial,sprev,stloc,vlen,splen = unpack(DATA_HDR, h)
if doid != oid: raise CorruptedDataError(h)
if vlen:
pnv=self._file.read(8) # non-version data pointer
self._file.read(8) # skip past version link
locked_version=self._file.read(vlen)
if version != locked_version:
raise POSException.VersionLockError, (
`oid`, locked_version)
else:
oserial = cached_serial
if serial != oserial:
rdata = self.tryToResolveConflict(oid, oserial, serial,
data)
if rdata is None:
raise POSException.ConflictError(
oid=oid, serials=(oserial, serial), data=data)
else:
data = rdata
else:
oserial=serial
tfile=self._tfile
write=tfile.write
pos=self._pos
here=pos+(tfile.tell()+self._thl)
self._tindex[oid]=here
newserial=self._serial
write(pack(DATA_HDR,
oid, newserial, p64(old), p64(pos),
len(version), p64(len(data))
)
)
if version:
if pnv:
write(pnv)
else:
write(p64(old))
# Link to last record for this version:
tvindex=self._tvindex
pv=tvindex.get(version, 0) or self._vindex_get(version, 0)
write(p64(pv))
tvindex[version]=here
write(version)
self._toid2serial_delete[oid] = 1
else:
self._toid2serial[oid] = newserial
write(data)
# Check quota
quota=self._quota
if quota is not None and pos+(tfile.tell()+self._thl) > quota:
raise FileStorageQuotaError, (
'The storage quota has been exceeded.')
return (serial == oserial and newserial
or ConflictResolution.ResolvedSerial)
finally:
self._lock_release()
def _data_find(self, tpos, oid, data):
# Return backpointer to oid in data record for in transaction at tpos.
# It should contain a pickle identical to data. Returns 0 on failure.
# Must call with lock held.
self._file.seek(tpos)
h = self._file.read(TRANS_HDR_LEN)
tid, stl, status, ul, dl, el = struct.unpack(TRANS_HDR, h)
self._file.read(ul + dl + el)
tend = tpos + u64(stl) + 8
pos = self._file.tell()
while pos < tend:
h = self._file.read(DATA_HDR_LEN)
_oid, serial, sprev, stpos, vl, sdl = struct.unpack(DATA_HDR, h)
dl = u64(sdl)
reclen = DATA_HDR_LEN + vl + dl
if vl:
reclen += 16
if _oid == oid:
if vl:
self._file.read(vl + 16)
# Make sure this looks like the right data record
if dl == 0:
# This is also a backpointer. Gotta trust it.
return pos
if dl != len(data):
# The expected data doesn't match what's in the
# backpointer. Something is wrong.
error("Mismatch between data and backpointer at %d", pos)
return 0
_data = self._file.read(dl)
if data != _data:
return 0
return pos
pos += reclen
self._file.seek(pos)
return 0
def restore(self, oid, serial, data, version, prev_txn, transaction):
# A lot like store() but without all the consistency checks. This
# should only be used when we /know/ the data is good, hence the
# method name. While the signature looks like store() there are some
# differences:
#
# - serial is the serial number of /this/ revision, not of the
# previous revision. It is used instead of self._serial, which is
# ignored.
#
# - Nothing is returned
#
# - data can be None, which indicates a George Bailey object
# (i.e. one who's creation has been transactionally undone).
#
# prev_txn is a backpointer. In the original database, it's possible
# that the data was actually living in a previous transaction. This
# can happen for transactional undo and other operations, and is used
# as a space saving optimization. Under some circumstances the
# prev_txn may not actually exist in the target database (i.e. self)
# for example, if it's been packed away. In that case, the prev_txn
# should be considered just a hint, and is ignored if the transaction
# doesn't exist.
if self._is_read_only:
raise POSException.ReadOnlyError()
if transaction is not self._transaction:
raise POSException.StorageTransactionError(self, transaction)
self._lock_acquire()
try:
prev_pos = 0
if prev_txn is not None:
prev_txn_pos = self._txn_find(prev_txn, 0)
if prev_txn_pos:
prev_pos = self._data_find(prev_txn_pos, oid, data)
old = self._index_get(oid, 0)
# Calculate the file position in the temporary file
here = self._pos + self._tfile.tell() + self._thl
# And update the temp file index
self._tindex[oid] = here
if prev_pos:
# If there is a valid prev_pos, don't write data.
data = None
if data is None:
dlen = 0
else:
dlen = len(data)
# Write the recovery data record
self._tfile.write(pack(DATA_HDR,
oid, serial, p64(old), p64(self._pos),
len(version), p64(dlen)))
# We need to write some version information if this revision is
# happening in a version.
if version:
pnv = self._restore_pnv(oid, old, version, prev_pos)
if pnv:
self._tfile.write(pnv)
else:
self._tfile.write(p64(old))
# Link to the last record for this version
pv = self._tvindex.get(version, 0)
if not pv:
pv = self._vindex_get(version, 0)
self._tfile.write(p64(pv))
self._tvindex[version] = here
self._tfile.write(version)
self._toid2serial_delete[oid] = 1
else:
self._toid2serial[oid] = serial
# Finally, write the data or a backpointer.
if data is None:
if prev_pos:
self._tfile.write(p64(prev_pos))
else:
# Write a zero backpointer, which indicates an
# un-creation transaction.
self._tfile.write(z64)
else:
self._tfile.write(data)
finally:
self._lock_release()
def _restore_pnv(self, oid, prev, version, bp):
# Find a valid pnv (previous non-version) pointer for this version.
# If there is no previous record, there can't be a pnv.
if not prev:
return None
pnv = None
# Load the record pointed to be prev
self._file.seek(prev)
h = self._file.read(DATA_HDR_LEN)
doid, x, y, z, vlen, w = unpack(DATA_HDR, h)
if doid != oid:
raise CorruptedDataError, h
# If the previous record is for a version, it must have
# a valid pnv.
if vlen > 0:
pnv = self._file.read(8)
pv = self._file.read(8)
v = self._file.read(vlen)
elif bp:
# XXX Not sure the following is always true:
# The previous record is not for this version, yet we
# have a backpointer to it. The current record must
# be an undo of an abort or commit, so the backpointer
# must be to a version record with a pnv.
self._file.seek(bp)
h2 = self._file.read(DATA_HDR_LEN)
doid2, x, y, z, vlen2, sdl = unpack(DATA_HDR, h2)
dl = u64(sdl)
if oid != doid2:
raise CorruptedDataError, h2
if vlen2 > 0:
pnv = self._file.read(8)
pv = self._file.read(8)
v = self._file.read(8)
else:
warn("restore could not find previous non-version data "
"at %d or %d" % (prev, bp))
return pnv
def supportsUndo(self):
return 1
def supportsVersions(self):
return 1
def _clear_temp(self):
self._tindex.clear()
self._tvindex.clear()
self._toid2serial.clear()
self._toid2serial_delete.clear()
if self._tfile is not None:
self._tfile.seek(0)
def _begin(self, tid, u, d, e):
self._nextpos = 0
self._thl = TRANS_HDR_LEN + len(u) + len(d) + len(e)
if self._thl > 65535:
# one of u, d, or e may be > 65535
# We have to check lengths here because struct.pack
# doesn't raise an exception on overflow!
if len(u) > 65535:
raise FileStorageError('user name too long')
if len(d) > 65535:
raise FileStorageError('description too long')
if len(e) > 65535:
raise FileStorageError('too much extension data')
def tpc_vote(self, transaction):
self._lock_acquire()
try:
if transaction is not self._transaction:
return
dlen = self._tfile.tell()
if not dlen:
return # No data in this trans
self._tfile.seek(0)
user, desc, ext = self._ude
luser = len(user)
ldesc = len(desc)
lext = len(ext)
self._file.seek(self._pos)
tl = self._thl + dlen
stl = p64(tl)
try:
# Note that we use a status of 'c', for checkpoint.
# If this flag isn't cleared, anything after this is
# suspect.
self._file.write(pack(
">8s" "8s" "c" "H" "H" "H"
,self._serial, stl,'c', luser, ldesc, lext,
))
if user:
self._file.write(user)
if desc:
self._file.write(desc)
if ext:
self._file.write(ext)
cp(self._tfile, self._file, dlen)
self._file.write(stl)
self._file.flush()
except:
# Hm, an error occured writing out the data. Maybe the
# disk is full. We don't want any turd at the end.
self._file.truncate(self._pos)
raise
self._nextpos = self._pos + (tl + 8)
finally:
self._lock_release()
# Keep track of the number of records that we've written
_records_written = 0
def _finish(self, tid, u, d, e):
nextpos=self._nextpos
if nextpos:
file=self._file
# Clear the checkpoint flag
file.seek(self._pos+16)
file.write(self._tstatus)
file.flush()
if fsync is not None: fsync(file.fileno())
self._pos = nextpos
self._index.update(self._tindex)
self._vindex.update(self._tvindex)
self._oid2serial.update(self._toid2serial)
for oid in self._toid2serial_delete.keys():
try:
del self._oid2serial[oid]
except KeyError:
pass
# Update the number of records that we've written
# +1 for the transaction record
self._records_written += len(self._tindex) + 1
if self._records_written >= self._records_before_save:
self._save_index()
self._records_written = 0
self._records_before_save = max(self._records_before_save,
len(self._index))
self._ltid = tid
def _abort(self):
if self._nextpos:
self._file.truncate(self._pos)
self._nextpos=0
def supportsTransactionalUndo(self):
return 1
def _undoDataInfo(self, oid, pos, tpos):
"""Return the serial, data pointer, data, and version for the oid
record at pos"""
if tpos:
file=self._tfile
pos = tpos - self._pos - self._thl
tpos=file.tell()
else:
file=self._file
read=file.read
file.seek(pos)
h=read(DATA_HDR_LEN)
roid,serial,sprev,stloc,vlen,splen = unpack(DATA_HDR, h)
if roid != oid:
raise UndoError('Invalid undo transaction id', oid)
if vlen:
read(16) # skip nv pointer and version previous pointer
version=read(vlen)
else:
version=''
plen = u64(splen)
if plen:
data = read(plen)
else:
data=''
pos=u64(read(8))
if tpos: file.seek(tpos) # Restore temp file to end
return serial, pos, data, version
def _getVersion(self, oid, pos):
self._file.seek(pos)
h = self._file.read(DATA_HDR_LEN)
doid, serial, sprev, stloc, vlen, splen = unpack(DATA_HDR, h)
assert doid == oid
if vlen:
h = self._file.read(16)
return self._file.read(vlen), h[:8]
else:
return '', ''
def getSerial(self, oid):
self._lock_acquire()
try:
result = self._get_cached_serial(oid)
if result is None:
try:
result = self._getSerial(oid, self._index[oid])
except KeyError:
raise POSKeyError(oid)
except TypeError:
raise TypeError, 'invalid oid %r' % (oid,)
return result
finally:
self._lock_release()
def _getSerial(self, oid, pos):
self._file.seek(pos)
h = self._file.read(16)
if len(h) < 16:
raise CorruptedDataError(h)
h += self._file.read(26) # get rest of header
if h[:8] != oid:
raise CorruptedDataError(h)
oid2, serial, sprev, stloc, vlen, splen = unpack(DATA_HDR, h)
if splen == z64:
# a back pointer
bp = self._file.read(8)
if bp == z64:
# If the backpointer is 0 (encoded as z64), then
# this transaction undoes the object creation.
raise KeyError(oid)
return serial
def _transactionalUndoRecord(self, oid, pos, serial, pre, version):
"""Get the indo information for a data record
Return a 5-tuple consisting of a pickle, data pointer,
version, packed non-version data pointer, and current
position. If the pickle is true, then the data pointer must
be 0, but the pickle can be empty *and* the pointer 0.
"""
copy=1 # Can we just copy a data pointer
# First check if it is possible to undo this record.
tpos=self._tindex.get(oid, 0)
ipos=self._index.get(oid, 0)
tipos=tpos or ipos
if tipos != pos:
# Eek, a later transaction modified the data, but,
# maybe it is pointing at the same data we are.
cserial, cdataptr, cdata, cver = self._undoDataInfo(
oid, ipos, tpos)
# Versions of undone record and current record *must* match!
if cver != version:
raise UndoError('Current and undone versions differ', oid)
if cdataptr != pos:
# We aren't sure if we are talking about the same data
try:
if (
# The current record wrote a new pickle
cdataptr == tipos
or
# Backpointers are different
_loadBackPOS(self._file, oid, p64(pos)) !=
_loadBackPOS(self._file, oid, p64(cdataptr))
):
if pre and not tpos:
copy = 0 # we'll try to do conflict resolution
else:
# We bail if:
# - We don't have a previous record, which should
# be impossible.
raise UndoError("no previous record", oid)
except KeyError:
# LoadBack gave us a key error. Bail.
raise UndoError("_loadBack() failed", oid)
# Return the data that should be written in the undo record.
if not pre:
# There is no previous revision, because the object creation
# is being undone.
return '', 0, '', '', ipos
version, snv = self._getVersion(oid, pre)
if copy:
# we can just copy our previous-record pointer forward
return '', pre, version, snv, ipos
try:
# returns data, serial tuple
bdata = _loadBack(self._file, oid, p64(pre))[0]
except KeyError:
# couldn't find oid; what's the real explanation for this?
raise UndoError("_loadBack() failed for %s", oid)
data=self.tryToResolveConflict(oid, cserial, serial, bdata, cdata)
if data:
return data, 0, version, snv, ipos
raise UndoError("Some data were modified by a later transaction", oid)
# undoLog() returns a description dict that includes an id entry.
# The id is opaque to the client, but contains the transaction id.
# The transactionalUndo() implementation does a simple linear
# search through the file (from the end) to find the transaction.
def undoLog(self, first=0, last=-20, filter=None):
if last < 0:
last = first - last + 1
self._lock_acquire()
try:
if self._packt is None:
raise UndoError(
'Undo is currently disabled for database maintenance.<p>')
us = UndoSearch(self._file, self._pos, self._packt,
first, last, filter)
while not us.finished():
# Hold lock for batches of 20 searches, so default search
# parameters will finish without letting another thread run.
for i in range(20):
if us.finished():
break
us.search()
# Give another thread a chance, so that a long undoLog()
# operation doesn't block all other activity.
self._lock_release()
self._lock_acquire()
return us.results
finally:
self._lock_release()
def transactionalUndo(self, transaction_id, transaction):
"""Undo a transaction, given by transaction_id.
Do so by writing new data that reverses the action taken by
the transaction.
Usually, we can get by with just copying a data pointer, by
writing a file position rather than a pickle. Sometimes, we
may do conflict resolution, in which case we actually copy
new data that results from resolution.
"""
if self._is_read_only:
raise POSException.ReadOnlyError()
if transaction is not self._transaction:
raise POSException.StorageTransactionError(self, transaction)
self._lock_acquire()
try:
return self._txn_undo(transaction_id)
finally:
self._lock_release()
def _txn_undo(self, transaction_id):
# Find the right transaction to undo and call _txn_undo_write().
tid = base64.decodestring(transaction_id + '\n')
assert len(tid) == 8
tpos = self._txn_find(tid, 1)
tindex = self._txn_undo_write(tpos)
self._tindex.update(tindex)
# Arrange to clear the affected oids from the oid2serial cache.
# It's too painful to try to update them to correct current
# values instead.
self._toid2serial_delete.update(tindex)
return tindex.keys()
def _txn_find(self, tid, stop_at_pack):
pos = self._pos
# XXX Why 39? Only because undoLog() uses it as a boundary.
while pos > 39:
self._file.seek(pos - 8)
pos = pos - u64(self._file.read(8)) - 8
self._file.seek(pos)
h = self._file.read(TRANS_HDR_LEN)
_tid = h[:8]
if _tid == tid:
return pos
if stop_at_pack:
# check the status field of the transaction header
if h[16] == 'p' or _tid < self._packt:
break
raise UndoError("Invalid transaction id")
def _txn_undo_write(self, tpos):
# a helper function to write the data records for transactional undo
ostloc = p64(self._pos)
here = self._pos + (self._tfile.tell() + self._thl)
# Let's move the file pointer back to the start of the txn record.
self._file.seek(tpos)
h = self._file.read(TRANS_HDR_LEN)
if h[16] == 'u':
return
if h[16] != ' ':
raise UndoError('non-undoable transaction')
tl = u64(h[8:16])
ul, dl, el = struct.unpack(">HHH", h[17:TRANS_HDR_LEN])
tend = tpos + tl
pos = tpos + (TRANS_HDR_LEN + ul + dl + el)
tindex = {}
failures = {} # keep track of failures, cause we may succeed later
failed = failures.has_key
# Read the data records for this transaction
while pos < tend:
self._file.seek(pos)
h = self._file.read(DATA_HDR_LEN)
oid, serial, sprev, stloc, vlen, splen = \
struct.unpack(DATA_HDR, h)
if failed(oid):
del failures[oid] # second chance!
plen = u64(splen)
prev = u64(sprev)
if vlen:
dlen = DATA_VERSION_HDR_LEN + vlen + (plen or 8)
self._file.seek(16, 1)
version = self._file.read(vlen)
else:
dlen = DATA_HDR_LEN + (plen or 8)
version = ''
try:
p, prev, v, snv, ipos = self._transactionalUndoRecord(
oid, pos, serial, prev, version)
except UndoError, v:
# Don't fail right away. We may be redeemed later!
failures[oid] = v
else:
plen = len(p)
self._tfile.write(pack(DATA_HDR,
oid, self._serial, p64(ipos),
ostloc, len(v), p64(plen)))
if v:
vprev=self._tvindex.get(v, 0) or self._vindex.get(v, 0)
self._tfile.write(snv + p64(vprev) + v)
self._tvindex[v] = here
odlen = DATA_VERSION_HDR_LEN + len(v)+(plen or 8)
else:
odlen = DATA_HDR_LEN + (plen or 8)
if p:
self._tfile.write(p)
else:
self._tfile.write(p64(prev))
tindex[oid] = here
here += odlen
pos += dlen
if pos > tend:
raise UndoError("non-undoable transaction")
if failures:
raise MultipleUndoErrors(failures.items())
return tindex
def versionEmpty(self, version):
if not version:
# The interface is silent on this case. I think that this should
# be an error, but Barry thinks this should return 1 if we have
# any non-version data. This would be excruciatingly painful to
# test, so I must be right. ;)
raise POSException.VersionError(
'The version must be an non-empty string')
self._lock_acquire()
try:
index=self._index
file=self._file
seek=file.seek
read=file.read
srcpos=self._vindex_get(version, 0)
t=tstatus=None
while srcpos:
seek(srcpos)
oid=read(8)
if index[oid]==srcpos: return 0
h=read(50) # serial, prev(oid), tloc, vlen, plen, pnv, pv
tloc=h[16:24]
if t != tloc:
# We haven't checked this transaction before,
# get its status.
t=tloc
seek(u64(t)+16)
tstatus=read(1)
if tstatus != 'u': return 1
spos=h[-8:]
srcpos=u64(spos)
return 1
finally: self._lock_release()
def versions(self, max=None):
r=[]
a=r.append
keys=self._vindex.keys()
if max is not None: keys=keys[:max]
for version in keys:
if self.versionEmpty(version): continue
a(version)
if max and len(r) >= max: return r
return r
def history(self, oid, version=None, size=1, filter=None):
self._lock_acquire()
try:
r=[]
file=self._file
seek=file.seek
read=file.read
try:
pos=self._index[oid]
except KeyError:
raise POSKeyError(oid)
except TypeError:
raise TypeError, 'invalid oid %r' % (oid,)
wantver=version
while 1:
if len(r) >= size: return r
seek(pos)
h=read(DATA_HDR_LEN)
doid,serial,prev,tloc,vlen,plen = unpack(DATA_HDR, h)
prev=u64(prev)
if vlen:
read(16)
version=read(vlen)
if wantver is not None and version != wantver:
if prev:
pos=prev
continue
else:
return r
else:
version=''
wantver=None
seek(u64(tloc))
h=read(TRANS_HDR_LEN)
tid, stl, status, ul, dl, el = unpack(TRANS_HDR,h)
user_name=read(ul)
description=read(dl)
if el: d=loads(read(el))
else: d={}
d['time']=TimeStamp(serial).timeTime()
d['user_name']=user_name
d['description']=description
d['serial']=serial
d['version']=version
d['size']=u64(plen)
if filter is None or filter(d):
r.append(d)
if prev: pos=prev
else: return r
finally: self._lock_release()
def _redundant_pack(self, file, pos):
assert pos > 8, pos
file.seek(pos - 8)
p = u64(file.read(8))
file.seek(pos - p + 8)
return file.read(1) not in ' u'
def pack(self, t, referencesf):
"""Copy data from the current database file to a packed file
Non-current records from transactions with time-stamp strings less
than packtss are ommitted. As are all undone records.
Also, data back pointers that point before packtss are resolved and
the associated data are copied, since the old records are not copied.
"""
if self._is_read_only:
raise POSException.ReadOnlyError()
stop=`TimeStamp(*time.gmtime(t)[:5]+(t%60,))`
if stop==z64: raise FileStorageError, 'Invalid pack time'
# If the storage is empty, there's nothing to do.
if not self._index:
return
# Record pack time so we don't undo while packing
self._lock_acquire()
try:
if self._packt != z64:
# Already packing.
raise FileStorageError, 'Already packing'
self._packt = None
finally:
self._lock_release()
p = FileStoragePacker(self._file_name, stop,
self._lock_acquire, self._lock_release,
self._commit_lock_acquire,
self._commit_lock_release)
try:
opos = p.pack()
if opos is None:
return
oldpath = self._file_name + ".old"
self._lock_acquire()
try:
self._file.close()
try:
if os.path.exists(oldpath):
os.remove(oldpath)
os.rename(self._file_name, oldpath)
except Exception, msg:
self._file = open(self._file_name, 'r+b')
raise
# OK, we're beyond the point of no return
os.rename(self._file_name + '.pack', self._file_name)
self._file = open(self._file_name, 'r+b')
self._initIndex(p.index, p.vindex, p.tindex, p.tvindex,
p.oid2serial, p.toid2serial,
p.toid2serial_delete)
self._pos = opos
self._save_index()
finally:
self._lock_release()
finally:
if p.locked:
self._commit_lock_release()
self._lock_acquire()
self._packt = z64
self._lock_release()
def iterator(self, start=None, stop=None):
return FileIterator(self._file_name, start, stop)
def lastTransaction(self):
"""Return transaction id for last committed transaction"""
return self._ltid
def lastSerial(self, oid):
"""Return last serialno committed for object oid.
If there is no serialno for this oid -- which can only occur
if it is a new object -- return None.
"""
try:
return self.getSerial(oid)
except KeyError:
return None
def cleanup(self):
"""Remove all files created by this storage."""
cleanup(self._file_name)
def shift_transactions_forward(index, vindex, tindex, file, pos, opos):
"""Copy transactions forward in the data file
This might be done as part of a recovery effort
"""
# Cache a bunch of methods
seek=file.seek
read=file.read
write=file.write
index_get=index.get
vindex_get=vindex.get
# Initialize,
pv=z64
p1=opos
p2=pos
offset=p2-p1
# Copy the data in two stages. In the packing stage,
# we skip records that are non-current or that are for
# unreferenced objects. We also skip undone transactions.
#
# After the packing stage, we copy everything but undone
# transactions, however, we have to update various back pointers.
# We have to have the storage lock in the second phase to keep
# data from being changed while we're copying.
pnv=None
while 1:
# Read the transaction record
seek(pos)
h=read(TRANS_HDR_LEN)
if len(h) < TRANS_HDR_LEN: break
tid, stl, status, ul, dl, el = unpack(TRANS_HDR,h)
if status=='c': break # Oops. we found a checkpoint flag.
tl=u64(stl)
tpos=pos
tend=tpos+tl
otpos=opos # start pos of output trans
thl=ul+dl+el
h2=read(thl)
if len(h2) != thl:
raise PackError(opos)
# write out the transaction record
seek(opos)
write(h)
write(h2)
thl=TRANS_HDR_LEN+thl
pos=tpos+thl
opos=otpos+thl
while pos < tend:
# Read the data records for this transaction
seek(pos)
h=read(DATA_HDR_LEN)
oid,serial,sprev,stloc,vlen,splen = unpack(DATA_HDR, h)
plen=u64(splen)
dlen=DATA_HDR_LEN+(plen or 8)
if vlen:
dlen=dlen+(16+vlen)
pnv=u64(read(8))
# skip position of previous version record
seek(8,1)
version=read(vlen)
pv=p64(vindex_get(version, 0))
if status != 'u': vindex[version]=opos
tindex[oid]=opos
if plen: p=read(plen)
else:
p=read(8)
p=u64(p)
if p >= p2: p=p-offset
elif p >= p1:
# Ick, we're in trouble. Let's bail
# to the index and hope for the best
p=index_get(oid, 0)
p=p64(p)
# WRITE
seek(opos)
sprev=p64(index_get(oid, 0))
write(pack(DATA_HDR,
oid,serial,sprev,p64(otpos),vlen,splen))
if vlen:
if not pnv: write(z64)
else:
if pnv >= p2: pnv=pnv-offset
elif pnv >= p1:
pnv=index_get(oid, 0)
write(p64(pnv))
write(pv)
write(version)
write(p)
opos=opos+dlen
pos=pos+dlen
# skip the (intentionally redundant) transaction length
pos=pos+8
if status != 'u':
index.update(tindex) # Record the position
tindex.clear()
write(stl)
opos=opos+8
return opos
def search_back(file, pos):
seek=file.seek
read=file.read
seek(0,2)
s=p=file.tell()
while p > pos:
seek(p-8)
l=u64(read(8))
if l <= 0: break
p=p-l-8
return p, s
def recover(file_name):
file=open(file_name, 'r+b')
index={}
vindex={}
tindex={}
pos, oid, tid = read_index(
file, file_name, index, vindex, tindex, recover=1)
if oid is not None:
print "Nothing to recover"
return
opos=pos
pos, sz = search_back(file, pos)
if pos < sz:
npos = shift_transactions_forward(
index, vindex, tindex, file, pos, opos,
)
file.truncate(npos)
print "Recovered file, lost %s, ended up with %s bytes" % (
pos-opos, npos)
def read_index(file, name, index, vindex, tindex, stop='\377'*8,
ltid=z64, start=4L, maxoid=z64, recover=0, read_only=0):
"""Scan the entire file storage and recreate the index.
Returns file position, max oid, and last transaction id. It also
stores index information in the three dictionary arguments.
Arguments:
file -- a file object (the Data.fs)
name -- the name of the file (presumably file.name)
index -- dictionary, oid -> data record
vindex -- dictionary, oid -> data record for version data
tindex -- dictionary, oid -> data record
XXX tindex is cleared before return, so it will be empty
There are several default arguments that affect the scan or the
return values. XXX should document them.
The file position returned is the position just after the last
valid transaction record. The oid returned is the maximum object
id in the data. The transaction id is the tid of the last
transaction.
"""
read = file.read
seek = file.seek
seek(0, 2)
file_size=file.tell()
if file_size:
if file_size < start: raise FileStorageFormatError, file.name
seek(0)
if read(4) != packed_version: raise FileStorageFormatError, name
else:
if not read_only: file.write(packed_version)
return 4L, maxoid, ltid
index_get=index.get
pos=start
seek(start)
tid='\0'*7+'\1'
while 1:
# Read the transaction record
h=read(TRANS_HDR_LEN)
if not h: break
if len(h) != TRANS_HDR_LEN:
if not read_only:
warn('%s truncated at %s', name, pos)
seek(pos)
file.truncate()
break
tid, stl, status, ul, dl, el = unpack(TRANS_HDR,h)
if el < 0: el=t32-el
if tid <= ltid:
warn("%s time-stamp reduction at %s", name, pos)
ltid = tid
tl=u64(stl)
if pos+(tl+8) > file_size or status=='c':
# Hm, the data were truncated or the checkpoint flag wasn't
# cleared. They may also be corrupted,
# in which case, we don't want to totally lose the data.
if not read_only:
warn("%s truncated, possibly due to damaged records at %s",
name, pos)
_truncate(file, name, pos)
break
if status not in ' up':
warn('%s has invalid status, %s, at %s', name, status, pos)
if tl < (TRANS_HDR_LEN+ul+dl+el):
# We're in trouble. Find out if this is bad data in the
# middle of the file, or just a turd that Win 9x dropped
# at the end when the system crashed.
# Skip to the end and read what should be the transaction length
# of the last transaction.
seek(-8, 2)
rtl=u64(read(8))
# Now check to see if the redundant transaction length is
# reasonable:
if file_size - rtl < pos or rtl < TRANS_HDR_LEN:
nearPanic('%s has invalid transaction header at %s', name, pos)
if not read_only:
warn("It appears that there is invalid data at the end of "
"the file, possibly due to a system crash. %s "
"truncated to recover from bad data at end."
% name)
_truncate(file, name, pos)
break
else:
if recover: return pos, None, None
panic('%s has invalid transaction header at %s', name, pos)
if tid >= stop: break
tpos=pos
tend=tpos+tl
if status=='u':
# Undone transaction, skip it
seek(tend)
h=read(8)
if h != stl:
if recover: return tpos, None, None
panic('%s has inconsistent transaction length at %s',
name, pos)
pos=tend+8
continue
pos=tpos+(TRANS_HDR_LEN+ul+dl+el)
while pos < tend:
# Read the data records for this transaction
seek(pos)
h=read(DATA_HDR_LEN)
oid,serial,sprev,stloc,vlen,splen = unpack(DATA_HDR, h)
prev=u64(sprev)
tloc=u64(stloc)
plen=u64(splen)
dlen=DATA_HDR_LEN+(plen or 8)
tindex[oid]=pos
if vlen:
dlen=dlen+(16+vlen)
read(16)
pv=u64(read(8))
version=read(vlen)
# Jim says: "It's just not worth the bother."
#if vndexpos(version, 0) != pv:
# panic("%s incorrect previous version pointer at %s",
# name, pos)
vindex[version]=pos
if pos+dlen > tend or tloc != tpos:
if recover: return tpos, None, None
panic("%s data record exceeds transaction record at %s",
name, pos)
if index_get(oid, 0) != prev:
if prev:
if recover: return tpos, None, None
error("%s incorrect previous pointer at %s", name, pos)
else:
warn("%s incorrect previous pointer at %s", name, pos)
pos=pos+dlen
if pos != tend:
if recover: return tpos, None, None
panic("%s data records don't add up at %s",name,tpos)
# Read the (intentionally redundant) transaction length
seek(pos)
h=read(8)
if h != stl:
if recover: return tpos, None, None
panic("%s redundant transaction length check failed at %s",
name, pos)
pos=pos+8
if tindex: # avoid the pathological empty transaction case
_maxoid = max(tindex.keys()) # in 2.2, just max(tindex)
maxoid = max(_maxoid, maxoid)
index.update(tindex)
tindex.clear()
return pos, maxoid, ltid
def _loadBack_impl(file, oid, back):
# shared implementation used by various _loadBack methods
while 1:
old = u64(back)
if not old:
# If the backpointer is 0, the object does not currently exist.
raise POSKeyError(oid)
file.seek(old)
h = file.read(DATA_HDR_LEN)
doid, serial, prev, tloc, vlen, plen = unpack(DATA_HDR, h)
if vlen:
file.read(16)
version = file.read(vlen)
if plen != z64:
return file.read(u64(plen)), serial, old, tloc
back = file.read(8) # We got a back pointer!
def _loadBack(file, oid, back):
data, serial, old, tloc = _loadBack_impl(file, oid, back)
return data, serial
def _loadBackPOS(file, oid, back):
"""Return position of data record for backpointer."""
data, serial, old, tloc = _loadBack_impl(file, oid, back)
return old
def _loadBackTxn(file, oid, back):
"""Return data, serial, and txn id for backpointer."""
data, serial, old, stloc = _loadBack_impl(file, oid, back)
tloc = u64(stloc)
file.seek(tloc)
h = file.read(TRANS_HDR_LEN)
tid = h[:8]
return data, serial, tid
def getTxnFromData(file, oid, back):
"""Return transaction id for data at back."""
file.seek(u64(back))
h = file.read(DATA_HDR_LEN)
doid, serial, prev, stloc, vlen, plen = unpack(DATA_HDR, h)
assert oid == doid
tloc = u64(stloc)
file.seek(tloc)
# seek to transaction header, where tid is first 8 bytes
return file.read(8)
def _truncate(file, name, pos):
seek=file.seek
seek(0,2)
file_size=file.tell()
try:
i=0
while 1:
oname='%s.tr%s' % (name, i)
if os.path.exists(oname):
i=i+1
else:
warn("Writing truncated data from %s to %s", name, oname)
o=open(oname,'wb')
seek(pos)
cp(file, o, file_size-pos)
o.close()
break
except:
error("couldn\'t write truncated data for %s", name)
raise POSException.StorageSystemError, (
"Couldn't save truncated data")
seek(pos)
file.truncate()
class Iterator:
"""A General simple iterator that uses the Python for-loop index protocol
"""
__index=-1
__current=None
def __getitem__(self, i):
__index=self.__index
while i > __index:
__index=__index+1
self.__current=self.next(__index)
self.__index=__index
return self.__current
class FileIterator(Iterator):
"""Iterate over the transactions in a FileStorage file.
"""
_ltid = z64
_file = None
def __init__(self, file, start=None, stop=None):
if isinstance(file, StringType):
file = open(file, 'rb')
self._file = file
if file.read(4) != packed_version:
raise FileStorageFormatError, file.name
file.seek(0,2)
self._file_size = file.tell()
self._pos = 4L
assert start is None or isinstance(start, StringType)
assert stop is None or isinstance(stop, StringType)
if start:
self._skip_to_start(start)
self._stop = stop
def __len__(self):
# Define a bogus __len__() to make the iterator work
# with code like builtin list() and tuple() in Python 2.1.
# There's a lot of C code that expects a sequence to have
# an __len__() but can cope with any sort of mistake in its
# implementation. So just return 0.
return 0
# This allows us to pass an iterator as the `other' argument to
# copyTransactionsFrom() in BaseStorage. The advantage here is that we
# can create the iterator manually, e.g. setting start and stop, and then
# just let copyTransactionsFrom() do its thing.
def iterator(self):
return self
def close(self):
file = self._file
if file is not None:
self._file = None
file.close()
def _skip_to_start(self, start):
# Scan through the transaction records doing almost no sanity
# checks.
while 1:
self._file.seek(self._pos)
h = self._file.read(16)
if len(h) < 16:
return
tid, stl = unpack(">8s8s", h)
if tid >= start:
return
tl = u64(stl)
try:
self._pos += tl + 8
except OverflowError:
self._pos = long(self._pos) + tl + 8
if __debug__:
# Sanity check
self._file.seek(self._pos - 8, 0)
rtl = self._file.read(8)
if rtl != stl:
pos = self._file.tell() - 8
panic("%s has inconsistent transaction length at %s "
"(%s != %s)",
self._file.name, pos, u64(rtl), u64(stl))
def next(self, index=0):
if self._file is None:
# A closed iterator. XXX: Is IOError the best we can do? For
# now, mimic a read on a closed file.
raise IOError, 'iterator is closed'
file=self._file
seek=file.seek
read=file.read
pos=self._pos
while 1:
# Read the transaction record
seek(pos)
h=read(TRANS_HDR_LEN)
if len(h) < TRANS_HDR_LEN: break
tid, stl, status, ul, dl, el = unpack(TRANS_HDR,h)
if el < 0: el=t32-el
if tid <= self._ltid:
warn("%s time-stamp reduction at %s", self._file.name, pos)
self._ltid=tid
if self._stop is not None and tid > self._stop:
raise IndexError, index
if status == 'c':
# Assume we've hit the last, in-progress transaction
raise IndexError, index
tl=u64(stl)
if pos+(tl+8) > self._file_size:
# Hm, the data were truncated or the checkpoint flag wasn't
# cleared. They may also be corrupted,
# in which case, we don't want to totally lose the data.
warn("%s truncated, possibly due to damaged records at %s",
self._file.name, pos)
break
if status not in ' up':
warn('%s has invalid status, %s, at %s', self._file.name,
status, pos)
if tl < (TRANS_HDR_LEN+ul+dl+el):
# We're in trouble. Find out if this is bad data in
# the middle of the file, or just a turd that Win 9x
# dropped at the end when the system crashed. Skip to
# the end and read what should be the transaction
# length of the last transaction.
seek(-8, 2)
rtl=u64(read(8))
# Now check to see if the redundant transaction length is
# reasonable:
if self._file_size - rtl < pos or rtl < TRANS_HDR_LEN:
nearPanic('%s has invalid transaction header at %s',
self._file.name, pos)
warn("It appears that there is invalid data at the end of "
"the file, possibly due to a system crash. %s "
"truncated to recover from bad data at end."
% self._file.name)
break
else:
warn('%s has invalid transaction header at %s',
self._file.name, pos)
break
tpos=pos
tend=tpos+tl
if status=='u':
# Undone transaction, skip it
seek(tend)
h=read(8)
if h != stl:
panic('%s has inconsistent transaction length at %s',
self._file.name, pos)
pos=tend+8
continue
pos=tpos+(TRANS_HDR_LEN+ul+dl+el)
user=read(ul)
description=read(dl)
if el:
try: e=loads(read(el))
except: e={}
else: e={}
result = RecordIterator(tid, status, user, description, e, pos,
tend, file, tpos)
pos = tend
# Read the (intentionally redundant) transaction length
seek(pos)
h = read(8)
if h != stl:
warn("%s redundant transaction length check failed at %s",
self._file.name, pos)
break
self._pos = pos + 8
return result
raise IndexError, index
class RecordIterator(Iterator, BaseStorage.TransactionRecord):
"""Iterate over the transactions in a FileStorage file."""
def __init__(self, tid, status, user, desc, ext, pos, tend, file, tpos):
self.tid = tid
self.status = status
self.user = user
self.description = desc
self._extension = ext
self._pos = pos
self._tend = tend
self._file = file
self._tpos = tpos
def next(self, index=0):
pos = self._pos
while pos < self._tend:
# Read the data records for this transaction
self._file.seek(pos)
h = self._file.read(DATA_HDR_LEN)
oid, serial, sprev, stloc, vlen, splen = unpack(DATA_HDR, h)
tloc = u64(stloc)
plen = u64(splen)
dlen = DATA_HDR_LEN + (plen or 8)
if vlen:
dlen += (16 + vlen)
tmp = self._file.read(16)
version = self._file.read(vlen)
else:
version = ''
datapos = pos + DATA_HDR_LEN
if vlen:
datapos += 16 + vlen
assert self._file.tell() == datapos, (self._file.tell(), datapos)
if pos + dlen > self._tend or tloc != self._tpos:
warn("%s data record exceeds transaction record at %s",
file.name, pos)
break
self._pos = pos + dlen
prev_txn = None
if plen:
data = self._file.read(plen)
else:
bp = self._file.read(8)
if bp == z64:
# If the backpointer is 0 (encoded as z64), then
# this transaction undoes the object creation. It
# either aborts the version that created the
# object or undid the transaction that created it.
# Return None instead of a pickle to indicate
# this.
data = None
else:
data, _s, tid = _loadBackTxn(self._file, oid, bp)
prev_txn = getTxnFromData(self._file, oid, bp)
r = Record(oid, serial, version, data, prev_txn)
return r
raise IndexError, index
class Record(BaseStorage.DataRecord):
"""An abstract database record."""
def __init__(self, *args):
self.oid, self.serial, self.version, self.data, self.data_txn = args
class UndoSearch:
def __init__(self, file, pos, packt, first, last, filter=None):
self.file = file
self.pos = pos
self.packt = packt
self.first = first
self.last = last
self.filter = filter
self.i = 0
self.results = []
self.stop = 0
def finished(self):
"""Return True if UndoSearch has found enough records."""
# BAW: Why 39 please? This makes no sense (see also below).
return self.i >= self.last or self.pos < 39 or self.stop
def search(self):
"""Search for another record."""
dict = self._readnext()
if dict is not None and (self.filter is None or self.filter(dict)):
if self.i >= self.first:
self.results.append(dict)
self.i += 1
def _readnext(self):
"""Read the next record from the storage."""
self.file.seek(self.pos - 8)
self.pos -= u64(self.file.read(8)) + 8
self.file.seek(self.pos)
h = self.file.read(TRANS_HDR_LEN)
tid, tl, status, ul, dl, el = struct.unpack(TRANS_HDR, h)
if tid < self.packt or status == 'p':
self.stop = 1
return None
if status != ' ':
return None
d = u = ''
if ul:
u = self.file.read(ul)
if dl:
d = self.file.read(dl)
e = {}
if el:
try:
e = loads(self.file.read(el))
except:
pass
d = {'id': base64.encodestring(tid).rstrip(),
'time': TimeStamp(tid).timeTime(),
'user_name': u,
'description': d}
d.update(e)
return d
def cleanup(filename):
"""Remove all FileStorage related files."""
for ext in '', '.old', '.tmp', '.lock', '.index', '.pack':
try:
os.remove(filename + ext)
except OSError, e:
if e.errno != errno.ENOENT:
raise
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